Overview

A custom 301 stainless steel leaf spring is a thin, flat elastic element — an arm, a contact tongue or a preloaded tab — cut from cold-rolled 301 stainless steel by photochemical etching instead of stamping. A dry-film resist is imaged with the spring outline, developed, and the exposed metal is dissolved, leaving a burr-free profile with no work-hardened shear edge and no die-induced stress. Cold-rolled 301 in the spring temper delivers high yield strength and long fatigue life, with stock typically 0.1–0.8 mm. Because the whole sheet is etched at once, a custom 301 stainless steel leaf spring stays flat and its spring-back is uniform from the first article through volume production.

For mechanical designers, the custom 301 stainless steel leaf spring removes the classic limits of miniature stamped springs: arms narrower than 0.2 mm tear in a die, burrs lift mating surfaces in stacked assemblies, and stamped edges create stress raisers that shorten cycle life. Etching forms the arm, the contact zone and the mounting holes in one operation, so changing arm length or preload geometry is a new film, not a new progressive tool. Connector contacts, switch blades, snap preload tabs and micro-probe flexures all benefit from thin, springy, repeatable geometry.

Parameter Window

• Available Materials: 301 stainless steel (spring temper, 1/2 hard to full hard), 304 and 316L on request
• Material Thickness Range: 0.1–0.8 mm (0.15–0.3 mm covers most contact springs)
• Tolerance: ±0.02 mm on arm width, ±0.03 mm on hole position, ±0.05 mm on outline
• Minimum Feature: 0.15 mm arm width, 0.2 mm minimum slot, 0.25 mm hole diameter at 0.2 mm stock
• Surface Options: as-etched, passivated, electropolished, Ni/Au plating, formed and heat-set preload
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork Review — Vectorize the spring outline, verify arm width, bend relief and hole position against thickness, and flag stress concentrations.
2. Material Selection — Match 301 temper and rolling direction to the required spring force; confirm grain direction along the flexing arm.
3. Cleaning & Lamination — Degrease and laminate dry-film resist on both faces so fine arms are fully protected during exposure.
4. UV Exposure — Expose through high-resolution film registered to grain direction and sheet edge for consistent spring orientation.
5. Development — Open the outline and slot areas, then inspect narrow arms for under-developed resist before etching.
6. Etching — Spray ferric-chloride chemistry matched to stainless steel; control time and temperature to protect thin arm edges.
7. Stripping & Forming — Remove resist, neutralize, then set the preload angle by controlled forming and low-temperature heat setting.
8. Inspection & Packaging — Measure arm width, flatness and spring force against the approved sample, then pack in trays to protect the flexure.

Core Advantages

1. Burr-free, stress-free edges: Chemical removal leaves no sheared burr or work-hardened zone, so no secondary deburring and no edge cracks.
2. No progressive die: Every geometry revision is a new film, making prototypes and low-volume runs economical without hard tooling.
3. Very fine arms: 0.15 mm arms and 0.2 mm slots hold on 0.2 mm stock, enabling springs too delicate to stamp reliably.
4. Uniform spring-back: Whole-sheet etching adds no mechanical stress, so force and deflection match across a batch.
5. Flat for stacking: Parts leave the line flat and burr-free, so multi-leaf assemblies seat evenly without shims.
6. Fatigue-friendly material: A custom 301 stainless steel leaf spring pairs the high cycle life of spring-temper 301 with clean etched geometry for long service.

Typical Applications

• Connector contacts: Spring tongues in board-to-board and battery connectors that need stable normal force over many mating cycles.
• Switch blades: Thin movable contacts in micro-switches and relays where a burr-free edge prevents welding and sticking.
• Snap preload tabs: Flat springs that hold a latch or cover under constant preload in compact housings.
• Probe flexures: Elastic arms in test fixtures and probe cards that must deflect repeatably without taking a set.
• Grounding clips: Low-profile EMI grounding springs that press a shielded cover against a chassis rail.
• Valve and sensor reeds: Thin cantilever reeds for pressure and flow sensors where consistent stiffness sets the calibration.

Design Notes & Process Considerations

1. Grain direction: Orient the flexing arm along the rolling direction; cross-grain bending lowers fatigue life and widens force scatter.
2. Arm-to-thickness ratio: Keep the narrowest arm at or above stock thickness; a 0.15 mm arm on 0.2 mm sheet needs an etch-factor allowance.
3. Bend relief: Add generous radii at the arm root, because sharp inside corners concentrate stress and start cracks under cycling.
4. Force callout: Specify spring force at a defined deflection, not just material temper, and state the test point on the drawing.
5. Forming and heat setting: If a preload angle is needed, define the angle tolerance and whether a low-temperature set is acceptable.
6. Sampling and lock: Approve a sample for force, flatness and arm width before locking the film for a custom 301 stainless steel leaf spring, then keep rolling direction fixed per lot.