Manufacturing Process

ChemArt’s manufacturing process is called Photochemical Machining (PCM) and is unique and precise. It is comprised of the following components:

Photochemical Etching - Often called photo chemical machining or chemical milling, ChemArt provides a state of the art facility with etching capability from the smallest jewelry findings and precision components to larger decorative and commercial applications. We etch metals in the iron, copper, nickel, and brass families using environmentally controlled processes and waste treatment protocols.

Plating - Better known as electrostatic plating, the plating process is precision tested and timed to provide for the best coverage and adhesion using chemical baths. Both plating and finish techniques can be employed. Four standard plating baths are used: gold, nickel, copper and imitation rhodium. We can also provide additional platings including different colors of gold and silver plate.

Screen Printing - Precision screen printing is accomplished with the use of semi automatic and hand -operated screening equipment. We can register up to 19 colors per piece with precise detail. We have perfected the art of trapping within .005+/- registration and line weight of .007. The use of epoxy paints and curing processes turn out a high quality component or keepsake.

Assembly - Full metal sheets containing 30-40 ornaments are received from the plating and screening department. The ornament pieces are cut by hand, deburred on a rubber wheel, inspected and several parts assembled together to make the ornament, using a sample as a guide. After the ornament is completed, it is strung with a gold cord or ribbon, placed in a handsome gift box ready to be shipped to customer.

For more information please view our Making of an Ornament movie and our Advantages of the PCM process page.

The PCM process itself involves multiple processes to form a pattern on the metal surface and then subjects the masked part to the etching solution. Metal thicknesses between 0.0005" (0.0127 mm) to 0.0600" (1.500 mm) are typical, although we have the capability up to 0.0900". The maximum size of the metal sheet is usually 24" (0.6m) X 24" (0.6m), although 24" x 30" (0.76m) is available. Size can actually be as large as one's imagination and process creativity allows. For jobs outside these specs contact us for further information.

The metal is first cleaned of any contaminates such as machining oils, oxidation or fingerprints. It is then coated with a photosensitive resist that chemically alters when exposed to a UV light source. The chemical alterations cause the resist to act differently when immersed in a developing solution thus forming a pattern of clean metal and masked metal areas.

Once the masked image is formed, the metal is immersed in the etching solution. The solution type depends on the type of metal to be etched. It is typically either strongly acidic or caustic. The chemistry of the etching solution has different effects on the metal such as etch time, surface smoothness and resist undercut. Therefore, it is usually tightly controlled within specific chemical and physical parameters.

Spraying the etching solution onto the surface of the metal greatly enhances the etching characteristics. The metal is etched to a specific depth or dimension as required by the CAD drawing. Tolerances are typically ±10% of metal thickness, but depend on a variety of conditions, especially metal thickness. Metals that are typically etched are copper alloys, steel alloys, and nickel.

Because the metal can be etched to different depths, score lines can be placed in the design for precise and easy bending of the piece. Raised letters, features or company logos can be incorporated into the design with minimal considerations. The metal part can be etched from one side but is more commonly etched from both sides after the image is precisely aligned by top and bottom photo tools.

After the etching process is complete the photo resist is removed in a stripping solution resulting in a clean, residue-free surface. The part is then ready for subsequent processing, such as forming, plating, anodizing, etc.

The etching process tends to round off both inside and outside corners of the metal. The smallest inside radius diameter is approximately equal to the thickness of the metal while the smallest outside corner radius is equivalent to 75% of the metal thickness. If desired, the rounding off can be compensated for in the photo-tool by adding serifs at the required positions to overcome the etching effects.

Overall, the smallest metal feature width should be at least the thickness of the metal and practical hole sizes should be 110% of the metal thickness.

Often Photo Chemical Machining is confused with chemical milling. This is because both processes utilize etching solutions to reduce the metal dimensions. During the machining process, the etching solution causes an oxidation or dissolution of the metal from unwanted areas. Consequently, the etching solution reduces to a lower chemical state and becomes "spent". Chemical milling is used to reduce the weight or dimensions of a 3-D part that was formed by a previous process.