February 2011 / Volume 63 / Issue 2|
By Bill Kennedy, Contributing Editor
Courtesy of Mazak Turning a lathe vertical can be a productivity turn for the better—for large and small parts.
Courtesy of MAG IA
In contrast to a focus on facilitating the turning of large components, an inverted vertical spindle lathe can maximize throughput when turning parts of nearly any size. Inverted vertical spindle machines generally do not require additional automation to run higher volumes. In an inverted spindle machine, the part does not rest on a table but rather is gripped in a movable overhead spindle. That spindle can pick up parts and replace them in a conveyor or chain, making the VTL a self-contained machining system. For processing low-profile parts such as brake rotors and transmission components, the arrangement produces high throughput and consistency.
Courtesy of EMAG
About the Author: Bill Kennedy, based in Latrobe, Pa., is contributing editor for CTE. He has an extensive background as a technical writer. Contact him at (724) 537-6182 or by e-mail at firstname.lastname@example.org.
Images courtesy of B. Kennedy
Gearing up vertical
Courtesy of MAG
Milwaukee's best for big parts
ranging from 10 " to 20 " in diameter and as large as 180 " in diameter, are a mainstay for Busch Precision Inc., Milwaukee. The job shop manufactures and repairs machinery components and performs subcontract and on-site machining, as well as machine rebuilding.
According to Matt Pettigrew, production supervisor, the shop’s vertical lathes are good for machining large, heavy parts. “You’re not fighting gravity, and that facilitates part holding and part handling,” he said. However, he added, a horizontal boring mill, with its large work envelope, is a better choice for some very large parts, especially long ones. “With the horizontal boring mill, you can have stuff hanging off the table; it doesn’t matter. It won’t get in your way.”
The vertical machine is the right choice for large parts that fit because setup is easier. “You can set the part down on the table,” said Pettigrew. “On a horizontal lathe you have to hang it in the air and get everything perfect, but on a vertical you are basically setting it on the floor. If it’s a little crooked it’s not going to kill you; you can finesse it to where you want it a little easier.”
The shop’s newest VTC is a VTC 3500 from MAG. The machine has a 3,500mm table with a maximum swing capacity of 3,700mm, Z-axis travel of 1,250mm and X-axis travel of ±2,060mm. It is fitted with two 250mm-square rams to enable pinch turning (cutting with both rams simultaneously).
The shop doesn’t always perform pinch turning because taking the time to program two tools where one can do the job is not cost-effective. “However, we try to do it whenever we can, usually for roughing,” Pettigrew said. “Instead of trying to rough with one ram at one depth of cut, if it is real hard material I can divvy up the DOC to take half and half. I am still removing the same amount of material because the machine is taking two cuts at once. That saves on chip load.”
For roughing big parts, the shop typically uses inserts in a mid-range 433 size. “But we also go all the way up to 866, which is 1 "-wide carbide,” Pettigrew said. “That’s for roughing cuts with interruptions; it’s a real big brute of an insert.”
Despite the large dimensions of the parts it handles, the shop holds tight tolerances, he added. “I just finished a 118 "-dia. part that was +0.002 ", minus nothing.”
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