Turning Three Days Of Work Into Three Hours Of Work

Read how the Arbor Department of this major manufacturer greatly reduced set-up time to deal with increased capacity.

Case Study From: 4/15/1998 Modern Machine Shop

The Arbor Department at the Gleason Works (in Rochester, New York) faced a major capacity crunch about a year ago. Despite a major innovation in process, the crunch has eased but not vanished. This department manufactures arbors, collets, setup gages—in fact, all of the workholding and setup devices for Gleason's entire line of gear processing machines.

The market for machines to process bevel gears has soared. The largest single market for these gears is in rear-wheel drive vehicles. The truck market has mushroomed, particularly since it now includes the tremendously popular recreational pickup truck and sport utility vehicles with four-wheel drive; plus a continuing market for larger cars and rear-wheel drive vehicles. Another factor in the growth of this business for Gleason is a recently-developed full line of CNC bevel gear processing machines, with reduced setup times and enhanced flexibility. This line is said to make machines currently in use today obsolete .

The blessing of increased business brought with it challenges of capacity in the form of backlogs and deliveries. In no department have those problems been more difficult than in the 67-employee Arbor Department. Most jobs are run in lots of three parts or fewer, so setup time is a major factor; it's not just a matter of running machines faster. Products are mostly custom made, tailored to adapt the customer's products to the Gleason machines.

Flexibility was and is essential. Until now, flexibility meant using a series of seven to eight machines, each with a skilled operator. Parts were turned, then milled in one or two setups, laid out for hole locations and then drilled. "The process necessitated the moving and queuing of parts, multiple fixtures, multiple operators on all three shifts and despite our best efforts, some tolerance stacking. In fact, when we looked for ways to boost our capacity and throughput, we never considered duplication or even augmenting that sequence," says Charles Menz, facilitator of the Arbor Department.

"We knew we had to add significantly to our capability, and we had to do it quickly. We searched for a machine that could complete our parts in a single setup and one that we could get into production in a hurry. We already had a Mazak (Florence, Kentucky) Integrex 40, so we knew about the machine's multi-tasking capabilities and our ability to use it.

"When we found that we could get a larger Integrex 50 built with the additional Y-axis, we bought it. The Y axis lets us complete all operations, including a substantial amount of milling, without removing the parts from the machine."

The 40-hp main spindle goes to 3,000 rpm and produces 2270 ft-lbs output for turning. The No. 50 taper rotary tool spindle has 15-hp output for secondary milling and drilling operations. Mr. Menz points out that they are still developing the tooling processes and the programs for the machine. In time, it will take an increasing percentage of the work going through the department. For example, on those products which are most likely to be repeated with some frequency, it will make more sense to develop the machine programs for them and then have them available and optimized the next time.

Mr. Menz explains: "We are programming off-line and then downloading the programs to the machine control. On the first run, the operator and the programmer go through the cycle. When the job is finished, it will be that optimized program that is stored and ready for the next use.

And Mr. Menz says that even the person who works on process routing understands the concept of multitasking and explores all possible capabilities of the Integrex 50 with the Y axis. "Since we produce both rotating and prismatic parts, I challenge them to think round first, then prismatic. In most cases, we do the round portion of the workpiece first, and then turn it around in the chuck to finish the other end.

As with most multitasking CNC turning centers, the Integer 50 has three axes of motion control: the C axis is spindle rotation in the feed mode, the Z axis is parallel with the spindle centerline and the X axis is the vertical axis perpendicular to the Z axis. In addition, the Integrex has an operational fourth axis, Y, which is perpendicular to the Z axis, but it is horizontal, moving in and out across the part. It is the addition of this axis that simplifies the production of prismatic parts by crossfeeding for milling or by producing off-center holes for example. And at Gleason, it's this axis that takes the place of one or more milling and drilling machine operations in the traditional multi-machine production sequence.

In a setup gage, the Y axis mills the large flat and the flange. In the small expander, a saw-type milling cutter mills the grooves. The advantage of this operation is that the cutter does not have to be the same width as the groove, as would be required with an end mill. The cutter makes its first pass down the Z axis; then with a reposition in the Y axis, completes the groove on a return pass. Thus, the bottom of the groove is flat and the two side walls are vertical and perpendicular to the bottom. The same procedure is used to generate keyways and other longitudinal geometries.

According to Mr. Menz, standard procedure is to produce the round portion of the parts in the first operation, and then turn the part around in the chuck to complete the prismatic geometry. "In fact, we sometimes make a prismatic part from bar stock, and then just cut it off."

Although, as Mr. Menz says, the department is still ramping up on the learning curve, and although the new machine is producing only a portion of the work in the department, benefits are already obvious. "We are getting more precise parts, because we have virtually eliminated the tolerance stack up," he explains.

"We also know that the department used to operate on the basis of a six-week leadtime. It is now down to four, which would mean that we also have eliminated a third of our work-in-process inventory.

"The same measure applies to the first problem: capacity, up a third."

The company plans to include software that will enable them to download engineering data directly into their machines.

Rapid growth, while always welcome, also has its share of growing pains, but at Gleason, no one seems to mind. MMS

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