The forming of flow plates
Stepping into our forming facility you'll see a compact 3x3 meters forming unit, perfect for a standard industrial concrete floor. The forming unit is easy to assemble and maintain – a crucial point as demand for flow plates rapidly increases.
Cell Impact FormingTM is an innovative new way to create complex patterns in thin metall. It's a dry process which uses high-kinetic energy to stamp a very accurate design into a thin sheet of metal. By precisely controlling the velocity of the forming process, it's possible to produce flow plates with unsurpassed thickness uniformity and channel accuracy.
Forming a plate
01. Rolling out material from a big metal coil.
02. The feeding system positions the material.
03. Adding pre-tension to the material stretches the material, preparing it for impact.
04. An impact cylinder is accelerated to a specified velocity.
05. As the cylinder impacts with the upper tool assembly, the tool is pushed down.
06. As the upper tool meets the lower tool, the material between them is formed.
07. The formed material is cut in pieces and collected by our operators.
08. Formed plate is ready for next step.
After the flow plate pattern has been formed, the plate is separated from the metal sheet by laser cutting the outer edge and any interior holes. For highest efficiency we use our own re-built machines with shuttles (tables) making the machine semi-automatic. While one table is inside cutting plates, the outside table is loading new plates.
We design our own fixtures and use control patterns to position the plate. To make sure the plate is positioned correctly, we use dimples. By using vacuum, we are able to lock the plate in the fixture so that it doesn’t move during cutting. Laser cutting is a highly flexible method during prototyping since cutting paths is easily modified.
For higher volume production, we are currently developing a new method for precise mechanical trimming of flow plates. This process will be faster than laser cutting, more cost-efficient, and better suited for large series production. The mechanical trimming will be available from Q1, 2024.
In this step, we are welding the formed and cut anode and cathode plates to create a bipolar flow plate. We currently use both cartesian laser and galvo laser welding. The technologies work similarly, but galvo welding is several times faster. Both technologies create a leak-free bipolar flow plate with high-quality welding seams.
Cartesian laser works in the same semi-automated way as the laser cutting. One table is inside welding, and the other table is outside loading. By using heavy lids, creating pressure on the fixtures, electromagnets pull the lids down locking the plate into its position. It is very important that the plate is absolutely still as the tolerances for the lasers are very narrow.
Galvo systems use mirror technology to move the laser beam in different directions by rotating and adjusting mirror angles within the boundaries of a work area. This is a technology that will be implemented in 2024.
To ensure consistent, high-quality flow plates, samples are collected at different intervals throughout the production process for rigorous manual inspection. This includes both optical inspection and inspection with high-accuracy measurement machines.
Inspection and measuring
During the forming step, it is important to measure the positioning of the tools, thus making sure they stay centralized and preforming impact evenly. This is done by:
- measuring the formed thickness of the plates,
- using a leak-detector to look for cracks, and
- uysing a loop looking for blank areas, indicating the tool is out of position.
Checks are made against a master plate. Every 10th plate is checked against the master with a magnifying glass to check the position, and every 50th plate is checked under a microscope to check for cutting edges, burrs, etc. Every plate is checked individually after welding, making sure that the weld lines are complete, have no discoloration, and that there is overlap at the beginning and the end of the lines. Plates are also checked for pin holes, by placing the plate on a light table and looking along the entire weld line.
The last step before shipping and packing, our bipolar plates are leak-tested. This is done using our own uniquely developed helium-based testing system. The fully automated system will verify material and welding seam integrity by testing for any minute coolant, reactant or overboard leakage. During the prototype phase, the test is done on all produced plates.
Our process is oil-free and doesn’t require major cleaning. But during manufacturing, particles of course get stuck on the plate and cleaning is included in all the steps. Depending on whether the plate is pre-coated or not, different cleaning methods can be applied. A pre-coated plated is more resistant against particles than an uncoated plate.
Cell Impact offers optional dry and wet cleaning methods for the removal of dust and particles. Depending on requirements, these optional cleaning steps can be placed at various stages of the manufacturing process.
Packaging and shipping
The last step in the manufacturing process is the packaging. To make sure our orders are delivered in a safe way, we use special ocean wrapping and customized boxes and other packing material – making sure that plates are not damaged during shipping.