Latch Bolts

This powder metal latchbolt is used in vertical rod safety exit devices. Because of the internal cavity, it was originally manufactured from an investment cast stainless steel. By switching to a powder metallurgy weldment, the cavity could be produced in a part retaining all the inherent qualities of stainless, with a cost reduction of 40%. It is comprised of two asymmetrical halves that are welded together, re-sintered to stress-relieve the weld, and then deburred, producing a surface finish superior to the cast parts. Only UL-listed devices may be used in commercial buildings, so the latchbolt is extensively tested. With the casting, the force required to release the latch was 40 lbs. The powder metallurgy part's superior surface finish (and lower coefficient of friction) reduced the release values to 20-25 lbs., allowing for an easier, safer exit. In another UL test, the assembly is heated to 1900°F for three hours, then subjected to a fire hose water stream. It must remain intact and hold the door secure throughout the entire test.

• Cost reduction of more than 40% vs. investment casting
• Winner of Stainless Steel Grand Prize in 1998 MPIF Part-of-the-Year Competition
• Surface finish superior to investment cast parts
• Reduced release force required by 35-50%

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