Keep machines running with modular workholders

As a job shop starts a workday, the faces and machine tools on the shop floor look familiar, but the orders that come through the door and the parts that need to be produced may not. As a result, modular, quick-change workholders are needed to reduce setup times and keep chips flying while providing rigidity, repeatability and accuracy.

“The goal is to have as much uptime as possible,” said David Pynakker, facility administrator at Lang Technovation Co., adding that workholders must ensure that machinists easily can swap back and forth among various machining operations.

To enable that, the Hartland, Wisconsin-based company offers the Quick-Point zero-point clamping system as one option. Everything works off two different pull stud sizes and spacings of 52 mm and 96 mm (2.05″ and 3.78″) on center from pull stud to pull stud, he said.

Modular workholders can be set up and rearranged quickly to handle a variety of parts. Image courtesy of Bluco

According to the company, the system can be used on vertical and horizontal machining centers, on three- and five-axis tables and with fourth-axis rotary or trunnion systems. The attachment of the zero-point plate to the machine table or faceplate is done through prefabricated hole patterns, which can be modified to fit a table, and mechanical clamping is performed via an actuation screw.

“It’s a very easy-to-use system once you set up a plate on your table,” Pynakker said. “With the Quick-Lock, you just have to turn the handle 180 degrees, and it locks in your fixture. Turn it back, and it unlocks so you are ready to swap in your next fixture. It’s a very quick changeover when it comes to putting anything with clamping studs into it.”

Having a common interface like the 52/96 system allows end users to use workholding devices, such as vises, from any workholder manufacturer that supports that system — if not directly, then through a simple adapter, said Joe Schneider, vice president of marketing for Mate Precision Technologies in Anoka, Minnesota. Launching this spring, the company’s 52/96 zero-point, quick-change workholding system is a line of self-centering vises, quick-change bases and mounting systems for three-, four- and five-axis machining centers.

“Customers are willing to swap top tools,” he said, “but they don’t want to be swapping out the interfaces to their machines.”

Schneider said another key consideration is maintaining a compact form.

“We don’t want to force customers to reprogram their machines,” he said. “That would be a cardinal sin to have them reprogram their machines because of a big, bulky top tool.”

DynoGrip self-centering vises (left) and DynoLock quick-change bases (right) provide zero-point quality engagement with a four-post pull stud pattern. Image courtesy of Mate Precision Technologies

One characteristic of Mate Precision Technologies’ new DynoLock bases is the poka-yoke alignment feature. An element of lean manufacturing, the poka-yoke feature is a way to reduce opportunities for mistakes with a mechanism that enables an operator to identify the orientation of the base of a vise so setups are repeatable by design, said Frank Baeumler, vice president of workholding.

“If you create a system that causes you to repeat the same way all the time,” he said, “errors are reduced, which is the intent of (the) poka-yoke feature.”

Regardless of which manufacturer makes the workholding system, Schneider said end users seek to reduce setup time through repeatability and by not having to probe a part every time.

“We have looked at it from a machinist’s perspective in understanding what’s impeding setup time,” he said.

Clamping Head Swaps

Eliminating the need to indicate when going from one clamping head size to another is an important benefit when performing quick changeovers, said Timothy J. Wachs, president of Hainbuch America Corp. in Germantown, Wisconsin.

“They repeat within 5 to 10 microns (0.0002″ to 0.0004″),” he said about clamping heads using the company’s quick-change system. “You don’t need to re-indicate or anything. You change the size, and away you go.”

Although some people refer to a clamping head as a collet, Wachs said a clamping head has three sections separated by vulcanized rubber, whereas a workholding collet is one solid piece with slits. Hainbuch America offers a fixture changer, which is a hand-held installation gun, to change a head in seconds from one diameter to another.

“We invented the clamping head,” he said.

To change a clamping head, Wachs said the company’s installation gun is needed.

Pulling the trigger releases the clamping head from the chuck and enables an end user to change to a new diameter “in a matter of seconds,” he said.

In addition, Hainbuch America offers quick-change adaptations for its chucks. So instead of clamping on a part’s OD, an ID mandrel allows a user to change bushings to different sizes to hold a part’s ID, Wachs said.

To hold large parts in a chuck up to 304.8 mm (12″), the company developed the centroteX quick-change chuck system. He said the system permits changing a chuck in 10 to 15 minutes compared with the hours that might be needed to change a chuck conventionally.

“We put a flange plate that goes onto the spindle and then quick-connects to all the other plates,” Wachs said, “and you can put anybody’s chuck on that flange plate.”

Automation Trends

He said Hainbuch America’s latest development is the centroteX S clamping device changeover system, a miniature version of the technology. Actuation takes place with one cap head screw to further minimize setup time.

“We’ve automated it so you can change out a whole chuck with a robot,” Wachs said, “being able to change over robotically lights out to keep moving with different part numbers and different part families.”

Automating quick-change workholding typically requires a significant initial investment, but the productivity gains can provide a quick payback. Pynakker said Lang Technovation offers a robot-based cart system to continuously change carts while swapping jobs.

From left to right are a TOPlus chuck with a clamping head, a two-jaw module, a Mando Adapt ID mandrel, a Morse taper workholder, two views of a three-jaw module and a face driver. Image courtesy of Hainbuch America

“It’s not a pallet-changing system,” he said. “It allows up to 84 parts to be placed on two carts. Even shops that don’t have a lot of space can get 168 vises for smaller parts in a four-cart system that can be modified to fit your available area and installed within four weeks via Gamache Systems.”

Gamache Systems in New Berlin, Wisconsin, provides CNC machine tending automation.

Pynakker said Lang Technovation’s first U.S. customer for the cart system purchased a second system within a few months of the initial purchase and bought a third by the time the second was installed.

“Automation is a great answer to those shops needing a small footprint, high volume and increasing return on investment,” he said, “especially for lights-out machining.”

Schneider said pallet systems are one of the most common types of automation being employed for workholding.

“Pallet systems have been the first place people start when they pursue automation in this space,” he said.

Baeumler said a key element in an automated system is a mechanism that performs “the handshake” between the vise and base, or object No. 1 and object No. 2, to ensure they can communicate with each other.