Tack Welding
Sheet metal tack welding fuses two parts with a short weld, a tack, that holds them in position until the full weld, the continuous weld along the whole joint, is made. K-Display tack welds frames, door subassemblies, and brackets in Chicago and delivers them tacked, for you to finish-weld, adjust, or install, or finish-welded here.
What tack welding does to a frame
A tack melts a short length of both parts into one, in carbon steel, stainless steel, or aluminum, and leaves the rest of the joint open. The full weld then melts the tacks back into the seam, so a tack laid in the joint becomes part of it.
MIG and TIG welding, the arc processes that melt wire or rod into the joint as they go, run one continuous bead the full length of the seam and leave it finished, which is the weld a tack only holds a place for. Resistance spot welding joins one sheet laid over another, point by point, with no filler.
Parts we tack weld
Tack welding fits an assembly delivered tacked or held in position before its seam is welded. A joint whose finished seam is the product goes to MIG and TIG welding, and an overlap in sheet goes to resistance spot welding.
- Machine frames, with the corners tacked so the full weld starts from a square frame
- Door subassemblies, tacked together for the door maker to finish-weld and install
- Brackets, tacked square to a plate or frame so the bracket can be set and checked before it is finish-welded
- Materials
- Carbon steel, Stainless steel, Aluminum
Holding the joint gap until the full weld
The full weld shrinks as it cools and pulls the joint closed, so the tacks go on first and hold the gap against that pull.
Hold the parts together
We hold the parts against each other so their edges meet along the joint.
Tack the joint
We tack the ends of a joint before its middle, because tacking from one end to the other lets shrinkage close the gap at the far end.
Reset what is out of line
We check the alignment with the tacks on and break loose any tack that holds a part out of position, then set the part again.
Weld in full or ship tacked
We make the full weld along each joint of an assembly we finish, and ship an assembly for you to finish with only its tacks holding the joints.
Design for tack welding
On some weldments the weight of the parts passes through the tacks when the assembly is lifted, and an improperly tacked assembly can rupture when hoisted. Send how the assembly is lifted and shipped, and that decides where we put the tacks.
On thin sheet, a gap between mating edges leaves no metal under the arc to take the heat, and the full weld can burn through there. Draw the mating edges to meet, and we tack them where they touch.
What to send for a tack welding quote
- Assembly drawing
- Drawing of the frame, door unit, or bracket at its current revision, with overall dimensions.
- Joint marks
- Each joint marked tack-only or full weld, with weld symbols on the full welds.
- Material
- Metal and thickness of each part.
- Delivered state
- Finish-welding, adjustment, coating, or installation you do after delivery.
- Handling
- The assembly's weight and how it is lifted or shipped before the full weld.
- Quantity
- Pieces per order and how often the order repeats.