In this article, we’ll take an introductory look into the two metal manufacturing processes of chemical etching and micro-stamping. Both are used to create precision metal parts that are applied within a number of machines/ appliances/ technical instruments across a wide range of industries. At Tecan where we specialize in the chemical etching process; our metal parts are used in aerospace, electronics, and the medical industry to name just a few. These are industries where reliability and accuracy are a requirement so the manufacturing processes have to be of a very high standard.
Firstly we’ll go over the different processes of chemical etching and micro-stamping before looking at some of the key benefits and differences of each. The chemical etching technique is basically using a carefully-formulated etchant to dissolve away the unwanted parts on the sheet metal. The desired shapes or stencils are applied via a photoresist which protects the desired parts while the rest is removed leaving the final shape at the end of the process.
Micro-stamping is a very different process as it involves physical tools and presses to remove (stamp out) the desired shapes. The stencils here have to be machined to the correct shapes and measurements for use in each metal part. The stamping shape is designed, then it has to be re-tooled onto the presses and then the multi-stroke stamping process begins.
Complexity of Design
As you might imagine, the possibilities in terms of design complexity are bound only by the parameters of the metal in the chemical etching process. As the stencils are computer-aided design (CAD) we’re able to achieve whatever shapes as long as they’re technically achievable. Thanks to the process being completely automated and computerized, we’re able to produce absolutely precise metal parts.
Micro-stamping can likewise produce fantastically intricate metal parts but it is limited by the tooling process as the stamps have to be cut to size and are therefore limited by the physical parts. This isn’t a problem for a great deal of metal parts but it is limiting for very fine-detail pieces where the apertures could be as small as 25 μm. This is where chemical etching really shines as the process isn’t limited by physical parts.
Accuracy of Each Process
As demand for precision metal parts is constantly increasing, this requires that the complexity of design along with maintaining the metal’s inherent properties is a must. Chemical etching can achieve not only precise designs but also leaves the resulting metal parts structurally unaltered. Preserving the metal’s properties, ductility and structure are absolutely essential for a great number of industries where reliance and precision are required to get the job done. Medical instruments for one need to be relied upon which is why chemical etching is so practical in this instance.
Thanks to the nature of the chemical process, this also means that it’s a repeatable process that can achieve absolute precision across the entire production run without defects or deformities. A lot of other etching or cutting techniques leave the metal parts with burrs or stresses that then require a secondary production process to remove and fix. Micro-stamping is a very high energy process as it literally stamps through the sheet metal to cut out the shapes. Because of the high energy this inevitably creates friction and heat which can warp or affect the metal. Obviously, the process is carefully controlled to avoid this but the process must be monitored closely for defects.
Cost of Production
As with any industrial production, there are initial costs to be factored into the total cost. The great thing about chemical etching is that thanks to its efficiency, this means that the lead times are reduced which is reflected in the total cost. The speed of the chemical process is also improved thanks to prototyping which in many cases can take mere days. This, as mentioned before, is thanks to the fact that it’s a CAD process that is completely computer-controlled so going through iterations until the final one is found isn’t a problem.
Micro-stamping isn’t quite as simple as the stamp needs to be constructed and tooled correctly before the production run can begin. This takes time but once it is refined, industrial-scale production can begin and it is quick once the run has started. Depending on the production scale, the micro-stamping can quite comfortably manage many thousands of strokes per minute which is reflected like thousands of metal parts. So once it gets going, micro-stamping is fantastically efficient.
Chemical etching, too, is a quick process not only because of quick prototyping and the fact that there’s no need for post-production but because the etchant is applied to and works on the entire sheet metal. As the process happens simultaneously across the entire metal surface, the designs are worked on by the etchant very quickly which again translates to reduced lead times.