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Fuel Cell Layers – Metalic Mesh and Foam

System 1:
CD400DP, 400ws capacitive discharge resistance welder
WH1125A, opposed, air actuated weld head
1/8″ copper upper electrode (with tip tapered to 1/16″)
Copper grounding plane lower electrode
Custom flexible tip flat electrode
High Force Springs
1awg cables

We tried two different methods for bonding the mesh and foam layers. Both methods involve the WH1125A weld head but could easily be duplicated using a PASP-HP pressure actuated hand piece coupled with a grounding plane if desired. For method 1 the weld head is configured with an 1/8″ copper upper electrode that is tapered at the tip to achieve smaller spot sizes. The lower electrode is a copper grounding plane. For method 2 we swap out the upper electrode for a flexible tip electrode that has a 1inch square surface area. Although we did not attempt it, a third method is available — roll spot. The roll spot method uses a circular electrode that rolls along the layers and the CD400 would be configured to discharge pulses at a set interval.

Method 1:
Opposed electrodes can often offer the strongest welds. The tip diameter can be altered to achieve desired spot sizes but keep in mind that energy levels will need to change accordingly.

2 layer mesh:
The two layer mesh welds are best performed with the larger diameter wire mesh on top.

Pulse 1 — off, Pulse 2 — 7ws, total energy — 10ws, 5lbs spring force.

Small weld spots are easily achieved and several can be placed.

3 layer mesh:
Similar to the 2 layer mesh welds.

Pulse 1 off, Pulse 2 at 12ws, total energy at 15ws, 5lbs spring force.

Foam and mesh:
Due to the compressible nature of the nickel foam it is necessary to adjust the stop nut on the top of the weld head to limit the amount of distance the electrode can be lowered. The mesh layer is placed on top for best adhesion.

Pulse 1 — off, Pulse 2 — 7ws, total energy 10ws, spring force at 5lbs.

Foam and sintered plate:
Once again the stop nut is adjusted to minimize compression of the foam layer and the sintered layer is placed on top.

Pulse 1 — off, Pulse 2 -17ws, total energy — 20ws, 5lbs spring force.

Foam and Filter:
The filter layer is on top for these welds. The large wire can also face the nickel foam if desired. The stop nut was adjusted normally for these welds (no limited descent distance).

Pulse 1 — 10ws, Pulse 2 — 90ws, total energy — 100ws, 5lbs spring force.

Method 2:
The 1 inch square flexible electrode can cover large amounts of area on the layers for each weld actuation. We set the spring force to 20lbs for all the welds pictured below. Since the pressure is distributed more evenly, the nickel foam has less chance of deforming too much.

3 layer mesh:
It is best to keep the large diameter wire as the top layer but it is possible to have the small mesh on top if necessary. The two layer mesh welds can be made the same way.

Pulse 1 — off, Pulse 2 — 90ws, total energy — 90ws

Foam and mesh:
Pulse 1 — off, Pulse 2 — 300ws, total energy — 300ws.

Foam and sintered plate:
Pulse 1 — off, Pulse 2 — 400ws, total energy — 400ws

Foam and Filter:
Pulse 1 — off, Pulse 2 -400ws, total energy – 400ws

Summary:
The CD400DPand WH1125A are ideal for welding these fuel cell layers. The flexible tip electrode seems to give the quickest results for bonding layers. The WH2125A could be used to attach the layers to whatever substrate you choose because it can perform series welds (both electrodes contact the upper layer).