When the operations manager at Schafer Gear Works, Paresh Shah, visited the Gleason booth at Gear Expo 2015, he wasn’t looking for a new Gleason gear grinder. Schafer Gear’s hard-finish grinding cell at its 100,000-square-foot South Bend, Indiana, facility, managed by Shah, was already equipped with two Gleason Genesis® 160TWG threaded wheel grinding machines, and a second cell had a larger Gleason 300TWG, with another 300TWG on order. These machines, along with four other gear grinders, would give Schafer Gear one of the highest gear-grinding capacities of any privately owned gear manufacturer in the U.S. and the ability to handle the throughput requirements of about 15 to 20 different tight-tolerance, 150- to 200-mm-diameter gears in volumes as high as 100,000 annually.
“We weren’t planning on buying another grinder, but when we saw the new Gleason 200GX on display, the many benefits of the new system were almost immediately apparent,” Shah said. “Most obvious were the twin-spindle design, which would allow us to save enormously on non-productive time, and the integration of Gleason automation that saves on floor space while still putting many more parts in the queue unattended. We made the decision to purchase the 200GX, and it’s proven to be a very good one.”
Faster Chip-To-Chip
The latest threaded wheel grinding technology has been instrumental in helping Schafer Gear meet ever-increasing demand for faster production of high-quality gears. Yet seeking to gain more productivity, Shah and his team at Schafer have increasingly focused on reducing costly chip-to-chip time. Cutting mere seconds in unproductive idle and setup time can quickly add up to significant savings in a high-volume production environment like Schafer Gear’s, where throughput is measured in hundreds of parts per machine per day.
“Where load/unload might take 16 seconds per part on one of our single-spindle grinders, it takes less than four seconds on the twin-spindle 200GX since auxiliary processes, such as spindle acceleration, are all done in parallel to grinding rather than sequentially,” Shah said.
According to Shah, the 200GX makes significant reductions in setup times due to the innovative new features that greatly simplify and automate the typically time-consuming and labor-intensive changeover from one part type to another.
“We typically run our work orders in large batches of hundreds of parts, with new-part changeover every day or two, and a process that would take 30 to 40 minutes on our other grinders has been cut in half on the 200GX,” Shah said. “It’s not only faster, but a much easier process for our machine operators.”
Schafer’s machine operator, Jim Smith, runs the finish grinding cell that now includes the new 200GX, an existing Gleason 300TWG, and a new Gleason 300GMSP “shop-hardened” gear inspection system. Smith credits the 200GX’s fast, simple setup as one of the reasons he’s able to juggle so many tasks.
“Everything is easier on the 200GX,” Smith said. “For example, I use the same simple tool to chuck and unchuck the workholding, change over the grippers on the loader, and change the grinding and dressing wheels, rather than having to find and apply the multiple tools required on other machines.”
Smith relies on the 200GX’s setup menu for support. On request, the 200GX’s control unit can show Smith all the steps necessary to re-tool the machine, using helpful images. Depending on the activity in progress, the machine will also move into “ergonomic” positions, which are more comfortable to reach. For changing the workholding equipment or dressing tool, for example, the turret is moved into the position closest to the operator.
Smith also said that Gleason’s Quik-Flex®Plus workholding system is beneficial to the setup process. It consists of a base unit, which is installed and aligned on the machine work spindle just once, and part-specific modules that can be installed or removed from the base unit in just seconds using the tool.
Completing First Parts Automatically
On traditional grinding machines, mechanical setup is followed by additional steps needed to prepare the machine for grinding. On the 200GX, a new, fully automatic “First Part Cycle” process is available to speed up and simplify a procedure that is typically done manually. It performs all the steps required — from after completion of mechanical setup through grinding the first two new parts. The operator starts by setting the nozzle for the cooling oil and setting the ideal position for the stream of lubricant using the hand wheel. Automatic cooling oil nozzle adjustment then ensures that once found, this position is maintained even if the diameter of the grinding wheel becomes smaller. Then, the dressing tool is engaged fully automatically into the gaps in the grinding worm. A sensor integrated in the grinding spindle is combined with the corresponding algorithm to make this process fast, simple, and reliable. The grinding worm is given its first dressing immediately after the dressing tool has been engaged.
After dressing, the worm is engaged with the workpieces. Once the workpiece is engaged, it is then measured by the index sensor and serves as a reference for all the following workpieces. The “First Part Cycle” is completed by grinding two workpieces, one on each work spindle, which then are easily extracted for inspection from a convenient drawer. Tooling-up for a new component is thus completed simply, accurately, and in the shortest possible time.
Many Benefits of a Complete System
The easy integration of Gleason Automation Systems’ 1200 Machine Tool Loader (MTL) into the 200GX platform was also an attractive feature, according to Shah.
“This automation stores and conveys parts in stackable trays, which allows us to load and unload up to 180 parts at a time,” Shah said. “Compared to the conveyors servicing the other grinders, this puts three to six times more parts, depending on part size, in-process and unattended, thus freeing up our machine operators to be doing more productive things than loading and unloading parts. The machine and automation also take up considerably less floor space — an important consideration in a particularly confined area.”
Additionally, the MTL can be equipped to perform secondary operations that typically would have to be done off-machine with additional equipment. In this case, the MTL is equipped with an oil spinning station that spins off coolant from each part after grinding, thus allowing parts to be off-loaded ready for shipment.
Shah and his team also came away from Gear Expo with the first shop-hardened gear metrology system, the Gleason 300GMSP. This system now resides in Schafer Gear’s finish grinding cell — right on the shop floor where Smith and other machine operators use it to check setup parts and random production parts.
“Bypassing the quality assurance lab and performing inspections in close proximity to the grinding cells has cut part inspection time from an average of 20-30 minutes per part when done in the lab, to just five minutes per part on the shop floor,” Shah said. “Multiply this by two or three times a day, and the savings are enormous.”
Shah added, “Gleason is excellent to work with, and their service is second to none. By sourcing a complete system with them, we have never been better positioned to take on the high-precision, custom-engineered gear projects that Schafer excels at.”
