This page contains a Flash digital edition of a book.
New Alternative Low-Lead Copper Alloy Shows Promise

C83470 is a viable option to produce castings that will be in compliance with the Safe Drinking Water Act or other standards requiring castings to be low in lead. AFS COPPER ALLOY DIVISION

metalcasting facilities for use in pro- ducing castings that will be in compli- ance with the Safe Drinking Water Act or other standards. Recently, a new no-lead alloy has entered the market that provides a combination of improved casting pressure tightness, mechanical strength, machinability (chip-breaking), alloy recyclability and pattern yield when compared to other low-lead alloy alternatives. T e Copper Development Associa-


tion (CDA) lists a number of low-lead alloys identifi ed by UNS number on its website ( and in print. Most of these alloys are also listed in applicable ASTM standards, specifying their required chemical composi- tion and mechanical property requirements. Each of these alternative alloys have properties that make them unique from the others, and though they are all low in lead, each alloy presents diff ering challenges to metalcast- ers and machine shops when chosen to replace traditional lead-bearing alloys. To date, no low-lead alloy

alternative has proven to be an identical replacement for traditional lead-bearing alloys

36 | MODERN CASTING February 2016

any alternative low- lead brass and bronze alloys are available to

regarding casting, machining, pres- sure tightness and overall performance characteristics in typical waterworks casting applications. A new sulfi de-bearing tin bronze

was developed in the 2000s by Shiga Valve Cooperative, Hikone, Japan, in conjunction with Kansai University, Suita, Japan. T e new alloy has since been added to the CDA alloy database and given UNS number C83470. With the introduction of this new

alloy, copper-based casting facilities will have another tool to help meet the needs of the castings produced in no- or low-lead applications.

Learning by Trial Beginning in 2011, the AFS Cop-

applicable ASTM standards, specifying per Alloloy Division performed trials

at Ford Meter Box Co., Inc., Wabash, Indiana, and A.Y. McDonald Mfg. Co. Inc., Dubuque, Iowa, to study alloy use in North American facilities. Green sand molds were produced with automatic molding machines utilizing warm box and shell cores. T e C83470 material was melted in a coreless induction furnace and a lift-swing furnace. Many diff erent castings were manufactured in a size range consistent with standard cast- ing sizes of these facilities. Casting weights were from 0.25-7.7 lbs., with wall thicknesses varying from 0.10-0.75 in. C83470 appears to be sensitive to high turbulence during pouring. While some existing gating and risering tech- niques designed for traditional leaded allo s, such as C83600,

alloys, such as C83600, were successfulere successful without modifi ation, other casting

without modifi cation, other casting geometries required larger ingates. In some cases, due to the higher copper content of C83470, increased riser volumes were needed. In most cases, the thin ingates in a pressur- ized system resulted in poor casting quality. A non-pressurized gating system, along with generous parting- line venting, tended to result in more favorable casting quality.

Overabundance of superheat A water fi lter body, left, and pump body are shown.

can cause problems, so degassing the metal is advised. Targeting the maximum of the zinc range

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60