These two manufacturing processes are often put together and compared because in many ways they do the same things but there are some key differences to take into consideration when it comes to manufacturing metal parts which is what this article aims to explore. Water jetting as you might imagine forces water out of a fine nozzle at very high pressures in order to cut through various different materials similar to how a laser would cut but without any heat damage to the material’s integrity. Chemical etching applies a different process which is to coat a sheet of metal with a photoresist stencil of the design you require after which an etchant is applied which removes all the unwanted material, leaving the parts you require untouched and without any change in the metal’s integrity.
Water jetting certainly has more materials that it can be applied to such as wood, plastic or glass but generally speaking chemical etching only deals with metals of which the majority can be worked on. Water jetting has an advantage on thicker materials over 12mm as it offers better tolerances when cutting through. Where chemical etching comes into its own is the precision and repeatability of this precision on large volume runs. As the process is chemical it can create fine detail and complex shapes required in highly accurate instruments such as aerospace or medical industries. For example if we’re etching stainless steel it’s possible to go as small as 25μm, making it one of the most precise metal-cutting methods. The results of chemical etching are especially suitable when round holes, sharp edges and straight or profiled edges are desired.
Both manufacturing processes are controlled by software as the designs are created using computers so the intricacy of the end result depends only on the software. The limitations of water jetting in terms of design comes down to time as it’s done using physical nozzles it takes time to actually cut the shape whereas the chemical process is quick and as a result of it being a stencil applied to the whole sheet means it works on the whole material at the same time. This means that it’s a quicker manufacturing process from getting the initial shape right to industrial-scale production runs.
Quality and Accuracy
As touched on above, the opportunity for precision is higher with chemical etching than water jetting and as a result of the etchant chemical application, it means the end result is both stress and burr free. The metal’s integrity is left intact because the etchant is only active on the unwanted and exposed parts of the metal – this also exemplifies the level of precision. A direct result of this means that no time is spent on ‘cleaning up’ the end results as they’re ready to be employed in whatever device.
The accuracy and quality of water jetting is similarly precise but it can be limiting where the ‘piercing’ takes place as this is the first point of entry for the jet and so creates a larger hole than perhaps necessary. This is easily factored into the cutting process as the jet can start its cut into a bit of ‘scrap’ metal away from where the actual parts will be cut from. Generally speaking, water jetting is only for cutting metals all the way through as measuring the depth of the cut is a bit more complicated and cannot be relied upon with 100% accuracy. Chemical etching on the other hand, can etch a non-directional surface finish in the sheet metal which is excellent for fluid transport (among other uses). So this is another advantage the chemical etching process has overwater jetting.
As mentioned briefly earlier, the lead time for water jetting is restricted by the speed of the jet as it cuts the desired shape one by one. Using more jets does certainly reduce the total time taken but it also increases costs quite drastically. Conversely, by virtue of the very nature of the etching process, it’s done simultaneously across the entire sheet metal. This translates to shorter lead times from prototype to finished large-scale production run. Chemical etching also allows for quick prototyping to finalize the correct design which can then be put into production virtually instantaneously
As always with large-scale manufacturing, always check first with the service provider to see what options are available regarding your specific needs. There’s a great deal of versatility regarding both chemical etching and water jetting and depending on your needs one may be more suitable than the other. The manufacturer will always be accommodating for overcoming potential challenges and will no doubt work hard to ensure the desired results.