This article will look at some of the key differences between two commonly-used metal etching/ cutting techniques. Chemical etching is a subtractive method that removes unwanted parts by using a stencil to achieve the correct shape while micro-stamping uses high pressure machinery to stamp out the desired shape in the metal. Both have similar capabilities and produce precision metal parts but here we’ll take a look at some of the differences between each. It’s also a great idea to contact the manufacturer first to see what options are available for your specific needs: at Tecan for instance, we’ve worked with our clients to find innovative solutions whatever the request may be.
Flexibility of Design
One of the most flexible options in terms of stencil and pattern complications is chemical etching. Thanks to the very nature of the production process, it’s possible to create micro precision metal parts on a large industrial scale. The etchant is applied to the entire sheet metal which then erodes the unwanted metal, leaving the desired parts untouched. As the stencil is applied as a layer of photoresist on the metal, we’re able to create shapes and designs that feature a lot of intricacy from fine-mesh medical sieves to bipolar fuel-cell plates.
The example of the fuel-cell plate is another good one that identifies the level of exact detail possible. By using chemical etching to create the plate channels, it means that they’re completely free of any tooling marks or stresses on the metal’s surface which is ideal for transporting gases or liquids through, as there’s nothing impeding or influencing their movement or direction. With other etching/ cutting methods like mirco-stamping, there can be leftover marks on the surface of the metal that would then reduce the part’s efficacy.
This is another area where chemical etching has a strong advantage thanks to, as mentioned above, the etchant being applied to the entire sheet metal rather than in parts. This means that the manufacturing time is greatly reduced when compared to other techniques. It’s not only thanks to the chemical reaction taking place at once and acting on the total surface area but it’s also thanks to the very nature of the chemical etching process which means that the end result is both stress and burr-free. There is no need for any post-production tidying or smoothing out rough edges as the process doesn’t affect the metal’s properties, ductility or integrity. This in turn is then reflected in the lead times which are reduced thanks to the overall efficiency of the process.
Another aspect that leads to a reduction in lead time in the speed of prototyping to finalised product. Because the stencil is created on CAD software and it’s sprayed onto the metal, there is huge scope for quick and easy alterations until the exact match is created. Stamping, on the other hand, requires tooling to create the actual mould; essentially from which the metal parts can be made from. This can take some time longer than chemical etching but then, once the machining is complete, the process can be repeated on a massive scale and with great speed too. It just depends on what you require whether to choose stamping or chemical etching.
There is increasing demand for precision metal parts that need absolute reliability for use in industries such as aerospace or medical where the part needs to function correctly. It’s this precise reason that both manufacturing methods are used across these two industries (and more) as they’re each able to provide very high quality results. Both are able to achieve precision micro metal parts and chemical etching can reach measurements as small as 25μm which is becoming more and more commonplace where certain appliances require such micro precision.
A key feature in terms of standard of quality and accuracy is that with chemical etching the metal’s properties and integrity remain untampered. Other techniques, like micro-stamping, can leave burrs or stresses on the surface of the metal which doesn’t suit certain requirements. To go back to the bipolar fuel cells; they require the channels to be perfectly smooth for unaffected movement of liquids or gases. The untampered surface, made by the chemical etching process, is what makes them so practical and efficient within their given application.
Stamping does require significant investment because of initial tooling costs whereas chemical etching can go straight from idea to prototyping within days. Of course, once the tooling is set up, the stamping technique can be put on a massive industrial scale which is then reflected in the price as large-quantity orders are more economical. Chemical etching can certainly produce industrial-scale production runs but micro-stamping, once the tooling is complete can produce millions of units which then makes it more affordable.
Chemical etching presents great value due to the fact that the manufacturing method is so efficient that it requires no post-production deburring or tidying. This is then reflected in the cost as the lead times are drastically reduced because the process is able to move so quickly from start to finish. The chemical process is easily repeatable which is also true for stamping but then maintenance has to be taken into consideration for the high pressures the machines are put under. Chemical etching obviously requires maintenance but is less expensive in terms of replacing machine equipment for example.
Each different technique has their place within manufacturing precision metal parts and for that reason it’s always advisable to get in contact with the company beforehand to see which service meets your needs best.