Short answer: Stamped spring contacts should be quoted with a force-deflection condition, not only a free height. The RFQ should define working height, overtravel, contact point, force range, test fixture, sample stage, plating or heat exposure, relaxation or cycling requirement, and whether force is checked together with contact resistance or retention.
Spring contacts, grounding clips, EMI fingers, battery contacts, and latch clips often fail by losing force before they fail dimensionally. A contact can look correct in a free-state inspection and still miss the required pressure once it is compressed in the assembly.
Use this page with the stamped EMI/RF spring contacts guide, beryllium copper spring contact guide, copper alloy contact stamping guide, and stamped spring clips guide.
Force test details that change the quote
| Detail | Why it matters | RFQ evidence |
|---|---|---|
| Working height | Force changes quickly with compression distance. | Free height, installed height, tolerance, and stop condition. |
| Contact point | Testing the wrong area gives a misleading force number. | Tip location, probe shape, mating surface, and load direction. |
| Life state | Force can drop after cycling, heat, plating, or overtravel. | Initial, post-cycle, heat-aged, or vibration condition. |
| Fixture method | A flat probe may not represent the real mating part. | Fixture drawing, probe radius, speed, and acceptance range. |
Specify force at the working condition
Free height is useful, but it is not the functional requirement by itself. The drawing should state the installed height or compression range where force matters. If the spring has a hard stop, overtravel limit, or anti-overstress feature, include that condition in the quote package.
The contact location should also be clear. A formed bead, coined point, bent finger, lance, or rounded tip may carry the load. If the probe pushes on a nearby flat area, the test can pass while the real contact underperforms. Pair the requirement with the contact resistance guide when electrical stability depends on force.
Review material and finish before freezing the force target
Material temper, grain direction, bend radius, stress relief, heat exposure, and plating can all change spring behavior. Beryllium copper, phosphor bronze, stainless spring steel, and brass do not relax the same way. A tight spring design may need a force-deflection curve instead of a single go/no-go dimension.
If the part sees repeated mating, vibration, or heat, define whether force is measured only at first article or after cycling. A good អ្នកផ្គត់ផ្គង់ response should discuss forming strain, stress relaxation, plating cracks, contact wear, and packaging protection. For service conditions, connect this page to the vibration fatigue validation guide.
RFQ details to include
- Drawing with free height, working height, contact point, load direction, stop feature, and allowed overtravel.
- Material grade, thickness, temper, heat treatment or stress relief, plating, and burr direction.
- Force range, deflection point, test speed, fixture or probe shape, sample size, and report format.
- Life condition: initial only, after cycling, after heat aging, after plating, after vibration, or after assembly.
- Related acceptance: contact resistance, continuity, retention, insertion force, noise, or visible deformation.
- Annual volume, sample stage, packaging method, and current failure mode if the design is being fixed.
How to approve spring contact samples
Approve samples by function first. Compress the part to the working height, measure force at the correct location, inspect for cracks or plating damage, and check whether the spring returns after the test. For electrical contacts, check resistance at the same mated condition rather than on a loose part.
Ask the អ្នកផ្គត់ផ្គង់ what process variables will be controlled during production. Strip grain direction, forming station wear, heat lot, plating route, and handling can all move the force result. For production lots, a simple dimensional check may need to be paired with a periodic force audit.
Do not let the gauge method drift between prototype and production. If the prototype is measured with a lab fixture and production uses a shop-floor gauge, define the correlation method, calibration interval, fixture wear check, and who decides when a force trend requires tool maintenance.
Send drawings, material, working height, and force target through the contact page. If the force target is not final, use the RFQ form to request sample feedback before the spring geometry is locked.
FAQ
Why is free height not enough for spring contacts?
Free height does not prove contact pressure. Force should be checked at the working height or compression condition used in the assembly.
What affects stamped spring contact force?
Material temper, thickness, bend radius, forming strain, heat, plating, overtravel, cycling, and measurement fixture can all affect force.
Should force be tested after plating?
If plating affects the spring surface or heat exposure, final-condition force testing is usually more useful than testing before plating.
What should be sent for a spring force RFQ?
Send drawings, material, thickness, plating, working height, force range, test fixture, cycling or heat condition, quantity, and report needs.