Firstly we must acknowledge that we’ve reached this point of industrial-scale chemical etching thanks to the discovery of hydrofluoric acid in the late 18th century by Swedish pharmaceutical chemist Carl Wilhelm Scheele. More specifically when the acid began to be used to etch glass in the mid-1800s. Since then it’s come forward leaps and bounds and the process of chemical etching on various metals can achieve incredibly precise and accurate results that are used across many industries. Very often the chemically etched parts are employed in the aerospace or medical industry where there can be no margin for error nor any compromise to the metal’s integrity.
The Process of Chemical Etching
The basic process of chemical etching on metals is that a photoresist is applied across sheet metal for the design that is required. The photoresist is applied in the manner of a stencil so the patterns that are desired have the photoresist sprayed on which protects that part of the metal while the etchant will eat away at the unwanted parts. While other metal machining involves high energy processes like stamping or lasers that can affect the metal’s integrity, the chemical process doesn’t alter its structure at all. In fact it doesn’t leave any burrs or stresses at all so the production time is also reduced thanks to the manufacturing process’s efficiency.
As the process involves applying a stencil over the entire sheet, it means that it gets worked on simultaneously. The production times really benefit from this quick and efficient manufacturing process that cuts lead times down massively. This is also beneficial for working on the prototypes before putting the approved iteration into production. Once prototyping is done, large volume production runs can begin immediately which is oftentimes a great deal quicker than any other etching methods.
There is only the initial tooling cost required for chemical etching unlike other etching processes which require regular maintenance and replacement parts after they’re worn out from continued use. There is, of course, required maintenance for any large-scale manufacturing but because of the very nature of chemical etching, machines and parts are not worn down by continuous use as compared to others.
Intricate Precision
Chemical etching can achieve details as small as 30 μm which allows for absolutely precise features without any signs of the manufacturing process unlike laser cutting which obviously has to apply massive energies directly to the metal in order to cut it. For this reason, chemical etching is being chosen by industries that require precision and reliability such as the ones mentioned above and as a result of its accuracy and success, chemical etching is being picked by more and more industries that expect and require such parts for their products.
Rapid Lead Time
As touched on briefly earlier, the speed of production is really advantageous when time scale is a factor. This is also reflected in the cost as the times are so short it means that less labour is required and then more etching can be done. The lead times are especially useful if you’re still prototyping the form of the final product because it’s quite simple enough to adjust the stencil and etch the new design onto a sheet metal. If there’s a certain shape or requirement that you require there’s no doubt that the manufacturer will work with you to find a solution. Here at Tecan, we endeavour to meet every request and have succeeded in creating a number of precision cut solutions for our clients.
Versatility
One particular and recent development has been the process of etching channels into the metal for fluids to run through. By applying the photoresist on both sides of the metal, we can achieve channels that are great for non-directional fluids as there are no burrs. The channels therefore allow fluids to flow without obstruction because, as we’ve mentioned, the manufacturing process leaves no burrs or any unwanted malformations.
Chemical etching’s versatility is one of the main reasons why it’s so often chosen to produce a plethora of intricate parts such as grilles, flow discs, heat exchangers, filters and bipolar fuel plates to name but a few. Chemical etching has really increased in popularity as a result of the above benefits that essentially improve on other etching manufacturing.
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