Sandvik Coromant insert grades boost steel milling operations

Sandvik Coromant is launching GC4330 and GC4340, two insert grades for steel milling. With the development of advanced production technologies, such as a new substrate, Inveio coating and an improved post-treatment technology, the grades provide opportunities for increased tool life and process security in comparison to the previous generation GC4230 and GC4240 grades, which will now be superseded.

Manufacturers face many challenges when milling ISO P workpieces. For instance, some hard and abrasive steels can generate wear along the flank face of the insert, especially at higher speeds and longer time in cut. In addition, machining in unstable conditions due to compromised clamping or long overhang elevates the risk of insert chipping, while thermal fluctuations during machining, especially under wet conditions, can cause crack formation and subsequent sudden breakages.

“Our new grades overcome these issues in many ways,” states Magnus Engdahl, product application manager at Sandvik Coromant. “For instance, the optimised Inveio coating increases wear resistance and tool life dramatically, without jeopardising security. With its uni-directional crystal orientation, the coating has a high resistance to thermal cracks, which in turn promotes long and reliable tool life, a factor further supported by a new post-treatment process that strengthens the insert by modifying its mechanical properties.”

A newly developed substrate provides well-controlled grain size distribution, which provides more reliable and predictable tool behaviour. In addition, consistent tool life is supported with a tighter edge-rounding (ER) tolerance.

GC4330 is a medium-hard grade and is the first choice for roughing to semi-finish face milling, with the tough GC4340 grade preferred for rough shoulder milling and groove milling. Wet and dry machining is supported, although the latter is recommended.

Both GC4330 and GC4340 are available in the following product families: CoroMill 390 and CoroMill 490 for shoulder milling; CoroMill 345 and CoroMill 745 for face milling; CoroMill 210 for high-feed milling; CoroMill 200 for profile milling; and CoroMill 331 for grooving and parting off.

Although the grades are optimised for steel, they also offer suitability for mixed production involving ISO K (cast iron) and ISO M (stainless steel) workpieces.