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> Pin hole when Mig welding stainless steel
fleetroot mac
post Mar 20 2018, 04:29 PM
Joined: 17-Aug 13



Does anyone have any pointers to try and eliminate the pin holes I keep getting at the end of my welds..? I am using a Jasic Mig 350p synergic machine welding 2mm wall 304l stainless pipe using the dual pulse setting running at around 65 - 70 amps, gas flow 10 lpm, slope down amps at 45, wire diameter 0.8mm. My optional parameters using the crater control function are wire speed which is currently set at 3.5 which is directly related to my voltage due to the nature of the synergic machine. Any increase or decrease in wire speed affects the voltage accordingly. Hope Iím not talking rubbish here but thatís my understanding!! Any advice would be extremely beneficial and gratefully received

Cheers
Buk
post Mar 23 2018, 09:02 PM
Joined: 23-Mar 18



If your welding amperage is an average of 70 you should be able to set your crater amperage as a percentage so 50% is 35 amps this you can then time out in seconds Are you using 2% Co2 in argon
fleetroot mac
post Mar 27 2018, 08:45 AM
Joined: 17-Aug 13



No time option on the crater control setting only amps voltage and speed !! I can set time on the post weld setting but not on the crater control . Been using 40 amps on the slope off and am currently running Specshield 2% O2 in argon ??? Cheers for the reply
tominwicken
post Mar 27 2018, 10:47 PM
Joined: 14-Jan 10



Ive found pulse sets seem to need a lot of gas, try something around 18 lpm. Keeping a longer stick out than conventional mig might help too.
matt1978
post Mar 29 2018, 07:00 AM
Joined: 19-Oct 07



Pin holes at the end are usually due to the weld pool freezing too fast, which is usually crater fill current not low enough or on for a long enough time. Itís really quite poor if you canít set the time for your crater fill, what about if you put it into latch/4-step mode? Can you set the time for the hot start and crater fill by how long you keep the trigger pressed?
Technic Al
post Mar 29 2018, 01:14 PM
Joined: 14-Oct 03



I agree with Matt....most likely shrinkage....needs to be hotter at the crater
fleetroot mac
post Apr 13 2018, 11:33 AM
Joined: 17-Aug 13



Sorry for late reply .. I have put the machine into 4 step and am able to control the slope off time using the trigger like u said. I am still getting an indentation when I finish the weld but when I grind it down it isnít going through so thatís a positive!!! I have been welding branches onto a stainless header recently using the straight mig settings as opposed to the dual pulse settings that I was using on the butts but canít seem to stop these pinholes occurring when using these settings. I have also tried using s/s stick rods but seem to get the same issues when welding sockets with these. Any help once again greatly appreciated 🤯
Technic Al
post Apr 13 2018, 12:53 PM
Joined: 14-Oct 03



They often weld past the crater and then go back over it.
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