Solving costly lining problems became our business. Most lining applications of induction furnaces use silica. A number of common problems are associated with conventional methods of installation and as a manager responsible for the melting operations at General Motors Foundry, St. Catharines, Ontario, Canada, it was Ayton Grady's responsibility to overcome them.

Some problems associated with installing a lining were:

Conventional lining

• silica dust exposure to workers was very difficult to control and commonly exceeded permissible exposure levels set by health and safety regulations. Furthermore, legislation was and continues to tighten; recently the International Agency for Research on Cancer reclassified overexposure to inhaled crystalline silica from occupational sources as carcinogenic.
• the lining procedure was strenuous and labour intensive. Workers were at risk of compensable injury in particular the lower back from lifting many bags of refractory and repetitive strain injury arising from manual deaeration or forking the material.
• worker fatigue in hazardous working conditions and human variabilities contributed to inconsistencies in material distribution and density of the lining. This contributed to unpredictable lining life and production schedules from one rebuild to the next.
• conventional methods inadequately vibrated material in the tapered section that can contribute to premature wear and failure.

Necessity became the mother of invention. As pressure from the union, health and safety association, and supervisors intensified, finding a solution to deplorable working conditions and lining inconsistencies became paramount. Following an extensive ergonomic study of the existing problems, Ayton, "A.J." developed crude sketches of a machine to line the furnace automatically that he believed would provide a solution. The machine was fabricated, and a pilot project began 1987.

The primary motivation was to remove workers from hazardous conditions associated with manually lining a furnace with silica. This was successfully accomplished with respirable silica dust test results measuring below OSHA's permissible exposure levels. Unexpected benefits followed. It was found that an additional 600 pounds of material was added to the furnace sidewalls using the refractory installation machine. As a result, the increased density yielded 33 percent longer lining life. Hours of labour to line the furnace was reduced 68 percent as was the number of workers required to line the furnaces when compared with former conventional methods.