Every machine sits on something. A conveyor, a press, a pump and motor, a packaging line, a test rig, a robot cell: under all of it there is a welded steel frame that somebody had to build, and nobody thinks about it until the equipment will not line up. A frame that is a sixteenth out of square over ten feet turns a one day install into a week of shimming. We build frames, bases and skids for manufacturers and machine builders at our Burlington shop, and the frame in the photo above is a good example of the kind that leaves here on a flatbed.
What We Mean by a Frame
Machine frames. The skeleton of a piece of equipment, usually square or rectangular tube, that everything else bolts to. Built to a machine builder's drawing, often several at a time.
Equipment bases. A heavy base under a motor, pump, gearbox or press, made from channel, beam and plate, with mounting pads and anchor holes for the floor.
Skids. A base that carries a whole system so it can be lifted and moved as one unit: pumps, tanks, piping and controls on one frame with lifting lugs and fork pockets. The water purification skid in our sketch to steel post is one of these.
Stands, tables and carts. Lighter frames for tooling, fixtures, inspection benches and material handling, in carbon steel, stainless or aluminum.
Why Frames Go Out of Square
Every weld shrinks as it cools, and it pulls the steel toward it when it does. One weld on one corner of a tube frame pulls that corner in. Weld all the way around one end before touching the other, and the frame comes off the table with a twist that no amount of clamping will take back out. The steel did exactly what steel does. The sequence was wrong.
So a frame that has to be true is built in a set order. The parts are cut to length square, because a frame built from crooked cuts starts crooked. It is tacked together on a flat table, measured corner to corner, and adjusted while it is still only tacked. Then it is welded in a balanced pattern, a bit on one side and a bit on the opposite side, so the pulls cancel instead of adding up. Long welds are stitched in stages. The frame is measured again before it leaves the table. None of that shows in the finished part, and it is the whole job.
When the Pads Get Machined
Even a well built weldment is not a machined surface. If a gearbox has to sit flat, if two bearing housings have to line up, or if a hole pattern has to match a casting, the mounting surfaces need to be cut true after the welding is finished and the frame has settled. That is why the mounting pads on a base are left thick: so there is material to take off.
On frames and bases that fit our mill, the pads are milled flat and the holes are put in here, as covered in when a welded part needs to be machined. On a frame that is bigger than the machine, the design does the work instead: machined mounting plates fitted and welded last, away from the heavy welds, or adjustable mounts that take up the difference. Which approach suits your frame is settled at the quote, not after it is built.
Tube, Channel or Plate
Square and rectangular tube is the usual choice for a machine frame. It is stiff in every direction, clean to look at and easy to bolt guards and panels to. Channel and beam make sense for heavy bases where the load is mostly down and the frame gets anchored to the floor. Plate comes in for gussets, pads and decks, and for bases stiffened with ribs. Bent sections off the brake press often replace several welded pieces with one formed part, which means fewer welds and less to pull the frame around. If the drawing calls for one and another would do the job better, we will say so.
Built to Fit a Truck
A frame is only useful once it is at your plant, so how it ships is part of how it is built. The overhead cranes and the 18,000 square foot floor let us build and turn long, heavy frames in one piece when one piece will travel. When it will not fit a truck, or will not go through the door at the other end, the frame is designed in sections with bolted splices and put together once on our floor to prove the holes line up before it is taken apart to ship. Lifting lugs go on where the rigger needs them, not where it was convenient to weld them. Customers bring work to us at 3485 Mainway and collect it or send a carrier, so tell us what truck is coming and we will build to suit it.
Finish Before It Leaves
Most frames leave here primed and painted, done in the building so the welds are coated along with everything else. Powder coat and hot dip galvanizing are arranged through our finishing partners for frames that need a harder finish or will live outdoors, and the frame is sized and vented to suit the oven or the kettle. The options are laid out in metal finishing for fabricated steel. Machined pads and threaded holes are masked so they are still clean when the equipment goes on.
What to Send for a Quote
The drawing or CAD file, with the surfaces and hole patterns that matter marked. Tight tolerances on everything cost money and buy nothing, so tell us which ones the equipment depends on. If there is no drawing, send the footprint and weight of what the frame carries, the mounting hole pattern, the height it has to sit at, how it will be moved, and where it will live. Tell us how many you need, because five frames built on one jig cost less each than one. We build this work for plants and machine builders across Burlington, Hamilton, Oakville, Milton and Mississauga, and there are more frames and bases on our work page.