Photo etching critical components

Features - Cover Story

Choose a cost-effective process that offers tight tolerances and produces accurate parts with minimal waste.

May 3, 2022

Etched heat elements delivered on a reel, 105µm clad material SS/Cu.
All photos courtesy of micrometal.

The aerospace sector is driven by weight, cost, and time-to-market so aerospace original equipment manufacturers (OEMs) must engage with companies with the right expertise to ensure the efficient and cost-effective manufacture of safety critical precision and micro components. Engaging a qualified micro manufacturing partner early in the design cycle for new product development is vital to avoid multiple, costly, and time-consuming design and tooling iterations.

Cost & time

Aerospace airframe and engine OEMs are constantly demanding dramatic reductions in product development lead-times, and to remain competitive, are focused on eliminating waste from all their processes. This pressure from the leading aerospace OEMs impacts aerospace supply chain companies, which must slash product development cycle lead times while ensuring adherence to strict regulatory controls and the demand for ever stronger, lighter, and more complex components.

Supply to the aerospace industry is relatively low in volume compared to other industry sectors, so it’s innovation and cost that differentiates suppliers. 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.

For precision and micro parts in aerospace applications, supply chain OEMs should embrace the possibilities of using photo-chemical etching (PCE) and engage and work with expert micro manufacturing companies – such as micrometal, a global provider of PCE services – at the earliest stages of product development.

Key takeaways

PCE is a versatile and increasingly sophisticated metal machining technology used to mass manufacture complex and feature-rich metal parts and components. The process uses photoresist 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.

Micro-perforated cutting foil (smooth front side, sharp back side) in 75µm stainless steel.

PCE uses easily re-iterated and low-cost digital tooling and also provides a cost-effective, highly accurate, and fast manufacturing alternative to traditional machining technologies such as metal stamping, pressing, CNC punching, laser cutting, and waterjets.

Traditional machining technologies can produce less than perfect effects in metal at the cut line, often deforming the material, leaving burrs, heat-affected zones, and recasting layers. In addition, they struggle to meet the detail resolution required in the ever smaller, more complex, precise metal parts aerospace OEMs require. When an application requires multiple millions of parts and absolute precision isn’t a priority, 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 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 waterjet cutting causing disproportionate and unacceptable degrees of heat distortion and material shredding. 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 25µm foils.

It’s in the manufacture of intensely complex and feature-rich precision parts that PCE really finds its perfect application, as it’s agnostic when it comes to shapes and unusual features. The nature of the process means that feature complexity isn’t 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 at the design, tooling, manufacture, assembly, validation, and measurement stages of the micro product and component development process, micrometal can help minimize the requirement for lengthy and costly design reiterations. Cost-effective and timely manufacturing solutions can be exploited using one key characteristic of PCE – digital tooling, which allows for very inexpensive design changes without the need for costly and time-consuming re-cutting of tool steel.

The onus on aerospace manufacturers is to reduce weight, and so the drive toward miniaturization is key, as is the use of light-weight parts using materials such as titanium and aluminum to replace heavier metals. Therefore, aerospace suppliers must tap into the latest in material and process R&D and ensure they partner with companies that have experience in cutting-edge processing techniques.

Photo-etching & aerospace considerations

In aerospace applications, absolute precision is key, and for a 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 and can achieve tolerances of 7µm on metal thicknesses of 3µm to 2,000µm.

Detailed view of a sharp edge (back side) with transition to a rounded edge (front side) in 75µm stainless steel.

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

The inexpensive and quickly 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. PCE’s ability to produce parts of geometric complexity not possible with alternative traditional metal fabrication processes underscores the fit 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.

For many aerospace applications, all these attributes from PCE combine to make it the manufacturing process of choice for especially critical and exacting applications.

micrometal

About the author: Jochen Kern is head of sales & marketing at micrometal GmbH. He can be reached at jochen.kern@micrometal.de.