Custom Industrial Flywheels | Ductile & Gray Iron Castings | Kurt Foundry<\/title>\n<style>\n @import url('https:\/\/fonts.googleapis.com\/css2?family=Playfair+Display:wght@400;500;600;700&family=Open+Sans:wght@300;400;600&display=swap');\n\n :root {\n --primary-dark: #0a0e0d;\n --primary: #2b3a36;\n --primary-light: #445851;\n --accent: #d4af37;\n --bg-light: #f9f8f4;\n --bg-white: #ffffff;\n --bg-gray: #f0efe9;\n --text-main: #333333;\n --text-muted: #666666;\n --text-light: #e0e0e0;\n --border: #e2dfd5;\n --transition: all 0.4s cubic-bezier(0.25, 1, 0.5, 1);\n --text: #333333;\n }\n\n * { margin: 0; padding: 0; box-sizing: border-box; }\n\n .fw-page {\n font-family: 'Open Sans', sans-serif;\n background-color: var(--bg-light);\n color: var(--text-main);\n line-height: 1.7;\n overflow-x: hidden;\n width: 100%;\n font-size: 15px;\n }\n\n .fw-page h1, .fw-page h2, .fw-page h3, .fw-page h4 {\n font-family: 'Playfair Display', serif;\n font-weight: 600;\n color: var(--primary-dark);\n line-height: 1.3;\n }\n\n .fw-page p { margin-bottom: 1.5rem; }\n\n .fw-page a {\n color: var(--primary);\n font-weight: 600;\n text-decoration: underline;\n text-decoration-color: var(--accent);\n text-underline-offset: 4px;\n transition: var(--transition);\n }\n\n \/* VERBATIM REQUIRED RULES *\/\n .faq-question { cursor: pointer; color: var(--text); transition: all 0.3s ease; }\n .faq-question:hover { background-color: var(--bg-gray); color: var(--text); }\n .faq-question.active { color: var(--primary); }\n a:hover { color: var(--primary); }\n .product-img { width: 100%; aspect-ratio: 3 \/ 2; object-fit: cover; border-radius: 12px; }\n\n .fw-container { width: 100%; max-width: 1280px; margin: 0 auto; padding: 0 5%; }\n .fw-section { padding: 4rem 0; }\n\n \/* Animations *\/\n .reveal-up { opacity: 0; transform: translateY(40px); transition: all 0.8s ease-out; will-change: opacity, transform; }\n .reveal-scale { opacity: 0; transform: scale(0.95); transition: all 0.8s ease-out; will-change: opacity, transform; }\n .reveal-up.active, .reveal-scale.active { opacity: 1; transform: translate(0) scale(1); }\n .delay-1 { transition-delay: 0.15s; }\n .delay-2 { transition-delay: 0.3s; }\n\n \/* Buttons *\/\n .btn {\n display: inline-flex; align-items: center; justify-content: center;\n gap: 10px; padding: 1rem 2rem; font-size: 0.9rem; text-transform: uppercase;\n letter-spacing: 1.5px; font-weight: 600; cursor: pointer; transition: var(--transition);\n border-radius: 2px; position: relative; overflow: hidden; z-index: 1;\n border: 1px solid transparent; text-align: center; text-decoration: none;\n min-width: 44px; min-height: 44px;\n }\n .btn-accent { background-color: var(--accent); color: var(--primary-dark); border-color: var(--accent); }\n .btn-accent::before { content: ''; position: absolute; top: 0; left: 0; width: 0%; height: 100%; background-color: #c19b2e; transition: var(--transition); z-index: -1; }\n .btn-accent:hover::before { width: 100%; }\n .btn-accent:hover { color: var(--primary-dark); border-color: #c19b2e; transform: translateY(-2px); box-shadow: 0 8px 20px rgba(212,175,55,0.3); text-decoration: none; }\n .btn-dark { background-color: var(--primary); color: var(--bg-white); border-color: var(--primary); }\n .btn-dark::before { content: ''; position: absolute; top: 0; left: 0; width: 0%; height: 100%; background-color: var(--primary-dark); transition: var(--transition); z-index: -1; }\n .btn-dark:hover::before { width: 100%; }\n .btn-dark:hover { color: var(--bg-white); border-color: var(--primary-dark); transform: translateY(-2px); box-shadow: 0 8px 15px rgba(0,0,0,0.1); text-decoration: none; }\n .fw-page .btn-outline { background-color: transparent; color: var(--bg-white); border-color: var(--bg-white); }\n .fw-page .btn-outline:hover { background-color: var(--bg-white); color: var(--primary-dark); transform: translateY(-2px); text-decoration: none; }\n\n \/* Hero *\/\n .fw-hero {\n position: relative; padding: 8rem 0 6rem;\n background-color: var(--primary-dark); min-height: 85vh; display: flex; align-items: center;\n }\n .fw-hero-bg { position: absolute; top: 0; left: 0; width: 100%; height: 100%; object-fit: cover; z-index: 0; opacity: 0.6; }\n .fw-hero-overlay {\n position: absolute; top: 0; left: 0; width: 100%; height: 100%;\n background: linear-gradient(135deg, rgba(10,14,13,0.95) 0%, rgba(43,58,54,0.6) 100%); z-index: 1;\n }\n .fw-hero-content { position: relative; z-index: 2; }\n .fw-hero-subtitle {\n display: inline-block; font-size: 0.9rem; text-transform: uppercase;\n letter-spacing: 2px; color: var(--accent); margin-bottom: 1.5rem;\n font-weight: 600; border-left: 3px solid var(--accent); padding-left: 1rem;\n }\n .fw-hero h1 { font-size: 2.4rem; color: var(--bg-white); margin-bottom: 1.5rem; line-height: 1.15; text-wrap: balance; }\n .fw-hero p { color: var(--text-light); font-size: 1.1rem; margin-bottom: 2.5rem; max-width: 650px; }\n .fw-hero-badges { display: flex; flex-wrap: wrap; gap: 1rem; margin-bottom: 3rem; }\n .fw-hero-badge {\n padding: 0.5rem 1rem; background: rgba(255,255,255,0.05);\n border: 1px solid rgba(255,255,255,0.1); border-radius: 50px;\n color: var(--bg-white); font-size: 0.85rem; font-weight: 600;\n display: flex; align-items: center; gap: 0.5rem;\n }\n .fw-hero-badge::before { content: ''; display: block; width: 8px; height: 8px; background-color: var(--accent); border-radius: 50%; }\n .fw-hero-actions { display: flex; flex-direction: column; gap: 1rem; }\n\n \/* Intro *\/\n .fw-intro { background-color: var(--bg-white); }\n .fw-intro-grid { display: grid; grid-template-columns: 1fr; gap: 3rem; }\n .fw-intro-text h2 { font-size: 2rem; margin-bottom: 1.5rem; }\n .fw-intro-highlight { background-color: var(--bg-gray); padding: 3rem 2rem; border-right: 4px solid var(--accent); border-radius: 8px; }\n .fw-intro-highlight p:last-child { margin-bottom: 0; }\n\n \/* Image Placeholder *\/\n .fw-img-placeholder {\n width: 100%; border-radius: 12px; overflow: hidden;\n background: var(--bg-gray); position: relative;\n display: flex; flex-direction: column; align-items: center; justify-content: center;\n border: 2px dashed var(--border); gap: 0.3rem; padding: 1.5rem;\n }\n .fw-img-placeholder[data-ratio=\"3\/2\"] { aspect-ratio: 3 \/ 2; }\n .fw-img-placeholder[data-ratio=\"4\/3\"] { aspect-ratio: 4 \/ 3; }\n .fw-img-placeholder[data-ratio=\"16\/9\"] { aspect-ratio: 16 \/ 9; }\n .fw-img-placeholder[data-ratio=\"1\/1\"] { aspect-ratio: 1 \/ 1; }\n .fw-img-placeholder-icon { font-size: 1.8rem; opacity: 0.35; }\n .fw-img-placeholder-size {\n font-size: 1rem; font-weight: 700; color: var(--primary); letter-spacing: 0.5px;\n }\n .fw-img-placeholder-ratio {\n font-size: 0.75rem; font-weight: 600; text-transform: uppercase; letter-spacing: 1px;\n color: var(--bg-white); background: var(--primary-light);\n padding: 2px 10px; border-radius: 20px;\n }\n .fw-img-placeholder-label {\n font-size: 0.78rem; color: var(--text-muted); text-align: center;\n line-height: 1.5; margin-top: 0.3rem; max-width: 380px;\n }\n .fw-img-placeholder img {\n position: absolute; top: 0; left: 0; width: 100%; height: 100%;\n object-fit: cover; border-radius: 10px;\n }\n\n \/* Material Deep Dive \u2014 NEW section *\/\n .fw-materials { background-color: var(--bg-light); }\n .fw-materials-header { text-align: center; margin-bottom: 3rem; }\n .fw-materials-header h2 { font-size: 2.2rem; margin-bottom: 1rem; }\n .fw-materials-header p { max-width: 750px; margin: 0 auto; color: var(--text-muted); }\n .fw-materials-grid { display: grid; grid-template-columns: 1fr; gap: 2rem; }\n .fw-material-card {\n background: var(--bg-white); border-radius: 12px; border: 1px solid var(--border);\n padding: 2.5rem; box-shadow: 0 8px 24px rgba(0,0,0,0.04);\n border-top: 4px solid var(--accent);\n }\n .fw-material-card h3 { font-size: 1.4rem; margin-bottom: 1rem; color: var(--primary); }\n .fw-material-card p { color: var(--text-muted); margin-bottom: 0; }\n .fw-material-card p + p { margin-top: 1rem; }\n\n \/* Specs Table *\/\n .fw-specs { background-color: var(--bg-white); }\n .fw-specs-header { text-align: center; margin-bottom: 3rem; }\n .fw-specs-header h2 { font-size: 2.2rem; }\n .fw-table-card { background: var(--bg-white); border-radius: 12px; box-shadow: 0 20px 40px rgba(0,0,0,0.04); overflow: hidden; border: 1px solid var(--border); }\n .fw-table-wrapper { width: 100%; overflow-x: auto; }\n .fw-table { width: 100%; min-width: 800px; border-collapse: collapse; text-align: left; }\n .fw-table th, .fw-table td { padding: 1.2rem 1.5rem; border-bottom: 1px solid var(--border); }\n .fw-table th { background-color: var(--primary-light); color: var(--bg-white); font-family: 'Playfair Display', serif; font-size: 1.1rem; white-space: nowrap; }\n .fw-table tr:last-child td { border-bottom: none; }\n .fw-table tr:hover td { background-color: var(--bg-gray); }\n .fw-table td:first-child { font-weight: 600; color: var(--primary-dark); }\n\n \/* Features *\/\n .fw-features { background-color: var(--bg-light); }\n .fw-features-grid { display: grid; grid-template-columns: 1fr; gap: 3rem; align-items: center; }\n .fw-features-content h2 { font-size: 1.8rem; margin-bottom: 1.5rem; }\n .fw-features-image-wrap { position: relative; }\n .fw-features-image-wrap::after { content: ''; position: absolute; bottom: -20px; right: -20px; width: 100%; height: 100%; border: 2px solid var(--accent); border-radius: 12px; z-index: -1; }\n\n \/* Process Timeline *\/\n .fw-process { background-color: var(--primary-dark); color: var(--bg-white); padding: 6rem 0; }\n .fw-process-header { text-align: center; margin-bottom: 4rem; }\n .fw-process-header h2 { color: