Pin hole at start stop

By S raj Date 02-24-2018 16:11

Hi, I use a special purpose machine with Gmaw mechanized welding a T joint of spud to a tank base of thickness 2mm MS sheet. I find a pin hole at the start position always when the weld overlaps the start position before completion/stopping. To be more clear the weld starts and the rotary torch welds along the joint. it again comes to the start position with some overlap and stops. The pinhole is exactly at the start position overlap. I use 1.2mm ER 70S-6 weld wire with 230 to 250A and 26 V with 90/10 ACM. Can you please suggest a solution. Thank you.

By 803056

Date 02-25-2018 15:40

Are you employing any preflow of the shielding gas?

Al

By S raj Date 02-25-2018 16:12

Thanks for the response. My wire feeder has no preflow control but has post flow and burnback. The pinhole is not when the arc starts but when the arc again overlaps the start position before completion of weld.

By Tyrone

Date 02-26-2018 12:33

Try using a crater fill function.

By S raj Date 02-26-2018 14:09

There is no crater fill function in the power source/wire feeder.

By Tyrone

Date 02-26-2018 17:59

When you say "mechanized", do you mean a robot?

By S raj Date 02-28-2018 14:09

Except loading and unloading, everything is automatic through controls.

By Tyrone

Date 02-28-2018 17:05

Then program the robot to give the weld an extra zap or two at the end. That will in essence fill the crater.