- November 11, 2014
New technology improves tool life and cycle times
Grooving and parting-off are cornerstone operations for any shop that does turning. While it is a mature technology, a lack of awareness of the current generation of technology and some simple operational oversights might be hamstringing competitiveness in many shops.
Since many users are comfortable with an older generation of grooving and parting-off tooling, they may not be cutting as aggressively as they could. "They are often underutilizing the newer tools – not pushing the tools hard enough," says Don Halas, product manager, threading/threadmilling/grooving/MDT, Seco Tools, Troy. MI.
When people are concerned about an operation, "the first thing they do is slow it down. That might actually be absolutely the wrong thing to do," says Steve Geisel, senior product manager, Iscar Tools Inc., Oakville ON. Chip control in particular may suffer from slow speeds. "You have to push the chip into the chip breaker," he says.
"In grooving, especially, there are geometries that have been around for quite a while. It is important that people realize that technology has changed by leaps and bounds," says Eric Jenkins, senior applications engineer, Kyocera Precision Tools, Inc., Hendersonville, N.C. "You can take advantage of higher feed rates and still evacuate the chip out of the groove cleanly."
Increasing the feed rate means creating a thicker chip, so chip evacuation becomes more of an issue. "The moulded chipbreakers that are available today can play a big role in pulling that chip effectively at the proper feed rate," says Jenkins.
"The current generation of chip breakers, coatings and substrates are all designed to run at higher temperatures and last longer. They create less friction between the tool and the material," notes Geisel.
"Make sure you're using the right grade and chipbreaker for what you're doing in the material that you are cutting," says Geisel. While that sounds like common sense, many people try to standardize their tooling. Many job shops, for example, do not want to inflate their tool inventories unnecessarily because the workload changes routinely.
"They want generic tools that can do everything. If that's what they want to do, we can help them," says Geisel. "But if you want to get the maximum out of your cutting tool, you should choose something that specific to what you're doing."
Multifunctional tooling has its applications, assuming the user is willing to accept some compromises on specific tasks. Besides reducing tool inventories, you can do more turning operations with the same tool and reduce cycle times.
"Cut-off is a very violent application," says Halas. "You're pushing that tool in there, chips are coming out and you're getting growling – that type of noise. It is very difficult to get coolant in there. The chips push the coolant away the deeper you get in and a lot of heat is generated," says Halas.
Effective cooling is vital. In grooving, overhead coolant will push the chip back down inside the groove, notes Geisel. "When the coolant comes out through the blade itself, it pushes the chip up and out of the groove."
Through-tool coolant has started to get a lot of attention.
"The most important recent technological development is over/under coolant delivery," says Kevin Burton, product specialist, Sandvik Coromant, Mississauga, Ont.
"It allows you to use tougher grades and get the same results as a more wear-resistant grade." With two sources of coolant adjacent to the tool edge, the flow of coolant on target is uninterrupted.
High-pressure coolant is also winning interest. "People are finally coming around to that," says Jenkins. "High pressure will help you break a chip in materials like titanium and stainlesses."
Optimizing your cooling can lead to 50 per cent improvements in tool life and 30 per cent increases in surface footage, according to some experts.
Toolholding is another piece of the puzzle. Grooving inserts are narrow and long – not that easy to hold. A rigid toolholder is key to more aggressive cutting and better part finish," says Burton.
Seco recently rethought its clamping system. Screw-clamped grooving tools were causing customers problems, often because the operator had accidentally over-tightened the screw, distorting the blade and reducing clamping force, not to mention the broken screws.
The new toolholder eliminates the screw with an internal pre-set spring set that provides the optimum torque relatively easily.
"No matter who your tool supplier is, take a look at the newer stuff. It's dangerous to think that the way you've been doing something is still the best way," says Jenkins. SMT