Vises Eliminate Multiple Setups

Manufacturing an array of component parts in small to medium quantities required that Purakal Cylinders Inc. (Eugene, Oregon) consider functionality and quality when deciding to upgrade its production capabilities. The manufacturer of hydraulic and pneumatic cylinders and manifolds, which offers standard and custom-built products, explored various options in an effort to streamline production.

The company’s management evaluated several different machines before opting for a NH6300 DCG from Mori Seiki, USA, Inc. (Irving, Texas) a six-pallet (630 mm per pallet) HMC, from distributor Ellison Machinery (Wilsonville, Oregon).

With the new HMC on order for delivery later in the year, Dale Poisel, Purakal’s project leader, had to consider his workholding options. The machine would be used primarily in dealing with steel parts in square and rectangular shapes, ranging in size from 1.5 inches by 1.5 inches to 14 inches by 14 inches. As such, tombstones would be needed to mount these parts. Earlier that year at Westec, Kevin Mikkelsen, Purakal’s general manager, had stumbled upon the Tombstone City (Huntington Station, New York) booth, picking up a catalog that he then handed off to Mr. Poisel.

At this point, Mr. Poisel contacted Andy Popky, the sales manager for Tombstone City, to discuss tombstones and workholding options. Mr. Poisel was pleased with the company’s selection but realized that the sizes offered in the catalog would not be compatible with the HMC.

“The machine has extended travels, and I wanted to use every inch of travel,” says Mr. Poisel.

Mr. Popky mentioned that his company offers custom tombstones as large as 1,500 mm, and that he could feasibly come up with a solution to accommodate the machine’s extended travel capabilities. Mr. Poisel decided to go with the 38 inches (in height) “Plus” and “Square” column tombstones, both of which were constructed of cast iron.

When asked how he was planning to grip the parts on the tombstones, Mr. Poisel mentioned that he had been investigating modular clamping systems because of their capability to maximize the number of parts in the machining envelope.

“I had yet to find something that would streamline production,” explains Mr. Poisel. “We rejected double vises as an option because of their inefficient use of real estate. A double vise limits holding to a maximum of two parts.

“I also concluded that double vises would not improve our cycle times,” he continues.

Consulting the catalog once again, Mr. Poisel came across Tombstone City’s SVF modular vises. Several calls and e-mails further piqued his interest in the modular vise system.

These vises are made of 100 percent tool steel and are available in 2-inch, 3-inch and 4-inch wide models, in lengths ranging from 12 inches to 28 inches. Moreover, they are equipped with enough jaw sets to hold as many as four parts per vise; they also adjust to parts of varying sizes.

Mr. Poisel realized that these characteristics would make the system a good fit for working with smaller parts, but he wondered if larger parts—those measuring 14 inches by 14 inches—could be accommodated as well. The vises are available in short sectional units, which can be spaced out as far as needed. One can gang two vises side by side; remove one or two jaw sets; and hold larger parts. Another feature of the modular design is being able to gang the vises in one row, thereby offering unlimited vise length, says the manufacturer. According to the company, the flexibility of this design essentially enabled the company to get a vise measuring 36 inches in length. In turn, the company says it was able to put to use all of the Y-axis travel.

Because the company had a lot riding on the modular vise concept, it was hesitant to have all production based on a vise the company had not actually seen or tried. Mr. Popky offered to provide a demo vise so that Mr. Poisel could test-drive it. After using the vise for about 1 week, Mr. Poisel reported that he was pleased with the fit and finish of the vise. The company had taken some test cuts to verify the vise’s holding strength.

“I then realized that the vise system would be able to streamline our production, so I proceeded to order enough vises to cover four tombstones, with Tombstone City installing the vise mounting grid holes on the tombstones,” says Mr. Poisel.

After having the new vises in production for less than a month, Mr. Poisel reported that the combination of the Mori Seiki machine with six pallets and the flexible vise system has been a contributing factor in allowing the company to plan for implementing lights-out machining in the near future. The system eliminated the multiple setups that were previously needed to produce the company’s cylinder blind ends.

Purakal can now manufacture 12 parts per cycle in one setup, instead of four parts per two setups. In addition, not only has production increased because of the capability of the SVF vise to grip more parts in less space, but also the company says it has shortened setup time considerably. It attributes this to the vise jaws being drilled and tapped to accept bolt-on parallels, which stay in place without the use of springs or double-sided tape.