Thursday, January 22nd, 2015
I thought it would be useful to pick out 3 quite different sheet metal welding fabrication projects being manufactured during January 2015 to use as illustrations of the type of welding techniques we can employ when making fabrication assemblies.
Here I have shown a batch of 100 wall mounting bracket assemblies for supporting speaker systems. We normally manufacture 100 to 200 of the bracket assemblies at a time from mild steel square section tube, 5mm bar and 6mm thick mild steel plate. The 6mm thick plate is screwed to the wall with the welded tube projecting out at 90 degrees. The 5mm bar is used both sides of the tube to strengthen the joint and prevent the heavy speaker sagging once it has been fixed to the tube.
We used to buy the laser cut 6mm plates in from another source as they were too thick for us to CNC punch with our Trumpf punch presses. Now we have invested in a new Trumpf 3030 3KW fibre laser cutting machine we can easily laser cut them in house, out of interest the laser cutter is able to cut steel up to 20mm thick so 6mm was no problem. We also used to saw the mild steel tubes to length and then drill all the holes both sides with a standard pillar drill set up. We have now moved this operation onto the laser cutter as well with some customer built jigs. We still saw the tubes to length and then simply position them into the jig on the bed of the laser machine and as the laser head can move in the Z axis it can move onto the tubes and cut the holes require. We just cut a row of tubes and then flip them all over 180 degrees before cutting the other side. This has proven to be much quicker than having to drill them all out by hand. The tube, strengthening bars and wall mounting plate is positioned within a jig and then MiG welded together. By using anti-spatter spray we can keep the surface of the plates clean and they need little cleaning up before being ready to go for powder coating. MiG welding tends to be used on heavier sheet metal welding fabrication jobs than TiG welding as it’s quicker to apply and you can build up a lager weld quicker than TiG welding. I’s not a neat as TiG welding but in this case that was not important.
This is a simple sheet metal support shelf for a rack mounting enclosure. We often make 20-30 of these fabricated assemblies at a time with both parts being manufactured from 1.5mm mild steel. The main shelf and stiffening channel was laser cut from the same sheet of metal using nitrogen as the assist gas. Using nitrogen produced a very clean cut that didn’t need and edge de-burring and also is a perfect finish ready for zinc plating or powder coating.
Although you cannot see in this photo the stiffening channels have small tags laser cut in them and the main rack shelf has a small rectangular slot cut to match the tag. The welder who TiG welds them together doesn’t have to worry about positioning them or measuring point to tack weld as the 2 parts simply press together and are them welded. This method of assembly for welding is also a simple check that the 2 parts are being bent correctly as they can be checked once the first parts are bent to ensure they all line up before running the complete batch through the CNC press brakes.
These spot welded fabricated assemblies are used as part of a chassis used on some scientific measuring equipment. The batches can vary from 25 off up to several hundred at a time. They are laser cut from 2mm thick mild steel with nitrogen as the cutting assist gas in house on our Trumpf 3030 fibre laser cutter. The front section with the curved forms are folded up and the then extended sides are created but spot welding them to the front section with support strips as the overlapping joint inside the profile. The spot welding tips on the outside sheet metal surface were flat to reduce the amount of distortion and any indents to these surfaces. Spot welding is good for madding welded joints were great strength is not needed, they can be much quicker than TiG or MiG welding but as they are so small several spots are needed over a larger are to ensure sufficient joint strength is achieved.
After the spot welded joints had been made the outer surfaces were cleaned off and the orbital sanded before being powder coated silver.
If you have a sheet metal work project that needs welding then perhaps you might consider using our skills, please give us a call on 01489 577786 or e-mail us some drawings at firstname.lastname@example.org