var(--bg-white); font-size: 2.2rem; }\n .fw-timeline {\n position: relative; max-width: 900px; margin: 0 auto;\n padding-left: 2rem; border-left: 2px solid rgba(212,175,55,0.3);\n }\n .fw-step { position: relative; margin-bottom: 3rem; padding-left: 2rem; }\n .fw-step:last-child { margin-bottom: 0; }\n .fw-step::before { content: ''; position: absolute; left: -2.45rem; top: 0; width: 16px; height: 16px; background-color: var(--accent); border-radius: 50%; border: 4px solid var(--primary-dark); box-shadow: 0 0 0 2px rgba(212,175,55,0.5); }\n .fw-step h3 { color: var(--accent); font-size: 1.4rem; margin-bottom: 1rem; }\n .fw-step p { color: var(--text-light); margin-bottom: 0; }\n\n \/* Quality *\/\n .fw-quality { background-color: var(--bg-light); }\n .fw-quality-header { text-align: center; max-width: 850px; margin: 0 auto 3rem; }\n .fw-quality-header h2 { font-size: 2.2rem; margin-bottom: 1.5rem; }\n .fw-quality-layout { display: grid; grid-template-columns: 1fr; gap: 3rem; align-items: start; }\n .fw-checklist { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: 1fr; gap: 2rem; }\n .fw-checklist li { position: relative; background: var(--bg-white); padding: 2rem 2rem 2rem 4.5rem; border-radius: 8px; border: 1px solid var(--border); box-shadow: 0 4px 15px rgba(0,0,0,0.02); height: 100%; display: flex; flex-direction: column; justify-content: center; }\n .fw-checklist li::before { content: '\u2713'; position: absolute; left: 1.5rem; top: 2.2rem; color: var(--bg-white); background-color: var(--primary); width: 26px; height: 26px; display: flex; align-items: center; justify-content: center; border-radius: 50%; font-size: 0.95rem; font-weight: bold; }\n .fw-checklist strong { color: var(--primary-dark); display: block; margin-bottom: 0.5rem; font-size: 1.1rem; }\n .fw-checklist span { color: var(--text-muted); font-size: 0.95rem; }\n \/* Intro image *\/\n .fw-intro-img { margin-top: 1.5rem; border-radius: 8px; overflow: hidden; }\n .fw-intro-img img { width: 100%; aspect-ratio: 3 \/ 2; object-fit: cover; display: block; border-radius: 8px; }\n\n \/* Process banner *\/\n .fw-process-banner { margin-bottom: 4rem; border-radius: 12px; overflow: hidden; }\n .fw-process-banner img { width: 100%; aspect-ratio: 16 \/ 9; object-fit: cover; display: block; }\n\n \/* Shipping image *\/\n .fw-shipping-img { margin-top: 2rem; border-radius: 12px; overflow: hidden; }\n .fw-shipping-img img { width: 100%; aspect-ratio: 3 \/ 2; object-fit: cover; display: block; }\n\n \/* Reverse Engineering \u2014 NEW section *\/\n .fw-reverse { background-color: var(--bg-white); }\n .fw-reverse-inner {\n display: grid; grid-template-columns: 1fr; gap: 3rem; align-items: center;\n }\n .fw-reverse-badge {\n display: inline-block; font-size: 0.85rem; text-transform: uppercase;\n letter-spacing: 1.5px; color: var(--accent); font-weight: 600;\n border-left: 3px solid var(--accent); padding-left: 0.8rem; margin-bottom: 1.2rem;\n }\n .fw-reverse-content h2 { font-size: 2rem; margin-bottom: 1.5rem; }\n .fw-reverse-content p { color: var(--text-muted); }\n .fw-reverse-highlight {\n background: var(--bg-gray); border-radius: 12px; padding: 2.5rem;\n border-left: 4px solid var(--accent);\n }\n .fw-reverse-highlight h3 { font-size: 1.3rem; margin-bottom: 1rem; color: var(--primary); }\n .fw-reverse-highlight p { color: var(--text-muted); margin-bottom: 0; }\n .fw-reverse-highlight p + p { margin-top: 1rem; }\n\n \/* North America DDP Shipping \u2014 NEW section *\/\n .fw-shipping { background-color: var(--primary); color: var(--bg-white); }\n .fw-shipping-inner { display: grid; grid-template-columns: 1fr; gap: 3rem; align-items: center; }\n .fw-shipping-content h2 { color: var(--bg-white); font-size: 2rem; margin-bottom: 1.5rem; }\n .fw-shipping-content p { color: var(--text-light); }\n .fw-shipping-content p:last-child { margin-bottom: 0; }\n .fw-shipping-cards { display: grid; grid-template-columns: 1fr; gap: 1.5rem; }\n .fw-shipping-card {\n background: rgba(255,255,255,0.06); border: 1px solid rgba(255,255,255,0.12);\n border-radius: 10px; padding: 1.8rem; display: flex; flex-direction: column; gap: 1rem; align-items: flex-start;\n height: 100%;\n }\n .fw-shipping-icon {\n flex-shrink: 0; width: 44px; height: 44px; border-radius: 50%;\n background-color: var(--accent); display: flex; align-items: center;\n justify-content: center; font-size: 1.2rem;\n }\n .fw-shipping-card h4 { color: var(--accent); font-family: 'Open Sans', sans-serif; font-weight: 600; margin-bottom: 0.4rem; font-size: 1rem; }\n .fw-shipping-card p { color: var(--text-light); font-size: 0.92rem; margin-bottom: 0; }\n\n \/* FAQ *\/\n .fw-faq { background-color: var(--bg-white); }\n .fw-faq-header { text-align: center; margin-bottom: 3rem; }\n .fw-faq-header h2 { font-size: 2.2rem; }\n .fw-faq-list { max-width: 850px; margin: 0 auto; display: flex; flex-direction: column; gap: 1rem; }\n .fw-faq-item { background: var(--bg-light); border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }\n .fw-faq-btn { width: 100%; text-align: left; background: transparent; border: none; padding: 1.5rem; font-family: 'Open Sans', sans-serif; font-size: 1.1rem; font-weight: 600; display: flex; justify-content: space-between; align-items: center; min-height: 44px; }\n .fw-faq-icon { font-size: 1.5rem; color: var(--accent); transition: transform 0.3s ease; display: flex; align-items: center; justify-content: center; width: 30px; height: 30px; border-radius: 50%; background: var(--bg-white); }\n .fw-faq-content { max-height: 0; overflow: hidden; transition: max-height 0.4s ease; background: var(--bg-white); }\n .fw-faq-content p { padding: 0 1.5rem 1.5rem; margin: 0; color: var(--text-muted); }\n .fw-faq-item.active .fw-faq-content { max-height: 500px; }\n .fw-faq-item.active .fw-faq-icon { transform: rotate(45deg); background: var(--primary); color: var(--bg-white); }\n\n \/* CTA *\/\n .fw-cta { background: linear-gradient(to right, var(--primary-dark), var(--primary)); padding: 6rem 0; text-align: center; color: var(--bg-white); }\n .fw-cta-content { max-width: 800px; margin: 0 auto; }\n .fw-cta h2 { color: var(--bg-white); font-size: 2.4rem; margin-bottom: 1.5rem; }\n .fw-cta p { color: var(--text-light); font-size: 1.1rem; margin-bottom: 2.5rem; }\n .fw-cta-note { font-size: 0.9rem; color: rgba(255,255,255,0.5); margin-top: 1.5rem; margin-bottom: 0; }\n\n \/* Responsive *\/\n @media (min-width: 480px) {\n .fw-page { font-size: 16px; }\n .fw-hero h1 { font-size: 3rem; }\n .fw-hero-actions { flex-direction: row; }\n }\n @media (min-width: 768px) {\n .fw-section { padding: 6rem 0; }\n .fw-hero h1 { font-size: 3.8rem; }\n .fw-intro-grid { grid-template-columns: 1fr 1fr; align-items: center; }\n .fw-features-grid { grid-template-columns: 1fr 1fr; }\n .fw-materials-grid { grid-template-columns: 1fr 1fr; }\n .fw-quality-layout { grid-template-columns: 1fr 1fr; align-items: start; }\n .fw-reverse-inner { grid-template-columns: 1fr 1fr; }\n .fw-shipping-inner { grid-template-columns: 1fr 1fr; }\n .fw-shipping-cards { grid-template-columns: repeat(4, 1fr); }\n .fw-timeline { padding-left: 0; border-left: none; }\n .fw-timeline::before { content: ''; position: absolute; left: 50%; top: 0; bottom: 0; width: 2px; background: rgba(212,175,55,0.3); transform: translateX(-50%); }\n .fw-step { width: 50%; padding-left: 0; padding-right: 3rem; text-align: right; margin-bottom: 4rem; }\n .fw-step:nth-child(even) { margin-left: auto; padding-right: 0; padding-left: 3rem; text-align: left; }\n .fw-step::before { left: auto; right: -10px; }\n .fw-step:nth-child(even)::before { left: -10px; right: auto; }\n }\n @media (min-width: 1024px) {\n .fw-hero h1 { font-size: 4.2rem; }\n }\n\n \/* \u2500\u2500 Mobile optimizations \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n @media (max-width: 767px) {\n\n \/* Section padding *\/\n .fw-section { padding: 3rem 0; }\n .fw-container { padding: 0 4%; }\n\n \/* Hero *\/\n .fw-hero { padding: 5rem 0 3.5rem; min-height: 70vh; }\n .fw-hero h1 { font-size: 2rem; }\n .fw-hero p { font-size: 1rem; }\n .fw-hero-badges { gap: 0.6rem; }\n .fw-hero-badge { font-size: 0.78rem; padding: 0.4rem 0.8rem; }\n .fw-hero-actions { flex-direction: column; }\n .fw-hero-actions .btn { width: 100%; justify-content: center; }\n\n \/* Intro highlight box *\/\n .fw-intro-highlight { padding: 1.5rem 1.2rem; }\n\n \/* All images \u2014 full width, comfortable aspect ratio *\/\n .product-img,\n .fw-intro-img img,\n .fw-features-image-wrap img,\n .fw-img-placeholder,\n .fw-quality-layout img,\n .fw-shipping-inner img {\n width: 100% !important;\n aspect-ratio: 4 \/ 3 !important;\n min-height: unset !important;\n border-radius: 10px;\n }\n\n \/* Remove decorative border offset on mobile \u2014 overflows viewport *\/\n .fw-features-image-wrap::after { display: none; }\n \/* Add top margin so image isn't flush after text *\/\n .fw-features-image-wrap { margin-top: 2rem; }\n\n \/* Material cards \u2014 full width, image takes natural height *\/\n .fw-material-card { padding: 1.5rem; }\n .fw-material-card .fw-img-placeholder { aspect-ratio: 4 \/ 3; }\n\n \/* Specs table \u2014 reduce padding, smaller font *\/\n .fw-table { min-width: 600px; font-size: 0.82rem; }\n .fw-table th,\n .fw-table td { padding: 0.7rem 0.8rem; }\n .fw-table th { font-size: 0.85rem; white-space: normal; }\n\n \/* Process *\/\n .fw-process { padding: 3rem 0; }\n .fw-process-header h2 { font-size: 1.6rem; }\n .fw-process-banner { margin-bottom: 2.5rem !important; }\n .fw-step { padding-left: 1.5rem; }\n\n \/* Quality checklist *\/\n .fw-checklist li { padding: 1.2rem 1.2rem 1.2rem 3.5rem; }\n .fw-checklist li::before { top: 1.4rem; left: 1rem; }\n .fw-quality-layout img { aspect-ratio: 4 \/ 3 !important; height: auto !important; }\n\n \/* Shipping section *\/\n .fw-shipping-inner { gap: 1.5rem; }\n .fw-shipping-cards { grid-template-columns: 1fr 1fr; gap: 1rem; }\n .fw-shipping-card { padding: 1.2rem; }\n .fw-shipping-inner > div[style*=\"aspect-ratio\"] {\n aspect-ratio: 4 \/ 3 !important;\n min-height: unset !important;\n }\n\n \/* FAQ *\/\n .fw-faq-btn { font-size: 0.95rem; padding: 1.2rem; }\n\n \/* CTA *\/\n .fw-cta { padding: 3.5rem 0; }\n .fw-cta h2 { font-size: 1.8rem; }\n .fw-cta p { font-size: 1rem; }\n .fw-cta .btn { width: 100%; justify-content: center; }\n\n \/* Placeholder size\/ratio labels *\/\n .fw-img-placeholder-size { font-size: 0.88rem; }\n .fw-img-placeholder-ratio { font-size: 0.7rem; }\n .fw-img-placeholder-label { font-size: 0.72rem; }\n }\n\n @media (max-width: 480px) {\n .fw-shipping-cards { grid-template-columns: 1fr; }\n .fw-table { min-width: 480px; font-size: 0.78rem; }\n .fw-table th,\n .fw-table td { padding: 0.6rem 0.6rem; }\n }\n<\/style>\n<\/head>\n<body>\n\n<div class=\"fw-page\">\n\n \n <section class=\"fw-hero\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/03\/custom-flywheels-1-1.webp\" alt=\"Wide-angle photograph of a massive, freshly CNC-machined custom gray iron flywheel resting on a heavy-duty wooden shipping pallet inside a bright, modern foundry.