Request information for robotic servo spot welding guns


Thread Starter


Hi everybody,

Our penumatic robotic guns sometimes cause some defects (benting) on the surface of the roof of car bodies and I want to check the possibility of using robotic servo spot welding guns instead of them.
Many thanks in advance for your help.


Email: [email protected]
A lot of problems with welding guns are often caused by mechanical considerations such as poor (cheap) construction or by wear. Inspect the guns carefully. If there is any play or misalignment in the jaws then the tips will be pushed off centre when the gun closes. Once the tips are misaligned then you will get uneven wear which will cause even more misalignment which will get continually worse. I don't think that servo can help you with that.

Thank you Griffin. But I think the main surface problem caused by penumatic guns raised from their fixed pressure. If fix tip and moving tip recieve together on the surface then the surface doesn't damage by the tip's force. But if one tip recieve to the surface sooner than the other then its force damage the surface.

In servo guns I read in the net that there is a mechanism that can increase the pressure after recieving the tips to the surface and I need to know more about this capability. Also is it possible to set the clearance of the fixed tip and moving tip separately in servo guns for each welding point?

Many thanks in advance for your help.
Your question isn't quite clear, but you seem to be asking about increasing pressure after the tips are closed. This is a very common feature in all but the very smallest conventional weld guns.

This is usually called "close" and "intensify". With air over oil systems, these work by combining a conventional air over oil tank with a hydraulic intensifier for high pressure. You use two valves for this, with the valves often driven directly by the weld controller. Some companies (e.g. Centreline) have the intensifier built directly into the weld cylinder.

Cosmetic problems with welds are usually mechanically related. The gun *has* to be very robustly built, and it must be well maintained. At high pressure the tips will inevitably be forced out of alignment if there is any weakness or play in the gun.

The other thing to look into is what sort of weld caps you are using. On a cosmetic surface you usually need a special cap for the side which will be showing.

I've looked at "servo" welding equipment, but I haven't seen anything that would address these sorts of problems. Some of the "servo" stuff simply allows you to set the pressure using an analogue valve. This allows you to adjust pressures without turning knobs on regulators, and it allows you to use different pressures for different welds (which is sometimes useful in robot applications). You can probably fit something like this onto your existing equipment provided your control system (e.g. the weld controller) can handle it.

Also, you said you are using "penumatic guns". Hydro-pneumatic guns might work a lot better. Straight pneumatic weld cylinders usually only work well on very small equipment or on things like projection welds.
Thank you for your great answer. If I have enough time in the spot welding station then I can change the pressure of guns in 2 steps (low pressure-high pressure) in order to first two tips reach to the welding surface with low force and then increasing the force. But time is very critical in this station.

Please help me to find a good solution.

Many thanks in advance for your help.