TABLE OF CONTENTS The design of industrial equipment was simple, sturdy, heavy, and robust prior to World War II. Repairs were fairly simple, and could easily be done at site using ordinary hand tools. Breakdown strategies were common, which meant that equipment operated till failures occurred. The introduction of mass production techniques meant that interruptions of production machinery or conveyors resulted in large losses. At the same time, the design of equipment became more complex. Greater knowledge of materials of construction led to better designs with a reduction in weight and cost. Computer-aided analysis and design tools became available, along with computing capacity. As a result, the designers could reduce safety factors (which included a factor for uncertainty or ignorance). In order to reduce investment costs, designers reduced the number of standby equipment installed and intermediate storage or buffer stocks.
These changes resulted in slender, light, and sleek machinery. They were not as rugged as their predecessors, but met the design conditions. In order to reduce unit costs, machine uptime was important. The preferred strategy was to replace complete sub-assemblies as it took more time to replace failed component parts.
A stoppage of high volume production lines resulted in large losses of revenue. In order to prevent such breakdowns, manufacturers used a new strategy. They replaced the sub-assemblies or parts at a convenient time before the failures occurred, so that the equipment was in good shape when needed. The dawn of planned preventive maintenance had arrived.
Prior...