\" class=\"fw-hero-bg\" title=\"\">\n <div class=\"fw-hero-overlay\"><\/div>\n <div class=\"fw-container fw-hero-content reveal-up\">\n <span class=\"fw-hero-subtitle\">Heavy Industrial Sand Casting \u2014 Direct Foundry<\/span>\n <h1>Custom Industrial Flywheels<br>in Cast Iron & Ductile Iron<\/h1>\n <p>Kurt Foundry engineers and manufactures heavy-duty custom cast iron flywheels \u2014 from 50 lbs to 5,000 lbs per piece \u2014 for industrial machinery, diesel power plants, stamping presses, and large compressors. We deliver fully CNC-machined, porosity-verified components directly to your facility worldwide.<\/p>\n <div class=\"fw-hero-badges\">\n <span class=\"fw-hero-badge\">ISO 9001 Certified<\/span>\n <span class=\"fw-hero-badge\">ASTM A48 & A536 Compliant<\/span>\n <span class=\"fw-hero-badge\">Worldwide Export Shipping<\/span>\n <span class=\"fw-hero-badge\">Up to 5,000 lbs Per Piece<\/span>\n <\/div>\n <div class=\"fw-hero-actions\">\n <a href=\"\/contact\/\" class=\"btn btn-accent\">Request a Direct-Factory Quote<\/a>\n <a href=\"#specs\" class=\"btn btn-outline\">View Material Specs<\/a>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-intro\">\n <div class=\"fw-container\">\n <div class=\"fw-intro-grid\">\n <div class=\"fw-intro-text reveal-up\">\n <h2>When Rotational Mass Cannot Fail<\/h2>\n <p>A flywheel failure is not a maintenance event \u2014 it is a production catastrophe. Internal casting defects invisible to the naked eye can trigger a full burst at operating speed, taking out the machine and the line with it.<\/p>\n <p>Kurt Foundry pours custom cast iron flywheels from 50 lbs to 5,000 lbs, with every casting verified by 3D solidification simulation, ultrasonic testing, and CMM inspection before it leaves our facility.<\/p>\n <p>We handle everything in-house \u2014 casting, CNC machining, and quality documentation \u2014 then ship directly to your facility anywhere in the world. No brokers, no middlemen, no surprises on landed cost.<\/p>\n <\/div>\n <div class=\"fw-intro-highlight reveal-scale delay-1\">\n <p>Whether your application needs the vibration-damping of <a href=\"\/capabilities\/custom-gray-iron-castings\/\">custom gray iron castings<\/a> or the burst resistance of <a href=\"\/capabilities\/custom-ductile-iron-castings\/\">custom ductile iron castings<\/a>, our engineering team works directly from your 2D drawings and 3D CAD files.<\/p>\n <div class=\"fw-intro-img\" style=\"margin-top:1.5rem;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/kurt-foundry-is-doing-cnc-for-custom-flywheels.webp\" alt=\"Kurt Foundry CNC machining a custom industrial flywheel \u2014 single-source manufacturing from casting to finished component.\" loading=\"lazy\" width=\"900\" height=\"600\" style=\"width:100%; border-radius:8px; display:block; object-fit:cover;\" title=\"\">\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-materials\">\n <div class=\"fw-container\">\n <div class=\"fw-materials-header reveal-up\">\n <h2>Choosing the Right Iron Grade for Your Custom Flywheel<\/h2>\n <p>Material selection is the most critical engineering decision in any custom flywheel project. The wrong grade can mean a part that cracks under cyclic stress, warps during machining, or bursts at operating speed. Below is how our engineering team evaluates material fit for every heavy-duty application.<\/p>\n <\/div>\n <div class=\"fw-materials-grid\">\n <div class=\"fw-material-card reveal-up\">\n <div style=\"margin-bottom:1.5rem; border-radius:8px; overflow:hidden;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Gray-Iron-Flywheels.webp\" alt=\"Gray iron custom flywheel casting with turned outer diameter on factory floor.\" loading=\"lazy\" width=\"900\" height=\"600\" style=\"width:100%; aspect-ratio:3\/2; object-fit:cover; display:block;\" title=\"\">\n <\/div>\n <h3>Gray Iron Flywheels (ASTM A48)<\/h3>\n <p>Gray iron is the most widely specified material for heavy industrial flywheels. Its flake graphite microstructure absorbs and dissipates torsional shock loads \u2014 protecting drivetrain bearings and gearboxes from vibrational damage.<\/p>\n <p>We cast gray iron flywheels to ASTM A48 Class 30 and Class 40, covering standard industrial presses, jaw crushers, and large compressor drives.<\/p>\n <p>Gray iron machines exceptionally well, allowing our CNC team to hold tight bore concentricity on pieces that other materials would resist \u2014 at a lower cost per kilogram than ductile iron.<\/p>\n <\/div>\n <div class=\"fw-material-card reveal-up delay-1\">\n <div style=\"margin-bottom:1.5rem; border-radius:8px; overflow:hidden;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Ductile-Iron-Flywheels.webp\" alt=\"Ductile iron custom flywheel showing precision-machined hub bore and keyway.\" loading=\"lazy\" width=\"900\" height=\"600\" style=\"width:100%; aspect-ratio:3\/2; object-fit:cover; display:block;\" title=\"\">\n <\/div>\n <h3>Ductile Iron Flywheels (ASTM A536)<\/h3>\n <p>When a flywheel operates at high RPM or faces sustained impact loading, ductile iron is the correct choice. Its spheroidal graphite nodules allow the material to deform plastically before fracturing \u2014 preventing catastrophic burst failure.<\/p>\n <p>We cast ductile iron flywheels to ASTM A536 Grade 65-45-12 and 80-55-06, specified for high-RPM diesel generator sets, heavy marine propulsion systems, and severe-duty industrial equipment.<\/p>\n <p>Where burst containment is a hard engineering requirement \u2014 not a preference \u2014 ductile iron delivers the tensile strength and ductility that gray iron cannot.<\/p>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section id=\"specs\" class=\"fw-section fw-specs\">\n <div class=\"fw-container\">\n <div class=\"fw-specs-header reveal-up\">\n <h2>Custom Flywheel Material Grades & Mechanical Properties<\/h2>\n <\/div>\n <div class=\"fw-table-card reveal-up delay-1\">\n <div class=\"fw-table-wrapper\">\n <table class=\"fw-table\">\n <thead>\n <tr>\n <th>Standard \/ Grade<\/th>\n <th>Tensile Strength (MPa)<\/th>\n <th>Yield Strength (MPa)<\/th>\n <th>Elongation (%)<\/th>\n <th>Typical Flywheel Applications<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td>ASTM A48 Class 30 (Gray Iron)<\/td>\n <td>≥ 207<\/td>\n <td>N\/A (Brittle)<\/td>\n <td>N\/A<\/td>\n <td>Standard industrial press flywheels, machine tools, vibration-damping drives.<\/td>\n <\/tr>\n <tr>\n <td>ASTM A48 Class 40 (Gray Iron)<\/td>\n <td>≥ 276<\/td>\n <td>N\/A (Brittle)<\/td>\n <td>N\/A<\/td>\n <td>Heavy-duty jaw crushers, large compressor flywheels requiring higher tensile strength.<\/td>\n <\/tr>\n <tr>\n <td>ASTM A536 65-45-12 (Ductile Iron)<\/td>\n <td>≥ 448<\/td>\n <td>≥ 310<\/td>\n <td>≥ 12<\/td>\n <td>High-RPM diesel engine flywheels, generator drive flywheels, high-stress rotational assemblies.<\/td>\n <\/tr>\n <tr>\n <td>ASTM A536 80-55-06 (Ductile Iron)<\/td>\n <td>≥ 552<\/td>\n <td>≥ 379<\/td>\n <td>≥ 6<\/td>\n <td>Severe-duty industrial flywheels requiring maximum burst resistance and impact tolerance.<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n <\/div>\n <\/div>\n <div class=\"reveal-up\" style=\"margin-top:3rem;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Engineering-drawing-spec-sheet-\u2014-2D-cross-section-of-a-custom-flywheel-with-dimension-callouts-and-ASTM-grade-annotations.jpeg\" alt=\"2D engineering drawing and spec sheet of a custom flywheel with dimension callouts and ASTM grade annotations.\" loading=\"lazy\" width=\"1600\" height=\"900\" style=\"width:100%; border-radius:12px; display:block; object-fit:cover;\" title=\"\">\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-features\">\n <div class=\"fw-container\">\n <div class=\"fw-features-grid\">\n <div class=\"fw-features-content reveal-up\">\n <h2>Single-Source CNC Machining & Guaranteed Concentricity<\/h2>\n <p>Casting and machining are handled in the same facility. Our 5-axis CNC centers turn the OD, bore the center hole, and cut the keyway \u2014 all held to strict runout tolerances verified by CMM.<\/p>\n <p>Single-source control eliminates the tolerance stack-up that occurs when casting and machining are split between two suppliers.<\/p>\n <p>Every flywheel ships with a full CMM inspection report \u2014 statically balanced and ready for your drive assembly.