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Vertical Turning 101

March 18, 2008
Vertical turning centers give foundries with machine shops as well as those that outsource machining the ability to cut bigger and heavier castings.
Vertical turning centers and lathes are ideal for cutting large and heavy castings for a number of industries.

Foundries with machining capabilities, or even those that outsource their machining, can benefit from vertical turning technology. Essentially, a vertical turning center configuration takes a traditional lathe and stands it on end. This design provides a number of important production and cost benefits, and is particularly well suited to cutting a variety of castings: brake discs, pump housings, aircraft parts, heavy-equipment parts, energyfield parts, and more.

Two main types of vertical turning machines are used to finish castings. Vertical turning centers (VTCs) are fully enclosed compact systems designed for standalone applications or easy integration into production lines. Vertical turning lathes (VTLs) are large, ram-type machines, also called vertical boring mills (VBMs). These lathes are not high-production machines, but they are ideal for heavy-duty and high-power cutting of medium and large parts.

A third type of vertical turning center is the inverted spindle machine. These systems flip over the vertical design, lifting parts with the chuck. These machines are used almost exclusively in the automotive industry to finish small, high-volume parts such as brake discs. These units are not as suitable for machining larger, heavier parts, however.

Why go vertical?

Vertical turning provides a number of benefits to those looking to expand capabilities, or those looking for a downstream supplier that can handle larger parts. First, the machines are more affordable than ever before – often approaching the cost of a conventional horizontal turning center. In addition, high demand for vertically turned parts from industries such as energy, aerospace, and construction ensures that companies see a quick return on investment that they can then pass on to their customers.

The second advantage of vertical turning centers is that they work with gravity rather than fight against it. With horizontal turning centers, operators have to load, fight, and fixture heavy or large-sized parts. This adds time and cost to the production cycle and can lead to operator injuries. With a VTC, operators simply load the part on the table. Often, relatively light clamping holds the part in place. This is an important benefit when working with thin-walled parts, where clamping can induce warpage.

In terms of productivity, vertical turning centers typically improve cycle times because shops can be more aggressive with their cuts. Why? Again, it’s Physics 101: Gravity holds parts on the table so shops can use the full power of the machine to remove material.

Live tooling also makes vertical turning more productive than ever. Shops can mill, drill, and tap on today’s vertical turning machines. They can even equip VTCs and VTLs with grinding wheels for deburring, and where tolerances are acceptable, for actual grinding operations.

Finally, vertical turning machines take up less floor space than their horizontal counterparts. With VTCs, two machines can be placed close together in a right/ left configuration — essentially gaining twice the productivity of a horizontal turning center in a footprint of the same size. Adding automation, such as a robot arm, makes these machines even more productive. Shops can do Op 10 in one VTC and have the robot transfer the part to the other for Op 20.

Facilities looking to add a VTC or VTL to their operations should seek out vertical turning centers that are strong, stable, and extremely rigid to ensure the best performance for turning large parts. Machines should be heavyweights, with cast iron construction that damps vibration. Rams and columns should be built strong to withstand heavy-duty cutting forces.

Absolute Machine Tools offers an array of You Ji brand VTCs that feature heavy-duty, Meehanite cast iron construction, gang-type tooling, and high-speed linear ways. Turnkeys can be engineered with fixtures and full automation.

You Ji VTCs offer maximum swings from 16 to 48 in. and handle maximum cutting diameters from 10 to 40 in. The machines have a generous work envelope, with cutting heights ranging up to 32 in. on standard machines. Special designs can be built, also.

Absolute’s larger You Ji VTLs are well suited to aerospace, construction, and oil-gas applications. These machines are very rigid, featuring cast iron frames and boxways. They also boast geared table drives that generate tremendous torque. In addition, heavy-duty spindle motors deliver high torque for heavy-duty machining and high speeds for fine finishing. You Ji VTLs have maximum swings from 45 to 140 in., cutting diameters from 45 to 140 in., and cutting heights from 48 to 80 in.

If additional productivity is necessary, You Ji also has a series of large twin-ram VTLs for simultaneous four-axis cutting. These heavy-duty machines double productivity by using twin independent rams and twin ATC units to cut exceptionally large castings and other workpieces. Maximum swings range from 98 to 189 in., cutting diameters from 91 to 177 in., and maximum cutting heights from 63 to 71 in.

Machine shop tackles castings with VTC

Davan roughs these 580-lb 4140 steel castings and sends the parts out to be heat treated, and then brings them back for finish turning. According to Davan president Mark Vanistendael, the You Ji YV-500E VTC has no problem turning the 50 Rc heat-treated zone.

Mark Vanistendael, president of Davan Manufacturing Inc. is always on the lookout for a new piece of technology to bolster his machining arsenal and serve his customers better. Expanding Davan’s machining capabilities gives the Washington, PA, company the flexibility to handle new and bigger castings, and other workpieces.

So far, Davan’s YV-500E VTC has helped him tackle castings at a fraction of the time his customers cut the same parts. “For example, we’re running down-hole drill equipment on our vertical turning center,” remarks Vanistendael. “Previously, our customer did these castings in-house on manual Bullards, maybe 12 or 13 pieces a year. Cycle times were typically 10 hours. Now, they’re looking at 30, 40, even 50 pieces orders. We can do the part in half the time. And, the quality is better.”

In addition to better quality and faster turnarounds, Davan also is passing on the cost savings to the customers sending him their castings.

Finally, according to Vanistendael, “The You Ji YV-500E puts us in a new size class. We’re now quoting on bigger pieces. There’s a demand for parts we hadn’t run prior to the acquisition of the VTC.”

A typical part showcasing Davan’s capabilities is a 15-in. diameter bearing sleeve for an oilwell. The precision part weighs approximately 580 lb and is made from a 4140 steel casting. It also includes a heat-treated zone where the seal rides.

Davan rough-cuts its first and second op on the You Ji (about 0.0150 in. D.O.C.), sends the part out for heat treatment, and then finish cuts all the bearing surfaces, cutting through the heat-treated material, taking it to size and finishing a groove. “We flip the part over and finish the counterbore and the bore on the other side,” comments Vanistendael. “The part has a rather large groove in it that’s about 1.5 in. deep. It also has a 6-pitch thread. The You Ji handles the heat-treated part without a problem. It’s about 50 Rc, and we’re running about 600 fpm. On the drop cuts, we run light, probably 0.020 IPR. When we hit the finish cut, it’s probably about 0.005 IPR.”

The main concern with the part is quality. The part goes straight to assembly, so it has to fit right the first time. Cycle time is another consideration because Davan wants to take big cuts to get the parts out the door as quickly as possible.