12.4.1 Introduction
With better understanding of new technologies such as this, it is often possible to push productivity considerably further. The example described before, based on grinder technology that is now 15 years old, had a cycle time of about 6 min limited by burn. On the latest grinders with much more sophisticated CNC controls, higher wheel speeds and faster linear motor technology, it is possible to grind camshafts up to 50% faster, albeit with higher abrasive cost initially. Capital equipment is very expensive and industry is trying to drive up their return on investment by limiting such expenditures. A project engineer must, therefore, weigh up carefully capital against process costs. The following example shows how more expensive tooling can bring down costs.
12.4.2 Effect of Tooling Costs in Camlobe Grinding
Consider the example of a camlobe grinding operation at a high production automotive engine plant as shown in Table 12.4.
Comparison of Capital Equipment Costs Versus Tooling Costs for Various Production Rates
Camlobe grinding of automotive camshafts
Production requirement = 1,000,000 cams/annum Machine cost with gantry loading, installation, etc. = $1M Production rates 10/hr @ $0.25/camshaft
15/hr @ $0.40/camshaft 20/hr @ $0.60/camshaft
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Grinders Capital Cost Tooling Cost
25 $25M $250K/annum
17 $17M $400K/annum
13 $13M $600K/annum
For an increase in tooling costs of $350K per annum, a capital cost saving of $12M can be achieved. Again past history would indicate that processing costs would be further reduced over the expected life of the grinders and would be a primary focus for future cost savings from both process optimization and competition between tooling suppliers.