Overview

A spring etching service produces flat, stress-free metal springs by photochemical machining instead of stamping. A photoresist mask is exposed with the spring profile, developed, and the unprotected metal is dissolved in a matched etchant, so the entire flat spring — arms, tabs, slots and holes — is cut in one pass without any die contact. Typical substrates are 301/302 stainless steel, beryllium copper (C17200) and phosphor bronze (C52100), supplied between 0.05 mm and 0.8 mm.

Because the metal is removed chemically, the part leaves the bath flat and burr-free, with no tool marks, no roll-over and no work-hardened edge that would shorten fatigue life. Spring force and deflection are then set purely by material, thickness and geometry, and the same profile can be formed, heat-treated or plated downstream. The process is especially economical for prototypes, short runs and spring profiles that change often, since every revision is a new film rather than a new die.

Parameter Window

• Available Materials: 301/302 stainless steel, beryllium copper (C17200), phosphor bronze (C52100), Inconel
• Material Thickness Range: 0.05–0.8 mm
• Tolerance: ±0.05 mm on profile, slot width and hole position
• Minimum Feature: 0.1 mm slot width and 0.2 mm arm width
• Surface Options: passivation, electroless nickel, electrolytic Ni/Au, tin, stress-relief heat treatment
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork Review — Convert the spring drawing to vector artwork and check arm width, slot width and bend relief against thickness.
2. Material Selection — Match alloy and temper to force, conductivity and corrosion needs; beryllium copper for contacts, stainless for corrosive sites.
3. Cleaning & Lamination — Degrease the strip and laminate dry film resist so no bubbles sit under fine arms or slots.
4. UV Exposure — Expose the profile through high-resolution film registered to the strip edge for repeatability across the sheet.
5. Development — Wash out unexposed resist to open the outline, then inspect thin arms for under-developed resist.
6. Etching — Spray or immerse in chemistry matched to the alloy; edge quality is controlled by time, temperature and conveyor speed.
7. Stripping & Finishing — Remove resist and neutralize, then passivate, plate or heat-treat to set final temper and spring properties.
8. Inspection & Packaging — Verify profile, thickness, flatness and bend relief against the sample, then pack flat or on reels.

Core Advantages

1. No die, no tool marks: Flat springs are cut without a stamping die, so parts arrive burr-free with no tool marks or edge cracks.
2. Stress-free edges: The chemical process leaves no work-hardened edge, giving repeatable spring force and longer fatigue life.
3. Fast, low-cost revisions: A changed spring shape is a changed film, so prototypes and design changes ship in days without new tooling.
4. Fine detail: Slots down to 0.1 mm and arms down to 0.2 mm hold across the sheet, ideal for compact contact springs.
5. Full-sheet consistency: Every spring on the strip etches at the same rate, so dimensions and force stay uniform in a batch.
6. Broad material range: Stainless, beryllium copper, phosphor bronze and Inconel run on one line. A spring etching service can mix materials and profiles in a single order.

Typical Applications

• Battery contact springs: Flat beryllium copper springs that press against cells with controlled, repeatable force.
• Connector leaves: Small contact leaves etched with fine slots for retention and compliance in connectors.
• Switch springs: Repeatable flexure springs for push-button and slide switch mechanisms.
• Preload and shim springs: Flat springs used to set preload, clamping or alignment force in assemblies.
• Relay springs: Thin, stress-free springs for relay armatures and contact carriers.
• Sensor flexures: Thin flexure springs for scales, load cells and micro-switch mechanisms.

Design Notes & Process Considerations

1. Arm versus thickness: Keep the narrowest arm at or above 1.5 × material thickness, or the arm will etch unevenly and weaken.
2. Bend relief: Add a small radius at the bend line and mark its location, since etched blanks are formed after etching.
3. Grain direction: Specify grain orientation relative to the bend axis; bending across the grain improves fatigue life.
4. Temper and heat treat: State the final temper, as forming is usually done on a softer condition before aging or hardening.
5. Plating: Name the plating and thickness on contact areas; selective plating keeps cost down where only tips need gold.
6. Flatness: Call out flatness per 100 mm, since etched blanks arrive flat and must stay flat through forming. For a spring etching service, these six points on the drawing reduce back-and-forth.