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What’s the Difference Between Chemical Etching and Micro-Stamping?

In this article we’ll take a look into the key differences between chemical etching and micro-stamping in relation to manufacturing precision metal parts. Both are subtractive techniques that can achieve similar results but there are some differences which we’ll go over. Firstly we’ll do a quick overview of what exactly is involved in each process. 

Chemical etching is a manufacturing technique whereby a chemical etchant is applied to a sheet of metal and begins to dissolve the unwanted parts – the desired shapes and patterns are protected by a photoresist lacquer that’s already been applied. Once the metal has undergone the etching process, all that’s left are the precisely measured metal parts. 

Micro-stamping involves carefully constructed stencils that are custom-made for each requirement set by the client or industry that they’re needed in. The stamping tool shape or design is fabricated and then begins the multi-stroke stamping process to punch out the precision metal parts.

Accuracy

There is rising demand for precision metal parts as so many industries from automotive to medical require such parts for their appliances. And as the metal components are getting smaller and smaller in order to fit into the increasingly compact devices, the need for the parts to be flawless and also complex in design is essential. This is where chemical etching really shines because it’s able to reach apertures and measurements as small as 25μm without any compromise on quality or reliability. In fact, because it’s a chemical process, it means that the manufacturing method is repeatable across an entire production run without any defects or negative changes to the metals’ structure and integrity. 

Micro-stamping is also repeated throughout a production run many hundreds of thousands, even millions of times. The one problem is that while it’s also extremely accurate, because it’s a high energy process there can be slight warps or burrs on the metals through high heat and friction. This means that a secondary production process is required to deburr the metal parts at the end of their production run. This might not suit certain industries that require absolute precision. 

For example, bipolar fuel cell plates that require fluidic channels are etched into the plate surface. The benefit of doing this with chemical etching is that there are no tooling marks that might otherwise affect a liquid’s flow which is ideal for this specific requirement. The untampered metals that are the final product of chemical etching have many applications that really benefit from this process.

Design Adaptability

The ability to create complex and precise metal parts is ultimately thanks to the fact that chemical etching uses CAD software to create the metal part and then through the software, apply the stencil directly to the sheet metal. So it’s an entirely computer-controlled process which allows for incredibly high accuracy and precision wherever needed. Micro-stamping is also able to produce high accuracy parts but it is limited by the very nature of it being a stamp: the press punches out the metal parts with very high pressures to cut through the metals. This is a fantastic process for certain applications but if you want absolute design flexibility, chemical etching is the more suitable option.

Value 

There is quite significant investment involved in both processes, as with any large scale manufacturing process, but micro-stamping also requires the added cost of the initial tooling. Of course, once this is established, the production run can then begin on a massive scale which means that usually with larger runs, this cost is fairly quickly absolved.

Chemical etching can also produce industrial scale results within a short space of time as the process is so streamlined. Unlike other techniques like water-jetting or laser etching, the chemical spray acts at the same time across the entire sheet metal which means that it obviously has the advantage over these other two techniques that only depend on multiple lasers or multiple jets to work concurrently. 

Another factor that helps with value is its efficiency which means that there’s no post production required as the metal parts are stress and burr-free. While other techniques require a secondary process to have the parts ready, etching requires little further action for them to be ready. This is also reflected in the cost as it’s such an efficient process, the metal parts can be produced quicker. 

Total Lead Times

This is another area where chemical etching excels thanks in part to its speed in prototyping. While other techniques may require gradual retooling or adjusting physical parts, the chemical process only involves adjustments on computer software to make any changes to the physical object. Prototyping can be only a matter of days in some cases as cycling through various iterations until you settle on the right one takes little time. As mentioned before, it’s a stress and burr-free process which again is another factor in reducing overall lead times. It’s a very efficient process which is why the lead times are so short. 

Micro-stamping, once it gets started, is another quick process (depending on production scale of course) as the presses can do thousands of strokes per minute. There is a need for deburring at the end which has to be taken into consideration but it’s always worth checking with the manufacturer to see what options are available for your specific needs.

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