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Parting and Grooving for the Long Haul

Bill Koenig
By Bill Koenig Senior Editor, SME Media

Providers continue to innovate one of the toughest applications in machining

Horn’s 960 system mounted to a standard BMT connection, with opposite hand replacement cassette shown.

Some trends in machining remain constant. Machine speeds continue to increase. Difficult-to-cut materials are used more frequently. The desire for better cooling, chip control and reliability remains.

“Users are always demanding the same thing,” said John Kollenbroich, head of product management at Horn USA Inc., Franklin, Tenn. “More tool life and predictability, better chip control and surface finish. These demands have not changed in many years, nor will they change anytime soon.”

Added Steve Vanderink, national product specialist for grip products at Iscar USA, Arlington, Texas, “Users are demanding ease of indexing of the insert with accurate repeatability while increasing productivity with rigid support and strength in the pockets—all while keeping an eye on the economics. The market wants it all. Innovation is the driving force for solutions to the market’s needs.”

Higher machine speeds are also a big part of the demand on tools. “As the machines get more capable of higher speeds and torques, and the demand to get more out of the same tool constantly increases, manufacturers have to respond accordingly,” said Sarang Garud, product manager at Walter USA LLC, Waukesha, Wis.

As a result, toolmakers continue to step up their game.

“As tool designers, we need to increase the pocket security of our grooving platforms to allow customers the freedom (to) turn in all directions,” said John Winter, turning specialist at Sandvik Coromant, Fair Lawn, N.J.

The Sandvik Coromant CoroCut QD platform can part-off in both the X and Y axis and can also face groove, according to the company.

“We are seeing the increased usage of Y-axis grooving and parting-off. By using this axis of the machine, we are able to increase cutting data, allowing our customers to reduce their cycle times,” he said. “Machine tool builders are adding features to their machines that allow for the use of the Y axis. Also, builders are looking at increasing the stroke of the Y axis, allowing for increased diameters where you can use Y-axis part-off tools.”

Coolant and Coatings

At Horn USA, the company is offering coolant on more of its products. “This includes part-off and grooving holders and even some inserts,” Kollenbroich said. “Getting coolant to the cutting edge has many advantages. For one, having a more accurate delivery method for the coolant direction helps in cooling the work zone. It also offers the benefit of chip breaking when used with higher pressure applications.”

The company also looks to coating for product improvement. “We offer coatings that are capable of handling heat better, which in part-off and grooving is always a challenge,” he said.

Kollenbroich described how Horn addressed that challenge with its 960 part-off system. “This is a cassette-based, coolant-through design that offers a major upgrade in blade stability,” he said. “This additional stability results in great improvement in tool life. Customers can realize gains of double or triple the tool life while showing dimensional improvements in flatness and surface finish.”

Horn also offers a Y-axis part-off system. “This system uses the Y axis of certain lathes as feed direction,” Kollenbroich said. “This switch in axis feed directs forces back into the holder instead of against the holder. The improved strength allows for feed rate increases of two or three times that of standard X-axis part-off applications.”

The new Penta 17 has five cutting edges and allows for parting, grooving, side turning, back turning and threading. This new, smaller design is primarily for the Swiss machining industry, and is a Penta line expansion, joining the larger Penta 24 and Penta 34 tools.

Iscar has had a series of product launches to address customer demands. “Cut Grip is one of the most complete and comprehensive grooving lines on the market,” Vanderink said. “Iscar promotes and champions the GTO (groove turn operation) as a cornerstone process for this line. Straight grooving and then turning side to side utilizing all edges of the insert reduces cycle time while producing excellent part finishes.”

Another example: “Heli Grip is a game changer due to its unique twisted geometry, enabling depths of cuts to go beyond the second edge of the insert without damaging it.” He said that results in “much deeper depths of cut—grooving and excellent groove turn capabilities.”

Low Vibration, Longer Life

Walter USA has adjusted the way it clamps its inserts. “Usually the grooving inserts are held either through a self-clamping mechanism or through a ‘top-clamp’ screw-down mechanism,” Garud said. “The more secure the insert in the pocket, the lesser the tendency of vibration and longer the insert life.

“Also, lower vibrations lead to less pitting of the tool pocket, increasing toolholder life,” Garud continued. “The new patented design by Walter for our DX18 inserts securely clamps the inserts on three sides.” It also has “a secure prismatic base: a V-shaped top groove for the top clamping finger and a small double-faceted groove at the back of the insert to seat it securely in the insert pocket.”

