When change MIG gun consumables? Why popping sound? Setting CFM of MIGmix?

[aribert]

What is the criteria for changing the MIG gun nozzle and contact tip? What are the signs that the nozzle or the contact tip or both need to be replaced? I have a Century 130 115v, 20A welder. I've had it about 25 yrs. I bought a small package of consumables back then and still have most of them. I should note that I don't MIG much - maybe (5) 10 or 11 lb rolls of wire plus a few small rolls.

Recently I was building up a surface with MIG, had the "heat" rheostat at 100% and the feed rate at about 45%. 0.030 ER70S-6 wire. I was getting too much popping, sometimes in quick succession (when popping there is no welding for an instant) and sometimes I could feel the wire pushing the gun away from the weld. What causes the popping and how to reduce/eliminate? I lightly adjusted first the power and then the wire feed with no major improvement. I replace the contact tip (probably first time in several years) still no improvement. I just put up with the popping. Near the end of the welding project I aggressively began to adjust the feed rate and found that a feed rate of about 20% reduced the popping greatly. BTW, this was US Forge brand (China) wire purchased from Menards - not sure what effect the wire might have.

How does one determine the correct gas flow? I know from personal experience if one does not turn on the gas, the weld looks like a miniature sponge. Beyound that extreem, how does one know the correct gas flow has been dialed in? I use a 40 cu ft cylinder of MIGmix. Sometimes it lasts me several years. Last week it lasted 6 days and I used a little less than 10 lbs of .030 wire. 40 cu ft of MIGmix cost me $44 with tax/fees - I am trying not to waste it.

[BigMike782]

One contact tip should last through a 12 lb roll of wire.
Set your base parameters by the chart inside the machine for the material you are welding.
Start at 15 cfh, have someone turn the flow rate down as you weld until it shows then have them start adjusting up until it clears, increase by a couple of cfh and call it good.

[CarlByrns]

Start with the basics- a weak ground clamp or bad contact, check the positive and negative terminals - I had a loose one can cause all sorts of problems, exactly as you described. Check the wire and rollers for rust or dirt.

[Willy]

To me it sounds like some very conflicting feedback from the machine. Some mild popping is usually associated with too low of a wire feed rate for the voltage. Yet the "push-back of the wire against the work indicates too high of a wire feed rate..As mentioned set the machine to it's recommended settings as a starting point. It may not be perfect but it should get you in the ballpark and should not create any of the issues you are having now. And as BigMike782 mentioned, 15 CFH is a good starting point under no draft indoor conditions. This setting should give pretty decent coverage without being excessive and as he mentioned, you may be able to scale it back a touch.

CarlByrns has a good point of starting with the basics. Make absolutely sure that the wire is feeding S-M-O-O-T-H-L-Y, I can't over emphasize this as it can create some very conflicting issues when the wire is fed in a hit and miss or jerky fashion. If It isn't sooth and consistent check drive roll tension and condition as well as liner cleanliness.
Also check ALL electrical connections on both ground circuit and gun circuits, and I mean every connection in the system including gas diffuser, machine to gun and ground, etc. for cleanliness and integrity.

When you are satisfied that all is well with the machine please let us know how things are going. I suspect the machine was working well at some point in the past and that this issue is one that has crept up slowly over time to the point that it is now almost to the point of not being usable.
Your mission is to turn back the time machine to where both you and the machine are happy again.

[no704]

Probably due for a new torch liner after 25 years?

[aribert]

Thank you all for responding. I'm going to review all your suggestions (at the machine) early next week.

I need to replace the CFM gage on the regulator (bent needle from a previous clumsy cylinder bump on my part - I was in portable mode w/o the cart to secure the cylinder). I am guessing I have been using about 20 to 25 CFM based on needle displacement.

[wmgeorge]

If the liner has not been replaced in 25 years or whatever, time for a new one. You can get a "real" flow meter like this one for less that $40. Link> AGPTEK Mig/Tig Flow Meter Regulator, CO2 Argon Pressure Reducer Gauge Weld Flowmeter - Full Copper - 10 to 60 cfh - - Amazon.com

[aribert]

wmgeorge:

Thanks for the link to the flow meter.
Does the liner degrade from time? I don't think I have run a total of 75 lbs of wire in the machine in all the years. While this is a hobby/homwowner grade machine, I don't remember the liners being changed out frequently in the shops of my various employers over the years.

While I expect to do a little MIG welding later today or tomorrow, I don't have the time to dedicate going over all the suggestions given in this thread until next week (but I sincerely appreciate receiving the suggestions).

[wmgeorge]

wmgeorge:

Thanks for the link to the flow meter.
Does the liner degrade from time? I don't think I have run a total of 75 lbs of wire in the machine in all the years. While this is a hobby/homwowner grade machine, I don't remember the liners being changed out frequently in the shops of my various employers over the years.

While I expect to do a little MIG welding later today or tomorrow, I don't have the time to dedicate going over all the suggestions given in this thread until next week (but I sincerely appreciate receiving the suggestions).

Just because you did not see one being changed, does not mean it did not happen. Yes they wear, get kinked, rusted and dirty. Not that big a deal to change out.