May/June_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | M A Y / J U N E 2 0 2 0 3 2 TECHNICAL SPOTLIGHT H.M. and S.P. Rockwell hardness tester, patented on February 11, 1919. HARDNESS TESTING RETROSPECTIVE: A CENTURY OF WILSON From its earliest beginnings to today, development of hardness testing has evolved in a parallel manner to the engineering accomplishments of the times. S tanley P. Rockwell and Hugh M. Rockwell (not related) invented the internationally accepted Rockwell indentation test, first paten- ted in 1919. Stanley Rockwell later collaborated with instrument manu- facturer Charles H. Wilson of the Wilson-Maeulen Company to commer- cialize and improve his invention over the next few years. The true potential of the device was first recognized in 1920 by Wilson, who further developed the Rockwell test to become the indenta- tion depth test that is still applied today in material testing facilities around the world. In 1939, Stanley Rockwell was honored with ASM International’s fifth Albert Sauveur Achievement Award, which “recognizes pioneering materials science and engineering achievements that have stimulated organized work along similar lines to such an extent that a marked basic advance has been made in the knowledge of materials sci- ence and engineering.” Among Charles Wil- son’s most important mod- ifications to the test were the introduction of a dia- mond cone as a second in- denter and increasing the maximum test load from 100 to 150 kgf. Wilson also facilitated production and distribution of the tester, which led to rapid adoption of the Rockwell method. His company became the Wilson Mechanical Instru- ment Company. It changed ownership over time and was also known as the Wil- son Instruments Company. Today, the Wilson brand of hardness testers is owned by Buehler, an Illinois Tool Works (ITW) company. The Wilson line under Buehler includes a wide range of hardness testers including Rockwell, Knoop/Vickers, Universal, and Brinell as well as the DiaMet software that provides control, data management, and report- ing options including fully automatic production systems. Several ISO, ASTM, and JIS-certified hardness reference test blocks, accessories, and fixtures are also manufactured by the company. INITIAL HARDNESS TESTS Hardness testing methods have been used to supply valuable mate- rials information for more than two centuries, from the Industrial Revo- lution to the current information age and Industry 4.0. Over the past 200 years, hardness testing has significant- ly evolved from simple scratch testing in 1822 to motorized testers to fully au- tomated, computer-controlled systems. Development of hardness testing has been consistent with evolving technol- ogy trends, progressing in a parallel Stanley P. Rockwell.