b'Big Parts, Big Questionsrelative to part size. All lathes at Mitsubishi Hitachi Power Systems Americas utilize Capto C8 tool-holders with various types of in-serts in common shapes and sizes. With many of our parts, chatter can be a problem because lathe tools frequently have long extensions. Capto tools provide the option to use vibration damping tools, and the Capto interface gives support in multiple planes. Both features help eliminate chatter. Capto also sup-plies an exceptionally repeatable connection, so we do not need to remeasure tools each time they are changed.Big parts probably have big tol-erances, right? Not really. On the loose side, we are allowed 0.15 mm (0.006"), which may sound like a lot until considering that some Drills, Reamers and Endmills! parts can be 3.7 m (12\') tall with fea- bowed shafts or out-of-round rings. tures 3 m (9.8\') apart. On the tightSome machining processes start side, we hold some 850 mm (33.5")with a slow roll in which we allow shaft diameters to +0/-0.01 mma sizable shaft to rotate for an en-(+0/-0.0004"), which can be difficulttire shift to remove a bow before we for small parts. To achieve thesemachine. In some cases, like with a CJT Koolcarb and GenHam aretolerances, we spend large sumsring that has a thin section relative Manufacturers of High of money on calibration to ensureto the diameter, we must perform Production Cutting Tools!that machines are repeatable andstress-relieving heat-treat opera-Custom and Standards, Solid accurate. tions before taking a part to a ma-Carbide, Carbide Tipped, Diamond Tipped, Coolant andSmall parts are subjected to dis- chine. This prevents movement dur-Non Coolant fed. Builtto yourtortion from clamping, stress re- ing machining operations that re-tool print or designedto meet your applicationbased onlieving and aggressive machin- quire big ovens. Our largest oven is your part print.ing. Big parts are worse. They are10 m (33\') deep and 4 m (13\') tallsubjected to the same issues butalmost spacious enough for a semi-have an added challenge: weight.trailer.Large parts can distort under theirEstimating cycle times is simi-Diamond Tooling Plant, Colorado www.genham.comown weight, causing problems likelar to estimating for small parts. To PH. 1-970-249-1300 Carbide Tooling Plant, Illinois www.cjtkoolcarb.comabout the author PH. 1-800-323-2299 Christopher Tate is engineering manager of advanced All Proudly Made in the U.S.A. manufacturing engineering and machining at the Savannah, Call or visit our website to requestGeorgia, facility of Mitsubishi Hitachi Power Systems Ameri-a catalog or receive information!cas Inc., Lake Mary, Florida. Contact him at chris23tate@ISO9001:2008 CERTIFIED gmail.com.72AUGUST 2020MachiningLargeParts.indd 72 7/17/20 3:40 PM'