Overview

A disc spring for automotive parts is a thin, etched spring element — often a slotted or coned-profile disc — that delivers a controlled preload or contact force in a valve, connector or sensor assembly. Photochemical machining cuts the profile from spring-temper stainless or beryllium copper without mechanical force, so the part keeps its temper, leaves the line flat and burr-free, and has no stamped roll-over to crack under cyclic load — a real concern in high-vibration under-hood environments.

Because the geometry is defined by artwork, a disc spring for automotive parts can carry radial slots, tabs and complex spring legs at the same tooling cost, and force is tuned by profile and thickness rather than by a dedicated die. 301 stainless, 17-7PH and beryllium copper cover the fatigue and conductivity needs, with passivation or heat setting applied after etching. Prototype springs for force testing and volume production run on one line, so a stiffness revision is only a new film.

Parameter Window

• Available Materials: stainless steel 301 / 17-7PH, beryllium copper, phosphor bronze
• Material Thickness Range: 0.05–1.0 mm
• Tolerance: ±0.01 mm on profile and slot width
• Minimum Feature: 0.10 mm slot, 0.15 mm spring leg
• Surface Options: passivation, heat setting, Ni/Ag plating, deburr-free edges
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork & DFM Review — Convert the spring profile into vector artwork and check slot width, leg width and bend relief against the spring-temper stock.
2. Material Selection — Choose 301, 17-7PH or beryllium copper in the correct temper and certify flatness before lamination.
3. Cleaning & Lamination — Degrease and laminate dry-film photoresist on both faces under controlled heat and pressure.
4. UV Exposure — Expose the spring profile through high-resolution film registered to the sheet datum for panel-level accuracy.
5. Development — Wash out unexposed resist to open slots and outline, checking the narrowest spring legs.
6. Controlled Etching — Spray chemistry matched to the alloy, holding slot and leg geometry through time, temperature and conveyor speed.
7. Stripping & Finishing — Remove resist, neutralize, then passivate, heat set or plate and verify spring force.
8. Inspection & Packaging — Measure profile, flatness and force against the first article, then pack in trays.

Core Advantages

1. Burr-free edges: Chemical removal leaves no roll-over to initiate fatigue cracks under vibration.
2. Temper preserved: No mechanical force or heat means spring properties stay as certified.
3. Fine spring legs: Slots and legs down to 0.10 mm hold their geometry across the panel.
4. Stress-free flat parts: Thin discs leave the line flat and seat evenly in the assembly.
5. No hard tooling: A new profile is a new film, so force iterations stay economical.
6. Repeatable force: Lot-to-lot consistency removes selective matching at assembly.

Typical Applications

• Valve preload: Disc springs that hold a valve element seated.
• Connector contacts: Spring discs maintaining contact pressure.
• Sensor mounts: Preload elements for pressure sensors.
• Clutch shims: Spring washers that take up tolerance.
• Switch domes: Slotted discs with tactile force.
• Grounding springs: Burr-free discs for EMI contact.

Design Notes & Process Considerations

1. Slot versus thickness: Keep the minimum leg at or above 1.2 × material thickness so thin legs do not lift.
2. Force callout: State the target force at a defined deflection, not just the profile.
3. Temper spec: Name the alloy temper, since etching must not alter spring properties.
4. Burr and flatness: Require burr-free edges and flatness per 100 mm for even seating.
5. Surface spec: Name the plating and heat-set condition, since both affect final force.
6. Panelization: Group discs with shared registration marks to cut handling cost on repeat volumes.