Photochemical etching components for aerospace applications

When manufacturing parts for critical aerospace applications, it is vital that the process chosen is not only cost-effective and allows adherence to time-to-market objectives, but is also able to adhere to tight tolerances and produces accurate parts at the right volume with minimal waste. 

Micrometal — a leading global provider of photochemical etching (PCE) services — has considerable experience working with the aerospace sector, which is driven by weight, cost, and time-to-market considerations. 

Aerospace OEMs must engage with companies like micrometal to ensure the efficient and cost-effective manufacture of safety-critical precision and micro components. Engaging with a qualified micro manufacturing partner early in the design cycle for new product development is vital to avoid multiple designs and tooling iterations.

Cost & time

Aerospace airframe and engine OEMs are constantly demanding dramatic reductions in product development lead times. To remain competitive, companies are focused on eliminating waste from all their processes. Aerospace OEMs have to slash product development cycle lead times, while at the same time ensuring adherence to strict regulatory controls. They are also looking to deliver lighter and more complex components.

Supply to the aerospace industry is relatively low in volume terms when compared to other industry sectors (and especially the consumer industry). Often, it is innovation and cost that differentiates suppliers, there not being the usual economies of scale from mass high-volume manufacturing processes. Demand from aerospace manufacturers is often driven by weight concerns, sometimes aesthetics, and always safety, product reliability, and cost. 

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 the results necessary for competitive supply. 

When it comes to precision and micro parts for aerospace end-use applications, aerospace supply chain OEMs need to embrace the possibilities that exist through the use of PCE, and to engage and work with expert micro manufacturing companies such as micrometal at the earliest stages of product development.

Photoetching — key takeaways

PCE is a versatile and increasingly sophisticated metal machining technology, with an ability to mass manufacture complex and feature-rich metal parts and 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 PCE 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, and 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, HAZ, and recast layers. In addition, they struggle to meet the detail resolution required in smaller, complex, and precise metal parts that medical 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 PCE with its lower tooling costs is often by far 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 applied to the working of thin metals, stamping and punching being inappropriate in many instances, and laser and water cutting causing disproportionate and unacceptable degrees of heat distortion and material shredding respectively. While PCE can be used on a variety of metal thicknesses, one key attribute is that it can also work on ultra-thin sheet metal, even as low as 25-micron foils.

It is in the manufacture of intensely complex and feature-rich precision parts that PCE finds its perfect application, as it is agnostic when it comes 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, PCE is the only manufacturing process that can accommodate certain part geometries.

Innovation, partnership & process refinement

Lead-time pressures in the aerospace sector mean that so-called concurrent engineering is standard, with the concept of “over the wall” product development being replaced by different “departments” working in parallel. With expertise in the design, tooling, manufacture, assembly, validation, and measurement stages of the micro product and component development process, micrometal can help ensure that the requirement for lengthy and costly design reiterations will be minimized. In this way, cost-effective and timely manufacturing solutions can be exploited through the use of PCE. A key characteristic of which is digital tooling that allows for inexpensive design changes without the need for costly and time-consuming re-cutting of tool steel.

Aerospace considerations
In aerospace applications, absolute precision is key, and for processing technology, so is the ability to manufacture difficult-to-work metals with advantageous strength to weight ratios. PCE can successfully process an array of metals including aluminum and titanium and can achieve tolerances of 7 microns on metal thicknesses of 3 microns to 2000 microns.

Typical aerospace components include heater exchangers, grids, connectors, bending elements, feathers, and shielding components. The process is also very well suited to the production of decorative interior trim for commercial and private aircraft.

The inexpensive and adaptable digital and glass tooling used in the PCE process is the key to driving innovation. The process encourages experimentation and innovation in search of an optimal part, as different designs can be created with little additional cost and without significant impact on lead times. Coupled with PCE’s ability to produce parts of geometric complexity not possible with alternative traditional metal-fabrication processes, this underscores the utility for the aerospace industry.

Repeatability of extremely tight tolerances is also important in aerospace applications, and with no tool wear using the PCE process, the millionth part is the same as the first, which supports the longevity and quality of products manufactured.

Conclusion
PCE 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 which can occur using alternative metal forming technologies. PCE’s use of digital or glass tooling ensures that multiple tooling iterations that are often necessary to perfect the precise nature of such intricate metal parts are not costly in terms of time or money. 

In addition, the consistency of the process means no time-consuming and potentially costly retooling and revalidation are necessary. In the case of many aerospace applications, all these attributes combine to make PCE the manufacturing process of choice for especially critical and exacting applications.