Resistance Spot Welding
Resistance spot welding joins sheet metal at single points, with no filler, by clamping two overlapping sheets between electrodes and passing current through them. K-Display spot welds steel stiffeners, brackets, and flanges, the bent-up edges of a sheet, to panels and cabinet bodies in Chicago.
What resistance spot welding does to overlapping sheets
The current meets the most resistance where the two sheets touch, so the heat builds there and fuses a small region of both into a weld nugget. The electrodes keep pressing while the nugget solidifies. We supply steel panels, stiffeners, and brackets spot welded, then fitted with hardware, powder coated, or assembled.
MIG and TIG welding uses an electric arc to lay a continuous bead of filler metal along a joint, and it joins stainless steel and aluminum as well as steel.
The nugget forms where the two sheets touch and reaches partway into each, sealed inside the overlap. An electrode presses each outer face, so the joint needs both faces open.
Parts we spot weld
Spot welding fits steel parts joined at repeated points along an overlap. Choose it for stiffeners, flanges, and brackets on steel panels; choose MIG and TIG welding for a continuous seam, or for stainless steel and aluminum.
- Hat-section stiffeners on cabinet panels, each a raised crown with a flat foot on each side, held to the panel by spots along the feet.
- Reinforcement channels on sectional door panels, spot welded behind each hardware location to the outer sheet.
- Rails and panels in card cages, spot welded where they overlap to hold the frame together.
- Materials
- Steel
- Production fit
- Best fit depends on joint repetition, electrode access, material combination, and quantity.
Weld the overlap while both faces are open
We weld the overlap before a wall is folded up beside it, a cover goes on, or a nut is pressed in, since each would leave an electrode no room to reach a face of the overlap.
Form the overlapping foot
We cut the panel and the stiffener or bracket, and form the flat foot or flange that will overlap the panel.
Seat the overlap
We lay the foot flat on the panel and clamp it between the electrodes at each spot location.
Weld the spots
We weld the spots one at a time along the foot, and the electrodes hold the sheets together until each nugget sets.
Fit hardware, coat, and assemble
We press the nuts and studs into the welded part before it is powder coated, fit hinges, latches, and handles after the cure, and ship the part welded, coated, or built into a unit.
Design for spot welding
Both faces of an overlap need room for an electrode tip, and a closed box section has no way in for one. Draw the overlap on an open flat flange and we spot weld it; a joint inside a closed section goes to MIG or TIG welding from the open side.
Current takes the shortest path, so a spot close to an earlier spot, a bend, or an edge sends current through the metal beside it, and the new weld comes out weaker or the edge deforms. Draw the spots apart from each other and clear of edges and bends, and we weld them at that spacing.
Each electrode presses a shallow mark into the outer face it touches, so both outer faces of an overlap carry marks. Draw the overlap where those marks fall on hidden faces; where a face that shows cannot take them, we join that overlap with MIG or TIG welding from the hidden side.
The hat section's feet turn outward onto the panel, so one electrode lands on each foot beside the wall and the other presses up from under the panel.
What to send for a spot welding quote
- Assembly drawings
- Part and assembly files with revision, the overlap, and joint details.
- Sheet stack
- Steel grade and thickness of each layer in the joint.
- Weld pattern
- Spot locations, spacing, and overlap width, called out with weld symbols.
- Appearance
- Cosmetic faces, acceptable electrode marks, and the finish that follows.
- Production
- Quantity, repeat orders, and delivery date.