Chemical etching, also known as photochemical machining, photo etching, and chemical machining, refers to the process by which sheets of metal are cut into precise pieces using the application of a photoresist and phototool and then cut with some form of acid. It is a highly efficient form of cutting metal pieces, but because there are not many shops in the United States, it is relatively unknown compared to other manufacturing processes. Shops like Photofabrication Engineering Inc. have to follow a number of environmental, government, and internal standards, however, meaning that despite the efficiency of the process, it is not an industry, which is easily entered into.
Most chemical etching shops have to follow strict water standards, which includes using entirely aqueous solutions and processing waste water appropriately. Water is often even cleaned before its usage in the shop. Chemical etching also requires very special equipment, though many components to the process are very inexpensive, such as phototools, which only cost between 300 and 400 dollars. There are many different processes for cutting out flat pieces of metal, but chemical etching is one of the most precise.
For example, shops that punch or stamp metal use a different hard piece of metal to cut a tool. However, if the material that is being cut is much harder than the tool used to cut it, it wears down equipment very quickly. It can also produce burrs, which are small pieces of metal still attached to an already cut sheet. Often, additional processing is required to remove burrs, and this extra processing can increase manufacturing costs significantly.
There is also laser cutting, which directs a laser through a set of optics to cut a material. Laser cutting is also similar to plasma cutting and electrical discharge machining. These forms of cutting metal often thermally stress a piece of metal, which can create distortions from melting. These forms also produce a significant amount of heat and can be a drain on energy. Laser cutting also has some restrictions on the materials that can be used. Both forms also only support very thin gauges of metal.
Another type of metal cutting is waterjet cutting, which uses a very high pressure jet of water to cut through almost any material. Water can potentially be mixed with another abrasive material, depending on the shop and the material being cut. Harder materials like granite or metal require the addition of the abrasive substance. It has the advantage of not distorting the material being cut the same way that laser, plasma, or EDM cutting can.
However, unlike chemical etching, waterjet cutting can be more time-consuming, and is much more expensive due to the need for very specialized equipment and the cost of abrasive substances. While every metal cutting or etching process has distinct advantages and disadvantages, chemical etching has the benefit of being very low cost, extremely efficient, and very versatile. It also does not produce the same distortions that other methods can, making it a very precise method for cutting complex metal pieces in manufacturing.