The first of a PD&D three part series focusing on proper component selection to best achieve anticipated machine performance.
 The most comprehensive component catalogs will generally include material hardness conversion tables, such as this one, as well as material variety/application and surface treatment option/performance charts. The hardness chart here details and compares the various scales used in industry today, namely, Rockwell C, Vickers, Brinell, Shore) |
Among the many factors to consider in machine and equipment design, few are more critical than the material performance features. This series will explore some of the aspects of machine performance that a designer must consider in selecting the proper component materials for use in the end product. A chart is provided herewith to assist in the material hardness conversions often needed when specifying components from various suppliers, who use differing methodologies to determine their hardness ratings.
| Some very helpful literature that will address most questions regarding material types and properties include the following:
Metals Handbook published by ASM international: This is a very comprehensive book that will give engineers information about the structure and properties of metals, explain how they are processed, explain the testing methods for irons, steels, high performance alloys, nonferrous alloys and special purpose materials.
Materials Handbook published by McGraw-Hill: A more general book that explains properties and uses of over 15,000 materials ranging from metals to wood and other organic materials. It also provides some information on structure. Some suppliers will use products that were manufactured elsewhere and the materials used are unique for a particular market, so they do not have AISI equivalents. The engineers may realize the advantage of the product, but cannot make a decision to purchase those products, because of insufficient information provided by suppliers.
Casti Metals Black Book: European Ferrous Datapublished by Casti Pub: A book series that contains over 400,000 pieces of metals data from European Standard (EN) metal specifications. International specification cross-references include: DIN (Germany), ASTM/AISI (USA), BS (United Kingdom), AFNOR (France), JIS (Japan), SS (Sweden) and GOST (Russia). |
When choosing materials for the structures and especially the motion-related components on a machine or a piece of assembly equipment, the physical properties of those materials are vitally important to the overall life of the end product. The primary considerations when selecting materials must include the following:
- Strength: Will the material selected withstand the impact, torque and friction forces placed on it?
- Brittleness: If the part is to be impacted on a repetitive scale, will it crack/shatter?
- Hardness: If pressure is applied to the surface, how much will it deform?
- Weight: How much will the part weigh, if made from a certain material, and will that weight create problems in other areas of the machine’s design?
- Machinability: How difficult is the material under consideration to machine, as this will effect manufacturing and build times?
- Weldability: How well does the material react to various types of welding? What impact will welding have on the resulting structure?
- Price: How expensive is the material under consideration and is it available from local sources?
- Corrosion Resistance: Will the part corrode when subjected to the ambient conditions in use?
- Ferrous: Is the material magnetic?
- Conductivity: Does the material conduct electricity or is it subject to static electricity?
- Wear Resistance: When subjected to repeated forces over time, how well does the material under consideration resist wear and what surface finishes might be considered?
- Temperature?
A reliable component supplier will advise the designer in all the above areas, once the specifics of the application are known and examined. This checklist may need to be expanded and modified by the application environment, the particular restrictions on materials used, e.g. cleanroom applications, and even the local operating standards at the location of use.
Be sure to read part two of PD&D’s three-part series focusing on proper component selection en route to optimum machine performance.
Mr. Chris Blaszczyk and Mr. Mike Melone of Misumi contributed to this article. They may be contacted for further information at 1-800-681-7475.
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