ANCHOR BRONZE
& Metals, Inc.
Quality & Deliveries You Can Trust
MATERIAL TOLERANCES vs. FINISHING ALLOWANCES
Wrought Copper Alloy Bar & Plate (UNS "C" 100 through 700 series of WROUGHT copper alloy numbers) are produced to size within a plus and minus tolerance per the ASTM standards. For example if you order a 1" dia. brass rod the OD tolerance will be +/-.002". If you are finishing to 1.000" OD or less, you will need to order the next OD size up for example 1.125" OD. For rolled plate, for example, 1/2" thickness tolerance would be +/-.028". If you are finishing to 0.500" thickness or less you would need to order the next standard thickness up which for example may be 0.625" thick.
Cast Copper Alloy Bar & Plate (UNS "C" 800 & 900 series of CAST copper alloy numbers) are produced to "Nominal" sizes. This means finishing allowance already remains to finish to the published size. For example, if you order a CAST C95400 aluminum bronze bar to 3" solid dia. the actual cast size will be 3.063" (+/-.010") and will finish to 3.000" diameter or less. If you need a tin-leaded bronze tube in a cast alloy, for example, 2" ID x 3" OD the AS CAST ID will be 2" (-.031") ID x 3" (+.031") OD and will finish to 2.000" ID x 3.000" OD.
Large diameter Centrifugal Castings in CAST alloys are semi-finished with .125" finishing allowance remaining on all surfaces to finish to your requested size. With all alloys it is best that we know your actual exact finished dimensions. This way we can insure that you will receive the proper amount of clean-up allowance on your material per the ASTM specifications.
Cast Bronze Finishing Allowance for:
Hollow Tube (Round Only)
Tin Bronzes and Leaded Tin Bronzes
Cast Bronze Finishing Allowance for:
Hollow Tube (Round Only)
Aluminum Bronzes and Manganese Bronzes
Cast Bronze Finishing Allowance for:
Solid Round Bar, Rectangle & Hexagons
Tin Bronzes and Leaded Tin Bronzes
Cast Bronze Finishing Allowance for:
Solid Round Bar, Rectangles and Hexagons
Aluminum Bronze & Manganese Bronzes
TOLERANCES ARE NOT FINISHING ALLOWANCES
TOLERANCES ARE THE +/- ACTUAL SIZE AIM OF THE SPECIFICATION OR MANUFACTURE
Cast Bronze Diameter Tolerances for:
Solid Round Bar, Tube, Squares, Rectangles and Hexagons
Tin Bronzes and Leaded Tin Bronzes
Cast Bronze Diameter Tolerances for:
Solid Round Bar, Tube, Squares, Rectangles and Hexagons
Aluminum Bronzes & Manganese Bronzes
Cast Bronze Diameter Tolerances for:
ROUND HOLLOW TUBE
Tin Bronzes & Leaded Tin Bronzes
Cast Bronze Diameter Tolerances for:
ROUND HOLLOW TUBE
Aluminum Bronzes & Manganese Bronzes
THE DIFFERENCE BETWEEN FINISHING ALLOWANCE AND TOLERANCES:
For example, 3" ID x 4" OD C95400 Aluminum Bronze Tube. Referring to the Finishing Allowance Charts you will see that the Finishing Allowance is 3" (-.125") ID x 4" (+.094") OD. Therefore the cast AIM size is 2.875" ID x 4.094" OD. However, as with anything, there is a tolerance to these dimensions. The tolerances for this example, will be 2.875" (+.015" / - .050") ID x 4.094" (+/-.015") OD. The ACTUAL tube size can be 2.890"/2.860" ID x 4.079"/4.109" OD. In Cast Alloys this is what is called a NOMINAL 3" ID x 4" OD Tube and will finish to 3.000" ID x 4.000" OD.
Let us look at a Rectangle. NOMINAL 1" x 4" C86300 Manganese Bronze Rectangle will be 1" (+ .094") THICK x 4" (+ .094") WIDE. Therefore the CAST AIM is 1.094" THICK x 4.094" WIDE. Referring to the Tolerance Chart the actual cast size can be 1.094" (+/ .020") x 4.094" (+/- .040"). The Rectangle size can be 1.074"/ 1.114" THICK x 4.074"/4.114" WIDE. In Cast Alloys this is what is called a NOMINAL 1" THICK x 4" WIDE Rectangle and will finish to 1.000" Thick x 4.000" wide.
UNDERSTANDING TOLERACES & FINISHING ALLOWANCES WILL SAVE YOU TIME & MONEY
For Example, a buyer asks a supplier for C93200 (SAE 660) Bronze Tube and the buyer is finishing to 8.000" OD. A Buyer unaware of NOMINAL specifications, may ask for 8.250" OD adding the clean up allowance themselves. Since 8.250" OD is non-standard the buyer will be offered NOMINAL 8.500" (+ .125") OD or NOMINAL 9.000" (+ .125") OD WHEN THE NOMINAL 8" (+ .125") OD WOULD HAVE FINISHED TO 8.000" OD OR LESS. If buyers do not let us know their finished sizes or are unaware of the NOMINAL Finishing Allowances per the ASTM specifications they can waste many thousands of dollars over time by purchasing sizes with unnecessary extra finishing allowance.
