Sometimes there is more than one solution to the same problem. In this case study, we follow the journey of a compression limiter for overmolding from prototype to series production, exploring two industrial routes that ETMA masters for the same part — stamping and turning — and showing how we arrived at a stamped sheet-metal compression limiter with a fully leak-tight joint, ready for overmolding with no surprises. Along the way, our unique system of 10 Integrated Production Processes comes into play, together with co-engineering with the customer and the choices that make the difference in cost, cadence and quality. It is well worth reading: it is the story of how the right kind of flexibility opens up alternatives – and keeps performance at the top.
BACKGROUND
The client approached ETMA with a drawing for compression limiters to be overmoulded: metal inserts that prevent the plastic from cracking when the assembly is tightened with a screw. For this application, the joint could not have any clearance, since any gap would allow the polymer to seep in during injection, compromising the part. Until then, ETMA had been manufacturing the same type of component by turning; the new challenge was to industrialise it by stamping, while maintaining the performance of a turned part.
Defect resulting from overmoulding on a non-leak-tight insert.
THE TECHNICAL CHALLENGE
In strip stamping, the ring body is bent and a joint remains; the task was to close that joint to the point of making it imperceptible (target: < 0.02 mm), ensuring sealing during overmoulding. In parallel, it was critical to reduce cost and waste compared to the machined route, another key argument for migrating to sheet metal.
THE INDUSTRIALISATION SOLUTION
ETMA opted for automatic stamping with a specific bending/closing sequence that compresses the edges and neutralises springback, leaving the perimeter cylindrical and “closed” in the joint area. The result replicates the behaviour of the turned part — with no plastic leakage — while delivering total cost and sustainability gains (less scrap, more competitive cycle).
10 INTEGRATED PROCESSES, ONE COMPREHENSIVE RESPONSE
To speed up industrialisation and reduce interfaces, ETMA integrated several stages from its system of 10 production processes, ensuring control, traceability and time-to-market:
- Prototypes (interaction with the client and adjustment of tolerances/drawing details);
- Tools (tool manufacture);
- Stamping on Bihler 80 (special closing sequence);
- Surface Treatment – zinc plating (corrosion protection);
- 100% inspection on glass-disk vision systems, monitoring critical dimensions (such as diameter and height control) and ensuring dimensional conformity in the joint area.
The project is now moving from prototype to series production, still before the end of 2025. Annual volume forecast: approximately 3,500,000 parts, in batches of 600,000.
LESSONS LEARN
The controlled closing of the joint — using a bending sequence designed to eliminate springback — is the key differentiator that makes the stamping solution viable with performance equivalent to turning, opening the door to new applications and competitiveness gains.
WHAT CHANGES FOR THE CLIENT
- Safe overmoulding: sealed joint;
- Cost and efficiency: stamping with less waste than turning;
- Assured quality: 100% inspection and full traceability;
- Industrial flexibility: two production options under the same roof (stamping or turning), to be selected according to batch size, cost and requirements.
CONCLUSION
This project shows what sets us apart: co-engineering from the very first sketch, 10 Integrated Production Processes, and flexibility. The result: a part ready for overmoulding, a sealed joint, competitive cost, reduced waste and end-to-end traceability – a robust industrialisation, ready to scale.
Do you have a critical insert for overmoulding or a technical component with tight requirements?
Talk to us: we assess your project, design the right process and deliver turnkey technical parts for a wide range of sectors and other demanding applications.