Sandvik Coromant works to make its products flexible. Winter said that with CoroCut 1-2 “you can part-off, groove, face groove and do high-feed machining of hardened steel. The CoroCut QD platform can part-off in both the X and Y axis and face groove.”

Walter’s side-access insert clamping screw offers quick indexing on gang tooling.

Machines, Jet Coolant and Holders

Improvements in machine tools have also altered the way companies design tools. “The biggest improvement in machines that I have noticed is more machines are running high-pressure coolant,” Kollenbroich of Horn said. “Even the standard offering from most manufacturers is a considerable jump in pressure from what it was just a few years ago. High-pressure coolant offers benefits in chip breaking. Coolant-through tools, with better and more focused coolant delivery, remove chips from the work zone. This helps improve tool life and overall performance.”

Vanderink of Iscar described other considerations.

“Jet cut tooling is vital today,” he said. “Iscar has taken great care in making sure coolant is introduced to the cutting edge of the insert even when high pressure is not accessible. Data has shown that in all cases this makes a difference in tool life and part quality.

“Multi-axis, multi-spindle machine tools with Y-axis capabilities are emerging to complete parts in one setup,” Vanderink continued. “The use of robots on the shop floor is increasing and is becoming a viable operation for small to medium-sized shops now.”

According to Garud, Walter is also adjusting design. “The need for higher volumes and reduced cycle times is always weighing down on tool manufacturers,” he said. “Walter recently introduced a new line of G4014 toolholders specifically designed for gang tooling. One of the key features of these holders is the side-access screw to clamp the insert into the toolholder.

“The side-lock, or ‘smart lock’ as the technology is called, allows the users to index the inserts while the tool is still clamped onto the gang tooling of a Swiss machine,” he continued. “The side access to the indexing screws allows a time reduction of up to 70 percent in insert indexing, saving valuable time on high-volume Swiss machining operations.”

Horn’s Y-axis part-off blade 960 system mounted to HSK adapter.

Cutting Geometry Essentials

Industry changes also create other considerations for toolmakers and their customers. “Geometry always plays a critical role in grooving operations,” Walter’s Garud said. “But parting-off operations typically tend to need the inserts to go all the way to the center of the bar, so cutting speeds are zero at the center, which means tougher grades are always going to be better than the harder grades. Also, chip-crimping is quite important. Not only do the chips need to curl into ‘sixes and nines’ shapes, they also need to be folded axially, so the chip breakers need to be aggressive to fold the chips.”

Added Vanderink of Iscar, “Technically, center-height position of the tool is critical. The process of a square tool plunging into a round part is very abusive. The centerline dynamic is not fiction. It is real and essential for success in these applications.”

He also said clamping is an issue. “Using torque wrenches when clamping inserts in all parting and grooving tools is essential to maintain clamping force, tool integrity and finally part quality.”

Kollenbroich of Horn noted that managing centerline is critical. “Centerline can be your biggest friend and your worst enemy. All manufacturers design their tools to work on center. When a machine is off, even slightly, things become unpredictable. Customers typically experience a drop in tool life, maybe poor surface finish or, worse yet, catastrophic failure. It is critical to apply part-off and grooving tools properly, and on center.”

The Trend to Greater Control

One question is what to expect in the next few years. “I believe one thing we will see is machines equipped with sensor monitoring technology watching slight changes in the tool and adjusting accordingly,” Kollenbroich said. “Some machine manufacturers already have things like this, but they are not accurate or sensitive enough yet. Incorporating this sensor technology into the toolholder and tying directly into the machine control is a possibility.”

Said Winter of Sandvik Coromant, “We will see machines turning in all directions and the requirement for part-off and grooving tools is to do the same.”

Progress in various manufacturing technologies may play a role in the future for parting and grooving, Iscar’s Vanderink said. “Additive manufacturing will be a big player from here on out,” he said. “Already, new concepts are on the way due to this technology. Additive manufacturing producing near-net shaped parts will change how removing material is viewed. This concept alone will drive the innovation needed to accommodate these types of components.”

Advancements in carbide substrates are “ever changing and we are seeing new grades and coatings that are making a meaningful impact in tool life,” he added. “Industry 4.0 is expanding into tooling more and more. Tracking of tool life and wear is becoming a seamless part of the manufacturing process.”

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