Internal Grinding Machine for Engine Manufacture

Invented by James N. Heald, Class of 1884

After graduating from WPI, Heald became the third generation to run the blacksmith shop, foundry and machine shop his family had operated for 60 years in Heald Village, Mass. In 1903, he moved Heald Machine Co. to Worcester. By that time, he had already developed a lathe attachment for both internal and external grinding and a successful drill-point grinder.

In 1905, he invented a rotary grinder for machining the sides of piston rings. Through this work, he learned about the challenges manufacturers faced in producing cylinders for internal combustion engines. At that time, the cylinders were machined by boring, reaming or lapping. Attempts to grind out the cylinders had proven unsuccessful, since the thin walls of the cylinders would spring away from the grinding tool, producing an uneven surface.

Heald took on the challenge and invented a new type of internal grinding machine with a planetary action, which eliminated the problems previous grinding machines had exhibited. His device was so well designed that today's internal grinders differ little from his early production models. The breakthrough quickly became the standard method for manufacturing engines for automobiles and airplanes, and almost single-handedly paved the way for the mass production of internal combustion engines. Heald refined his initial design with the introduction of automatic size control, a hydraulic table feed, and centerless internal grinders. His accomplishments earned him a place in the Machine Tool Hall of Fame.

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