Burr Height Limits: The 5% Rule vs Absolute Values

Short answer: whichever is smaller — take the percentage rule and the absolute limit your downstream process tolerates, then keep the lower. The 5% figure everyone quotes is a commercial convention rather than a standard; EN 10140, EN 10143 and ASTM A568 each set their own scope, and none of them fixes one universal burr value. The practical answer to acceptable burr height for slitting steel strip therefore has two halves — choosing the right allowance, and owning a gauge that can read it.

1. Which burr limit actually applies to your strip?

The one your customer's next operation imposes, not the one your Slitting Line can hold. Every published answer to acceptable burr height for slitting steel strip was written for a different end fate, which is why one 1.5 mm coil attracts three different numbers depending on who is replying.

Two consequences matter more than the table itself. First, thicker does not mean looser: 5% of 4 mm is 0.20 mm, tall enough to cut gloves, score roll-coating rolls and break through paint film, so heavy gauge needs a hard absolute cap near 0.05–0.10 mm whatever the percentage suggests. Second, the material decides what any given micron is worth — annealed aluminium throws a tall soft lip that rolls over and can be brushed away, while work-hardened austenitic stainless throws a short hard one that does more damage per micron.

For a burr height limit for 1.5mm cold rolled steel slit edge, general fabrication lands at 0.075 mm, precision stamping feed drops it to roughly 0.030 mm, and anything a customer will stack, weld or paint should be agreed as a measured millimetre figure rather than a percentage. That is the version Ruilong puts on quoted inspection reports, because it removes the argument about which chart applies.

✅ Bottom line: specify burr as the smaller of a percentage and an absolute cap, and write down which downstream process that number protects.

2. How do you measure burr height on a slit strip edge?

With an instrument whose resolution is finer than the limit you wrote — which is where most inspection routines quietly fail. How to measure burr height on slit strip edge stock depends entirely on the number you are trying to defend.

Then five rules turn one reading into evidence:

• Never specify below your own resolution. Five per cent of 0.15 mm foil is 7.5 µm, and a dial gauge that reads in 0.01 mm steps passes material it never actually measured. Buy the metrology before agreeing the tolerance, which is why Ruilong names the method alongside the limit on every quotation.

• Sample both edges, at least three places — head, mid-length and tail — and re-check at an interval counted in running metres, because burr grows as the edge dulls and grows fastest on abrasive grades.

• Measure flat and unloaded. Burr folds against itself under rewind tension and reads low, so a sample taken straight off the coil can understate exactly what the customer receives.

• Record five fields: maximum height, position along the coil, strip thickness, measurement method, and the computed burr ratio of height ÷ thickness × 100.

• State burr direction on the order. It decides whether the lip faces the die, which changes the outcome for progressive tooling and lamination stacking.

Where the two rules collide, take the absolute value. A percentage tells you nothing about whether you can verify it, and nothing about what happens downstream — the two questions that decide whether the coil gets paid for.

✅ Bottom line: a burr limit finer than your gauge can resolve is decoration, so agree the tolerance and the metrology together.

FAQ

Q: What is the acceptable burr height for slitting steel strip? A: Around 5% of thickness for general fabrication, tightening to 2% or better for stamping feed, springs and laminations, and capped absolutely at roughly 0.05–0.10 mm on heavy gauge where the percentage becomes meaningless. Ruilong confirms each figure by the method named on the inspection report issued per coil.

Q: What burr height limit for 1.5mm cold rolled steel slit should I put on a purchase order? A: Write 0.075 mm maximum for general work and 0.030 mm where the strip feeds precision tooling. State the measurement method alongside it, otherwise two people will disagree about one coil.

Q: How to measure burr height on slit strip edge material without a full metrology bench? A: A bench burr gauge or a bench-mounted dial indicator with a reference block covers most steel work to 0.01 mm; below 1 mm thickness you need a microscope or a 0.001 mm gauge to have anything defensible, and Ruilong ships the sampling procedure with the line rather than leaving it to the shift supervisor.

CTA: Put Measurable Burr Limits on Your Orders

Send Ruilong your grades, gauge range and end application. As a slitting line manufacturer in China, Tai'an Ruilong Machinery Co., Ltd. builds each custom line around the burr limit customers will actually accept, ships matched OEM/ODM tooling as one kit, and quotes factory-direct with the inspection method written into the order — one tooling supplier accountable for the edge, not two.