What are bipolar plates for fuel cells?
Fuel cells are produced by stacking precise and intricate bipolar plates machined with complex grooves or channels which enable liquid and gases to flow.
Bipolar plate machining
Whilst CNC machining, stamping and hydroforming can be used to produce these channels, traditional metalworking has limitations, such as compromising planarity (flatness) and introducing stresses and burrs. Single-point machining processes and presswork tooling can also be slow and uneconomical to produce.
Benefits of etching bipolar plates
Complexity at no added cost
Chemical etching removes metal simultaneously, meaning complex channels or flow fields can be etched on both sides of the bipolar plate. This versatility enables designers to vary the size and shape of channels and incorporate headers, collectors and port features without additional cost.
Digital tooling, which is low-cost and quick to produce, can be adapted easily and inexpensively to optimise designs.
Burr-free, stress-free and flat
Unlike CNC machining, stamping and hydroforming, chemical etching imparts no mechanical or thermal stress on the plates which can compromise stack bonding.
Materials
Typically etched from 316 stainless steel, photo etched bipolar plates can also be etched by Precision Micro in titanium for lighter-weight and corrosion resistance.
Benefits at a glance
- Unlimited complexity – headers, collectors and port features without additional cost
- Low-cost tooling/design iterations
- Burr-, stress-free and flat
- Channels to 0.025mm and accuracy to ±0.025mm
- In-house pressure drop testing
- Widest range of metals, including 316 or 904-grade stainless steels and titanium
Typical Applications
- Fuel cell stacks
- Bipolar fuel cell plates
Processes
Materials
- Steel and chrome nickel steel
- Titanium and titanium alloys
- High temperature alloys
- Full material stock list
