The centerless grinder boasts a long and sometimes contentious history. During the machine’s early days, it wasn’t unusual to specify that parts “not be ground on a centerless grinder.” But today’s CNC centerless grinding machinesachieve tolerances of 10 millionths of an inch, making them a necessary part of technologically advanced manufacturing processes.
The invention of the centerless grinder was an indirect result of bicycle popularity in the U.S. during the early 1900s. As demand for new bicycles surged, Lewis Heim’s The Ball and Roller Bearing Company, in Danbury, Connecticut, received a large order for bicycle bearing rollers. These rollers had always been ground on a center-type grinder, but Heim’s company now needed a faster and less costly way to make the rollers.
After experimenting with several approaches to centerless grinding, Heim developed a grinding machine that did not use center holes for part location. This early concept used the sides of the grinding wheel and the regulating wheel along with a support for positioning and guiding the work.
Jim Daley, a former Heim employee, joined the F. C. Stanford Company owned by Francis Stanford. At Daley’s suggestion, Sanford built a centerless grinder, using the face of the grinding wheel and regulating wheel – an arrangement still in use today. More important, though, was Sanford’s development of throughfeed grinding. Unfortunately, this breakthrough was followed by a legal battle, as Heim and Sanford each claimed that the other had stolen his main principle of throughfeed grinding: tilting the regulating wheel of the grinder and giving it a concave shape.
The United States Supreme Court ruled in favor of Sanford, giving Sanford the right to continue the manufacture of throughfeed centerless grinders. In 1923, he and Heim reached a settlement agreement that gave Sanford the patent rights to Sanford’s early work on infeed centerless grinding. For the first time, the complete centerless process, both infeed and throughfeed, was brought together.
Changing times and improved technology would soon give centerless grinding another big push: Just as the demand for bicycles had inspired the original centerless grinder concept, the requirements of fast-increasing automobile production would guarantee the acceptance of the centerless grinder as a standard machine tool.
Today’s centerless grinders offer precision, reliability, flexibility, repeatability, versatility, and economy. In other words, modern centerless grinders feature every characteristic required by high-volume manufacturers.