Photochemical etching (PCE) is the ideal choice for manufacturing metal components in the rapidly changing supply chain of alternative drive systems. Its versatility and precision allow for the production of a wide variety of prototypes – regardless of the number of design iterations, even with shape memory alloys.
Weight reduction is an essential part of the EV revolution, a goal that can be achieved through etching processes. Suitable applications include connections for alkaline batteries and busbars. Furthermore, both sides of a plate can be etched simultaneously. Cooling plates for battery management systems can be manufactured from steel, titanium, or aluminum, as can bipolar plates for fuel cell stacks using the same materials.
The EV revolution
New and sustainable mobility technologies are in high demand as initiatives in Europe and the United States drive the transition to alternative drive systems.
In the EU, the European Commission has set a target that at least 30% of newly sold vehicles should be electrically powered by 2030. Various financial incentives are available to support this goal, including grants for the purchase of electric vehicles and the installation of charging stations. Additionally, the Commission is working on establishing a comprehensive network of charging infrastructure across Europe.
In the United States, the federal government offers a tax credit of up to $7,500 for the purchase of an electric vehicle. Furthermore, numerous states have their own incentive programs. Additionally, the US Department of Energy is investing over $4 billion in building a nationwide network of fast-charging stations.
PHOTOCHEMICAL ETCHING
As a precise process for manufacturing metal components, PCE is excellently suited for the production of central EV components such as bipolar plates for fuel cells. These can be manufactured cost-efficiently, precisely, and quickly, while simultaneously fostering innovation through great design freedom.
PCE is a subtractive metalworking process in which metal is selectively removed from a flat surface using a chemical etchant to create desired shapes or patterns. The process transfers CAD drawings onto transparent phototools, converts them into a negative image, and develops this onto a photoresist that covers the metal surface.
The process offers numerous advantages, as it enables the production of delicate components with complex patterns or varying opening profiles in thin metal sheets – from a few dozen micrometers to about 2 millimeters in thickness. It outperforms other methods such as traditional metal cutting and stamping.
Etching processes can be used on a wide variety of metals – from stainless steel to copper and nickel to aluminum, including composite materials and shape memory alloys. Each metal has its own etching characteristics, and the expertise of a PCE specialist allows the etching chemistry to be adapted to the respective material to achieve optimal results.
PCE & bipolar plate manufacturing
With the global fuel cell market expected to reach a volume of $25 billion by 2025, international pressure to diversify energy sources has triggered strong investment interest in alternative energies – with fuel cells being among the most promising solutions.
The requirements for higher efficiency and lower costs in fuel cells have a significant impact on the materials and manufacturing processes used.
Historically, CNC-machined graphite was the preferred material for bipolar plates. However, this is relatively expensive and has high permeability, making it unsuitable for mass production. Metal alloys such as stainless steel and titanium are increasingly gaining importance due to their cost-efficiency and ease of processing. Stainless steel also offers advantages such as high strength, chemical resistance, and durability.
Fuel cells consist of complexly machined plates with channels for gas and liquid flow. However, the scalability and performance of CNC machining, hydroforming, and stamping processes are limited.
While stamping and hydroforming are common processes, they can cause issues such as lack of flatness as well as stress and burrs. Furthermore, single-point machining and press tools are time-consuming and costly – especially in research and development.
PCE offers manufacturers a viable way to produce complex components such as bipolar plates with significant advantages.
By using digital tooling instead of physical tools, PCE is particularly cost-efficient and allows for rapid design adjustments – a major advantage for optimization without high additional costs.
The process allows for rapid scaling from prototype to series production, with almost no restrictions regarding component complexity – ideal for bipolar plates, which must be free of defects to ensure a reliable connection in the stack. Material properties remain unchanged, the process is suitable for all steel grades, and an accuracy of ±0.025 mm is achieved – within days instead of months.
PCE is a versatile technology that enables simultaneous material removal. This allows complex patterns and channels to be etched with an accuracy of 0.025 mm on both sides of a plate. Elements such as manifolds, collectors, or connectors can be realized without additional costs.
The micrometal Etching Group is also capable of manufacturing such components from difficult-to-machine and exotic metals such as titanium – for lower weight and better corrosion protection in high-temperature fuel cell applications.
Due to its versatility, the PCE process is a compelling solution for the production of complex sheet metal components in a wide variety of applications. It fosters innovation, eliminates the limitations of traditional manufacturing technologies, and offers designers more freedom of design.
SUMMARY
PCE offers flexibility and cost-efficiency in the production of bipolar plates and enables the rapid production of a wide variety of designs. Furthermore, the potential is enhanced by the ability to etch materials such as stainless steel, nickel alloys, copper, aluminum, titanium, and other alloys.
