Part Leveling After Laser and Plasma Cutting: Why Flat Parts Matter and Which Leveler to Buy

Who this guide is for

This guide is for a laser, plasma or punching shop that cuts flat parts and then loses time straightening them by hand, or sends bent parts on to bending and welding and pays for it there.

Why cut parts come off the table bent

Steel sheet carries stress from the mill. Rolling, coiling, uncoiling and cooling leave stress locked into the sheet, balanced across its width and length. While the sheet is whole, the stresses hold each other in balance and it lies flat enough. Cutting changes that.

• Residual stress is released. When you cut out a part, you remove the material that was holding the stress in balance. The part springs into a new shape. Long thin parts bow, and parts cut near the sheet edge twist.
• Heat input. The cut edge is heated and then cools quickly. The heated strip expands, then shrinks as it cools, and pulls the part with it. Plasma and flame cutting put in much more heat than fibre laser, so distortion is usually worse on those parts, but thin laser-cut parts still curl.
• Skeleton and micro-joints. A skeleton that stays connected, or parts held by micro-joints, carries stress while it is cut. When you break the parts out or lift the skeleton away, that stress is released.
• Punching and stamping. Punched parts are distorted by the plastic deformation around each hole and, on a stamped part, by the forming itself. Dense hole patterns make a thin sheet dish or wave.

It gets worse as parts get thinner, longer and more perforated.

What goes wrong downstream

• Press brake. A part that rocks on the die or bows along the bend line gives a different bend angle from one part to the next.
• Welding fit-up. Two bowed parts do not sit together. Gaps vary along the joint, tack welding takes longer, and heat then adds new distortion on top of the old.
• Robot welding. A robot follows a programmed path, and seam tracking can only correct so much. When parts differ in flatness, the torch is off the joint in places, and you either slow the cell or stand a person at it.
• Painting and powder coat. Coating shows waviness, and a part that is not flat does not hang or rack the same way each time.
• Assembly. Panels that do not lie flat do not close flush, and holes drift out of line when you stack parts for bolting.

Hand straightening fixes the visible bow, but it is slow, depends on the operator, and leaves stress in the part that can move again.

How a roller leveler works

A roller leveler passes the sheet or part through two rows of rolls, one above and one below, offset from each other so the material is bent up and down in turn. The bend is deepest at the entry rolls, where the material is pushed past its yield point on each side of the thickness, and the amplitude gets smaller at each roll toward the exit. By the last rolls the bending is almost nothing, so the part leaves with the stress evened out and lying flat.

Number of rolls and thickness. Thin material needs small work rolls and a tight roll pitch, so it bends sharply enough in each cycle to be pushed past yield. Thick plate needs larger rolls, which carry more load. That is why the catalogue pairs small-diameter rolls and dense roll layouts with thin sheet, and fewer, bigger rolls with thick plate. The thin-sheet leveler lists work rolls of 20, 32, 40 or 50 mm and an optional dense pack of 23, 25 or 27 rolls. The heavy plate leveler lists rolls from 125 to 400 mm in 9 to 19 roll layouts.

Back-up rolls. A small work roll flexes along its length under load, so the middle of the sheet is bent less than the edges. Back-up rolls behind the work rolls hold them straight. Our part and thin-sheet levelers use a 4-high roll system, and the 6-High Precision Leveler adds a further row of back-up rolls so the work rolls are fully supported. That gives even bending force edge to edge and helps keep the surface free of roll marks.

Entry and exit gap. The entry gap sets how deep the bending is, and the exit gap sets how far it dies away. Stored recipes per thickness and material let you recall a known setting for each part family.

Choosing by thickness, width and material

Work out your thinnest and thickest parts, your widest part, and your materials. Then match them to a machine. Every figure below is a catalogue figure from the machine page and is confirmed on the quotation.

• Part Leveler: 0.5 to 30 mm, working width up to 3000 mm, 4-high precision roll system with 17, 19, 21, 23 or 25 rolls, roll diameter 65, 80 or 100 mm, speed 0 to 10 m/min stepless, for high-strength steel, carbon steel and stainless. This is the machine for mixed batches of laser-cut, flame-cut and stamped parts of different shapes.
• 6-High Precision Leveler: 0.3 to 6.0 mm, with an ultra-thin option from 0.05 mm on custom small-diameter rolls, for carbon steel, stainless, aluminium and copper. Choose it when the surface matters, such as mirror or polished stainless, aluminium and copper, and for thin precision blanks.
• Thin-Sheet Precision Leveler: 0.1 to 6 mm, up to 2000 mm wide, 4-high, work rolls 20 to 50 mm, for cold-rolled, galvanized, stainless and aluminium alloy. It is the lower-cost option for thin laser and punched blanks where you need flat parts every day but not a mirror finish.
• Heavy Plate Hydraulic Leveler: 5 to 200 mm, up to 5200 mm wide, for thick and hot-rolled plate, including plate with mill scale or rust. The plate supplier or the plate cutting bay is the user here, more than the parts shop.