<\/p>\n <\/div>\n <div class=\"fw-features-image-wrap reveal-scale delay-1\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/CNC-Machining-for-flywheels.webp\" alt=\"CNC machining process for custom industrial flywheels at Kurt Foundry.\" class=\"product-img\" loading=\"lazy\" width=\"900\" height=\"600\" title=\"\">\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-process\">\n <div class=\"fw-container\">\n <div class=\"fw-process-header reveal-up\">\n <h2>How We Manufacture Your Custom Industrial Flywheel<\/h2>\n <\/div>\n <div class=\"fw-process-banner reveal-up delay-1\" style=\"position:relative; width:100%; aspect-ratio:16\/9; border-radius:12px; overflow:hidden; margin-bottom:4rem;\">\n <iframe\n src=\"https:\/\/www.youtube.com\/embed\/ROXBmpn4alE\"\n title=\"Kurt Foundry \u2014 Custom Industrial Flywheel Manufacturing Process\"\n frameborder=\"0\"\n allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\"\n allowfullscreen\n style=\"position:absolute; top:0; left:0; width:100%; height:100%; border:0;\">\n <\/iframe>\n <\/div>\n <div class=\"fw-timeline\">\n <div class=\"fw-step reveal-up\">\n <h3>1. DFM Review & 3D Solidification Simulation<\/h3>\n <p>Before any tooling is cut, our engineers import your CAD file into Magmasoft 3D simulation software. We model the complete solidification behavior of the flywheel casting \u2014 paying particular attention to the thick central hub, where the last metal to solidify is most vulnerable to internal shrinkage porosity. We engineer optimized gating and riser placements to feed molten iron into the hub directly, ensuring the finished casting is fully dense and porosity-free. No tooling order is placed until the simulation confirms a sound casting.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up delay-1\">\n <h3>2. Furan Resin Sand Molding<\/h3>\n <p>Our automated lines use furan resin sand to create rigid, dimensionally stable molds. Understanding the <a href=\"\/blog\/types-sand-used-sand-casting\/\" style=\"color: var(--accent);\">types of sand used in sand casting<\/a> is essential when producing heavy flywheels \u2014 the mold must resist the enormous metallostatic pressure of several thousand pounds of molten iron without wall movement. Furan resin binders provide the strength to hold exact tolerances during pouring.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up\">\n <h3>3. Spectrometer-Verified Pouring<\/h3>\n <p>Immediately before each pour, we conduct spectrometric chemical analysis of the molten iron. For gray iron flywheels, we verify the Carbon Equivalent (CE) to confirm the correct graphite flake morphology for maximum vibration damping. For ductile iron flywheels, we verify the nodularity rate to guarantee the spheroidal graphite structure that delivers burst resistance. Chemistry is documented and included in the Material Test Report (MTR) for your records.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up delay-1\">\n <h3>4. Controlled Thermal Stress Relief<\/h3>\n <p>Heavy flywheels present a thermal engineering challenge during solidification: the thick hub and the thinner outer web cool at significantly different rates. This differential cooling generates internal residual stresses locked into the casting. If not eliminated, these stresses relieve themselves during CNC machining \u2014 causing the part to warp and go out of tolerance. We perform controlled thermal stress relief heat treatment on all heavy flywheel castings before any machining begins, ensuring the part is dimensionally stable throughout the entire cutting process.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up\">\n <h3>5. CNC Machining, UT\/MPI Inspection & CMM Verification<\/h3>\n <p>After shot-blasting, the stress-relieved casting transfers to our 5-axis CNC machining centers for turning, boring, and keyway cutting. Critical hub sections are then scanned by ultrasonic testing (UT) to confirm zero internal voids. High-stress transition zones undergo magnetic particle inspection (MPI) for surface crack detection. Finally, a Coordinate Measuring Machine (CMM) verifies all critical dimensions \u2014 bore diameter, OD concentricity, and runout tolerances \u2014 before the part is approved for packaging.<\/p>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n <section class=\"fw-section fw-quality\">\n <div class=\"fw-container\">\n <div class=\"fw-quality-header reveal-up\">\n <h2>Quality Control Built for Global OEM Standards<\/h2>\n <p>Industrial flywheels are safety-critical rotating components. A quality escape that reaches your assembly floor can trigger a full line shutdown, a costly recall, or \u2014 in the worst case \u2014 an uncontained burst. Our quality system is designed so that every defect is caught in our facility before shipment. Lead engineers at our OEM customers worldwide receive a complete quality documentation package with every order.<\/p>\n <\/div>\n <div class=\"fw-quality-layout\">\n <div class=\"reveal-scale\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Quality-Control-for-customized-flywheels.webp\" alt=\"Quality control inspection of custom cast iron flywheels at Kurt Foundry \u2014 CMM dimensional verification and NDE testing.\" loading=\"lazy\" width=\"800\" height=\"600\" style=\"width:100%; border-radius:12px; display:block; object-fit:cover;\" title=\"\">\n <\/div>\n <ul class=\"fw-checklist reveal-up delay-1\" style=\"grid-template-columns:1fr;\">\n <li>\n <strong>Ultrasonic Testing (UT) \u2014 Hub Integrity:<\/strong>\n <span>We scan every heavy hub section with calibrated UT equipment to guarantee zero internal shrinkage cavities or gas voids. A clean UT scan is a prerequisite for machining approval.<\/span>\n <\/li>\n <li>\n <strong>Spectrometry & Full Material Test Reports (MTRs):<\/strong>\n <span>We provide fully traceable MTRs documenting the exact chemical composition of your specific casting batch \u2014 Carbon Equivalent for gray iron, nodularity rate for ductile iron \u2014 for your QA file.<\/span>\n <\/li>\n <li>\n <strong>CMM Dimensional Verification:<\/strong>\n <span>Our Coordinate Measuring Machine verifies the machined bore diameter, outer diameter concentricity, and runout tolerances on every flywheel before packaging. CMM reports ship with the part.<\/span>\n <\/li>\n <li>\n <strong>Magnetic Particle Inspection (MPI) \u2014 Surface Integrity:<\/strong>\n <span>We apply MPI to all high-stress transition areas \u2014 hub-to-web fillets and spoke roots \u2014 to detect microscopic surface cracks before the flywheel is approved for export.<\/span>\n <\/li>\n <\/ul>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-shipping\">\n <div class=\"fw-container\">\n <div class=\"fw-shipping-inner\" style=\"margin-bottom:3rem; align-items:stretch;\">\n <div class=\"fw-shipping-content reveal-up\">\n <h2>Worldwide Export Shipping \u2014 Direct from Foundry<\/h2>\n <p>Kurt Foundry exports to customers across North America, Europe, Southeast Asia, the Middle East, and Australia. We have refined the international logistics process over thousands of shipments and manage the entire chain from our foundry floor to your receiving dock.<\/p>\n <p>We offer flexible shipping terms including FOB, CIF, and DDP depending on your destination and preference. Your procurement team receives a single direct-factory price with full freight transparency \u2014 no hidden costs.<\/p>\n <p>All heavy flywheels are packaged in ISPM-15 certified fumigated wooden crates with rust-preventative oil coating and internal blocking to prevent movement under ocean transit vibration.<\/p>\n <\/div>\n <div class=\"reveal-scale delay-1\" style=\"aspect-ratio:1\/1; overflow:hidden; border-radius:12px; min-height:300px;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Two-workers-in-an-industrial-warehouse-surrounded-by-stacked-wooden-boxes-engaged-in-a-task.jpeg\" alt=\"Two workers in an industrial warehouse surrounded by stacked wooden export crates, preparing custom flywheel shipments for delivery to North American customers.\" loading=\"lazy\" width=\"900\" height=\"900\" style=\"width:100%; height:100%; object-fit:cover; display:block;\" title=\"\">\n <\/div>\n <\/div>\n <div class=\"fw-shipping-cards reveal-up delay-1\">\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\udea2<\/div>\n <div>\n <h4>Ocean Freight<\/h4>\n <p>We arrange full-container or LCL ocean freight from Qingdao to ports worldwide \u2014 USA, Canada, Europe, Southeast Asia, Middle East, and Australia.<\/p>\n <\/div>\n <\/div>\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\udccb<\/div>\n <div>\n <h4>Flexible Trade Terms<\/h4>\n <p>We support FOB, CIF, and DDP shipping terms. Choose the arrangement that fits your procurement process and import requirements.<\/p>\n <\/div>\n <\/div>\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\ude9b<\/div>\n <div>\n <h4>Last-Mile Delivery<\/h4>\n <p>Under DDP terms, we arrange customs clearance and inland trucking directly to your facility \u2014 available for USA, Canada, and select European destinations.<\/p>\n <\/div>\n <\/div>\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\udce6<\/div>\n <div>\n <h4>ISPM-15 Crating<\/h4>\n <p>All flywheels ship in certified fumigated wooden crates with rust-preventative coating and full export documentation.<\/p>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-faq\">\n <div class=\"fw-container\">\n <div class=\"fw-faq-header reveal-up\">\n <h2>Frequently Asked Questions<\/h2>\n <\/div>\n <div class=\"fw-faq-list reveal-up delay-1\">\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq1\">\n <span>What is the best material for a custom industrial flywheel?