Why You Must Ask About Tolerance When Buying Stainless Plate

What Tolerance Means

Tolerance is the accepted permissible deviation in length or thickness. It matters in the buying and selling of stainless plate and sheet as much as in the application. In measurement, the difference between the maximum and minimum size of the tolerable error is the tolerance, and error ranges recognised by industrial specifications are also called tolerance.

Reading a Drawing Tolerance

If a drawing records 60 with plus 0.045 and minus 0.000, the reference dimension is 60 and the tolerance limits are plus 0.045 and minus 0.000. The upper limit is therefore 60.045 and the lower limit is 60.000. One reason for setting tolerances at all is to balance accuracy against machining cost, because tighter accuracy always costs more.

Why Plate Is Rarely Nominal

During rolling, the roll deforms slightly as it heats, so the rolled plate ends up thicker in the middle and thinner at both edges. The actual thickness is often less than the theoretical figure. A nominal 5 mm plate can measure 4.824 mm, and that difference is the tolerance.

Related product: 304 304L and 304H Stainless Steel Sheet

Positive and Negative Tolerance

In the Chinese market most references to tolerance mean negative tolerance, although positive tolerance plate also exists and is less common. Negative tolerance plate is mostly sold on theoretical calculated weight, while positive tolerance plate is mostly sold on weighed weight. That difference changes the price per usable kilogram.

What to Ask Before You Order

Ask which tolerance the plate is rolled to, whether it is sold on theoretical or weighed weight, and what the thickness variation across the width is. Then design individual tolerances part by part to balance quality against cost, rather than applying one tight figure to everything.

Related product: 2205 Duplex Stainless Steel Sheet