Chemical machining (also known as photo chemical machining or PCM, photofabrication, or photo chemical milling) is a process through which decorative metal items and precision metal parts are formed.
Photo Chemical Machining is often used in the production of:
- Decorative ornaments
- EMI/RFI shielding
- Medical implants
- Fan screens for computers & other electronics
- Battery anodes & cathodes
- Step & flat lids
- Heat plates and sinks
- Fuel cell plates
- Filters or strainers
- Light encoders
- Lead frames
The Benefits of Chemical Machining
- No effect on the metal properties
Chemical Machining has no effect on the ductility, hardness, or grain structure of the metal. It also places no stress on the material, so that the metal is just as durable after the process as it was before.
- Burr free metal parts
While other processes may leave burrs on the finished product (impacting the functionality of precision parts), Chemical Machining produces completely burr-free parts, eliminating the need for time consuming burr removal processes.
- Low cost tooling
The tooling process can be accomplished quickly and affordably. As there’s no “tool wear” of the phototools, replacement costs are eliminated.
- Quick turnaround & Affordable short runs
Significantly more affordable than alternative methods, chemical machining makes it possible for a customer to test and prove new designs. In addition to high volume chemical machined parts, the exceptionally fast turnaround delivered by Photofabrication Engineering makes it ideal for prototypes.
The Chemical Machining Process
Photofabrication Engineering, Inc. (PEI) has perfected the Chemical Machining process, starting with the creation of phototools from a fully-dimensional drawing or CAD file supplied by the customer. The drawing is used to produce an exactly replicated Mylar tool. Unlike the hard tools required by metal stamping, the Mylar tool is impervious to tool wear, saving you money on the tooling process.
Once the tool is created, the chemical machining process continues:
Preparation of the Metal:
The metal is chemically cleaned of all foreign debris, dust, dirt, grease, rust, and other contaminants. This readies the material for the adhesion of the photoresist.
Photoresist, a UV light-sensitive material, is applied to the thoroughly cleaned metal sheet and processed in a yellow safe-light environment. PEI uses an aqueous dry-film photoresist – it’s more controllable than liquid types – that is rolled onto the metal sheets by a hot-roll lamination system.
Printing, Exposure & Development
The phototool image is then transferred to the metal sheet by applying the tool and exposing the sheet to UV light on both sides.
Once the image is formed, the sheets go through a conveyorized developing system that rinses-off the unexposed areas of the photoresist, while leaving resist on the areas that have to be protected from the etchant.
PEI can etch virtually any metal. The type of etchant used is determined by the particular base metal that is being etched. Examples of the types of etchants used by PEI can be found here. The etching occurs by spraying the metal sheets with the appropriate etchant, which dissolves the bare metal and leaves intact those areas still coated with resist.
Stripping & Inspection
The final step in the photo chemical machining process is remove the remaining resist from the newly created metal parts or decorative ornaments. Once the resist has been removed, the parts are cleaned and inspected to ensure they match the customer's specs and then either packed for shipment or move on for a secondary operation, like plating, welding, soldering, heat treating, forming, etc.
PEI specializes in using chemical machining to manufacture decorative items, including ornaments and bookmarks, and precision products, such as fuel cell plates and facial reconstruction implants. Located in Milford, MA, PEI’s 40,000 square ft. facility makes it one of the world’s largest photo etching company under one roof. Learn more by visiting PEI’s website, or contact PEI for a quote on your next Photo Chemical Machining project.