Photochemical machining

This process can offer economical alternatives to stamping, punching, laser or water jet cutting, or wire electrical discharge machining (EDM) for thin gauge precision parts.

The process starts by printing the shape of the part onto optically clear and dimensionally stable photographic film.

The etchant is typically an aqueous solution of acid, frequently ferric chloride, that is heated and directed under pressure to both sides of the plate.

Industrial applications include fine screens and meshes, apertures and masks, battery grids, fuel cell components, sensors, springs, pressure membranes, heat sinks, flexible heating elements, RF and microwave circuits and components, semiconductor leadframes, motor and transformer laminations, metal gaskets and seals, shields and retainers, electrical contacts, encoders and light choppers, EMI/RFI shields, jewelry and washers.

Due to the cost of hard tooling for stamping and fine blanking, significant volume is required to justify the expense.

Some parts, such as semiconductor leadframes, are so complex and fragile that, despite volumes in the millions of pieces, they can only be produced by photo etching.

In general, steel, copper or aluminium workpieces with a thicknesses up to 0.020 in (0.51 mm), part costs will approximate $0.15–0.20 per square inch.