Page 10 - PCMI Journal July 2018
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Product designers need to appreciate that etching can truly stretch the boundaries of what is possible, not only answering key questions on product features, complexity, and efficiency, but in some instances offering enhancements of component characteristics. The process can be applied to almost any sheet metal 0.01mm – 1.5mm thick in a variety of grades and tempers, and unlike stamping does not struggle with very hard materials. Precision Micro — Europe’s market- leading chemical etching supplier — produces over 50 million components each year from over 2,000 metals types, including those considered hard to machine such as titanium and aluminium.
Standard etching tolerances are typical to ±10% material thickness, but greater accuracy can be often be achieved. Minimum component features are 0.1mm, though surface-etched features can be finer and are not defined by the thickness of the material.
Unique characteristics can be designed into products manufactured using chemical etching by taking advantage of the inherent edge “cusp” created during the process. Etch cusp can be controlled, and by so doing, a range of profiles can be introduced that allow the manufacture of sharp cutting edges (such as those used in medical blades), or conical openings, such as those used to direct fluid flow in filtration meshes.
Low Barriers to Entry
Chemical etching not only copes well with difficult geometries, it also allows design engineers enormous flexibility, facilitating the adjustment of designs right up to the point of manufacture due to the use of digital tooling.
Digital tooling is hugely less expensive than the hard steel tools needed for punching and stamping (etch
tool costs around £100-£200), and is also extremely quick to create and adapt, making the process ideal for prototyping. Also, as the tooling is transferred to metal through a contact printing process, there is no tool wear ensuring that the first part produced is identical to the last.
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More often than not, when using stamping, part complexity adds cost, whether in low, medium, or high volume applications. The complexity of a product means the necessity for a complex mould tool, and complex tooling means increased costs, increased potential for tool failure, and increased lead-times for satisfactory completion.
Chemical etching is unaffected by the level of tool complexity, and it makes no difference in terms of costs or lead-time how complex the geometry of the part is and therefore the complexity of the digital tooling.
Flatness, Burrs and Stresses
Etched components are completely flat, making the process especially well suited to the manufacture of parts that require subsequent assembly by way of stacking and bonding, such as motor laminations, fuel cell plates, and heat exchangers.
Unlike stamping, there is no degradation or distortion of the metal being processed, and all parts are therefore burr and stress-free. Typical components specified include safety critical flexures for use in ABS braking systems and fuel injection, which must actuate millions of times without failure.
Conclusion
Photo etching is best suited to complex parts with high degrees of accuracy, or parts which rely on the integrity of the material. In extremely high volume runs where the tooling expense is justifiable, and where designs are not overly complex, stamping typically represents a more economical process.
As a global leader in photo chemical etching, Precision Micro has been active for over 50 years. However, it takes more than age to be a market-leader. Continual investment in its technologies, often driven by its customers engineering challenges, has ensured Precision Micro has remained at the forefront of chemical etching technology and remains the world leading supplier of intricate, often safety critical, precision metal parts and components for leading names across a range of high-tech industry sectors.
Issue 131 July 2018
PCMI Journal 9