Chemical etching materials: A Q&A guide

Chemical etching has the ability to manufacture burr and stress-free precision metal parts with complex geometries, while maintaining the flexibility to make last-minute design changes quickly.

Chemical etching is a metal machining technology that has numerous advantages over traditional sheet metalworking processes, key among which is its applicability to the widest range of metals and alloys — even those that are difficult to machine.

What are the benefits of chemical etching?

A: Chemical etching has the ability to manufacture burr and stress-free precision metal parts with complex geometries while maintaining the flexibility to make last-minute design changes and produce prototypes quickly. The use of inexpensive and easily re-iterated digital “photo-tools” allows for low-cost trial and error of design configurations, again often not possible with other methods.

Which materials are suitable for chemical etching?

A: Virtually any metal can be chemically etched, but as with most metal machining processes some are easier to etch than others. Demand from industry often focuses on metals that have attractive attributes, and it is with these metals that Precision Micro’s efforts are focused to ensure its processes are developed in line with its customers’ market demands.

How do you etch titanium?

A: Titanium is lightweight, strong and has excellent fatigue performance, as well as offering high resistance in aggressive environments. These favourable properties, however, prove to be a problem when machining.

Titanium’s high strength, low thermal conductivity and chemical reactivity with traditional tool materials (at elevated temperatures) significantly reduces tool life when machining. Its relatively low Young’s modulus leads to spring-back and chatter, causing poor surface quality on the finished product. In addition, during turning and drilling, long continuous chips are produced, which can lead to entanglement with the cutting tool, making automated machining challenging.

The use of chemical etching overcomes many of these issues, but even etching titanium is difficult as the metal forms a protective oxide coating when exposed to air meaning it cannot be etched with standard etch chemistries. To overcome this, Precision Micro has developed a propriety process, investing in specialist equipment and process chemistry to produce etched parts comparable in quality to those produced in more conventional materials.

Today, Precision Micro is one of the few companies in the world that can etch titanium on a production scale, supplying biocompatible medical devices to industry leading OEMs, such as cranial and dental implants, which benefit from complex openings with depth-etched countersink features.

How do you etch aluminium?

A: Aluminium exhibits many of the attributes of titanium — notably its high strength to weight ratio and natural corrosion resistance — but whereas titanium is stronger and more corrosion resistant than aluminium, aluminium has a better fatigue limit, which makes it ideally suited to aerospace applications.

When conventionally machining aluminium, there are a number of problems, the biggest being what is termed “the built-up edge” — basically the welding of work-piece material to the tool edge, and the subsequent loss of effective geometry which causes increases in cutting forces and quality problems such as scratches in the surface and cloudy finish. For many suppliers, aluminium is also difficult to etch effectively as the heat energy it releases during etching often results in a rough, granular edge.

As with titanium, Precision Micro has developed a method for etching aluminium and its alloys, producing edge profiles comparable with those etched in stainless steel.

As an AS 9100 accredited supplier, Precision Micro etches components for a wide range of aerospace applications, including lightweight helicopter air intake grilles and heat transfer plates used in aircraft dehumidifiers, the latter often requiring multiple designs which can be set-up cost-effectively.

How do you etch stainless steel?

A: While the likes of stainless steel, copper and nickel are less troublesome to etch, they still require the application of experience and significant investment in processing technologies to optimise customer outcomes.

Due to its versatility and range of available grades and tempers, stainless steel is used in a wide variety of applications.

Precision Micro etches more than 2,000,000 steel components each month from austenitic (300) and martensitic (400) series steel grades, as well as specialist grades including Sandvik Chromflex strip steels.

Precision Micro specialises in a number of stainless steel etching applications, including meshes, filters and sieves (where cost does not increase with design complexity) flexure springs for ABS braking systems, medical biosensors and fuel injection systems (etched springs are burr and stress-free meaning they can function for longer) and bipolar plates for liquid-to-liquid or liquid-to-gas heat exchange (complex channels can be etched into plates whilst remaining perfectly flat).

How do you etch copper?

A: As a relatively soft metal, copper etches quickly in standard etch chemistries, whereas contact machining processes can distort the metal, altering its properties.

Copper and its alloys are highly conductive, durable, ductile and malleable, meaning it is well suited to 2-D and 3-D electronics components.

Precision Micro etches thousands of 3-D electrical contacts, pins, terminals, EMI gaskets, shielding, lead frames and connectors each month for high-value automotive, electronics, aerospace and medical product applications.

How do you etch nickel?

A: Nickel exhibits high resistance to heat and corrosion, though again etching is relatively straightforward with standard etch chemistries.

Nickel silver is the most cost-effective material choice for electronics shielding as it can be soldered, will not oxidise and requires no additional plating. Digital photo-tooling offsets expensive press tools, and bend lines can be incorporated so EMI/RFI shielding components can be formed by hand.

Inconel is a high-temperature nickel-based super-alloy which offers superior heat resistance and exhibits excellent resistance to corrosion, pressure and oxidation. It is these properties which make it difficult to machine and indeed etch. However, as a “hard-to-machine metal” Precision Micro has developed a process for chemical etching Inconel, producing microfluidic plates with complex etched channels and flow discs that come into contact with corrosive gases.

Why should I choose Precision Micro as my chemical etching supplier?

A: Success in etching any metal is down to the experience and skill of your chosen chemical etching partner. Precision Micro has well over 50 years of experience and is Europe’s market-leading chemical etching company. Its continual investment in research and development of chemical etchants and process parameters means that today, even the most challenging metals can be processed in volume and to exacting standards in terms of tolerance and accuracy. All of this is underpinned with robust quality management systems, with its etching process accredited to ISO 9100, ISO 13485, IATF 16949, ISO 14001 and AS 9100.

Go back