Get the Spin on Rotors

Indexers, dividing heads, spin jigs and many other rotary devices are common hardware in toolrooms and machine shops. Having the ability to accurately rotate a part through a circular path simplifies machining everything from keyways to bolt-hole circles.

In the not-so-distant past, having a rotary device for a CNC machine in your job shop set you apart from the competition. Today, the devices are almost ubiquitous. Being able to accurately position and interpolate in multiple axes and planes is now a necessity.

Unconventional Uses

Even those who are only moderately familiar with machining easily recognize the common uses of rotary tables and understand how rotary devices can improve efficiency in traditional machining operations. With a little creativity and some design skill, rotary devices can also be incorporated in less conventional ways to help drive continuous improvement and improve efficiency.

With a rotating weld positioner to drive a rotor on rollers, Mitsubishi Hitachi Power Systems Americas can use smaller, more cost-effective equipment for rotor repairs. Image courtesy of C. Tate

At Mitsubishi Hitachi Power Systems Americas, we build various components for the manufacture of gas turbines. Many of these are complex weldments that require the welder to manipulate the components through a range of positions. We use tables that rotate and tilt, allowing the necessary range of motion. That is what the positioners were designed to do—nothing unusual or creative.

It is said that necessity is the mother of invention, and that is true in our shop. After working with these welding positioners for a while, we began to realize they could be used to perform other tasks.

After welding is completed, our combustion baskets must be assembled before installation in the gas turbine. Baskets are heavy and cumbersome. Because assembly requires accessing multiple sides, several crane moves are required.

Crane moves, however, are not only slow but dangerous, placing assemblers and parts in risky situations. Although combustion baskets are robust, they have special protective coatings that are delicate and can be chipped easily. Each crane move provides an opportunity to damage the coatings or, worse, the assembler.

It was one of our assemblers who suggested we use a welding positioner to manipulate the part for assembly. As a result, we cut a few pieces with our waterjet, welded them together and bolted the fixture onto an old weld positioner. Now, we lift the basket into and out of only the fixture. All other manipulation takes place safely on the positioner.