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CNC screw machine doubles production.

The thought of buying a sophisticated machine tool with a six-digit price tag is enough to scare the wits out of most small shop owners. But not Ken Emerick, owner of Emerick Machine Products, a six-man job shop in Burton, OH.

Over a year ago, he bought a GB 65 CNC screw machine from Index Corp, Shelton, CT. The GB 65 is a CNC-controlled screw machine with four cross slides and an eight-station turret. It has a 2 9/16" bar capacity and can handle chuck work up to 6 5/16" dia. The 26-hp main drive is infinitely variable from 50 to 5000 rpm.

What attracted him to the machine was the fact that it has five tool slides, plus the ability to use live tooling and perform backend working operations. Because up to five tools can be employed simultaneously, cycle time is greatly reduced. Emerick says that the machine's production is more than double that of his older four- and five-slide automatics.

The new machine is suitable for machining complex parts with multiple operations. Emerick works mostly with copper, brass, aluminum, stainless steel, and 4140 and 8620 steel alloys in producing a variety of screw-machine parts for commercial, electronic, and aerospace applications.

One such part is a 3/"-square, 3 5/8"long 4140 ANN bolt. Four tools are used to produce it: a grooving tool, cutoff tool, a 1/4" dog bone, and an insert turning tool.

In the first operation, the material is fed out 2.4". Next, the turning tool rough turns the material to 0.0600" for a distance of 2.268" at a feed of 0.011" and a turning speed of 400 sfm. It then rough turns to 0.455" at 0.15" feed and 450 sfm while the dog bone follows the turning tool to chamfer and turn the material to 0.3715", producing a high finish. The grooving tool follows to groove the part.

The material is then fed to full length, and the turning tool rough turns to 0.570" at 400 sfm. The dog bone follows to finish to 0.4985" and face the 3/4" square, and the turret indexes and drops the previous part into the ejection chute.

Meanwhile, the part is threaded with a die head mounted in the turret while being cut off. The part is then picked off by the synchronous spindle mounted in the turret. Since the part is kept rotating during cutoff, the end is free of buffs.

Cycle time for producing the bolt is now less than a minute. It had been 2.5 minutes using the old automatics, which doesn't include the secondary mining of the 3/4" square head.

The CNC machine produced several other benefits as well. Most parts can now be made in a single setup, eliminating the need for secondary operations such as milling, drilling, and tapping. The elimination of multiple setups, in turn, results in a significant increase in part quality.

Says Emerick, "I didn't think it was that big an investment for what you get. I've doubled production and improved part quality tremendously. The machine has opened totally new avenues for us. In fact, I'm planning to buy another one."

For more information from Index Corp, Shelton, CT, circle 373.
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Title Annotation:Manufacturing Solutions; computerized numerical control
Publication:Tooling & Production
Date:Feb 1, 1992
Previous Article:Smooth program speeds rough machining.
Next Article:Verify one-off programs without cutting metal.

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