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March 2, 1999

2 Min Read
Cut Tooling Costs with Smart Part Design

How much should part designers know about tool design? At Xerox Corp., Rochester, New York, USA, Bob Russell instructs company designers on the intricacies of tooling, stressing how smart design can save big tooling dollars. IMI has been given permission to share some of those tips with its readers. This is the first of several installments. The diagrams have been simplified to highlight specific points.

Components for computer or business machine housings often need louvers. Sometimes it's cost-effective to mould the louvers into a separate panel, even though that means adding another part, because moulding the louvers integrally into a complex piece of cabinetry will often require a tool with action. A separate louvered panel, however, does not eliminate the opportunities to add to the tooling bill.

A simple, straight-through louver makes an easy job of mould shutoff, as shown in Diagram A. But if open louvers are undesirable, then the addition of masking projections for fully hidden louvers will require lifters (Diagram B). This prospect will not please either the accountants or the maintenance department.

Shutoff can be provided without mould action, however, by using an angular parting line, as shown in Diagram C. What's wrong with this approach? The A and B plates have become very large for such a thin part. There's a lot of metal to remove. With a mould base measuring 10 by 18 inches, total mould cost is estimated at US$ 29,000.

Now consider the redesign shown in Diagram D, which applies the mould bypass concept with a 57 minimum shutoff. The mould base measures 11 by 15 inches; it's almost a third less expensive than the one for Diagram C. Total mould cost estimate is US$ 14,000, less than half of that of Diagram C. There is a slight opening at eye level for this louver design, but the louvers still look good, and the price is favourable.

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