Short answer: how do the three grades differ?
On an ERW tube mill, the shear & butt welder (also called a strip end welder) is installed after the uncoiler and leveling machine and before the spiral accumulator. It trims the tail of the finished coil and the head of the next coil, brings the two ends together, clamps them and welds them into one continuous strip. During this time the uncoiler stops while the spiral accumulator keeps feeding strip to the mill, so the line does not have to stop for a coil change.
InGen MillTek offers three grades. Integrated Shear & Manual Welder: a hydraulic shear with clamping plates; the operator butts the strip ends and welds the seam by hand, and centering is usually set by handwheel. Semi-automatic Shear & Welder: the same shear and clamps plus an automatic traveling torch that moves along a linear guide and welds the full seam; centering and butting are manual or assisted by hydraulic cylinders. Fully Automatic Shear & Welder: a PLC controls the whole sequence of shearing, butting, clamping, welding and reset.
No grade is right for every line. Wider, thicker or higher-strength strip, and stricter requirements for a flat and repeatable weld, call for closer attention to shear capacity, the butting method and the level of welding automation. Our engineers recommend a grade from your strip data and production needs, and each grade is quoted separately.
The three grades side by side
- Integrated Shear & Manual Welder: a hydraulic shear trims the strip head and tail, and clamping plates hold the strip. Butting is done by the operator, and centering is usually set with a handwheel mechanism. The seam is welded by hand, so weld flatness depends mainly on the welder.
- Semi-automatic Shear & Welder: hydraulic shear and clamping plates plus an automatic torch-travel unit. The torch moves at a steady speed along a linear guide, strikes the arc, welds the seam, stops the arc and returns. Centering and butting are manual or cylinder-assisted. Traveling refers to the torch moving along the seam, not to automatic wire feeding.
- Fully Automatic Shear & Welder: a PLC runs the full cycle of shearing, butting, clamping, traveling-torch welding and reset. Centering and butting of the strip ends are done automatically by pneumatic or hydraulic mechanisms; servo drives can be used when the buyer specifies them.
- Common to all three: the strip ends are cut by a hydraulic shear whose blade has a rake angle. Parallel shearing means that the head cut and the tail cut are parallel to each other; it does not mean a flat, square-edged blade.
Same grade name, different machine: four points to compare
Two machines sold under the same grade name can be built very differently. When you compare proposals, check the structural description, not only the grade name:
- Centering units: how many sets on the head side and on the tail side, and whether they are driven by handwheel, pneumatic cylinder, hydraulic cylinder, hydraulic motor or servo motor.
- What moves after shearing: four arrangements are common — separate fixed stations for shearing and welding; a shear and welding clamps on one carriage that moves along the line; a shear-and-weld frame that moves sideways on rails across the line; and a small shear that moves sideways out of the line as a whole unit. This affects the machine footprint and the motion sequence.
- Shear type: double-column (gantry) overhead hydraulic shear, bottom-mounted direct-lift shear, or swing-arm shear (an axe-type shear).
- Number of blades: a two-blade, single-edge shear cuts one strip end per stroke, so it normally cuts the tail first and then the head; a four-blade, double-edge shear cuts the head and the tail in one stroke. The shearing sequence described in a proposal should match the blade arrangement actually offered.
How strip width, thickness and strength affect the choice
These structural details decide the joining sequence, the machine size and the price, so ask for them to be written into the technical proposal. Beyond structure, check the following against your strip:
- Strip width: select the machine by your actual maximum strip width. The shear blade must be longer than the maximum strip width, so the number in a model name is not necessarily the usable strip width.
- Thickness and strength: when strip thickness or material strength moves up a class (for example to Q355 or higher-strength steel), the shear cylinder and clamping plates are also sized up one class. High-strength and heavy-gauge strip is assessed case by case.
- Welding process (general practice): thin strip and stainless steel are usually joined by TIG welding (argon arc, no filler wire, flat seam), while thicker carbon steel is usually joined by CO2 gas-shielded welding for higher productivity. The dividing thickness between the two is generally 1.5 mm, and you can also specify the process you prefer.
- Weld flatness: the joint passes through the forming rollers and other mill rollers downstream, and a high weld bead can strike and damage those rollers. Keep the seam as flat as possible; the welding process and the level of automation both affect how consistent the seam is.
- Feed direction: left-hand or right-hand operation must be stated in the contract, because the machine is drawn in mirror-image versions. The direction of the shear & butt welder follows the direction of the line layout.
- Pass height: the strip center height of the welder is set to match your line, project by project.
Plan the joining cycle together with the spiral accumulator
During a coil change the strip in the entry section stops, and the mill runs on the strip stored in the spiral accumulator. The accumulator's storage length must therefore cover the mill line speed over the whole coil change cycle, with a margin. That cycle is more than shearing and welding: it runs from loading the new coil and feeding its head to the welder, through shearing, butting and welding, to reset. After the joint is finished, the feeder refills the accumulator at a speed higher than the mill speed.
This is why the welder grade and the accumulator should be considered together: at the same line speed, a longer joining cycle needs more stored strip. The actual cycle depends on the uncoiler type, strip width and thickness, the welding process and operation, and our engineers check it for each project.
Buying a shear & butt welder on its own
A shear & butt welder can be supplied as a single machine, either for a new entry section or to replace or upgrade the welder on an existing line. Existing welders can also be modified component by component, with each item quoted separately. For a single-machine order, please tell us whether you need the hydraulic power unit, the control cabinet and the welding power source, and send the strip center height and feed direction of your line.
What to send with your inquiry
- Strip width range and thickness range
- Material grade, yield strength and tensile strength
- Line speed and uncoiler type (single-head or double-head)
- Preferred grade, or your requirements for weld appearance and automation
- Preferred welding process (TIG or CO2) and whether a welding power source should be included
- Feed direction (left-hand or right-hand) and strip center height of the line
- Local supply voltage and frequency, and any electrical specification you follow
Frequently asked questions
- Q: Do all three grades allow coil changes without stopping the mill? A: Non-stop coil change depends on the spiral accumulator holding enough strip for the whole coil change and joining cycle. All three grades do the same joining job; they differ in how much of the butting and welding is automated.
- Q: Does a traveling-torch welder feed wire automatically? A: No. Traveling means the torch moves along a linear guide over the seam. With TIG welding, strip joints are usually welded without filler wire.
- Q: Does parallel shearing mean a flat blade? A: No. The head and tail cuts are parallel to each other, but the blade still has a rake angle. The rake angle reduces the cutting force, which is why a moderately sized hydraulic cylinder can cut fairly thick strip.
- Q: What changes for Q355 or high-strength strip? A: The shear cylinder and clamping plates are sized up one class, and the welding process is chosen by thickness. Please send the material grade with its yield and tensile strength.
- Q: How much does a shear & butt welder cost? A: It is configured to order and quoted individually. Send the information listed above and we can quote each suitable grade as a separate configuration for comparison.
About this article
Prepared by the InGen Engineering Team. This is a general selection guide, not a specification or performance guarantee for any project. The final structure, parameters and scope of supply are set in the agreed technical proposal and technical agreement.