Field Notes: JetCut turning tools & CBN turning inserts

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supplier: Iscar Tools

end user: Quality Machine Services


Based in Windsor, NS, about 35 miles NW of Halifax, Quality Machining Services (QMS) Ltd. is a 2.601 sq m (28,000 sq ft), 38 employee fabrication and machine shop that’s been in business for 30 years. QMS does work in the automotive, construction/industrial, food service and military sectors. The shop has a full line of five CNC turning centres and six CNC milling centres, mostly Mazak units, as well as manual mills and lathes.

The work portfolio includes four-inch diameter shafts for moulding machines, turned on the shop’s Mazak Quick Turn 450 CNC turning centre. Aside from the hefty diameter, the shafts are machined from hardened 4140 steel, a one per cent chromium-molybdenum high tensile steel used in a range of heavy-duty industrial applications because of its exceptional hardness.

That hardness is a huge plus for end users requiring durability, but it’s also tough on tools. Up until about a year and a half ago, operator Nick McCarthy was finding he was burning through inserts way too fast. The inserts were made of cubic boron nitride (CBN), one of the toughest materials out there, and the material of choice to machine hard materials at high speeds and feeds, but the 4140 still seemed to be getting the better of them. “4140 has a Rockwell hardness rating of 60,” McCarthy says. “You need something as hard as diamond to cut it. Even with CBN inserts I was able to machine just one shaft per tip, and the inserts only had two tips each so I was spending a lot of time swapping them out, not to mention the cost.” 

A close-up look at the tougher grade Iscar turning inserts, which feature a four-edge design and a Titanium Nitride PVD coating.So McCarthy and QMS vice president Shawn Brown decided to make the switch to a tougher grade CBN insert from Iscar, the CNMA 120408-MW4 IB25HC, purchased from Iscar distributor Rideout Tool & Machine. In addition to being Titanium Nitride PVD coated with a medium grain size polycrystalline CBN (PCBN) substrate, the new inserts have a four-edge design. The new grade and geometry yielded immediate results. With four edges instead of two, the new inserts promised to double output, but it went beyond that.

“With the new ones I can do four shafts per edge,” McCarthy says. “On an insert that has four edges instead of two, that translates into big savings in time and money.” Even at a slightly higher price, the new inserts are way more cost effective.

Another QMS specialty is turning and parting thousands of bolts at a time. At about the same time that McCarthy and Brown decided to opt for the new tougher turning inserts, they also opted for Iscar’s Multi Connection (MC) JHP turning tools with a bottom fed high pressure coolant channel for the bolt turning and parting application. 

“The high pressure coolant helps with chip control,” McCarthy says. “The JetCut system directs the high pressure coolant directly on the insert, which keeps the insert cool, but it also ensures that the chips are cleared away efficiently. Heat is generally what breaks an insert down, but chip jams are a big cause also. The high pressure coolant eliminates both, which obviously saves time and money. It helps keep us competitive.”SMT

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