Raw material critical to manufacturing of any product. The final product is a direct result of the quality of the raw material and the potential cost of poor quality can be drastically reduced by ensuring high quality in raw materials. In the business of metal fabrication and assembly the quality of the metal has an enormous impact on the overall function and design limitation of the final product.
There is a wide variety of mills and foundries to produce metal bars, sheets, tubes, and castings according to the specifications of the customer to meet the required Chemical and Mechanical properties. Both chemical and mechanical properties can impact the final product.
Chemistry is generally performed at all mills and foundries by using spectrometry. Good metal produces often have 2 such machines in case one machine goes down for any reason.
Physical properties generally include metal hardness, impact tests, yield strength, and ultimate tensile strength. The most common methods to measure such properties are by using Rockwell and Brinell hardness testers, IZOD tester, and tensile bars for pull tests.
Something for quality professionals to keep in mind is that it is important to check incoming raw material from any distributor, mill, or foundry since there is always a possibility that a mix up may occur. One of the most economical methods of performing a quick quality check is via a Rockwell or Brinell hardness test. More often a Brinell Hardness test is performed due to the ability to perform more easily on raw materal since the tester can actually accomidate large bars and sheets and is more portable than a Rockwell tester. Digital hardness testers are not recommended since they do not fit the ASTM E10 or ASTM E18 requirements for Brinell and Rockwell testing.
Keep in mind it is the responsibility of the customer to provide well defined raw material specifications to the supplier. Most mills and foundries try to produce metal in a range that will satisfy multiple customer specifications so that it is most efficient for them. This process can produce materal that may be boardline to a particular customer’s needs. It is important to always check the mill test report (also known as an MTR) to determine what specifications the metal actually is.