Chemical Milling
The capabilities of this metal etching process are almost unbelievable.
GALLERY - click on images to see a larger picture
There are no rags, burrs, oily residues, holding marks, or heat marks. All edges are smooth, with no shear lines. If a 'fold line' is used bend radius is 0.5 thickness on the outside and zero on the inside. Aspect ratios can approach unity.
Folding operations on small parts require a minimum of force and machinery (we have a pressbrake 100mm long). The most delicate of parts can be made.
We can work in copper, brass, bronze, nickel silver and some stainless alloys.
Above about 1.0mm undercut becomes noticeable.
Figure 1. Resist is applied to both sides of a piece of sheet metal such that the desired 'part' is covered and the unwanted metal exposed.
Figure 2. This assembly is now exposed to a suitable aggressive chemical and the exposed metal is taken into solution leaving the metal covered by the resist unattacked.
Any thickness can be made by etching down a thicker sheet, the minimum practical is about 0.02mm. Dimensional control is good, typically ±0.1mm on 0.2mm sheet and ±0.2mm on 0.9mm.
In-process control can be done by inserting calibrated 'cones' into etched holes.
Image composition is done in a graphics program and with suitable tessellation metal wastage is very low.
It is practical to go from receipt of artwork to ready for production in one day. Initiation costs reflect this time.
When compared to the cost of some press tools, the savings in time and cost are very high. An additional feature is the speed at which design changes can be made, and the cost of those changes.
A fold line, etched halfway through, controls the placement of bends and some very complex folding can be done. Complex returns and curved bends are possible (See gallery images above).
By careful use of artworks and machinery the thickness of the sheet can be varied from 100% thickness downward in selected places so the properties of the part can be varied.
Once etching is complete, the parts or panel can have additional processes such as plating, printing, presswork, embossing, PEM insertion etc.
An emulsified adhesive can be printed, and once dry, release paper can be applied. Epoxy (electrical) insulation can be printed onto electrical work — very 'heavy' tracks for printed circuit boards can be made..
Some most attractive nameplate work can be done with this technique, paint filled, embossed, over-printed etc.
