With the ever-increasing popularity of chemically-etched metals, there’s more and more opportunity for these products to be used in a wide range of industries. The reason for its wide applicability is thanks to the process of chemical etching itself. By using etchants to treat certain metals we’re able to achieve incredibly fine detail, precise measurements as small as 25 μm. Because of the capability to produce intricate and structurally unchanged results, chemical etching has become a leading force in the precision metal parts manufacturing industry. In this guide, I’ll hope to shed some light on the process.
What is it Used For?
Before we look at the process, let’s investigate what it’s actually being used for? With the ever-increasing need for small precision parts to fit in computers, household appliances, cars etc. there is a massive increase in demand for chemically-etched parts. Products like speaker grilles, filters, fuel cell plates, encoder discs and many more are all made using this process as it’s one of the most reliable methods to get the necessary high-quality results. Chemical-etching is perfectly suited to deliver reliable precision on an industrial scale.
One of the great benefits is that as part of the very nature of the process, there are no burrs or stresses on the metal to be tidied up after the initial manufacturing; unlike in many other etching processes. The fact that the metal comes out more or less as an end-product also means that production times are greatly reduced as well as the fact that it’s a process that’s very quick anyway because the etchant is applied to sheet metal and acts at the same time. As you can see, there’s certainly a number of fantastic benefits when using chemical etching to produce micro precision parts.
The Production Process
At its core, chemical etching is a subtractive process that employs temperature-controlled etchants to selectively corrode and dissolve the unwanted material. In order to achieve the desired shapes a stencil in the form of a photo-resist is used as an outline that protects the metal parts we want to keep. Let’s look at the process we employ at Tecan in a little more detail:
1 – Cleaning
Firstly, the sheet metal is cleaned to remove any surface contaminants. An essential step to ensure the rest of the process goes successfully.
2 – Laminating
This is done in a class 6 clean environment where the photo-resist stencil can be applied to the metal. This lamination will then protect the parts of the metal we want to keep.
3 – Exposing
The metal is exposed to a UV lamp which hardens the photo-resist into the desired pattern or shape required. In this instance, the white areas are the hardened photo-resist while the black are the exposed metal which will later be treated with etchant.
4 – Developing
At this stage, the unexposed parts are developed away which then leaves the bare metal underneath, ready to receive the chemical etchant.
5 – Etching
The etchant is sprayed all over the sheet metal at high pressure which removes the exposed and unwanted metal.
6 – Stripping
Finally, the resist is completely removed to reveal the desired shape: burr and stress-free. This is the reason why it’s a simple and easily repeatable process that meets the rigorous demands of many industries.
Virtually any metal can undergo the etching process (always check with the company first!) but some of the most common include:
- austenitic, ferritic and martensitic stainless steels
- mild steel, tool steel, carbon steel, spring steel
- aluminum: including aerospace and aircraft grades
- nickel alloys: mu-metal, inconel and alloy 42
- phosphor bronze, brass, beryllium copper and nickel silver
The Benefits of Using Chemical Etching
As mentioned throughout, one of the key benefits of using chemical etching is the end result which is ready-to-go almost directly from the production line. A result of this is also that the total cost is reduced because of the lower production times. It’s also a quick process from prototype to final design; adjustments can be made quickly and on-the-go as it’s only the computer programme that needs altering.
By using chemical etching it removes the need for any high energy processes like laser-etching or stamping which can tamper with the ductility and structure of the metal which of course isn’t a desired side-effect. Chemical etching leaves the metal’s properties unaffected by the process which is exactly what you want when you need to rely on the final product, like in the medical or aerospace industries. It’s evident that chemical etching offers a great many benefits of use: precision, reliability, adaptability and repeatability on an industrial scale! All these reasons have served to make chemical etching one of the best solutions for precision metal parts manufacturing.
