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Photochemical Etching of Aluminum How to Retain Material Properties During Sheet Metal Working

Editor: MA Alexander Stark

Precision Micro has been offering photochemical etching of aluminum for several years. Their process produces burr-free and stress-free precision parts that can be manufactured with reproducible accuracy and have no areas affected by heat.

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The retention of material properties is characteristic for chemical etching.
The retention of material properties is characteristic for chemical etching.
(Source: http://www.jamesbastable.co.uk)

Aluminum and its alloys are often the metal of choice for many industrial applications requiring strong but light materials. Not only does aluminum have an excellent strength-to-weight ratio, it is also corrosion resistant and therefore ideal for use in extreme environments.

However, other attractive properties of aluminum - including formability, ductility and high conductivity - are however also its downsides when it comes to machining. Due to the ductility of aluminum, material hardening and discoloration of the machined areas can occur during machining due to friction caused by adhesion, especially in punching processes. Because of its heat reflectivity, laser cutting is also not ideal for processing aluminum. Aluminum is also a challenging material for etching technology, as heat energy is released during the machining process, which can result in a rough, granular edge.


What Happens During Photochemical Aluminum Etching?

The processing of aluminum is extremely demanding. The metal releases thermal energy (exothermic reaction) when it comes into contact with chemical etchants. Therefore, conventional etching partially destroys the photoresist applied to the aluminum surface to prevent certain areas of the metal from being treated. This affects the etching process and results in sub-optimal products. Add to this the well-known fact that aluminum is corrosion resistant (and that etching is a corrosive process) and the difficulties are obvious.

Strict process control is the key to successful chemical etching. Precision Micro's expertise in aluminum etching is based on the fact that the company pays particular attention to the chemical properties of the etchants, temperature control and the cleaning and preparation of the metal. All these factors are interlinked. Each one of them can have a negative impact on the others. Therefore, the success is based on the extensive experience the company has gained over many years and in numerous projects.

Photoresist and etching liquid are used in the precise chemical processing of individual areas. These results in burr-free and stress-free precision parts that can be manufactured with reproducible accuracy and have no areas affected by heat. The properties of the material are preserved. Furthermore, etching uses digital tools that are inexpensive and allow easy post-production of parts. This makes chemical etching a cost-effective, highly precise and fast production alternative to conventional sheet metal processing methods such as stamping, pressing, punching and laser or waterjet cutting. Therefore, etching is ideal for applications in extreme environments, such as aerospace, where the material properties of aluminum are of great advantage.

Air Intake Grilles, Heating Plates and Dashboards

Precision Micro has already used chemical etching of aluminum in many successful projects. As an AS 9100 and IATF 16949 certified chemical etching specialist, the company focuses on etching aluminum components for the automotive and aerospace industries, where the material's reduced weight enables higher fuel efficiency and lower CO2 emissions.

A leading helicopter manufacturer has been working with Precision Micro for more than 20 years and the etching expert supplies them with aluminum air intake grilles. Unlike conventional metalworking, which introduces stress into the grid, chemical etching ensures that material properties are maintained during the manufacturing process.

A major aerospace OEM also benefits from chemical etching in the manufacturing of cabin air dehumidifiers for commercial planes. The heating plates used in assembly require the subsequent stacking of several complex designs, which can be solved cost-effectively with etching. The process was preferred to stamping because it would have required many expensive steel tools and would not have achieved the required cross-section of the profiles, which is essential for the thermal properties of the profiles.

Many automotive OEMs use chemical etching to process aluminum parts in vehicle interiors such as scales for measuring instruments, dashboards and instrument covers, which are manufactured with high-resolution logos, surface textures and profiles.

This article was first published by konstruktionspraxis.

Original: Dorothee Quitter / Translation: Alexander Stark

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