Overview

An etched shim washer is a thin, flat spacing or adjustment part produced by photochemical machining, which cuts the outer profile, inner bore, slots and tabs out of sheet metal without a punch or die. Because the metal is dissolved rather than sheared, the part leaves the line completely burr-free and stress-free, with flat faces that stack cleanly when several shims are laminated to set a precise gap. Thickness is simply the stock thickness, so an etched shim washer can be specified from 0.02 mm up to about 1.0 mm and held to ±0.005 mm, a level that stamping and laser cutting struggle to match on thin, delicate profiles. Stainless 301/304/316L, beryllium copper, phosphor bronze and spring steel are the usual materials.

For assembly and maintenance teams, an etched shim washer solves the burr and distortion problem that plagues punched shims: a stamped edge carries roll-over and a raised lip, so stacked shims do not sit flat and the gap drifts, and deburring a 0.05 mm part is nearly impossible. Photochemical etching holds narrow webs, tiny bores and fine adjustment tabs at 0.02–1.0 mm, and every washer on a sheet is identical. Since the tooling is a film, custom diameters, odd shapes and small prototype batches cost the same to set up as a standard round, which is why precision shims for alignment, bearing preload and valve clearance are increasingly specified as etched.

Parameter Window

• Available Materials: stainless 301/304/316L, beryllium copper, phosphor bronze, spring steel, brass
• Material Thickness Range: 0.02–1.0 mm, thickness sets the assembled gap
• Tolerance: ±0.005 mm on thickness, ±0.02 mm on outer profile, ±0.01 mm on bore
• Minimum Feature: 0.3 mm inner bore, 0.15 mm narrow web, 0.2 mm slot, 0.3 mm tab
• Surface Options: burr-free, stress-relieved, flat, non-magnetic options, etched part numbers, laminated peel-off stacks
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Drawing Review — Confirm outer diameter, bore, slots, tab geometry and target gap stack against the assembly.
2. Material Selection — Match temper and alloy to the load: 301 spring stainless, BeCu for conductivity, 316L for corrosion.
3. Cleaning & Lamination — Degrease thin stock and laminate dry-film resist with low pressure to avoid stretching foil.
4. UV Exposure — Expose the profile artwork on both faces and register parts to shared panel fiducials.
5. Development — Open the outline, bore and slot areas, checking for resist loss on narrow webs.
6. Etching — Spray etchant matched to the alloy; thin stock needs short, tightly timed cycles to hold web width.
7. Stripping & Stress Relief — Strip resist, neutralize, and stress-relieve or flatten where stack flatness is critical.
8. Inspection & Packaging — Verify thickness, bore, flatness and burr-free edges, then pack in peel-off stacks or trays.

Core Advantages

1. Truly burr-free edges: Chemical removal leaves no lip, so shims stack flat and the set gap is exact.
2. Thin-gauge precision: Thickness down to 0.02 mm holds ±0.005 mm, which punched parts cannot keep.
3. No tooling cost: Custom outlines and small batches need only a film, not a punch and die set.
4. Stress-free and flat: No shearing distortion, so parts stay flat through heat cycles and clamping.
5. Fine features on thin stock: Narrow webs, tiny bores and peel-off tabs survive at foil thickness.
6. Material and stack flexibility: An etched shim washer can be made in stainless, BeCu or bronze and supplied as laminated peel-off stacks for field adjustment.

Typical Applications

• Bearing preload shims: Thin stacks that set axial play in gearboxes, motors and spindles.
• Alignment and leveling shims: Peel-off laminated packs for machinery installation and base leveling.
• Valve and pump clearance: Precision gap spacers in hydraulic and fuel systems.
• Optical and fixture spacers: Flat, non-magnetic shims for lens mounts and metrology fixtures.
• Electrical contact washers: Conductive BeCu or bronze spacers in switchgear and connectors.
• Aerospace assembly shims: Light, burr-free washers for airframe and actuator stack-ups.

Design Notes & Process Considerations

1. Thickness versus gap: Specify stock thickness as the gap value and state the lamination count for peel-off packs.
2. Web width versus thickness: Keep narrow webs at least 1.5 × stock thickness to prevent breakthrough on foil.
3. Bore and edge distance: Leave enough metal between the bore and the outer edge to keep the washer flat.
4. Flatness for stacking: Call out flatness per 100 mm, since stacked burr-free shims only seal if each layer is flat.
5. Material temper: State temper and any non-magnetic requirement, as spring properties depend on the alloy state.
6. Part marking: Use etched tabs or part numbers to identify thickness in a mixed stack without adding a separate label.