May 2011 / Volume 63 / Issue 5|
Killing setup time
By CTE Staff
Effectively delivering high-pressure coolant to the tool/workpiece interface when Swiss-style machining improves chip control, extends tool life and helps impart a finer surface finish.
To achieve those benefits, Highland Products Corp., Mentor, Ohio, was making 4"- to 6"-long external tubes from 3⁄16" steel brake line as part of a high-pressure coolant system for its machines. The system delivers straight oil at pressures from 500 to 2,000 psi when needed, noted Matt Nolan, the company’s plant manager. The Swiss job shop produces part volumes from one to more than a million for industries including medical, aerospace and automotive.
Courtesy of Highland Products
Courtesy of Streamliner
To control line output, Highland tapped the tube ID to insert a nozzle. “To make a new tube takes 20 minutes—if you’re good at it,” Nolan said.
The line also required bending to precisely position coolant flow. “That takes some finagling,” he added, noting that the approach was effective but prone to incorrect line positioning and lines being bumped out of position. In addition, changing a tool required moving the line out of the way and then repositioning it for the new tool.
Several years ago, the shop tested through-coolant tooling with two distribution ports, one down the tool face and one from the side, to effectively deliver coolant while reducing setup time, but elected to continue fabricating its custom lines. “It didn’t seem to offer much,” Nolan said about the product.
Then, about a year ago, Rolf Kraemer, owner of Streamliner & Associates Inc., Edinboro, Pa., dropped off literature at Highland about Streamliner’s through-coolant, Swiss-style screw-on insert toolholders that direct coolant halfway over the insert—about ½"—using a dovetailed distribution plate. Although the coolant stream gathers some air, it is significantly denser than coolant coming from a nozzle, and denser coolant extends tool life, according to Kraemer. (Streamliner also produces through-coolant holders for non-Swiss applications.)
After examining Streamliner’s tooling, Nolan indicated that he liked how the coolant inlet design enables flexible placement in a machine as well as the toolholder’s ease of use. For example, each holder has a dowel pin underneath the head that butts against the tool block. After a user indexes an insert, which requires removing the holder from the machine, the pin quickly and accurately relocates the holder when reinstalled.
Shortly after Kraemer delivered the first holders, Highland was running a new job that involved a relatively free-machining material, a large DOC and applying flood coolant. The cutting force exceeded the main spindle collet’s gripping force and pushed the workpiece material back in the collet, causing parts to be out of tolerance, Nolan explained. Rather than turning slower and reducing the feed rate to achieve the required part specifications, the shop decided to try a Streamliner tool and apply high-pressure coolant.
“We didn’t change anything except that toolholder and it totally eliminated that push-back scenario,” Nolan said. “I called Rolf the next day and said, ‘I’m good; we’re sold.’ ”
Nolan attributed the improvement to accurately directed high-pressure coolant creating a freer cutting condition. For the application, tool life tripled.
Since then, Highland has purchased additional holders and now has about 20. “We are phasing them in,” Nolan said. “For any repeat job that employs high-pressure coolant, we are switching to Streamliner tools.”
Streamliner offers three basic distribution plates with orifices of 0.094", 0.188" and 0.250" and a plate without an orifice, enabling users to customize the coolant passage. To maintain a high-pressure flow, Highland uses the largest size to maximize coolant volume when coolant is delivered from one of four lines and selects a smaller size when performing simultaneous operations.
With the Streamliner toolholders, Highland Products is significantly reducing setup times, increasing insert life overall about 20 to 50 percent and imparting finer surface finishes—in part by avoiding coolant from an external line knocking a chip back onto the finished product. “With increased tool life, product variability decreases,” Nolan said. “We definitely have a more stable process.”
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