Hold your fire: General Industry Coverage

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END USER: Colt Defense LLC, (800) 241-2485, www.colt.com. CHALLENGE: Eliminate concerns about part accuracy and cutting tool runout when machining faster than 9,000 rpm. SOLUTION: A press-fit toolholding system. SOLUTION PROVIDER: REGO-FIX Tool Corp., (800) 999-7346, www.rego-fix.com

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Colt Defense LLC is the only company contracted to manufacture M4 carbine rifles for the U.S. government. To maintain the necessary support for the U.S. armed forces, the company can produce up to 1,000 M4s—complete—per day. Colt Defense, West Hartford, Conn., also manufactures 240B machine guns, M16 rifles and barrels for M249 machine guns.

The company’s 300,000-sq.-ft. facility, with 350 employees, houses more than 60 horizontal and vertical machining centers.

According to Director of Manufacturing Engineering Ashot Ghokasiyan, Colt was not comfortable with its standard endmill holders because of serious part accuracy and tool runout concerns when machining faster than 9,000 rpm. Some of the high-speed machining at Colt involves milling small, intricate, tough-to-reach cavities in aluminum workpieces using long cutters run at 14,000 rpm. Standard toolholders were bulky, created interference issues and could not accurately hold the long, small-diameter cutters, mainly because there was too much runout and the cutters would push off center, Ghokasiyan noted.

Courtesy of REGO-FIX Tool

A machinist at Colt Defense (above) prepares a tool in one of the company’s powRgrip press-fit toolholding units from REGO-FIX as part of the process in manufacturing weapons, such as the Colt Law Enforcement Carbines seen below.

To overcome those issues, Colt standardized its ER collets to those made by REGO-FIX Tool Corp., Indianapolis. The compact, lightweight ER collets are available in standard and ultraprecision versions from ER 8 to ER 50 sizes in inch and metric sizes to clamp tool shanks from 0.0079 ” (0.2mm) to 1.3386 ” (34.0mm). At Colt, the ER collets range from ER 16 to ER 32 and accept cutters from 0.125 ” to 1.25 ” in diameter.