Photo etching aerospace components

The aerospace sector, like the automotive sector, is seen as one of the backbone industries in many industrialized countries in the world. Fierce competition is a characteristic of the niche, which is driven by imperatives such as cost control and speedy time-to-market cycles. While the commercial aerospace sector is prone to recessionary contraction, this is to an extent offset by the more robust military and defense markets.

Aerospace airframe and engine original equipment manufacturers (OEMs) constantly demand dramatic reductions in product development lead-times and focus on eliminating waste from all processes in order to remain competitive. This pressure has an unintended effect on all supply chain companies, which have to slash product development cycle lead times themselves, while adhering to strict regulatory controls and the demand for stronger, lighter, and more complex components.

Supply to the aerospace industry is relatively low in terms of volume when compared to the consumer industry and other industry sectors. As a result, innovation and cost differentiates suppliers because of the lack of economies of scale from mass high volume manufacturing processes. Demand from aerospace manufacturers is chiefly driven by safety, product reliability, and cost, with secondary demands for weight concerns and aesthetics.

Pressure on lead times requires analysis of engineering processes, process improvement, and waste reduction, and a concerted amount of attention at the design stage of product development is the only way to achieve these results.

So, when it comes to precision and micro parts for aerospace end-use applications, aerospace supply chain OEMs need to engage with expert micro manufacturing companies at the earliest stages of product development.
 

Maximizing innovation

Lead-time pressures in the aerospace sector mean that concurrent engineering is standard, with the concept of over-the-wall product development being replaced by different departments working in parallel. With expertise at the design, tooling, manufacture, assembly, validation, and measurement stages of the micro product and component development process, the right company can minimize lengthy and costly design reiterations. Cost-effective and timely manufacturing solutions can be exploited through use of photo-etching, one key characteristic of which is digital tooling, which allows for inexpensive design changes without costly and time-consuming re-cutting of tool steel.

When it comes to cost concerns, the onus on aerospace manufacturers is to reduce weight, so the drive toward miniaturization is key, as is the use of lightweight materials such a titanium and aluminum. Aerospace suppliers need to be able to tap into the latest in material and process R&D, by partnering with companies that have experience with cutting-edge processing opportunities.

Because of the highly dangerous environment in which many aerospace components work, there is no room for error in design or manufacture. Micro-tolerances, metrology, and security capabilities with military and aerospace components are vital for project success.
 

Cost-effective, highly accurate

Photo etching is a versatile and increasingly sophisticated metal machining technology with an ability to mass manufacture complex and feature-rich metal components. The process uses photo-resist and etchants to chemically machine selected areas accurately and is characterized by retention of material properties, burr free and stress free parts with clean profiles, and no heat-affected zones.

Coupled with the fact that photo etching uses easily re-iterated and low-cost digital tooling, it provides a cost-effective, highly accurate, and speedy manufacturing alternative to traditional machining technologies such as metal stamping, pressing, CNC punching, and laser and water-jet cutting.

Traditional machining technologies can produce less than perfect effects in metal at the cut line, often deforming the material being worked, and leaving burrs, heat-affected zones, and recast layers. In addition, they struggle to meet the detail resolution required in the ever smaller, more complex, and more precise metal parts that aerospace device OEMs require. There are instances – typically when an application requires multiple millions of parts and absolute precision is not a priority – when these traditional processes may be the most cost-effective. However, if OEMs require runs up to a few million, and precision is key, then photo etching with its lower tooling costs is often the most economic and accurate process available.

Another factor to consider in process selection is the thickness of the material to be worked. Traditional processes tend to struggle when working with thin metals, stamping and punching being inappropriate in many instances, and laser and water cutting cause an unacceptable degree of heat distortion and material shredding. Photo etching can be used on a variety of metal thicknesses and can work on ultra-thin sheet metal as low as 10µm foil.

Photo etching is agnostic to shapes and unusual features in products to be manufactured. The nature of the process means that feature complexity is not an issue, and in many instances, photo etching is the only manufacturing process that can accommodate certain part geometries.
 

Aerospace considerations

Photo-etching can successfully process an array of metals including aluminum and titanium, and can achieve tolerances of 10µm on metal thicknesses of 10µm to 1.5mm.

Typical aerospace components include heater elements for wing de-icing, heat exchanger plates for aero engines, stator and rotor laminations, and air intake grilles. A wide range of electronics components are also manufactured using photo etching, including lead frames, EMI/RFI shielding, precision connectors and contacts, and mechanical consumables such as springs and washers. The process is also suited to decorative interior trim for commercial and private aircraft.
 

Conclusion

Photochemical etching is precisely suited to applications where the requirement is for small, precise, complex, feature-rich parts with no burrs, and no stress related changes in the metal. Use of digital tooling ensures that multiple tooling iterations, often necessary to perfect the precise nature of intricate metal parts, are not costly or time intensive. The consistency of the process means no time consuming and potentially costly retooling and revalidation are necessary. For many aerospace applications, these attributes combine to make photochemical etching the manufacturing process of choice for especially critical and exacting applications.
 

Precision Micro
www.precisionmicro.com

About the author: Albert Tsang is the technical manager at Precision Micro, Birmingham, United Kingdom, with 13 years experiences at the company. He can be reached at +44 (0) 121 380 0100 or info@precisionmicro.com.