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq1\" class=\"fw-faq-content\">\n <p>The correct material depends on your operating speed, impact loading, and failure mode requirements. Gray iron (ASTM A48 Class 30 or 40) is the standard choice for heavy stamping presses, large compressors, and crusher drives because its flake graphite microstructure provides outstanding vibration and torsional shock damping. Ductile iron (ASTM A536 Grade 65-45-12 or 80-55-06) is specified when the flywheel operates at high RPMs or when a burst failure \u2014 rather than a crack \u2014 is an absolute engineering requirement. Our engineering team reviews your application parameters and recommends the grade before any tooling is ordered.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq2\">\n <span>How do you prevent internal porosity in a heavy flywheel hub?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq2\" class=\"fw-faq-content\">\n <p>The thick central hub of a heavy industrial flywheel is the highest-risk area for internal shrinkage porosity because it is the last section to solidify. We address this directly during the DFM stage using Magmasoft 3D solidification simulation. Before we cut a single pattern, our engineers model the complete thermal solidification sequence and design the gating and riser system to feed a continuous supply of molten iron into the hub until it is fully solid. To understand our approach in more detail, read <a href=\"\/blog\/sand-casting-how-it-works\/\">how sand casting works<\/a> and how proper riser engineering prevents internal voids.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq3\">\n <span>What sizes of custom industrial flywheels can you manufacture?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq3\" class=\"fw-faq-content\">\n <p>Our heavy resin sand molding lines and floor molding pits allow us to pour custom cast iron flywheels ranging from 50 lbs up to 5,000 lbs (approximately 2.5 tons) as a single casting. For flywheels above 500 lbs, we use floor molding with custom-fabricated patterns to accommodate the dimensional scale. Contact our team with your weight and diameter requirements to confirm feasibility.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq4\">\n <span>Do you dynamically balance the flywheels before shipping?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq4\" class=\"fw-faq-content\">\n <p>We supply fully CNC-machined flywheels held to tight concentricity and runout tolerances verified by CMM inspection. This precision machining ensures the flywheel is statically balanced and very close to dynamic balance. The majority of our OEM customers perform the final precision dynamic balancing step after mounting the flywheel onto their specific motor shaft or drive assembly \u2014 at which point the complete rotating assembly can be balanced as a system. If your application requires us to perform in-house dynamic balancing before export, please specify this requirement in your RFQ.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq6\">\n <span>Do you ship custom flywheels internationally?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq6\" class=\"fw-faq-content\">\n <p>Yes. We export to customers across North America, Europe, Southeast Asia, the Middle East, and Australia. We offer FOB, CIF, and DDP shipping terms depending on your destination and preference. All heavy flywheels are packaged in ISPM-15 certified fumigated wooden crates with rust-preventative coating for ocean transit. Contact us with your destination port and we will provide a full landed-cost breakdown.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq7\">\n <span>What documentation do you provide with each flywheel shipment?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq7\" class=\"fw-faq-content\">\n <p>Each custom flywheel shipment includes a full quality documentation package: a Material Test Report (MTR) with certified chemical composition and mechanical properties of the specific casting batch, UT inspection records for hub sections, MPI inspection records for high-stress surface areas, and a CMM dimensional inspection report verifying bore concentricity, outer diameter, and runout tolerances. Export documents include a commercial invoice, packing list, Bill of Lading, and ISPM-15 phytosanitary certificate for the wooden crating.<\/p>\n <\/div>\n <\/div>\n\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-cta\">\n <div class=\"fw-container reveal-scale\">\n <div class=\"fw-cta-content\">\n <h2>Ready to Quote Your Custom Industrial Flywheel?<\/h2>\n <p>Send us your 2D engineering drawings and 3D CAD files (STEP, IGES, or SolidWorks formats). Our foundry engineering team will conduct a complimentary Design for Manufacturability (DFM) review and return a competitive direct-factory quote within 48 business hours.<\/p>\n <a href=\"\/contact\/\" class=\"btn btn-accent\">Submit Your Drawings & Get a Quote<\/a>\n <p class=\"fw-cta-note\">No CAD files? No problem. Contact us first \u2014 our team will explain the reverse engineering process and guide your submission step by step.<\/p>\n <\/div>\n <\/div>\n <\/section>\n\n<\/div>\n\n\n<script type=\"application\/ld+json\">\n{\n \"@context\": \"https:\/\/schema.org\/\",\n \"@type\": \"Product\",\n \"name\": \"Custom Industrial Cast Iron Flywheels\",\n \"image\": \"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/03\/custom-flywheels-1-1.webp\",\n \"description\": \"Heavy-duty custom cast iron and ductile iron flywheels engineered for industrial machinery, diesel engines, stamping presses, and compressors. Fully CNC-machined and porosity-verified. 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{"id":510,"date":"2026-03-23T08:21:02","date_gmt":"2026-03-23T08:21:02","guid":{"rendered":"https:\/\/kurtfoundry.com\/?p=510"},"modified":"2026-06-24T03:07:58","modified_gmt":"2026-06-24T03:07:58","slug":"custom-flywheels","status":"publish","type":"post","link":"https:\/\/kurtfoundry.com\/fr\/product\/custom-flywheels\/","title":{"rendered":"Volants d'inertie sur mesure | Fonderie de moulage au sable"},"content":{"rendered":"\n\n\n\n\nCustom Industrial Flywheels | Ductile & Gray Iron Castings | Kurt Foundry<\/title>\n<style>\n @import url('https:\/\/fonts.googleapis.com\/css2?family=Playfair+Display:wght@400;500;600;700&family=Open+Sans:wght@300;400;600&display=swap');\n\n :root {\n --primary-dark: #0a0e0d;\n --primary: #2b3a36;\n --primary-light: #445851;\n --accent: #d4af37;\n --bg-light: #f9f8f4;\n --bg-white: #ffffff;\n --bg-gray: #f0efe9;\n --text-main: #333333;\n --text-muted: #666666;\n --text-light: #e0e0e0;\n --border: #e2dfd5;\n --transition: all 0.4s cubic-bezier(0.25, 1, 0.5, 1);\n --text: #333333;\n }\n\n * { margin: 0; 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border-radius: 12px; padding: 2.5rem;\n border-left: 4px solid var(--accent);\n }\n .fw-reverse-highlight h3 { font-size: 1.3rem; margin-bottom: 1rem; color: var(--primary); }\n .fw-reverse-highlight p { color: var(--text-muted); margin-bottom: 0; }\n .fw-reverse-highlight p + p { margin-top: 1rem; }\n\n \/* North America DDP Shipping \u2014 NEW section *\/\n .fw-shipping { background-color: var(--primary); color: var(--bg-white); }\n .fw-shipping-inner { display: grid; grid-template-columns: 1fr; gap: 3rem; align-items: center; }\n .fw-shipping-content h2 { color: var(--bg-white); font-size: 2rem; margin-bottom: 1.5rem; }\n .fw-shipping-content p { color: var(--text-light); }\n .fw-shipping-content p:last-child { margin-bottom: 0; }\n .fw-shipping-cards { display: grid; grid-template-columns: 1fr; gap: 1.5rem; }\n .fw-shipping-card {\n background: rgba(255,255,255,0.06); border: 1px solid rgba(255,255,255,0.12);\n border-radius: 10px; padding: 1.8rem; display: flex; flex-direction: column; gap: 1rem; align-items: flex-start;\n height: 100%;\n }\n .fw-shipping-icon {\n flex-shrink: 0; width: 44px; height: 44px; border-radius: 50%;\n background-color: var(--accent); display: flex; align-items: center;\n justify-content: center; font-size: 1.2rem;\n }\n .fw-shipping-card h4 { color: var(--accent); font-family: 'Open Sans', sans-serif; font-weight: 600; margin-bottom: 0.4rem; font-size: 1rem; }\n .fw-shipping-card p { color: var(--text-light); font-size: 0.92rem; margin-bottom: 0; }\n\n \/* FAQ *\/\n .fw-faq { background-color: var(--bg-white); }\n .fw-faq-header { text-align: center; margin-bottom: 3rem; }\n .fw-faq-header h2 { font-size: 2.2rem; }\n .fw-faq-list { max-width: 850px; margin: 0 auto; display: flex; flex-direction: column; gap: 1rem; }\n .fw-faq-item { background: var(--bg-light); border: 1px solid var(--border); border-radius: 8px; overflow: hidden; }\n .fw-faq-btn { width: 100%; text-align: left; background: transparent; border: none; padding: 1.5rem; font-family: 'Open Sans', sans-serif; font-size: 1.1rem; font-weight: 600; display: flex; justify-content: space-between; align-items: center; min-height: 44px; }\n .fw-faq-icon { font-size: 1.5rem; color: var(--accent); transition: transform 0.3s ease; display: flex; align-items: center; justify-content: center; width: 30px; height: 30px; border-radius: 50%; background: var(--bg-white); }\n .fw-faq-content { max-height: 0; overflow: hidden; transition: max-height 0.4s ease; background: var(--bg-white); }\n .fw-faq-content p { padding: 0 1.5rem 1.5rem; margin: 0; color: var(--text-muted); }\n .fw-faq-item.active .fw-faq-content { max-height: 500px; }\n .fw-faq-item.active .fw-faq-icon { transform: rotate(45deg); background: var(--primary); color: var(--bg-white); }\n\n \/* CTA *\/\n .fw-cta { background: linear-gradient(to