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Manufacturing Center

By Larry Olson, Editor 
Modern Applications News

Grinding System Meets Challenge Of Producing Precision HSK Tooling

Using dual wheels to grind the taper, shoulder, and V-groove in one setup reduced the processing time by 75%, eliminated a setup and an operation, and significantly improved precision.
Ingersoll was founded in Cleveland, OH in 1887, primarily as a heavy machine manufacturer. The company moved to Rockford, IL shortly thereafter and has operated at its present location for more than a century. Ingersoll International employs about 4,000 people, worldwide: approximately 2,000 in the U.S. and about the same number in Germany. Ingersoll subsidiaries focus primarily on the manufacture of special machine tools and cutting tools.

Scott Wenstrom (left) discusses tool-processing details with grinding machine operator Jerry Faldet.Ingersoll Cutting Tool Company in Rockford employs about 550 people and consists of three facilities: steel products, with about 40,000 sq.-ft. of manufacturing space; carbide inserts, with about 28,000 sq.-ft. of production space; and a prototype and repair center. Scott Wenstrom, senior manufacturing engineer in steel products, has responsibility on the shop floor for just about all aspects of cutting tool production; including fixture design, troubleshooting, and assigning required work to the proper machines. With 15 years’ experience at Ingersoll Cutting Tools, and 10 years in his current position, he supports the activities of nearly 100 people involved in manufacturing precision cutter bodies.

The cutting tools produced in the steel products shop are mainly for unique applications, with about 36% being standard designs and 64% specials. During 1999, steel products volume totaled about 40,000 units, although this figure is not entirely representative of the overall manufacturing picture. The tooling ranges in size from small ½" diameter endmills to aluminum scalpers with diameters in excess of 100". Typical lot sizes vary from one to 30 pieces for a wide variety of standard, nonstandard, and engineering special tools. Much of the tooling is manufactured specifically for its sister company, Ingersoll Milling Machines, that is involved in making high-velocity (40,000 rpm) milling machines.

The Kel-Varia grinding a V-groove in an HSK-type tooling part.Most of the shop’s production is batch-processed on 13 five-axis machining centers, two CNC (computer numerical control) grinders, and an assortment of manual grinders. Of the two CNC grinders, the Kellenberger Kel-Varia from Hardinge Inc. (Elmira, NY) is the one used in making HSK-type high-speed tools. Otherwise, standard tooling product is manufactured in a production cell comprised of another CNC grinder and an assortment of other machines.

According to Wenstrom, the Kel-Varia (the company’s first) was installed in December 1998. Previously, the shop had one CNC grinder in its operation, with four other CNC grinders installed at Ingersoll Milling Machines. With the pressure of increased production volume and higher precision requirements, Ingersoll Cutting Tools decided to expand the steel products shop by adding another CNC grinder. While reviewing the alternatives, Wenstrom narrowed the search to the Kellenberger machine. In the final analysis, having CNC on the B-axis and an excellent reputation for service gave the nod to the Kel-Varia.

In making the decision, Wenstrom studied machines in North Carolina, in the Milwaukee area, and locally in Rockford that were involved in similar applications. Based on his own experience and discussions with a North Carolina tooling manufacturer (who was doing work similar to Ingersoll Cutting Tools), he was able to collect some good information on the Kel-Varia’s operation. “When I talked with their engineers and shop floor people to get their opinions on service,” says Wenstrom, “the majority of the answers were, ‘We don’t know, since we never had to use it.’”

What Makes Grinding Integral HSK Tooling So Tough?

Ingersoll Cutting Tools was one of the first cutting tool companies to pioneer in manufacturing HSK-type tooling. Early in the 1990s, the company teamed up with Ingersoll Milling Machines in a project to build a line called the “Ford Factory of the Future.” This project featured the development of several groups of high-speed machines and nontraditional transfer-line equipment with HSK tooling.

Most of the tooling manufactured to HSK designs is integral; that is, the shank and the cutting tool are one piece. This is in direct contrast with several other makers of cutting tools that use a standard adapter with an endmill. This two-piece arrangement often has many inherent problems such as rigidity and runout. However, according to Wenstrom, manufacturing the tooling as a single unit presents some unique processing difficulties as well.

Inside the HSK taper, there is a 30° clamping angle to accommodate the drawbar in the machine tool. From the shoulder of the tool to that angle, there is a relatively tight tolerance. Wenstrom explains, “If that were the only dimension that had to be maintained to the shoulder (about ±0.001"), it wouldn’t be a problem. You could measure the stock, grind the excess off the shoulder, and be done with it. By making the tool integral, we also try to maintain a dimension over the insert at the opposite end from the same shoulder. So, we end up holding two dimensions from the same datum (or feature point) in opposite directions. That makes a very small window where the shoulder must be located.”

Wenstrom recalls that Ingersoll Cutting Tool’s steel products shop learned a lot about the tight tolerances involved, right from the beginning. “We knew what we wanted the machine to do,” he says. “Unfortunately, the one grinding machine that we had couldn’t do what we wanted it to do. The process was achievable, but it was very labor-intensive.” Originally, manufacturing the HSK tooling involved two separate operations. The taper and the shoulder were done in one operation, followed by grinding the V-groove on another machine. “Luckily, the operator at that time was very experienced,” he adds, “which bridged the gap between the (manual) machine’s shortcomings and what was needed.”

Now, the Kel-Varia’s setup with in-process gauging and automation has made life a lot easier for the shop. The machine’s features significantly reduce the cycle time and labor involved in producing a good part. On average, depending on the particular HSK tool design, a part that would take as much as 1½ hours of manual grinding to complete now can be finished in 15 minutes. In addition, grinding the tooling features in one setup on the Kel-Varia has paid dividends for Ingersoll Cutting Tools by producing parts with precision the first time, with much less scrap and wasted effort.

Another major advantage for the Kel-Varia is its CNC B-axis, which gives it the ability to achieve much more precise results. Accuracy and repeatability are further ensured by having hydrostatic ways on the X- and Z-axes, where other grinders may have this feature only on the Z-axis. Wenstrom is quick to point out that there is nothing custom about their Kel-Varia. As far as delivery and installation were concerned, he says, “We received the machine, and a week later the service representative came in to train the operator and me. It went really smooth, and he still supports the machine on a day-to-day basis, if needed.”

The Kel-Varia is presently running on one shift, 10 hours per day, six days per week, with the ability to expand to two shifts if needed. Most of the company’s HSK tooling is manufactured for sale with the milling machines made by Ingersoll Milling Machines. The market for this type of tooling to other customers is expanding as well, although it is still a relatively narrow niche. As the use of HSK tooling becomes more prominent in the marketplace, the steel products section of Ingersoll Cutting Tools is positioned to manufacture some of the most precise products of this type available anywhere. Kellenberger, A Hardinge Co - July 2000