I tried my first small aluminum job and the welds are acceptable but the end product is not. I’ve attached a drawing to help understand what I’m doing.
The project is meant to be a bridge plate for rolling big freezer units onto an elevator. The freezers have small diameter casters on the bottom they roll on, and and no matter how level the elevator is with the floor, these small casters are getting hung up in the 1 1/4” gap between the hoistway sill and the car sill. My question “finally” is … help with controlling distortion? I have 42”x24”x3/16” 6061 aluminum sheet and I welded a 38” 1x1x3/16” 6061 aluminum angle across the middle of the sheet to bridge the gap from the hoistway sill to the car sill to keep it from sliding when the freezer is rolled on it. I tacked both ends and the middle of the angle and then alternated from both sides and both ends of the angle with 2” stitch welds. I admit that I didn’t have enough clamps to clamp it all down like I would have liked to. Also, had heat issues on the back side of the sheet that I had to grind back flat. No burn thru but you could definitely see where it had been welded from the other side. Using a Miller 220 / w spool gun. I started with the default settings and turned both amps and wfs down a little before actually welding. Don’t remember what they were at the moment. Any comments or suggestions on aluminum would be greatly appreciated…I’ve got pretty thick skin.
Attachments
63BF28B9-0474-43DD-88EF-06319482D4BE.jpeg (3.83 MiB) Viewed 2551 times
Not much you can do to prevent distortion absent of clamping everywhere and allowing the material to cool while clamped. That is still not a guarantee to prevent it.
An “unrestrained” sheet that is welded in the middle only will curl on the “flaps”. 10:1 likelihood of that regardless of techniques.
Spoolgun works fine, I just did a 3/16” table welded to 1x1x.125 angle frame. Controlling the heat marks coming through can be controlled by optimizing wire size and using a preheat. MIG always starts cold. By the time you’ve poured enough heat into the part you’re depositing a large amount of wire. Reducing your wire size and preheating let’s you get that puddle faster and puts let’s total heat into the sheet. That too can reduce distortion. But ultimately, it’s the nature of welding and distortion that makes it more an art form than a pure science.
One option is to tack more longitudinal angle bars to the perimeter while welding the center to offset the curling. Then after it cools, break them off and flap down their tacks. Can leave a flatter a surface afterwards.
Those welds look a bit “cold”. If I recall, I was about 18.5v and 385 WFS on my MultiMatic 200 with a spoolgun running 0.030 wire on 3/16”. You might need to be a bit hotter on 3/16->3/16 where I was 3/16->1/8. Bumping your volts should help reduce the spatter too.
Nice job Barney. It does appear that you've got almost enough clamps available..LOL. Just wondering ... did you have to bevel the edge so you could climb onto the plate with the small casters on the appliances? And ONCE AGAIN, a place to go for valuable information. I want to thank all of the members of the forum for being there and participating. I do realize that there are posts that can be repetitive and sometimes hard to find while searching. Take me for instance, I can't drive this electronic stuff to save my butt. I can do enough to get into trouble and keep others on their toes, ask buggy. I've also noticed that the forum has been sort of quiet for a while, let's get it going again. Thanks folks.
grandpop.
Cj737
Yeah, I was wondering what might help reduce the spatter as well. The sheet material is 3/16” and that’s a piece of 3/4x3/4x1/8” channel in the pictures. I was afraid I might blow through the channel if I turned it up to much. I believe I was running about 20.2 volts, can’t remember the ws.
BillE.Dee
Thanks! And yes I did bevel the edges on both sides with a 4 1/2” grinding wheel for aluminum, then smoothed it with a 60 grit flap disc… also for working on aluminum. We tested them out today and had to tweak them a little here and there, but overall, they worked great.
Looks a bit “cold” but might have been running a bit “hot”? Difference in machines and prep possibly? I’d just like to get rid of the spatter at this point.
Barney wrote: ↑Fri Apr 08, 2022 5:26 pm
Looks a bit “cold” but might have been running a bit “hot”?
the problem with most spool gun setups is lack of hot start. a small amount of pre heat at the start can help.
also what manipulation are you doing?
i'm not a fan of people doing the "mig like tig" because it often ends up being cold welds.
Barney wrote: ↑Fri Apr 08, 2022 5:26 pm
Looks a bit “cold” but might have been running a bit “hot”? Difference in machines and prep possibly? I’d just like to get rid of the spatter at this point.
Your original post showed weld beads that look a bit cold. That can be due to lack of preheat and no hot start as Tweake mentions, can also be due to technique. Not holding long enough on the edges to wet in.
The post where you stated 22v I was stating that sounds a bit hot for the material.
A lot of this is subjective because we are looking at pictures and lack personal observation, all the parameters, and environmental conditions you’re welding under. So take all of this with a bit of salt.
Wire diameter and CFH? Pushing or pulling? Let’s see some sample coupons with no preheat, then same settings with a preheat. We can help you dial it in but it’s going to take a few more insights for that to happen.