right, var(--primary-dark), var(--primary)); padding: 6rem 0; text-align: center; color: var(--bg-white); }\n .fw-cta-content { max-width: 800px; margin: 0 auto; }\n .fw-cta h2 { color: var(--bg-white); font-size: 2.4rem; margin-bottom: 1.5rem; }\n .fw-cta p { color: var(--text-light); font-size: 1.1rem; margin-bottom: 2.5rem; }\n .fw-cta-note { font-size: 0.9rem; color: rgba(255,255,255,0.5); margin-top: 1.5rem; margin-bottom: 0; }\n\n \/* Responsive *\/\n @media (min-width: 480px) {\n .fw-page { font-size: 16px; }\n .fw-hero h1 { font-size: 3rem; }\n .fw-hero-actions { flex-direction: row; }\n }\n @media (min-width: 768px) {\n .fw-section { padding: 6rem 0; }\n .fw-hero h1 { font-size: 3.8rem; }\n .fw-intro-grid { grid-template-columns: 1fr 1fr; align-items: center; }\n .fw-features-grid { grid-template-columns: 1fr 1fr; }\n .fw-materials-grid { grid-template-columns: 1fr 1fr; }\n .fw-quality-layout { grid-template-columns: 1fr 1fr; align-items: start; }\n .fw-reverse-inner { grid-template-columns: 1fr 1fr; }\n .fw-shipping-inner { grid-template-columns: 1fr 1fr; }\n .fw-shipping-cards { grid-template-columns: repeat(4, 1fr); }\n .fw-timeline { padding-left: 0; border-left: none; }\n .fw-timeline::before { content: ''; position: absolute; left: 50%; top: 0; bottom: 0; width: 2px; background: rgba(212,175,55,0.3); transform: translateX(-50%); }\n .fw-step { width: 50%; padding-left: 0; padding-right: 3rem; text-align: right; margin-bottom: 4rem; }\n .fw-step:nth-child(even) { margin-left: auto; padding-right: 0; padding-left: 3rem; text-align: left; }\n .fw-step::before { left: auto; right: -10px; }\n .fw-step:nth-child(even)::before { left: -10px; right: auto; }\n }\n @media (min-width: 1024px) {\n .fw-hero h1 { font-size: 4.2rem; }\n }\n\n \/* \u2500\u2500 Mobile optimizations \u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500 *\/\n @media (max-width: 767px) {\n\n \/* Section padding *\/\n .fw-section { padding: 3rem 0; }\n .fw-container { padding: 0 4%; }\n\n \/* Hero *\/\n .fw-hero { padding: 5rem 0 3.5rem; min-height: 70vh; }\n .fw-hero h1 { font-size: 2rem; }\n .fw-hero p { font-size: 1rem; }\n .fw-hero-badges { gap: 0.6rem; }\n .fw-hero-badge { font-size: 0.78rem; padding: 0.4rem 0.8rem; }\n .fw-hero-actions { flex-direction: column; }\n .fw-hero-actions .btn { width: 100%; justify-content: center; }\n\n \/* Intro highlight box *\/\n .fw-intro-highlight { padding: 1.5rem 1.2rem; }\n\n \/* All images \u2014 full width, comfortable aspect ratio *\/\n .product-img,\n .fw-intro-img img,\n .fw-features-image-wrap img,\n .fw-img-placeholder,\n .fw-quality-layout img,\n .fw-shipping-inner img {\n width: 100% !important;\n aspect-ratio: 4 \/ 3 !important;\n min-height: unset !important;\n border-radius: 10px;\n }\n\n \/* Remove decorative border offset on mobile \u2014 overflows viewport *\/\n .fw-features-image-wrap::after { display: none; }\n \/* Add top margin so image isn't flush after text *\/\n .fw-features-image-wrap { margin-top: 2rem; }\n\n \/* Material cards \u2014 full width, image takes natural height *\/\n .fw-material-card { padding: 1.5rem; }\n .fw-material-card .fw-img-placeholder { aspect-ratio: 4 \/ 3; }\n\n \/* Specs table \u2014 reduce padding, smaller font *\/\n .fw-table { min-width: 600px; font-size: 0.82rem; }\n .fw-table th,\n .fw-table td { padding: 0.7rem 0.8rem; }\n .fw-table th { font-size: 0.85rem; white-space: normal; }\n\n \/* Process *\/\n .fw-process { padding: 3rem 0; }\n .fw-process-header h2 { font-size: 1.6rem; }\n .fw-process-banner { margin-bottom: 2.5rem !important; }\n .fw-step { padding-left: 1.5rem; }\n\n \/* Quality checklist *\/\n .fw-checklist li { padding: 1.2rem 1.2rem 1.2rem 3.5rem; }\n .fw-checklist li::before { top: 1.4rem; left: 1rem; }\n .fw-quality-layout img { aspect-ratio: 4 \/ 3 !important; height: auto !important; }\n\n \/* Shipping section *\/\n .fw-shipping-inner { gap: 1.5rem; }\n .fw-shipping-cards { grid-template-columns: 1fr 1fr; gap: 1rem; }\n .fw-shipping-card { padding: 1.2rem; }\n .fw-shipping-inner > div[style*=\"aspect-ratio\"] {\n aspect-ratio: 4 \/ 3 !important;\n min-height: unset !important;\n }\n\n \/* FAQ *\/\n .fw-faq-btn { font-size: 0.95rem; padding: 1.2rem; }\n\n \/* CTA *\/\n .fw-cta { padding: 3.5rem 0; }\n .fw-cta h2 { font-size: 1.8rem; }\n .fw-cta p { font-size: 1rem; }\n .fw-cta .btn { width: 100%; justify-content: center; }\n\n \/* Placeholder size\/ratio labels *\/\n .fw-img-placeholder-size { font-size: 0.88rem; }\n .fw-img-placeholder-ratio { font-size: 0.7rem; }\n .fw-img-placeholder-label { font-size: 0.72rem; }\n }\n\n @media (max-width: 480px) {\n .fw-shipping-cards { grid-template-columns: 1fr; }\n .fw-table { min-width: 480px; font-size: 0.78rem; }\n .fw-table th,\n .fw-table td { padding: 0.6rem 0.6rem; }\n }\n<\/style>\n<\/head>\n<body>\n\n<div class=\"fw-page\">\n\n \n <section class=\"fw-hero\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/03\/custom-flywheels-1-1.webp\" alt=\"Wide-angle photograph of a massive, freshly CNC-machined custom gray iron flywheel resting on a heavy-duty wooden shipping pallet inside a bright, modern foundry.\" class=\"fw-hero-bg\" title=\"\">\n <div class=\"fw-hero-overlay\"><\/div>\n <div class=\"fw-container fw-hero-content reveal-up\">\n <span class=\"fw-hero-subtitle\">Heavy Industrial Sand Casting \u2014 Direct Foundry<\/span>\n <h1>Custom Industrial Flywheels<br>in Cast Iron & Ductile Iron<\/h1>\n <p>Kurt Foundry engineers and manufactures heavy-duty custom cast iron flywheels \u2014 from 50 lbs to 5,000 lbs per piece \u2014 for industrial machinery, diesel power plants, stamping presses, and large compressors. We deliver fully CNC-machined, porosity-verified components directly to your facility worldwide.<\/p>\n <div class=\"fw-hero-badges\">\n <span class=\"fw-hero-badge\">ISO 9001 Certified<\/span>\n <span class=\"fw-hero-badge\">ASTM A48 & A536 Compliant<\/span>\n <span class=\"fw-hero-badge\">Worldwide Export Shipping<\/span>\n <span class=\"fw-hero-badge\">Up to 5,000 lbs Per Piece<\/span>\n <\/div>\n <div class=\"fw-hero-actions\">\n <a href=\"\/contact\/\" class=\"btn btn-accent\">Request a Direct-Factory Quote<\/a>\n <a href=\"#specs\" class=\"btn btn-outline\">View Material Specs<\/a>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-intro\">\n <div class=\"fw-container\">\n <div class=\"fw-intro-grid\">\n <div class=\"fw-intro-text reveal-up\">\n <h2>When Rotational Mass Cannot Fail<\/h2>\n <p>A flywheel failure is not a maintenance event \u2014 it is a production catastrophe. Internal casting defects invisible to the naked eye can trigger a full burst at operating speed, taking out the machine and the line with it.<\/p>\n <p>Kurt Foundry pours custom cast iron flywheels from 50 lbs to 5,000 lbs, with every casting verified by 3D solidification simulation, ultrasonic testing, and CMM inspection before it leaves our facility.<\/p>\n <p>We handle everything in-house \u2014 casting, CNC machining, and quality documentation \u2014 then ship directly to your facility anywhere in the world. No brokers, no middlemen, no surprises on landed cost.<\/p>\n <\/div>\n <div class=\"fw-intro-highlight reveal-scale delay-1\">\n <p>Whether your application needs the vibration-damping of <a href=\"\/capabilities\/custom-gray-iron-castings\/\">custom gray iron castings<\/a> or the burst resistance of <a href=\"\/capabilities\/custom-ductile-iron-castings\/\">custom ductile iron castings<\/a>, our engineering team works directly from your 2D drawings and 3D CAD files.<\/p>\n <div class=\"fw-intro-img\" style=\"margin-top:1.5rem;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/kurt-foundry-is-doing-cnc-for-custom-flywheels.webp\" alt=\"Kurt Foundry CNC machining a custom industrial flywheel \u2014 single-source manufacturing from casting to finished component.\" loading=\"lazy\" width=\"900\" height=\"600\" style=\"width:100%; border-radius:8px; display:block; object-fit:cover;\" title=\"\">\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-materials\">\n <div class=\"fw-container\">\n <div class=\"fw-materials-header reveal-up\">\n <h2>Choosing the Right Iron Grade for Your Custom Flywheel<\/h2>\n <p>Material selection is the most critical engineering decision in any custom flywheel project. The wrong grade can mean a part that cracks under cyclic stress, warps during machining, or bursts at operating speed. Below is how our engineering team evaluates material fit for every heavy-duty application.<\/p>\n <\/div>\n <div class=\"fw-materials-grid\">\n <div class=\"fw-material-card reveal-up\">\n <div style=\"margin-bottom:1.5rem; border-radius:8px; overflow:hidden;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Gray-Iron-Flywheels.webp\" alt=\"Gray iron custom flywheel casting with turned outer diameter on factory floor.\" loading=\"lazy\" width=\"900\" height=\"600\" style=\"width:100%; aspect-ratio:3\/2; object-fit:cover; display:block;\" title=\"\">\n <\/div>\n <h3>Gray Iron Flywheels (ASTM A48)<\/h3>\n <p>Gray iron is the most widely specified material for heavy industrial flywheels. Its flake graphite microstructure absorbs and dissipates torsional shock loads \u2014 protecting drivetrain bearings and gearboxes from vibrational damage.<\/p>\n <p>We cast gray iron flywheels to ASTM A48 Class 30 and Class 40, covering standard industrial presses, jaw crushers, and large compressor drives.<\/p>\n <p>Gray iron machines exceptionally well, allowing our CNC team to hold tight bore concentricity on pieces that other materials would resist \u2014 at a lower cost per kilogram than ductile iron.