Deposition techniques

Plasma Transferred Arc (PTA)

Ideal for high unit volume automated applications, such as thermal surfacing of exhaust valves, this technique offers low base metal dilution and can be used with a wide range of consumables.

Process

PTA (Plasma Transferred Arc) is a welding method, thus it enables a metallurgical bonding with the base material. It can be used on most alloys.
PTA can be fully automated and thus once the parameters are fixed for a certain design, consistent final results are achieved for all pieces.

Typical working range

  • Deposition rate: 2-12 kg/hour
  • Deposition thickness: 1 - 6 mm
  • Deposition hardness: up to 60 HRC

Benefits

  • Suitable for automation
  • 1-6 mm thickness

Problems with your PTA process?

PTA troubleshooting
Problem Cause Solution
Deposit peels off

1. Poor preparation of the surface (oxidized or dirty surface)
2. Too low preheating temperature
3. Wrong parameters / too low welding current resulting in bad bonding

Clean the surface well
Sand blast well
Increase preheat
Increase current

Cracks

1. Overheating / too high welding current resulting in too high dilution
2. Too fast cooling

3. Critical base material

Reduce welding current
Reduce cooling speed
Slow cooling / controlled cooling
Use buffer layer

Porosity

1. Poor preparation of the surface

2. Incorrect parameters (welding current, up-slope, down-slope)
3. Humidity due to e.g. poor sealing

Clean the surface well
Sand blast well
Adjust parameters
Replace seals
Flushing equipment with argon

Clogging

1. Incorrect particle size
2. Non-spherical particles in the powder used

Reduce fines content
Replace the powder

Courtesy of Jarvie Engineering Pty Ltd

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