Quick answer. A jounce bumper — also called a suspension bump stop — limits suspension travel and absorbs impact energy at the end of the stroke. Miku Foam manufactures NDI microcellular polyurethane jounce bumpers with a progressive load curve, density grades from 0.35 to 0.65 g/cm3, validated to 500,000 fatigue cycles, and produced under IATF 16949 quality system (certificate # 0552607). What we make, the specifications that matter, and how to source for OEM-replacement, aftermarket, off-road, and heavy-duty applications.
What we manufacture
Miku Foam produces microcellular PU jounce bumpers for:
- OEM-replacement suspension bump stops
- Automotive aftermarket (AM) channel distribution
- Off-road and heavy-duty (modified trucks, Jeep / Bronco / 1500 / 2500HD, HD truck)
- Cold-weather and extreme-temperature service
- Private label / white label programs for distributors
Every part uses NDI (naphthalene diisocyanate) microcellular PU — the premium chemistry for jounce bumpers, chosen for its progressive load curve, fatigue resistance, and temperature stability. For the technical reasons NDI microcellular PU outperforms rubber, see our guide: Microcellular PU Jounce Bumpers vs Rubber Bump Stops.
Specifications
| Property | Range / Spec |
|---|---|
| Chemistry | NDI microcellular polyurethane |
| Density grades | 0.35 / 0.45 / 0.55 / 0.65 g/cm3 |
| Load curve | Non-linear, progressive |
| Fatigue life | 500,000 cycles validated (height loss 5.5%, ≤10% pass line) |
| Operating temperature | approx. -40 to +120 C continuous |
| Compression set | low, tested per ASTM D395 |
| Quality system | IATF 16949 certificate # 0552607 |
Full fatigue reports and static stiffness curves are documented on our Quality & Testing page.
Density grade selection
The right density depends on the application and load:
- 0.35–0.45 g/cm3 — lighter-duty and ride-comfort biased applications
- 0.45–0.55 g/cm3 — typical OEM-replacement range
- 0.55–0.65 g/cm3 — heavy-duty, HD truck, off-road, high-load
For replacement parts, match the original equipment density. For new designs, we work from the load requirement.
Sourcing: inventory, MOQ, and private label
- US west coast inventory hub — critical SKUs stocked in California for fast replenishment
- Private / white label — from 5,000 units per SKU, with IATF certificate traceability on the packaging insert
- Replenishment — roughly 4 weeks on stocked SKUs via the continuous-flow pipeline
Distributors evaluating a second source away from single-supplier dependence may find this guide useful: Why AM Distributors Are Diversifying from Single-Source Cellasto.
OEM input checklist
Send these inputs together so density selection, geometry, validation, and the commercial quote refer to the same part:
- Vehicle/application, axle position, original-equipment part number, target market, and OEM-replacement, aftermarket, off-road, or heavy-duty use
- 2D drawing and 3D CAD where available, installed sample, mounting interface, free height, maximum diameter, available envelope, and tolerances
- Required travel, engagement point, load-deflection curve or load points, maximum compression, and target density grade
- Operating temperature, fluids/contaminants, corrosion exposure, and any special environmental conditions
- Fatigue-cycle, height-loss, compression-set, material, and inspection requirements, including required reports
- Prototype/sample quantity, annual volume, order quantity by SKU, launch timing, delivery country/postcode, and forecast pattern
- Marking, private-label artwork, barcode, packaging insert, traceability, and approval-document requirements
If no load curve exists, provide the vehicle mass/load case, suspension geometry, available stroke, and a reference part, then ask the engineering team what further measurements are needed. Do not select a density grade from vehicle name alone.
MOQ and sample questions to confirm
The currently verified private-label threshold is 5,000 units per SKU. Custom geometry, tooling, density, marking, packaging, and validation scope may affect the commercial minimum, so confirm:
- Does the 5,000-unit threshold apply to this exact SKU, density, label, and packaging version?
- Is an existing geometry available, or is new tooling required?
- Are sample units drawn from a current part or made from the proposed production tool?
- How many samples are required for fit, static load, fatigue, temperature, and road validation?
- Which tooling, validation, and sample charges are separate from production pricing?
- What approved drawing, load curve, test report, and golden sample will control production?
Send your jounce bumper RFQ and request samples
FAQ
Q: What is a jounce bumper? It is the suspension component that cushions the end of suspension travel, limiting metal-to-metal contact and absorbing impact energy. "Jounce bumper" and "bump stop" mean the same part.
Q: Why microcellular PU instead of rubber? Microcellular PU has a progressive load curve, far longer fatigue life, lighter weight, and wider temperature range. See the full comparison.
Q: What density should I order? Match the original equipment density for replacement parts, or specify by load for new designs. Grades run 0.35–0.65 g/cm3.
Q: Do you offer private label? Yes — from 5,000 units per SKU, with IATF 16949 certificate traceability on the packaging insert.
Q: Can I test before ordering volume? Yes. Sample units are available to order so you can run your own bench test. Contact our team to start.
Q: What should I send for a custom jounce bumper quote? Send the application and OE number, drawing/CAD or sample, mounting and envelope dimensions, required travel and load curve, density target, environment and validation requirements, quantity by SKU, timing, and delivery location.
Q: What is the MOQ for a private-label jounce bumper? The currently verified threshold is 5,000 units per SKU. Confirm that it applies to the exact geometry, density, marking, and packaging version, and request tooling, validation, and sample costs separately.
Sourcing this line
Qualifying a supplier for this part? See how to vet a jounce bumper manufacturer for the NDI chemistry, fatigue-report, and IATF certificate checks to run before committing to volume.
Get specs, samples, or a quote
For density selection, test data, private-label setup, or pricing, contact our team. We respond with the technical detail your application needs.
*Miku Foam manufactures NDI microcellular PU jounce bumpers. IATF 16949 certificate # 0552607. Related: Quality & Testing · Microcellular PU vs Rubber · How to Vet a Manufacturer.*