<\/p>\n <\/div>\n <div class=\"fw-material-card reveal-up delay-1\">\n <div style=\"margin-bottom:1.5rem; border-radius:8px; overflow:hidden;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Ductile-Iron-Flywheels.webp\" alt=\"Ductile iron custom flywheel showing precision-machined hub bore and keyway.\" loading=\"lazy\" width=\"900\" height=\"600\" style=\"width:100%; aspect-ratio:3\/2; object-fit:cover; display:block;\" title=\"\">\n <\/div>\n <h3>Ductile Iron Flywheels (ASTM A536)<\/h3>\n <p>When a flywheel operates at high RPM or faces sustained impact loading, ductile iron is the correct choice. Its spheroidal graphite nodules allow the material to deform plastically before fracturing \u2014 preventing catastrophic burst failure.<\/p>\n <p>We cast ductile iron flywheels to ASTM A536 Grade 65-45-12 and 80-55-06, specified for high-RPM diesel generator sets, heavy marine propulsion systems, and severe-duty industrial equipment.<\/p>\n <p>Where burst containment is a hard engineering requirement \u2014 not a preference \u2014 ductile iron delivers the tensile strength and ductility that gray iron cannot.<\/p>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section id=\"specs\" class=\"fw-section fw-specs\">\n <div class=\"fw-container\">\n <div class=\"fw-specs-header reveal-up\">\n <h2>Custom Flywheel Material Grades & Mechanical Properties<\/h2>\n <\/div>\n <div class=\"fw-table-card reveal-up delay-1\">\n <div class=\"fw-table-wrapper\">\n <table class=\"fw-table\">\n <thead>\n <tr>\n <th>Standard \/ Grade<\/th>\n <th>Tensile Strength (MPa)<\/th>\n <th>Yield Strength (MPa)<\/th>\n <th>Elongation (%)<\/th>\n <th>Typical Flywheel Applications<\/th>\n <\/tr>\n <\/thead>\n <tbody>\n <tr>\n <td>ASTM A48 Class 30 (Gray Iron)<\/td>\n <td>≥ 207<\/td>\n <td>N\/A (Brittle)<\/td>\n <td>N\/A<\/td>\n <td>Standard industrial press flywheels, machine tools, vibration-damping drives.<\/td>\n <\/tr>\n <tr>\n <td>ASTM A48 Class 40 (Gray Iron)<\/td>\n <td>≥ 276<\/td>\n <td>N\/A (Brittle)<\/td>\n <td>N\/A<\/td>\n <td>Heavy-duty jaw crushers, large compressor flywheels requiring higher tensile strength.<\/td>\n <\/tr>\n <tr>\n <td>ASTM A536 65-45-12 (Ductile Iron)<\/td>\n <td>≥ 448<\/td>\n <td>≥ 310<\/td>\n <td>≥ 12<\/td>\n <td>High-RPM diesel engine flywheels, generator drive flywheels, high-stress rotational assemblies.<\/td>\n <\/tr>\n <tr>\n <td>ASTM A536 80-55-06 (Ductile Iron)<\/td>\n <td>≥ 552<\/td>\n <td>≥ 379<\/td>\n <td>≥ 6<\/td>\n <td>Severe-duty industrial flywheels requiring maximum burst resistance and impact tolerance.<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n <\/div>\n <\/div>\n <div class=\"reveal-up\" style=\"margin-top:3rem;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Engineering-drawing-spec-sheet-\u2014-2D-cross-section-of-a-custom-flywheel-with-dimension-callouts-and-ASTM-grade-annotations.jpeg\" alt=\"2D engineering drawing and spec sheet of a custom flywheel with dimension callouts and ASTM grade annotations.\" loading=\"lazy\" width=\"1600\" height=\"900\" style=\"width:100%; border-radius:12px; display:block; object-fit:cover;\" title=\"\">\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-features\">\n <div class=\"fw-container\">\n <div class=\"fw-features-grid\">\n <div class=\"fw-features-content reveal-up\">\n <h2>Single-Source CNC Machining & Guaranteed Concentricity<\/h2>\n <p>Casting and machining are handled in the same facility. Our 5-axis CNC centers turn the OD, bore the center hole, and cut the keyway \u2014 all held to strict runout tolerances verified by CMM.<\/p>\n <p>Single-source control eliminates the tolerance stack-up that occurs when casting and machining are split between two suppliers.<\/p>\n <p>Every flywheel ships with a full CMM inspection report \u2014 statically balanced and ready for your drive assembly.<\/p>\n <\/div>\n <div class=\"fw-features-image-wrap reveal-scale delay-1\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/CNC-Machining-for-flywheels.webp\" alt=\"CNC machining process for custom industrial flywheels at Kurt Foundry.\" class=\"product-img\" loading=\"lazy\" width=\"900\" height=\"600\" title=\"\">\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-process\">\n <div class=\"fw-container\">\n <div class=\"fw-process-header reveal-up\">\n <h2>How We Manufacture Your Custom Industrial Flywheel<\/h2>\n <\/div>\n <div class=\"fw-process-banner reveal-up delay-1\" style=\"position:relative; width:100%; aspect-ratio:16\/9; border-radius:12px; overflow:hidden; margin-bottom:4rem;\">\n <iframe\n src=\"https:\/\/www.youtube.com\/embed\/ROXBmpn4alE\"\n title=\"Kurt Foundry \u2014 Custom Industrial Flywheel Manufacturing Process\"\n frameborder=\"0\"\n allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\"\n allowfullscreen\n style=\"position:absolute; top:0; left:0; width:100%; height:100%; border:0;\">\n <\/iframe>\n <\/div>\n <div class=\"fw-timeline\">\n <div class=\"fw-step reveal-up\">\n <h3>1. DFM Review & 3D Solidification Simulation<\/h3>\n <p>Before any tooling is cut, our engineers import your CAD file into Magmasoft 3D simulation software. We model the complete solidification behavior of the flywheel casting \u2014 paying particular attention to the thick central hub, where the last metal to solidify is most vulnerable to internal shrinkage porosity. We engineer optimized gating and riser placements to feed molten iron into the hub directly, ensuring the finished casting is fully dense and porosity-free. No tooling order is placed until the simulation confirms a sound casting.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up delay-1\">\n <h3>2. Furan Resin Sand Molding<\/h3>\n <p>Our automated lines use furan resin sand to create rigid, dimensionally stable molds. Understanding the <a href=\"\/blog\/types-sand-used-sand-casting\/\" style=\"color: var(--accent);\">types of sand used in sand casting<\/a> is essential when producing heavy flywheels \u2014 the mold must resist the enormous metallostatic pressure of several thousand pounds of molten iron without wall movement. Furan resin binders provide the strength to hold exact tolerances during pouring.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up\">\n <h3>3. Spectrometer-Verified Pouring<\/h3>\n <p>Immediately before each pour, we conduct spectrometric chemical analysis of the molten iron. For gray iron flywheels, we verify the Carbon Equivalent (CE) to confirm the correct graphite flake morphology for maximum vibration damping. For ductile iron flywheels, we verify the nodularity rate to guarantee the spheroidal graphite structure that delivers burst resistance. Chemistry is documented and included in the Material Test Report (MTR) for your records.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up delay-1\">\n <h3>4. Controlled Thermal Stress Relief<\/h3>\n <p>Heavy flywheels present a thermal engineering challenge during solidification: the thick hub and the thinner outer web cool at significantly different rates. This differential cooling generates internal residual stresses locked into the casting. If not eliminated, these stresses relieve themselves during CNC machining \u2014 causing the part to warp and go out of tolerance. We perform controlled thermal stress relief heat treatment on all heavy flywheel castings before any machining begins, ensuring the part is dimensionally stable throughout the entire cutting process.<\/p>\n <\/div>\n <div class=\"fw-step reveal-up\">\n <h3>5. CNC Machining, UT\/MPI Inspection & CMM Verification<\/h3>\n <p>After shot-blasting, the stress-relieved casting transfers to our 5-axis CNC machining centers for turning, boring, and keyway cutting. Critical hub sections are then scanned by ultrasonic testing (UT) to confirm zero internal voids. High-stress transition zones undergo magnetic particle inspection (MPI) for surface crack detection. Finally, a Coordinate Measuring Machine (CMM) verifies all critical dimensions \u2014 bore diameter, OD concentricity, and runout tolerances \u2014 before the part is approved for packaging.<\/p>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n <section class=\"fw-section fw-quality\">\n <div class=\"fw-container\">\n <div class=\"fw-quality-header reveal-up\">\n <h2>Quality Control Built for Global OEM Standards<\/h2>\n <p>Industrial flywheels are safety-critical rotating components. A quality escape that reaches your assembly floor can trigger a full line shutdown, a costly recall, or \u2014 in the worst case \u2014 an uncontained burst. Our quality system is designed so that every defect is caught in our facility before shipment. Lead engineers at our OEM customers worldwide receive a complete quality documentation package with every order.<\/p>\n <\/div>\n <div class=\"fw-quality-layout\">\n <div class=\"reveal-scale\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Quality-Control-for-customized-flywheels.webp\" alt=\"Quality control inspection of custom cast iron flywheels at Kurt Foundry \u2014 CMM dimensional verification and NDE testing.\" loading=\"lazy\" width=\"800\" height=\"600\" style=\"width:100%; border-radius:12px; display:block; object-fit:cover;\" title=\"\">\n <\/div>\n <ul class=\"fw-checklist reveal-up delay-1\" style=\"grid-template-columns:1fr;\">\n <li>\n <strong>Ultrasonic Testing (UT) \u2014 Hub Integrity:<\/strong>\n <span>We scan every heavy hub section with calibrated UT equipment to guarantee zero internal shrinkage cavities or gas voids. A clean UT scan is a prerequisite for machining approval.<\/span>\n <\/li>\n <li>\n <strong>Spectrometry & Full Material Test Reports (MTRs):<\/strong>\n <span>We provide fully traceable MTRs documenting the exact chemical composition of your specific casting batch \u2014 Carbon Equivalent for gray iron, nodularity rate for ductile iron \u2014 for your QA file.