By material. Stainless springs back more than mild steel at the same thickness, so it needs deeper bending and often a smaller roll, and a surface-critical grade needs the 6-high. Aluminium and copper are soft and mark easily, which is another reason to use fully supported rolls. High-strength steel has a higher yield point, so the bending has to be deeper to pass yield, which means more force, and it is where the roll layout needs the most care. Tell us the grade and yield strength and we choose rolls on that.

If you buy coil. A cut-to-length line uncoils, levels, measures, cuts and stacks in one pass, for coil up to 1600 mm wide and 10 t at 0.5 to 6.0 mm. It takes out coil set before cutting, so the starting sheet is flatter. It does not remove the distortion the cutting process adds, which is why some laser shops use both. See the whole range on the leveling and embossing machines page.

Leveling and deburring are different jobs

Leveling changes the shape of the part. Deburring changes the edge. A leveler does not remove burrs, dross or slag, and a deburring machine does not take out bow or twist. Most shops need both. For plasma and flame-cut parts with hard dross, knock the worst of it off before leveling.

How to measure flatness

Set the part on a surface plate or on a known flat table, with no clamping. Where a corner or edge lifts, slide a feeler gauge under it and record the largest gap. Do the same on the other corners. To report flatness as millimetres per metre, divide the gap by the length of part over which it appears, measured in metres. A 0.8 mm gap over a 400 mm span is 2 mm/m. For long parts, lay a straightedge along the part and measure under it.

Measure the same way before and after leveling, on the same sample parts, and agree the method with your supplier first. The figure on your own part is the one to test.

Checklist before you buy

1. What are your thinnest and thickest parts, and what share of your volume is each?
2. What is the widest part, and the longest?
3. Which grades do you cut, and is any of it high-strength or surface-critical?
4. Is the problem mostly bow and twist, or edge wave and coil set? Coil set points to a cut-to-length line as well.
5. How flat must the part be, measured how, and at which step downstream?
6. Can the supplier level your sample parts, or send a video of a similar part running?
7. What are the lead time, the warranty and the support for commissioning?

What we need from you to quote

• Photos or drawings of typical parts, and a few of the ones that go wrong most
• Thickness range, and the widest and longest part
• Material grades, including any high-strength or stainless
• Cutting method: laser, plasma, flame or punch
• How bent the parts are now, how flat they must be, and parts per shift
• Site power supply (voltage, phase, frequency) and destination port

Send photos of your parts for a quote in 12 hours →

Taokron supplies these levelers. Taokron (Melbourne) handles inquiry, specification review, quotation, pre-shipment inspection, shipping and after-sales support. Production for a standard machine is 60 to 120 days, and the exact time is confirmed at quotation. Warranty is 12 months, with remote support included and an on-site installation engineer available on request, quoted per order. There is no list price, because each machine is configured to your material, thickness and width.

FAQ

Can I level parts after laser cutting, or should I level the sheet before cutting?

Both help, and they fix different things. Leveling the sheet or coil before cutting removes coil set and wave, so the cutting starts from flat material. Leveling the parts afterwards removes the distortion that cutting adds, from heat and from stress released as material is cut away. If you buy coil, a cut-to-length line covers the first step.

Which Taokron leveler is for laser-cut parts?

The Part Leveler, 0.5 to 30 mm, is made for laser-cut, flame-cut and stamped parts of mixed shape. For thin laser and punched blanks, the Thin-Sheet Precision Leveler covers 0.1 to 6 mm up to 2000 mm wide. When the surface is critical, such as mirror stainless, aluminium or copper, look at the 6-High Precision Leveler, 0.3 to 6 mm.

Does a leveler also deburr the parts?

No. Leveling and deburring are different jobs. A leveler bends the part back and forth to take out warp and reduce residual stress. It does not grind or brush off burrs or dross. Plan a deburring step as well, and remove heavy dross or slag from plasma and flame cuts before the parts go through the rolls.

Will parts stay flat after welding and bending?

Leveling reduces residual stress as well as the visible bow, which is why a leveled part is more stable in later steps. It does not make welding stress-free, and a part that is cut again, or bent hard, can still move.

How flat will the parts be?

The catalogue gives a leveling accuracy for each machine, and the figure depends on material and thickness. The 6-High Precision Leveler is catalogued at up to 0.02 mm/m, with 0.01 mm/m stated for precision thin-sheet set-ups. The real result on your part depends on its shape, its cut-outs and its grade, so we ask for sample parts and confirm the figure at quotation.

What do I need to send for a quotation?

Photos or drawings of your typical parts, thickness range, the widest part, material grades, how bent the parts are now, how flat they must be, parts per shift, and your site power supply and destination port.

Machinery for this application

Leveling machines in the Taokron range: part leveler, 6-high precision leveler, thin-sheet leveler, heavy plate leveler, cut-to-length line and all leveling and embossing machines.