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Fuel cell

Driving tomorrow's car with today's manufacturing technologies

Fuel cell - Leading candidate on the electrical race

Fuel cell is a technology which is starting to stand up as one of the possible firm candidates to drive the future electrical vehicles(EV). The importance and the future possibilities of this generation method is pushing forward in a world where internal combustion engines(ICE) are currently suffering by international laws and available resources

What implies this technology? New breakthroughs comes with new challenges, and the producers are wondering what production resources do they need to feed the demand of the market 

Fuel cell - The basics!

First let's go to the basics. What is a fuel cell car ? New models keep being launch to the market such as the Mercedes GLC F-Cell, coexist with more experienced car such as the Toyota Mirai.

These type of cars they use a electrical motor connected to a battery, and the electricity needed to power it, is coming from a Fuel cell.

In an hydrogen fuel cell, the electricity is generated when mollecules of hydrogen and oxygen are mixed together, driving to a result of water (H2O) and energy.
 

These reaction is happening in the bipolar plates of the fuel cell. But each plate just generate 0.7 V (approx) so a stack of 250 to 1000 bipolar plates are necessary for powering one car.

There are several  types of fuel cell: Alkaline Fuel cell (AFC), Direct Methanol Fuel cell (DMFC), Phosphoric Acid Fuel cell (PAFC), Proton Exchange Membrane Fuel Cell (PEMFC)... and not only Hydrogen is used, also Methanol and Methane are used on fuel cells

*Picture from www.afdc.energy.gov

Fuel cell - The basics!

Fuel cell - Production necessities

Regardless of the fuel cell, the bipolar plates are around 50 µm thickness or even less. and currently each manufacturer is making their own design (No standard/dominant design yet)

Due to the high number of plates and the application where it is used, these plates have to have a parallelism in  around 10 µm, a countour accuracy of ± 5 µm and, due to the number, a low volume production costs


There are several ways to achieve these type of production:
  • Progressive stamping
  • Hydroforming
  • High-Velocity forming

All of them will be as good as the tool used for them. And here is where Makino comes in place.

 
Fuel cell - Production necessities

Fuel cell - Forming Die requirements

  • The tool used have a really high accuracy requirements, specially on a long time processing part. here is one example of typical forming die requirements (varies slightly with real one)
  • Tolerances:
    • Contour accuracy  = +/- 5 µm
    • Flatness   = 10 µm
    • Parallelism   = 10 µm
    • Roughness Ra  < 0.2 µm 
  • Materials:
    • ca. 60 HRC
  • Machining Times 
    • ca. 150 hours
  • Smallest radius 
    • 0.25 mm
Fuel cell - Forming Die requirements

Fuel cell - How can Makino support? IQ500

  • The active cooling of the IQ500 allow us to have an excellent thermal stability in the z-axis over long machining times (>150 hours)
 
  • The machine is prepared to achieve even tighter contour accuracies so shapes and radii of the dies, even when getting smaller, won't be a problem
 
  • IQ thanks to the linear motors, delivers the fastest feedrate while keeping accuracy even in small movements
 
  • Large amount of tools is necessary. All of these tools have to be measured precisely, so that there is no difference in z-direction between them.
    • This can only be achieved by a precise tool seating on the spindle and a precise measurement (in our case given by the Precision Tool Image Measurement Device
 
  • The tool wear can be kept to a low level due to the smooth spindle running and excellent axis control
 
  • Surface quality is better than on other machines (even with standard tools)
 
  • Finally and as important as the machine, our Application Engineers have experience in milling the plates and can support the end-user in technology and the development of cutting strategy
Want to know more?
Fuel cell - How can Makino support? IQ500