Polyurethane bump stops, buffers and vibration absorbers cushion impact and damp vibration in vehicles, machinery and rail. Cast PU is used because it can be tuned from soft and resilient to firm, absorbs energy without permanent set and outlasts rubber in fatigue. Parts are cast on a PU elastomer casting machine — we build the machine; you supply the PU system.
What You Need
- PU elastomer casting machine — meters and mixes polyol and isocyanate at fixed ratio and temperature
- Bump/absorber moulds — per part shape and size
- Metal inserts + primer where the part bonds to a bracket or shaft
- PU system — sourced by you
The Process
- Insert prep — clean and prime any metal insert for a reliable bond.
- Conditioning — preheat mould; hold components at set temperature.
- Meter, mix, pour — fixed-ratio dosing; fill from the bottom to avoid trapped air, which becomes a fatigue crack site.
- Gel, demould, post-cure.
- Inspect — check for voids and correct hardness.
Key Parameters
- Hardness / resilience — absorbers span Shore A 40–90 depending on load and travel; softer for isolation, firmer for hard stops
- Ratio accuracy — decides consistent stiffness and fatigue life part to part
- Void-free pour — trapped air is the main cause of early fatigue failure
- Post-cure — needed for full rebound and set resistance
Which Machine
We supply the PU absorber/bump making machine. See the full PU elastomer casting machine range.
FAQ
What hardness for a bump stop?
Typically Shore A 40–90. Softer parts isolate vibration; firmer parts act as hard stops with defined travel. Your PU system and part design set the value.
Why cast PU instead of rubber?
Cast PU absorbs energy with little permanent set and outlasts rubber in fatigue, so bump stops keep their properties longer.
Do you supply the PU material?
No — we build the casting machine. You run it with your own or sourced PU system.
Tell us your part, hardness and output — we will propose the right casting machine and quote.