Economical time-savers for manufacturers

Economical time-savers for manufacturers

VMC, pallet changer, and 4th axis increase throughput

Pallet changers and rotary tables can be economical time-savers for manufacturers with a need to maximize chip cutting time. And few manufacturers understand the flexibility of these performance-enhancing options and put them to use in as many ways as RB Industries (RBI), Harrisonville, MO.

RBI began as a production shop in 1929 and, under new owners in 1972, introduced a variety of woodworking equipment product lines. Today RBI manufactures the patented RBI Universal Woodplaner, RBI Precision Scroll Saw, and RBI PanelMaster II horizontal shaper, as well as owns 16 patents. With the variety of equipment that RBI manufactures, process flexibility is critical to maintain high productivity rates. Quality is an important factor, too. The quality of the parts that make up RBI’s woodworking equipment has a significant impact on the bottom line because it comes with a five-year warranty, longest in the woodworking industry “We purchased two Fadal VMC 4020s, both with a fourth axis rotary table and twin pallet changer,” says Kris Rice, president of RBI. “The pallet changer enables us to machine parts in kits, batches, and progressives. We’ve even mounted one of the fourth axes to a pallet so it’s a lot easier to move in and out of the VMC.”

RBI uses a number of methods that reduce the number of setups, handlings, and operations for significant increases in productivity For example, all the parts for an assembly are mounted on one pallet as a kit of parts, which makes scheduling a lot easier and reduces the need for large inventories. The Fadal VMC 4020’s control enables multiple zero positions and, through the use of macros, different part programs are called up automatically. The 19″x39″ pallet size allows a large number of different size and shape parts to be mounted for machining. The most common use for a pallet changer is to machine batches of the same parts that can go directly to assembly or into inventory. But another method that RBI uses is what Mr Rice terms “progressive” machining.

When a batch of parts must be machined on three sides and it is too large for the fourth axis, it must be turned manually so that each side can be machined. With progressive machining, the part is machined on the first pallet. It is turned on the second offline pallet to be machined on the second side, and then turned on the first pallet for the third side to be machined. By the time the third side is machined, a steady stream of parts is completed each time the first pallet moves to the offline position. The machine is down only when the pallet changes, which is set at the factory to 16 sec and can be reset by the operator as low as 10 sec.

“We run high speed tools,” says Mr Rice. “We run our machines at 10,000 rpm for maximum efficiency and have never been concerned about stalling. We have a fourth axis on both Fadals. One is mounted on a pallet and shuttled in when we need to do fourth axis work. That makes moving it around a lot easier.”

With a mechanical two-speed, gearless 15 hp 10,000 rpm Vector Posi-Lube Spindle Drive system, the Fadal delivers faster cutting speeds, which decrease cycle time correspondingly. The mechanical HI-LO system provides optimum performance under a wide range of cutting conditions, as well as eliminates the noise, heat, vibration, and power loss associated with gearboxes. Another benefit of the gearless system is no more broken gears when a crash occurs.

RBI’s fourth axis rotary table is hard-wired to the control and delivers fully-interpolated 4-axis machining and indexing. Typically, a rotary table will reduce cycle time by 40% or more by automatically repositioning parts, so that multiple sides can be machined without manually turning the parts. RBI puts its fourth axis rotary tables to work for indexing and contour machining operations.

The Fadal VMC 4020 features a random/bidirectional 21-pocket automatic toolchanger for very fast chip-to-chip toolchange times. The Fadal 88HS control, Fanuc compatible, reduces the time it takes to set tool offsets with powerful features that include multiple tool setup and read location from jog mode, which allow tool offsets to be loaded by pushing one button. “We added extra memory so we could store and run large programs,” says Mr Rice. “We are very satisfied with its fast processing speed.”

The Fadal 88HS control features parallel processing, which uses multiple microprocessors, one processor dedicated to each axis, for a fast 1000 blocks per sec processing speed. Processing speed often has different definitions. Fadal defines a block with as many CNC words that will fit on a line up to the carriage return. Other manufacturers would consider Fadal’s processing speed to be 3000 blocks per sec.

The 88HS features parallel processing that eliminates time-slicing, a primary cause of data starvation. During high feedrate operations such as contouring or drilling, inaccurate toolpaths result when the axis drives do not receive instructions fast enough. This can occur with almost any control, however it is prevalent with controls that have only one or two microprocessors, because the processors have to switch back and forth between axes. Parallel processing dedicates one microprocessor to each axis so they work together for quick and precise servocontrol.

“Years ago there were 15 different handlings to get a finished cutter head for our planer,” says Mr Rice. “Now there are only two handlings. One handling for the turning center and the other on the Fadal. The cutter head comes out a finished part, so we don’t even have to deburr it.

“We had roughly about four hours on each one of these cutter heads. Cycle time for milling and tapping was about 2 hours, 20 min,” says Mr Rice. “With the Fadal, we completely eliminated the deburr operation cut mill/tap time to 90 min.”

For more information from Fadal Engineering Co, Chatsworth, CA, circle 268.

Copyright Huebcore Communications Inc. Sep 1999

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