Thanks to the rising popularity of chemical etching and in particular, etched metals there’s now a great deal more opportunity for these products to be used across a wide range of industries. It’s because of the very process of chemical etching that means it has such wide applicability. By using chemical etchants to treat certain metals, we’re able to achieve incredibly fine details such as a positional tolerance of up to +/- 25 μm. This manufacturing technique has the capability to produce intricate designs and shapes along with leaving the metals structurally unaltered which benefits a number of demanding industries such as medical or automotive. All these reasons and more (that we’ll explore later in this article) explain how and why chemical etching has become such a dominant force in the precision metal parts manufacturing industry.
What are the Uses of Chemically-Etched Stainless Steel?
Before we go into detail about the etching process, let’s take a look at some of the various uses of chemically-etched metals. With the continuous demand for smaller and smaller precision parts to fit in cars, computers, household appliances, etc. there is, of course, concurrent demand for the manufacturing of these parts. Products like fuel cell plates, speaker grilles, encoder discs, filters and many more are made using this process as it’s one of the most reliable and efficient techniques to achieve the necessary high-quality results.Not only this but chemical etching is perfectly suited to completing this process on an industrial scale.
Where many etching techniques fall short in terms of end product, chemical etching is able to achieve perfect end results without the need for time-consuming secondary processes. In fact, the metal comes out more or less as a complete end-product which translates to greatly reduced production times. The process is already quick for the simple fact that while laser etching, for instance, obviously requires more lasers to produce industrial-scale results, with etching it works simultaneously across the entire sheet metal so the production time is greatly reduced when compared to others.
How to Etch Stainless Steel
In essence, chemical etching is a subtractive technique meaning that it uses temperature-controlled chemical etchants to selectively dissolve and remove the unwanted material. In order to keep the parts we want and remove those we don’t, a stencil is created by a photo-resist which then protects specific parts of the metal. Here we’ll explore the exact process we employ at Tecan in a bit more detail:
1 – Clean: Quite straightforward, the sheet metal needs to be cleaned to remove any surface contaminants. This is a key part of the process to ensure that the rest of the process doesn’t have any potential contaminants to hinder it.
2 – Laminate: Completed within a class 6 clean environment. The photo-resist stencil is then applied to the metal without any interference. The photosensitive coating protects the parts of the metal we want to keep.
3 – Expose: In order to harden the photoresist into the desired stencil we require, the sheet metal is exposed to UV light. In this example, the white sections are the hardened photo-resist while the black parts are the exposed metal sections which will soon be treated.
4 – Develop: Here we develop away the unexposed sections which then leaves the bare metal underneath, now ready to receive the chemical etchant in the next step.
5 – Etch: Now that everything has been properly prepared, we can spray the etchant over the sheet metal at high pressures which will then remove the exposed metal.
6 – Strip: At this last stage the photo-resist is removed to reveal the finished design which is burr and stress-free as well as structurally untampered. As you can see, the process is quite simple which means that it can be repeated on an industrial scale.
Almost any metal can be used in chemical etching manufacturing (please do check with the manufacturer first though!) but some of the most common include:
- Carbon steel, mild steel, spring steel, tool steel
- Aluminum: aerospace and aircraft grades
- Martensitic, austenitic, ferritic and stainless steels
- Brass, beryllium copper, phosphor bronze and nickel silver
- Nickel alloys: inconel, mu-metal and alloy 42
What are the Benefits of Using Chemical Etching?
As is probably clear by now, one of the main benefits of this manufacturing technique is the final product which is ready-to-go almost directly from the production line – it requires very little to no post-production. A knock-on benefit of this is that the total cost is significantly reduced (when compared to other similar techniques) because of the quicker production times. This is also true for the very beginning of the project as it’s a quick process from prototype to final design. Because the stencil is applied directly from the design of computer software, editing and making changes is fast and easy.
The other options for producing these types of product are often high-energy processes like laser-etching or metal stamping which can negatively affect the ductility and structure of the metal. It’s clear that chemical etching offers a great many benefits: reliability, precision, adaptability and repeatability. For these reasons and more, chemical etching has become one of the most efficient and capable manufacturing methods for producing precision metal parts.