Tolerances & Finishing Allowances
Standard dimensional tolerances and finishing allowances for continuous cast bronze, brass, and copper alloy products per ASTM B505. All products ship with machining stock included.
Understanding Cast Tolerances
Continuous cast bronze, brass, and copper products are produced to nominal dimensions plus machining stock. The material ships intentionally oversized on outside dimensions (OD) and undersized on inside dimensions (ID) so that a finish machining pass brings the part to the desired size.
Tolerances vary by alloy group. Group A covers most standard tin bronzes, leaded bronzes, and brasses. Group B covers manganese bronzes and aluminum bronzes (C86xxx, C952xx, C955xx, C958xx), which require wider tolerances due to their higher shrinkage rates during solidification.
Finishing Allowances — Solid Round Bar & Rod
Continuous cast bar is produced oversize to provide machining stock. A skin cut will bring the bar to nominal finished diameter.
Group A
Standard alloys (C83600, C90300, C90500, C92200, C93200, C93700, C93800, etc.)| Finished Diameter | Allowance Over Nominal |
|---|---|
| Up to 4" | +0.0625" (1.6 mm) |
| 4" to 5" | +0.093" (2.4 mm) |
| Over 5" | +0.125" (3.2 mm) |
Group B
Manganese & aluminum bronze alloys (C86200, C86300, C86500, C95200, C95400, C95500, C95800, etc.)| Finished Diameter | Allowance Over Nominal |
|---|---|
| Up to 3" | +0.031" (0.79 mm) |
| 3" to 4" | +0.063" (1.6 mm) |
| 4" to 5.5" | +0.094" (2.4 mm) |
Finishing Allowances — Hollow Bar & Tube
Tube is produced oversize on OD and undersize on ID to provide machining stock on both surfaces.
Group A
Standard alloys| Finished OD | OD Allowance (Over) | ID Allowance (Under) |
|---|---|---|
| Up to 4" | +0.031" | -0.031" |
| 4" to 5" | +0.063" | -0.063" |
| Over 5" | +0.094" | -0.094" |
Group B
Manganese & aluminum bronze alloys| Finished OD | OD Allowance (Over) | ID Allowance (Under) |
|---|---|---|
| Up to 3" | +0.063" | -0.125" |
| 3" to 4" | +0.094" | -0.125" |
| 4" to 5.5" | +0.125" | -0.188" |
| Over 5.5" | +0.188" | -0.250" |
Diameter Tolerances — Solid Round Bar & Rod
Dimensional tolerances on the finished (machined) diameter of continuous cast rod and bar, per ASTM B505.
Group A
Standard alloys| Diameter Range | Tolerance |
|---|---|
| Up to 4" | ±0.005" (0.13 mm) |
| 4" to 5" | ±0.008" (0.20 mm) |
| Over 5" | ±0.016" (0.41 mm) |
Group B
Manganese & aluminum bronze alloys| Diameter Range | Tolerance |
|---|---|
| Up to 3" | ±0.010" (0.25 mm) |
| 3" to 4" | ±0.015" (0.38 mm) |
| 4" to 5.5" | ±0.020" (0.51 mm) |
Diameter Tolerances — Hollow Bar & Tube
OD and ID tolerances for continuous cast tube, per ASTM B505.
Group A
Standard alloys| OD Range | OD Plus | OD Minus | ID Minus |
|---|---|---|---|
| Up to 4" | +0.005" | -0.012" | -0.033" |
| 4" to 5" | +0.008" | -0.016" | -0.046" |
| Over 5" | +0.016" | -0.032" | -0.064" |
Group B
Manganese & aluminum bronze alloys| OD Range | OD Plus | OD Minus | ID Minus |
|---|---|---|---|
| Up to 3" | +0.010" | -0.012" | -0.033" |
| 3" to 4" | +0.015" | -0.015" | -0.050" |
| 4" to 5.5" | +0.020" | -0.025" | -0.070" |
| Over 5.5" | +0.025" | -0.035" | -0.090" |
Roundness (Out-of-Round) Tolerances
Maximum permissible out-of-roundness for continuous cast round products.
Group A
Standard alloys| Diameter | Max Out-of-Round |
|---|---|
| Up to 4" | 0.020" (0.51 mm) |
| 4" to 5" | 0.032" (0.81 mm) |
| Over 5" | 0.064" (1.6 mm) |
Group B
Manganese & aluminum bronze alloys| Diameter | Max Out-of-Round |
|---|---|
| Up to 3" | 0.025" (0.64 mm) |
| 3" to 4" | 0.040" (1.0 mm) |
| 4" to 5.5" | 0.060" (1.5 mm) |
| Over 5.5" | 0.075" (1.9 mm) |
Tolerances — Rectangle, Square & Plate
Dimensional tolerances for continuous cast rectangular bar, square bar, and plate products.
All Standard Alloys
Per ASTM B505| Dimension | Tolerance |
|---|---|
| Outside dimensions | ±0.016" (0.41 mm) |
| Inside dimensions | +0.032" / -0.064" |
Straightness Tolerances
Maximum permissible curvature for continuous cast products.
Round Rod & Tube
| Length | Max Curvature |
|---|---|
| Up to 10 ft | 1/4" in any 5 ft section |
| Over 10 ft | 1/2" in any 10 ft section |
Bar & Shapes (Non-Round)
| Length | Max Curvature |
|---|---|
| Any length | 1/2" in any 6 ft section |
Concentricity
- •Standard alloys: maximum eccentricity of 2% of nominal wall thickness (for walls over 1/4").
- •Manganese & aluminum bronze alloys: maximum eccentricity of 4% of nominal wall thickness.
Standard Lengths
- •Standard stock length: 105" (8'-9")
- •Mill lengths available up to 144" (12')
- •Custom cut-to-length available: 1" to 144"
Reference Standards
Tolerance data on this page is based on ASTM B505/B505M (Standard Specification for Copper Alloy Continuous Castings). Actual tolerances may vary by alloy, size, and supplier. Contact us for specific tolerance requirements on your order.
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