Overview

Custom washer etching produces flat washers, spacers, sealing rings and shim washers by photochemical machining instead of stamping. Inner and outer diameters, keyways, tab features and oil grooves are all imaged on resist and etched out of metal strip, so bore-to-rim concentricity comes from a single artwork and the part leaves the bath flat on both faces. Stainless steel 304/316L, copper, brass, aluminium and carbon spring steel are processed between 0.05 mm and 2.0 mm, with bore diameters down to 0.3 mm and wall widths down to 0.1 mm.

Washers fail in service for reasons that are usually geometric: a burr on one face that lifts the joint, a bore that is off-centre so the bolt preload is uneven, or a thickness that varies around the rim and changes the clamp load. Etching addresses all three. There is no sheared edge to roll over, the bore and the rim are imaged together so they share one centre, and thickness is whatever the incoming strip measures, held to the coil tolerance rather than being thinned locally by a punch. For small bores, thin stock and mixed sizes on one order, the etch route is often the only economical option.

Parameter Window

• Available Materials: stainless steel 304/316L, copper, brass, aluminium 5052, carbon spring steel 1075
• Material Thickness Range: 0.05–2.0 mm; above 1.2 mm supplied half-etched where a step is needed
• Tolerance: ±0.05 mm on bore and outside diameter, 0.03 mm concentricity between bore and rim
• Minimum Feature: 0.3 mm bore, 0.1 mm wall between bore and edge, 0.15 mm slot
• Surface Options: passivation, nickel or zinc plating, black oxide, deburr-free as-etched, adhesive-free clean pack
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Washer Review — Check bore, wall and keyway against the thickness, confirm that no wall is thinner than 0.1 mm, and fix the datum for concentricity.
2. Material Choice — Stainless for corrosion, copper and brass for conductivity and thermal transfer, spring steel where the washer must act as a disc spring.
3. Levelling — Level and clean the strip before coating; a coil set that survives into the finished part shows up as a rocking washer on a flat plate.
4. Lamination — Apply dry film to both faces, thin enough that the resist does not bridge a 0.3 mm bore during development.
5. Exposure & Development — Expose both sides registered to the same datum, develop, and confirm bore roundness on a coupon.
6. Etching — Etch from both faces at matched rates so the bore wall is straight rather than tapered, and stop on dimension rather than on time.
7. Strip & Finish — Remove resist, neutralise, then passivate, plate or blacken; tumbling is avoided where face flatness matters.
8. Inspection & Pack — Check bore, OD, concentricity, thickness and flatness, then pack by size in bags or trays with a dimensional report.

Core Advantages

1. Bore and rim share one centre: Both diameters come from the same artwork, so concentricity is a drawing callout rather than a die-alignment problem.
2. No burr to lift the joint: Chemical removal leaves no roll-over, so the washer sits flat and clamp load distributes evenly around the rim.
3. Thickness stays as rolled: The punch does not thin the part locally, so thickness is uniform and stack height can be calculated from the strip spec.
4. Very small bores: Bores down to 0.3 mm are practical, which is below what a progressive die can punch in thin stock.
5. Mixed sizes on one sheet: A maintenance kit with twenty washer sizes can be etched on one panel and packed by size afterwards.
6. No tooling for new sizes: A new bore is a new film. Custom washer etching therefore keeps spare-part ranges and repair kits economical.

Typical Applications

• Fastener washers: Flat washers under screws and studs in electrical and instrument assemblies, supplied passivated.
• Sealing and compression rings: Soft copper and aluminium washers that crush to seal a fluid or gas joint.
• Shim washers: Thin stainless washers used in stacks to set bearing preload or gear backlash.
• Insulating washers: Etched from thin sheet with a defined wall so a screw is isolated from a chassis.
• Thermal interface washers: Copper washers that spread heat between a device and a heatsink.
• Spring and wave washers: Flat etched rings with tabs or slots that provide a light axial preload.

Design Notes & Process Considerations

1. Wall width: Keep the wall between bore and rim at 0.1 mm or more, and at least half the thickness, or the ring distorts during handling.
2. Concentricity callout: State concentricity separately from diameter tolerance; a ±0.05 mm bore tolerance does not by itself control how far the bore sits off centre.
3. Flatness: Specify flatness per 100 mm for washers that seal or set preload, and note whether tumbling is permitted, since it can bow thin rings.
4. Edge condition: Etched edges are smooth but slightly tapered; where a sharp sealing edge is needed, ask for a half-etch step instead of a through-cut.
5. Stack tolerance: When washers are used in stacks, give the thickness tolerance and the number of layers, so the total stack height can be checked at quotation.
6. Handling and packing: Thin washers nest and bend easily. Custom washer etching parts should be packed flat in counted bags, and the count method should be agreed before the first lot.