Flatness Tolerances
In perforated metals, flatness tolerance is key to the overall functionality and performance of a finished product. Flatness is the deviation of the surface of a sheet from a perfectly flat surface.
How to Measure Flatness
Flatness is measured by placing a sheet on a horizontal flat surface and measuring the distance to the highest point of the sheet from the flat surface, then subtracting the material thickness.
Material 10’ in length or less: Should not exceed the amount shown in the tables
- Material over 10’ in length: Should not exceed the table values in any given 10’ section
- Parts under 36” in both width and length: Should not exceed ¼”
- Parts whose length is between 36” and 72”: Should not exceed 75% of the flatness of a 10’ sheet for that specified width
Levels of Flatness Tolerance Quality
Choose between the three levels of quality for steel plate flatness tolerance:
- Commercial
- Superior
- Special
Up to 36" Width
| Thickness Range | Commercial Tolerance | Superior Tolerance | Special Tolerance |
|---|---|---|---|
| 28-20GA | 3/8" | 5/16" | - |
| 19-16GA | 1/2" | 7/16" | - |
| 15-12GA | 5/8" | 1/2" | - |
| 11GA-1/4" | 5/8" | 1/2" | - |
| 5/16-3/8" | 9/16" | 15/32" | - |
| 7/16"-1/2" | 1/2" | 7/16" | - |
| 9/16"-3/4" | 7/16" | 11/32" | - |
Over 36" - 48" Width
| Thickness Range | Commercial Tolerance | Superior Tolerance | Special Tolerance |
|---|---|---|---|
| 28-20GA | 1/2" | 7/16" | - |
| 19-16GA | 5/8" | 1/2" | - |
| 15-12GA | 3/4" | 5/8" | - |
H.R. & C.R. STEEL SHEET, PLATE & HOT DIPPED GALVANIZED SHEETS
| Thickness Range | Commercial Tolerance | Superior Tolerance | Special Tolerance |
|---|---|---|---|
| 28-20GA | 3/8" | 5/16" | - |
| 19-16GA | 1/2" | 7/16" | - |
| 15-12GA | 5/8" | 1/2" | - |
| 11GA-1/4" | 5/8" | 1/2" | - |
| 5/16-3/8" | 9/16" | 15/32" | - |
| 7/16"-1/2" | 1/2" | 7/16" | - |
| 9/16"-3/4" | 7/16" | 11/32" | - |
Heat Treated Steel Plate (Hardness Range 185-360 Brinell)
| Thickness Range | Commercial Tolerance | Superior Tolerance | Special Tolerance |
|---|---|---|---|
| Το 14" | 1-5/16" | 1-5/32" | - |
| 1/4"-3/8" | 1-1/4" | 1-1/8" | - |
| 7/16"- 1/2" | 1-1/4" | 1-1/8" | - |
| 9/16"-3/4" | 1-1/8" | 1" | - |
Stainless Steel and Other Heat Resistant Alloys Sheet & Plate
| Thickness Range | Commercial Tolerance | Superior Tolerance | Special Tolerance |
|---|---|---|---|
| 30-20Ga | 1/2" | 7/16" | - |
| 19-16GA | 5/8" | 1/2" | - |
| 15-12GA | 3/4" | 5/8" | - |
| 11GA-1/4" | 3/4" | 5/8" | - |
| 5/16"-3/8" | 11/16" | 9/16" | - |
Aluminum & Copper
| Thickness Range | Commercial Tolerance | Superior Tolerance | Special Tolerance |
|---|---|---|---|
| .012"-.032" | 5/16" | 1/4" | - |
| .033"-.063" | 7/16" | 11/32" | - |
| .064"-.125" | 9/16" | 15/32" | - |
| .126"-.500" | 5/8" | 9/16" | - |
| .501"-.750" | 11/16" | 5/8" | - |
Specific Flatness Requirements
Discuss your flatness requirements with Hendrick Manufacturing for more specific requests, including:
- Perforated sheets with margins other than “safe” or “no”
- Perforated sheets with a significant percentage of open area
- Blank areas required within the perforated area
- Perforated sheets and coils with wide or unequal wide unperforated blank edges on the long side that may result in wave edges
- Special perforations like ringed perforations or countersunk that may deviate from the flatness of the edges, especially when using soft materials such as aluminum or copper
- Hole diameter is less than the material thickness
- Special alloys
Learn More About Flatness Tolerances From Industry Experts
Hendrick Manufacturing is an industry expert in perforated metals with flatness tolerances that meet your strict standards. Our expertise allows us to achieve your specific flatness variation requirements and special requests.
We are an industry leader with reputable capabilities in custom perforated sheets and coils, providing a variety of hole patterns and material types. Contact us today to discuss your product specifications.
