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116 MMS June 2014 mmsonline.com better production Shops Using Technology p o p u l a r, m e a s u r i n g a b o u t 2, 3.25 and 4 inches in diameter, r e s p e c t i v e l y. T h e h o l d e r s var y in length from about 2 to 4 inches to as long as 12 to 18 inches. To produce varying toolholder le ngths a nd also to e nha nce th e i r p e r fo r m a n c e, th e s h o p m a ke s th e h o l d e r s f ro m r aw steel stock. According to Mr. L e h m a n, m a n y s p e c i a l H S K toolholder makers buy the blanks with the critical HSK tapered connection already completed and then machine the custom features in the other end. The c o n n e c t o r e n d o f t h e p r e - machined blank is hardened, but the other end is not, making it susceptible to greater wear in use, he says. For ETW's HSK holders, the company uses H13 steel that is vacuum hardened between 47 a n d 4 9 H R c t o p r o v i d e good core hardness throughout t h e h o l d e r. " We a r e a b l e to through-harden the whole thing because we have the ability to g r i n d t h e c o n n e c t i o n ," M r. Lehman says. "We get a stron- ger, stiffer tool, something that is going to last longer." Machining the holders from r aw s to c k r e q u i r e s f i ve - a x i s machining, heat treating and grinding to final dimension. In the machine tool spindle, the HSK shank is engineered to flex just enough to create a zero- backlash, essentially solid con- nection. "After heat treatment, the shank is ver y good about springing back to where it was, regaining its shape after forces are not being exerted on it. That p r o v i d e s t h e c u s to m e r w i t h excellent repeatability," he says. Eliminate investing in multiple sets of master jaws or using expensive monoblock jaws while retaining the benefits and cost savings of quick change chucking. Introducing Rapid Change Chucking ™ ■ ■ ■ ■ 0614_MMS_better.indd 116 5/14/2014 8:47:02 AM