Consider typical manufacturing tolerances when designating brass, bronze and nickel silver extrusions. When in doubt always contact your mill. Tighter tolerances may be achievable.
Extruded Shape Manufacturing Tolerances
1. Alloy
Production Alloys include: Architectural Bronze C38500, Free-Cutting Brass C36000, Free-Cutting Muntz Metal C37700, Naval Brass-High Lead C48500. Commercial Redd and Rose Redd Brass (Proprietary)
Specialty Alloys include: Nickel Silver C77600, Brown Nickel Silver C79600
2. Dimensional Tolerances
Diameter or Distance Between Tolerance (Inches) Tolerance (Inches)
Parallel Surfaces (Inches) Production Alloys Specialty Alloys
| Up to 0.125, incl. | +/- 0.010 | Not applicable |
| Over 0.125” —-0.500” | +/- 0.015 | +/- 0.025 |
| Over 0.500” —-1.000” | +/- 0.020 | +/- 0.030 |
| Over 1.000” —-2.000” | +/- 0.025 | +/- 0.040 |
| Over 2.000” —-3.000” | +/- 0.030 | +/- 0.050 |
| Over 3.000” —-4.000” | +/- 0.035 | +/- 0.060 |
| Over 4.000” —-5.000” | +/- 0.040 | +/- 0.090 |
| Over 5.000 | Consult Mac Metals | Consult Mac Metals |
Note 1: Tighter tolerances may be achieved by prior agreement at the design stage.
Note 2: Certain open space dimensions may require wider tolerances.
3. Straightness
½” Maximum in 12 feet.
4. Twist Tolerance
+/- 1 Degree per foot.
5. Flatness Tolerance
Allowable deviation from flat = 0.007” per inch of width.
6. Cut End Tolerance
Maximum deviation from square = +/- 1 degree
Length tolerance +.250”/-0”
7. Angularity
Allowable deviation from specified angle = +/- 1 degree
8. Radii and Fillets
Minimum radius for sharp corner = .015”
9. Mill Finish
Mac Metals supplies all extrusions in “mill finish” condition. This is the original surface appearance and texture created by the extrusion process, straightening equipment and customary handling marks. Traces of graphite, superficial stains and scratched and a thin layer of lubricant are common
Please share this post with others who are interested in manufacturing tolerances for bronze extrusions. You can also view more info on what an extruded shape is and understand different design considerations for bronze extrusions. You may also view our manufacturing tolerances on the MAC Metals website.
