T 1
he machinability of a casting is influenced by the metal. Metallur- gists and quality assur- ance managers wish to
use machinability testing methodol- ogy to measure and record the effect of alloy type, metal alloy grade, com- position, microstructure, mechanical properties and/or physical proper- ties on enhancing machinability. Michael Finn, Finn Metalworking and Cutting Solutions, with support from the American Foundry Society (AFS), developed a manual for using factorial designed experiments to reduce the number of metalcasting experimental runs and identify the processing conditions affecting the machinability values. Te user’s manual for testing the
machinability of cast metals, now available from AFS and written by Finn, contains recommended pro- cedures designed for testing gray and ductile iron castings and may be adapted to machinability testing of other cast metals. It includes recom- mended parameters for: • Workpiece shape and size
Background Metal makers have used a
variety of machining proce- dures and measuring methods to quantify the machinability
of their products. Tey usually simu- late their major customers’ machining procedure such as turning, milling, and drilling. During the machining procedure they measure response attributes such as surface roughness, chip form, part tolerance, cutting forces and cutting tool wear and/or failure. Finn chose to measure cutting tool wear as the response attribute while face tuning cast iron discs. Face turning cast iron discs simulates the surface milling procedure used most often in making parts from cast iron. Te procedure in the ASTM E618- 81 specification is the only standard machinability testing methodology for metal alloys, namely for cold rolled bars. It is not applicable to disc workpieces and the shapes and sizes
• Machine and cutting tools • Cutting fluid • Machining parameters and data measurements
• Data recording and analysis • Presentation of the results. The testing methodology
measures machinability value rela- ADDING IT ALL UP Breaking down the latest research is as easy as 1-2-3.
“User’s Manual on a Machinability Testing Methodology for Cast Iron,” Michael Finn, Finn Metalworking and Cutting Solutions, Loveland, Ohio.
1 2 3
Background—Te new manual for testing the machinability of cast met- als contains recommended procedures designed to test gray and ductile
cast iron. Procedure—Multiple test campaigns at different cutting speeds are conducted, during which the time to take one pass, along with the flank
wear width of the wear land, is measured and recorded. Results and Conclusions—A graph of the results plotted on a graph with a Taylor Line is used to compare the different heat lots and grades of cast iron for machinability. Te test has been verified at multiple machining locations.
tive to a casting’s performance in machining, reducing the amount of time and money spent on chemical, tensile and microstructure rechecks of the castings. The methodology also can help predict machinability values for components produced in a specific cast alloy.
Fig. 1. Shown is the workpiece for machinability testing of cast iron used in this study. March 2013 MODERN CASTING | 59
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