Original Date: 07/21/2003
Revision Date: 01/18/2007
Best Practice : Implementation of Cold Form in Lieu of Hot Form
Electric Boat Corporation Quonset Point Facility realized considerable reduction in cost and schedule and an increase in quality by replacing a costly and time-consuming hot press technique with a cold form technique to produce complex sheet and plate metal parts.
Hot forming techniques are an expensive and cumbersome process to manufacture sheet and plate metal parts with complex curved surfaces. Each part requires a set of one-of-a-kind forming dies (male and female) to represent its configuration. To form the part, the material undergoes a series of heating and pressing steps in the dies until the final shape is achieved. If the heating exceeds the material’s temperature parameters, then its properties will be breached and it will require annealing, tempering, or possibly replacement. In many cases, Electric Boat Corporation, Quonset Point Facility (EBQP) had to enlist outside vendors to manufacture its complex metal parts using these techniques, which added additional expense.
Searching for a more economical and faster way to produce these parts, along with a diminishing number of available vendors, EBQP developed in-house cold forming techniques using existing equipment. EBQP developed multi-purpose dies, which can be readily made in-house at a fraction of the cost of hot forming dies (Figure 2-4 shows this three-part tool). The multi-purpose female die is used for a wide range of part sizes and shapes; the male die is used for parts within a specific range of radii. The operation employs a 3,000-ton Southpark press with a 50- inch press opening and a 20-foot width. To manufacture a part, the press operator gradually rotates and presses the material until the desired shape is achieved. The shape is confirmed by using radius gauges.
The cold press technique has proven so successful that EBQP uses it to produce all its complex shaped metal parts, and hot forming is no longer used at the facility. By using this new forming process, the company has improved quality and cut both time and costs of manufacturing submarine parts. These savings are realized primarily through the elimination of expensive special dies and furnaces, and the reduced number of formed surfaces with each unit. Cost savings are also realized by reducing the fabrication time for these parts. Savings have been more than $80,000 per typical part, with more than a 60% total reduction in cost. With the new process, quality has been improved, much tighter tolerances achieved, and a reduced number of test points to find a location is now in use. Additionally, the new cold forming capabilities have been added to the CATIA design rules, so that overall producibility and quality continue to improve.
Figure 2-4. Three Parts of Multi-Purpose Dies
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