<\/span>\n <\/li>\n <li>\n <strong>CMM Dimensional Verification:<\/strong>\n <span>Our Coordinate Measuring Machine verifies the machined bore diameter, outer diameter concentricity, and runout tolerances on every flywheel before packaging. CMM reports ship with the part.<\/span>\n <\/li>\n <li>\n <strong>Magnetic Particle Inspection (MPI) \u2014 Surface Integrity:<\/strong>\n <span>We apply MPI to all high-stress transition areas \u2014 hub-to-web fillets and spoke roots \u2014 to detect microscopic surface cracks before the flywheel is approved for export.<\/span>\n <\/li>\n <\/ul>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-shipping\">\n <div class=\"fw-container\">\n <div class=\"fw-shipping-inner\" style=\"margin-bottom:3rem; align-items:stretch;\">\n <div class=\"fw-shipping-content reveal-up\">\n <h2>Worldwide Export Shipping \u2014 Direct from Foundry<\/h2>\n <p>Kurt Foundry exports to customers across North America, Europe, Southeast Asia, the Middle East, and Australia. We have refined the international logistics process over thousands of shipments and manage the entire chain from our foundry floor to your receiving dock.<\/p>\n <p>We offer flexible shipping terms including FOB, CIF, and DDP depending on your destination and preference. Your procurement team receives a single direct-factory price with full freight transparency \u2014 no hidden costs.<\/p>\n <p>All heavy flywheels are packaged in ISPM-15 certified fumigated wooden crates with rust-preventative oil coating and internal blocking to prevent movement under ocean transit vibration.<\/p>\n <\/div>\n <div class=\"reveal-scale delay-1\" style=\"aspect-ratio:1\/1; overflow:hidden; border-radius:12px; min-height:300px;\">\n <img decoding=\"async\" src=\"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/06\/Two-workers-in-an-industrial-warehouse-surrounded-by-stacked-wooden-boxes-engaged-in-a-task.jpeg\" alt=\"Two workers in an industrial warehouse surrounded by stacked wooden export crates, preparing custom flywheel shipments for delivery to North American customers.\" loading=\"lazy\" width=\"900\" height=\"900\" style=\"width:100%; height:100%; object-fit:cover; display:block;\" title=\"\">\n <\/div>\n <\/div>\n <div class=\"fw-shipping-cards reveal-up delay-1\">\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\udea2<\/div>\n <div>\n <h4>Ocean Freight<\/h4>\n <p>We arrange full-container or LCL ocean freight from Qingdao to ports worldwide \u2014 USA, Canada, Europe, Southeast Asia, Middle East, and Australia.<\/p>\n <\/div>\n <\/div>\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\udccb<\/div>\n <div>\n <h4>Flexible Trade Terms<\/h4>\n <p>We support FOB, CIF, and DDP shipping terms. Choose the arrangement that fits your procurement process and import requirements.<\/p>\n <\/div>\n <\/div>\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\ude9b<\/div>\n <div>\n <h4>Last-Mile Delivery<\/h4>\n <p>Under DDP terms, we arrange customs clearance and inland trucking directly to your facility \u2014 available for USA, Canada, and select European destinations.<\/p>\n <\/div>\n <\/div>\n <div class=\"fw-shipping-card\">\n <div class=\"fw-shipping-icon\">\ud83d\udce6<\/div>\n <div>\n <h4>ISPM-15 Crating<\/h4>\n <p>All flywheels ship in certified fumigated wooden crates with rust-preventative coating and full export documentation.<\/p>\n <\/div>\n <\/div>\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-section fw-faq\">\n <div class=\"fw-container\">\n <div class=\"fw-faq-header reveal-up\">\n <h2>Frequently Asked Questions<\/h2>\n <\/div>\n <div class=\"fw-faq-list reveal-up delay-1\">\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq1\">\n <span>What is the best material for a custom industrial flywheel?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq1\" class=\"fw-faq-content\">\n <p>The correct material depends on your operating speed, impact loading, and failure mode requirements. Gray iron (ASTM A48 Class 30 or 40) is the standard choice for heavy stamping presses, large compressors, and crusher drives because its flake graphite microstructure provides outstanding vibration and torsional shock damping. Ductile iron (ASTM A536 Grade 65-45-12 or 80-55-06) is specified when the flywheel operates at high RPMs or when a burst failure \u2014 rather than a crack \u2014 is an absolute engineering requirement. Our engineering team reviews your application parameters and recommends the grade before any tooling is ordered.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq2\">\n <span>How do you prevent internal porosity in a heavy flywheel hub?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq2\" class=\"fw-faq-content\">\n <p>The thick central hub of a heavy industrial flywheel is the highest-risk area for internal shrinkage porosity because it is the last section to solidify. We address this directly during the DFM stage using Magmasoft 3D solidification simulation. Before we cut a single pattern, our engineers model the complete thermal solidification sequence and design the gating and riser system to feed a continuous supply of molten iron into the hub until it is fully solid. To understand our approach in more detail, read <a href=\"\/blog\/sand-casting-how-it-works\/\">how sand casting works<\/a> and how proper riser engineering prevents internal voids.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq3\">\n <span>What sizes of custom industrial flywheels can you manufacture?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq3\" class=\"fw-faq-content\">\n <p>Our heavy resin sand molding lines and floor molding pits allow us to pour custom cast iron flywheels ranging from 50 lbs up to 5,000 lbs (approximately 2.5 tons) as a single casting. For flywheels above 500 lbs, we use floor molding with custom-fabricated patterns to accommodate the dimensional scale. Contact our team with your weight and diameter requirements to confirm feasibility.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq4\">\n <span>Do you dynamically balance the flywheels before shipping?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq4\" class=\"fw-faq-content\">\n <p>We supply fully CNC-machined flywheels held to tight concentricity and runout tolerances verified by CMM inspection. This precision machining ensures the flywheel is statically balanced and very close to dynamic balance. The majority of our OEM customers perform the final precision dynamic balancing step after mounting the flywheel onto their specific motor shaft or drive assembly \u2014 at which point the complete rotating assembly can be balanced as a system. If your application requires us to perform in-house dynamic balancing before export, please specify this requirement in your RFQ.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq6\">\n <span>Do you ship custom flywheels internationally?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq6\" class=\"fw-faq-content\">\n <p>Yes. We export to customers across North America, Europe, Southeast Asia, the Middle East, and Australia. We offer FOB, CIF, and DDP shipping terms depending on your destination and preference. All heavy flywheels are packaged in ISPM-15 certified fumigated wooden crates with rust-preventative coating for ocean transit. Contact us with your destination port and we will provide a full landed-cost breakdown.<\/p>\n <\/div>\n <\/div>\n\n <div class=\"fw-faq-item\">\n <button class=\"fw-faq-btn faq-question\" aria-expanded=\"false\" aria-controls=\"faq7\">\n <span>What documentation do you provide with each flywheel shipment?<\/span>\n <span class=\"fw-faq-icon\">+<\/span>\n <\/button>\n <div id=\"faq7\" class=\"fw-faq-content\">\n <p>Each custom flywheel shipment includes a full quality documentation package: a Material Test Report (MTR) with certified chemical composition and mechanical properties of the specific casting batch, UT inspection records for hub sections, MPI inspection records for high-stress surface areas, and a CMM dimensional inspection report verifying bore concentricity, outer diameter, and runout tolerances. Export documents include a commercial invoice, packing list, Bill of Lading, and ISPM-15 phytosanitary certificate for the wooden crating.<\/p>\n <\/div>\n <\/div>\n\n <\/div>\n <\/div>\n <\/section>\n\n \n <section class=\"fw-cta\">\n <div class=\"fw-container reveal-scale\">\n <div class=\"fw-cta-content\">\n <h2>Ready to Quote Your Custom Industrial Flywheel?<\/h2>\n <p>Send us your 2D engineering drawings and 3D CAD files (STEP, IGES, or SolidWorks formats). Our foundry engineering team will conduct a complimentary Design for Manufacturability (DFM) review and return a competitive direct-factory quote within 48 business hours.<\/p>\n <a href=\"\/contact\/\" class=\"btn btn-accent\">Submit Your Drawings & Get a Quote<\/a>\n <p class=\"fw-cta-note\">No CAD files? No problem. Contact us first \u2014 our team will explain the reverse engineering process and guide your submission step by step.<\/p>\n <\/div>\n <\/div>\n <\/section>\n\n<\/div>\n\n\n<script type=\"application\/ld+json\">\n{\n \"@context\": \"https:\/\/schema.org\/\",\n \"@type\": \"Product\",\n \"name\": \"Custom Industrial Cast Iron Flywheels\",\n \"image\": \"https:\/\/kurtfoundry.com\/wp-content\/uploads\/2026\/03\/custom-flywheels-1-1.webp\",\n \"description\": \"Heavy-duty custom cast iron and ductile iron flywheels engineered for industrial machinery, diesel engines, stamping presses, and compressors. Fully CNC-machined and porosity-verified. 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