Overview

Shim washer etching uses photochemical machining to cut thin, flat adjustment shims and washers out of metal sheet without a stamping die or mechanical shear. A photoresist mask carries the outline, bore and slot artwork; after development the unprotected metal is dissolved in a matched etchant, so the part is formed by chemistry rather than by pressure. Typical substrates are stainless 301/304/316L, beryllium copper and brass, supplied from 0.02 mm to 1.0 mm. The result is a burr-free, stress-free shim that holds its flatness and thickness, which is exactly what a precision gap or preload stack depends on.

For buyers, shim washer etching addresses three common failures. Stamped shims carry a rolled edge and burr that scratch mating faces and change the effective stack height; ground shims are costly at the thin end and slow to revise; and assemblies often need a whole family of thickness steps that would each require a separate die. Chemical machining produces every thickness grade from the same artwork, holds ±0.01 mm on thickness, and lets half-etched thickness marks or alignment tabs be built into the part at no extra tooling cost. From prototype to volume, the same film repeats the same geometry, so a shim selected during assembly behaves identically across batches.

Parameter Window

• Available Materials: stainless steel 301/304/316L, beryllium copper C17200, brass, spring steel, also nickel
• Material Thickness Range: 0.02–1.0 mm
• Tolerance: ±0.01 mm on thickness, ±0.025 mm on cut profile
• Minimum Feature: 0.20 mm slot/web width, 0.5 mm inner bore
• Surface Options: passivation, deburring, polishing, Ni/Au plating, half-etched thickness mark, adhesive tab
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Drawing & Thickness Stack — Convert the tolerance chain and thickness grades into artwork, check bore, slot and outline, and plan the sheet layout.
2. Material & Temper — Select alloy and temper for spring or corrosion duty, then verify thickness tolerance and flatness of the incoming coil or sheet.
3. Cleaning & Lamination — Degrease and laminate dry film resist; use a carrier for foil below 0.1 mm so the thin stock does not crease.
4. UV Exposure — Expose through high-resolution film with every profile registered to the sheet edge for consistent part-to-part size.
5. Development — Wash out unexposed resist to open the outline and slot areas, and inspect for residue that would leave unwanted metal.
6. Controlled Etching — Spray matched chemistry, tuning time and temperature to hold sidewalls; half-etch thickness marks and tabs in the same pass.
7. Stripping & Finishing — Remove resist, passivate, deburr and polish or plate; anneal where flatness must be restored after processing.
8. Inspection & Sorting — Gauge thickness, verify profile on a vision system, then sort and label parts by thickness grade for assembly.

Core Advantages

1. Accurate thickness grades: Every step in a shim stack comes from controlled foil and etch depth, so assembled clearance lands on target.
2. Burr-free mating faces: Chemical removal leaves no roll-over, so shims sit flat and will not score housings, bearings or optical seats.
3. No die cost per size: A new thickness or outline is a new film, keeping short runs and multi-grade kits economical without stamping tools.
4. Stable flatness: With no shear or heat, thin washers stay flat and stress-free, so a stacked pack compresses evenly and repeats.
5. Built-in features: Half-etched thickness marks, alignment tabs and serials can be added during etching to simplify kitting and traceability.
6. Material choice: shim washer etching runs stainless, beryllium copper and brass on one line, so the alloy can be matched to spring or corrosion needs.

Typical Applications

• Bearing preload shims: Thin adjustment washers that set axial preload in gearboxes and spindles, sorted by 0.01 mm steps.
• Gear backlash spacers: Gap shims that tune mesh clearance in transmissions and reducers without re-machining housings.
• Mold and fixture packs: Laminated shim stacks for leveling dies, jigs and tooling plates where flatness is critical.
• Valve and pump clearances: Spacers that set axial float in pumps and valve trains, resistant to oil and temperature cycling.
• Optical mount washers: Flat, burr-free rings for lens seats and mirror cells that must not tilt the optic.
• EMI and grounding washers: Conductive contact rings for shielding and grounding paths in electronic enclosures.

Design Notes & Process Considerations

1. Thickness and tolerance chain: Define the full stack and each grade, and state whether thickness is nominal or measured, to avoid cumulative error in assembly.
2. Bore and web ratio: Keep the narrowest web or slot at 0.20 mm or 1.5 × thickness, whichever is larger, or thin sections will etch through unevenly.
3. Flatness and parallelism: Call out flatness per 100 mm and parallelism of the two faces when the shim is clamped in a precision stack.
4. Temper and spring: Choose annealed stock for flat spacers or spring temper for resilient washers, and note the required hardness on the drawing.
5. Nesting and burr direction: Specify tie-bar layout, final cut method and burr-free edges so thin parts survive stripping and do not snag in feeders.
6. Marking and sorting: With shim washer etching, define half-etched thickness marks, grade labeling and packaging so each kit is traceable and easy to pick.