Overview

Shim chemical etching is a stress-free way to cut thin metal shims, washers and spacing parts. A dry film resist is laminated to the sheet, exposed through artwork and developed, and the unprotected metal is dissolved in a matched etchant — no punch, no laser, no mechanical force ever touches the part. Shim chemical etching therefore keeps full-hard stainless, copper and nickel in their delivered condition: no burr, no work-hardened rim, no heat-affected zone and no camber from shearing. Stock runs from 0.03 mm foil to 1.5 mm plate in stainless steel 304/316L, copper C11000, brass, nickel 200, Invar 36 and titanium.

What matters in shimming is repeatability of thickness and outline, and that is where the process earns its place. Thickness is set by the purchased foil gauge rather than by tooling, so stack height is predictable; profiles repeat identically across a sheet and across batches because every part etches under the same spray conditions. Half-etched features are also possible — step shims, bend lines and recessed pockets are formed in one pass by controlling etch depth — and shims can be tabbed together in assembly sequence so fitters cannot pick the wrong part.

Parameter Window

• Available Materials: stainless steel 304/316L (full hard), copper C11000, brass C2680, nickel 200, Invar 36, titanium Grade 1/2
• Material Thickness Range: 0.03–1.5 mm
• Tolerance: profile ±0.03 mm; thickness held by foil gauge (±0.005–0.01 mm); etched step depth ±10% of nominal
• Minimum Feature: 0.1 mm slot or web; half-etch step from 0.02 mm depth; tab width 0.5 mm
• Surface Options: passivation, oil-free degreasing, protective interleaving film, tabbed shim sets, leveling, kitted sequences
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Drawing & Stack Review — Check the shim drawing or assembly stack, confirm thickness class, half-etch features and where tabs or handles are allowed.
2. Material & Gauge Selection — Order foil to the required gauge and temper; Invar for thermal compensation, full-hard stainless for spring-loaded fits, copper for conformability.
3. Cleaning & Lamination — Degrease the strip and laminate dry film resist so the surface is flat and bubble-free before exposure.
4. UV Exposure — Expose contour and any half-etch windows through registered artwork, keeping step locations aligned to the outline.
5. Development — Open the cut-through areas and the depth-control windows, then check that half-etch zones are cleanly defined.
6. Etching — Dissolve metal in matched chemistry; full cuts and controlled-depth pockets are etched in the same pass by managing time and temperature.
7. Stripping & Leveling — Strip resist, neutralize, degrease to an oil-free state and level the sheet where flatness is critical to stack height.
8. Inspection & Packaging — Verify outline, step depth and gauge thickness, then supply tabbed sets, interleaved stacks or kitted sequences.

Core Advantages

1. No stress and no heat: Etching never bends, hardens or warps the sheet, so thin shims stay flat and metallurgically unchanged.
2. Burr-free edges: Chemical removal leaves no roll-over, so stacked shims seat face-to-face and measured stack height is honest.
3. No tooling cost: Irregular outlines, slots and compound shapes are a film change, not a die, so short runs and design changes stay cheap.
4. Half-etch features in one pass: Step shims, bend lines and recessed pockets are depth-controlled in the same cycle as the through-cut.
5. Gauge-based thickness accuracy: Thickness comes from certified foil gauge, typically ±0.005–0.01 mm, instead of from tooling wear.
6. Batch repeatability: Every part on a sheet etches at the same rate, and chemical machining of shims keeps depth and outline consistent run to run.

Typical Applications

• Turbine and compressor shims: High-strength stainless shims for blade and casing clearance adjustment in rotating equipment.
• Motor and pump alignment shims: Tabbed stainless sets that set air gap and coupling alignment without re-machining housings.
• Valve and spool shims: Thin brass and stainless shims that meter spool travel and preload in hydraulic assemblies.
• Gearbox lash adjustment shims: Precision outline shims that tune gear backlash in production and service rebuilds.
• Thermal gap compensation shims: Invar 36 shims whose low expansion holds clearance across wide temperature swings.
• Laminate and washer sets: Tabbed or interleaved sets for service kits where each step must stay in build sequence.

Design Notes & Process Considerations

1. Gauge tolerance class: State the foil gauge and tolerance class on the drawing — stack height can only be as good as the purchased strip.
2. Half-etch depth: Call out step depth and tolerance, and say whether the feature is a depth pocket, a bend line or a full through-cut.
3. Tab position: Locate tabs on non-functional edges so they can be twisted off without marking the seating face.
4. Flatness callout: Specify flatness per 100 mm wherever shims stack or bolt through; ask for leveling if the strip was coiled before etching.
5. Edge condition: Require burr-free edges on any face that seats against a machined flange, since even a small roll-over skews the stack.
6. Narrow features: Keep slots and webs at 0.1 mm or wider for stock up to 0.5 mm; below that, half-etched relief is safer than a fragile through-slot.