CASE STUDY · DRG-SOL-001

A jounce bumper, taken from sketch to certificate.

One automotive suspension bumper — cast in PU 72 ShA — carried through all six Croslynk stages. This page shows the real numbers at every step: the spec, the simulation, the mold, and the machine data that proved the part.

N/mm target stiffness (0–27 mm)

0 mm

free height · Ø41.2 top / Ø55 base

0 kN

full-bound load

elongation at break

01 · DESIGN INPUT

The customer handed us a curve, not a part.

The requirement arrived as a load–deflection envelope: linear 21.4 N/mm over the first 27 mm of travel, staying under 5,038 N at 43.2 mm (bound 2G), and surviving full bound at 46,802 N without damage. Envelope: Ø41.2 mm top seat, Ø55 mm base, 92 mm free height.

Our design study set the waisted profile and convolutions that shape that progressive rate — soft entry, controlled ramp, sharp rise near bottom-out.

Requirement	Value
Linear stiffness (0–27 mm)	21.4 N/mm
Bound 2G @ 43.2 mm	< 5,038 N
Full bound	46,802 N
Envelope	Ø41.2 / Ø55 × 92 mm

Engineering drawing DRG-SOL-001 of the jounce bumper

02 · MATERIAL & SIMULATION

PU 72 ShA, proven virtually before any steel was cut.

Cast polyurethane at 72 Shore A gave the best mix of load capacity, rebound and fatigue life for this duty. Coupon data: tensile 7.25 MPa, elongation 342%.

The profile was iterated in FEA until the predicted curve sat inside the customer envelope — the interactive model on the right shows the stress pattern at working load. Drag it. This is the same in-browser engine you can run on your own part.

Progressive rate tuned via waist & convolution geometry
Stress concentration held below compound limits at bound 2G
Mold shrinkage compensated in cavity dimensions

drag to orbit · scroll to zoom

Illustrative closed-form FEA — full solver runs are part of the paid stage.

03 · TOOLING & CASTING

Mold cut in-house, cast in-house.

CNC-machined casting mold for the jounce bumper

The two-part casting mold was CNC-machined on our own floor — cavity polished, vents and risers placed for bubble-free hot casting. Because tooling and molding share one roof, the loop from “simulation says change the waist by 0.4 mm” to a revised cavity is days, not weeks.

Item	Detail
Mold type	Open-cast, 2-part, single cavity
Process	Hot-cast PU, oven post-cure
First article	Dimensional + hardness verified

04 · TESTING — THE PART EARNS ITS CERTIFICATE

Measured on our 50 kN UTM, against its own prediction.

Compression testing on the in-house UTM traced the full load–deflection curve; the measured points landed inside the customer envelope on the first article.

Deflection	Spec / envelope	Measured
20 mm	~428 N (21.4 N/mm line)	520 N ✓
43.2 mm	< 5,038 N	within envelope ✓
59 mm	progressive zone	13,000 N ✓
Full bound	46,802 N, no damage	passed ✓

Every production batch since ships with hardness, dimensional and stiffness checks — the same data loop that keeps our simulations honest.

Jounce bumper under compression test on the Croslynk 50 kN UTM

Your part could be the next case study.

Bring a drawing, a curve, or just a problem. We’ll take it through the same six stages — and hand you the data that proves it.

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