The idea for the KM Micro, a modular Swissstyle quickchange tooling system, resulted from the observations of Kennametal's metalcutting sales engineers (MSEs), who noticed that it was difficult for machinists to change inserts on conventional shanks.
By taking proven KM technology, Kennametal (Latrobe, Pennsylvania) developed a solution that makes it easier to change cutting inserts on Swissstyle machines that produce aerospace fasteners and fittings, automotive parts, medical, dental and electronics components, and telecommunications equipment.
"Kennametal has set new standards in Swiss machining," says Steve Rose, owner and founder of Rose Training Systems (RTS), a Solon, Ohio, based provider of customized CNC machine training that has been using KM Micro from Kennametal since March 2001 to train machinists from many North American companies.
"From the moment I was introduced to KM Micro, I was impressed with the results," says Mr. Rose, a 35year veteran of the machine tool industry who has owned a job shop and is the author of numerous books, manuals and articles on CNC machine training. "It is a welcome relief to avoid removing the complete tool from the toolblock to change the insert. This improvement decreases setup time and improves tool changing efficiency, repeatability and accuracy."
With this quick-change tool system, setup time is reduced from 30 minutes to fewer than 10 minutes. Previously, the machinist had to:
- Install toolholders in the toolblock;
- Perform a test cut of the piece being machined;
- Calibrate the face difference between one tool and the 4 or 5 others in the block;
- Enter the difference into the machine's controller;
- Make a part;
- Inspect the part;
- Determine whether the part met specifications; and
- Make any necessary adjustments.
A machinist using KM Micro:
- Changes the cutting unit, complete with insert;
- Makes the required part; and
- Makes any necessary adjustments.
According to Bill Foldery, an RTS instructor and a machinist by trade, "Changing a cutting unit takes about 30 seconds, compared to the several minutes it used to take, and KM Micro has reduced offsets to almost zero. With previous tooling, it was necessary to determine (measure) the relative distance between each tool type. With KM Micro, that step is not necessary because all of the tools cut on the same plane."
A Tale Of Two Pieces
In manufacturing an aerospace bolt from bar stock (stainless steel 321) on a Citizen Cincom L25 machine, using 5/8-inch square shank tooling system retrofit units for standard slotted tool-blocks, Mr. Foldery programs the machine to turn a hex from the 5/8-inch bar stock to form the bolt head, as well as shaft with a diameter of 0.070 inch, and cut threads on the narrow part of the piece.
In the roughing stage of this particular application, cutting conditions are 300 sfm, 0.004 ipr and 0.125-inch depth of cut. "We really like using KM Micro with insert grade KC5025," says Mr. Foldery. "The insert has a long life and is easy to change on those rare occasions when it needs to be replaced."
In the finishing stage, cutting conditions are 4,000 rpm at a feed rate of 0.003 ipr.
With other conventional Swiss tooling, it took 4 hours to manufacture the same quantity of aerospace bolts that a machine using this new tool system produces in half that amount of time.
Similar productivity gains occur when RTS uses ½-inch square shank KM Micro retrofit units for standard slotted toolblocks on a Citizen Cincom L20 machine to produce flow control valves (such as the internal components of industrial valve handles) from stainless steel 316.
"Due to the accuracy and repeatability of the F and C dimensions, KM Micro provides more efficient setup times and tool changes than any other Swiss tooling system because the tool tip dimensions are repeatable," says Stephanie Horvatich, an instructor and machinist at RTS.
Cutting conditions for this application are 3,500 rpm, 350 sfm, 0.125-inch depth of cut and 0.004 ipr.
Other parts that RTS is machining with the Swiss tool holding system include anodized aerospace parts, electronics components, orthopedic screws, tool parts and hydraulic adapters.
"The tool change process is what makes the system better than all other Swiss tooling options," says Don DiTurno, a Kennametal engineer who serves northern Ohio and southeast Michigan. "Users are always amazed at how little time the sixstep operation takes."
To change a cutting unit, a machinist:
- Turns the lock screw in a counterclockwise direction until it reaches an internal stop.
- Removes the cutting unit.
- Uses shop air to clean the clamping unit/cutting unit.
- Inserts the new cutting unit into the taper.
- Tightens the lock screw in a clockwise direction, torquing to the required specification.
- Adjusts machine offsets as required, if the machine has pregauging capability.
Quick-change tooling is said to make a machinist's life easier by reducing setup time and improving the efficiency of tool change procedures. These advantages translate into productivity and profitability gains for the companies whose machinists are trained by RTS, and they also provide an incentive for RTS to expand training activities centered on KM Micro.