Conard's Photo Etching Blog

What are the Problems of Photo Etching?

Posted by Kathleen Stillman on Feb 25, 2013 9:46:00 AM
Kathleen Stillman
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photo chemical etchingThe primary problem is a case of multiple identity disorder: photo chemical machining, PCM, photo chemical etching, photo etching, chemical etching and chemical machining all refer to the same process.  We don’t wonder why you are confused.  In speech, I always call the process “photo etching.”  However, if you want to be found, you have to be known all the different ways.

There are three additional, similar sounding processes that are NOT photo etching. 

  • Electro chemical etching (sometimes called electrolytic etching) is a process used for part marking on metal parts. 
  • The MetalPhoto process utilizes pre-treated aluminum panels to create nameplates and identification products.
  • Chemical milling is a process used to modify parts by selectively removing metal from specific areas.  Chemical milling is most often used on airframe components to reduce weight.  In this context, chemical milling may be subject to Nadcap checklist 7108/5.  Nadcap (formerly NADCAP, the National Aerospace and Defense Contractors Accreditation Program) is a global cooperative accreditation program for aerospace engineering, defense and related industries.  Nadcap covers a range of special processes with uniform standards.  Photo chemical etching is not subject to Nadcap because the etching process does not alter the properties of the material.

The biggest problem with chemical etching is that it is not well known and is little understood.

Photo etching is a metal fabricating technique that fits in a spectrum of processes that include metal stamping, CNC punching, laser and water-jet cutting  and wire EDM.  The end result of all of these processes is flat metal parts.  (Yes, I know, formed parts can be produced by stamping with compound dies, but let’s just stick with the basics.) 

Stamping and punching are processes that require hard metal tooling to cut parts from sheets of metal.  Laser and water jet use narrow beams of focused energy.  In the case of the laser, the energy comes from colimated light, and the water jet uses a pressurized abrasive slurry.  Wire EDM uses a wire electrode to burn the parts out of metal.

One of the chief advantages of photo chemical etching when compared to these other processes is that photo etched parts do not acquire any thermal or mechanical stresses during fabrication.  The unwanted metal is dissolved by the etchant and rinsed away.

Another problem with photo chemical machining is that it is a relatively rare process.  There are only about 100 PCM shops in the country and barely a few hundred globally.  Compare that to about 2,000 metal stamping shops just in the US.  Photo etching is often a better solution to fabricating flat metal parts, but too few people are familiar with the process.  This video provides a 2-minute overview of the photo etching process:

We also have to overcome the problem of the misperception about photo etching and the environment.  Photo chemical etching is closely monitored by environmental protection departments in every state where there are PCM shops.  We take environmental responsibility very seriously.  We have state of the art water treatment facilities.  Our process waste water is cleaner than the municipal water supply.  You can drink it.  We actually have to clean the city water before we can use it in the photo etching process.

Despite the problems, photo etching is a versatile and cost effective solution for producing 

Topics: Photo chemical etching, Quality