In this issue of the column, MEGA Tech is pleased to present the inserts from Sandvik, which has launched an innovative new milling concept and a new grade for high feed roughing of steel. The properties of this new milling and a new grade will be discussed in this article.
“CoroMill® MR80 is a double-sided round insert concept with a higher number of inserts compared to regular round insert cutters”, says Sangram Dash, Global Product Application Specialist for indexable milling tools at Sandvik Coromant. “It is ideally suited to low depth of cut — up to 3 mm — face milling and profile milling applications in both steel and stainless steel.”
Originally designed for machining cast stainless components in the automotive sector, in particular turbochargers and exhaust manifolds, this product has been further developed to cater to steel milling applications, which require the security of a round cutting edge — such as the die and mold segment. As a result, CoroMill® MR80 is an extremely capable and versatile milling concept that offers both higher productivity and economical machining in a wide range of operations, with no compromise on security.
“The round cutting edge is considered to be the most secure edge for challenging materials as well as tough cutting conditions”, explains Dash. “Furthermore, the shim offers additional security for the cutter body, protecting against coining deformation and machining accidents, while also securing the insert in the tip seat by restricting micro-movements during cutting.”
An economical solution, CoroMill® MR80 features double-sided inserts with 12 indexing possibilities when operated within a 3 mm depth of cut. “That means more parts for each set of inserts”, says Dash. “Also, a higher number of inserts on a cutter body enables a higher table feed and increased productivity. On top of that, the overall security and reliability mean less damage to the cutter body and inserts which, ultimately, helps to cut costs.”
Thanks to its lightweight cutting geometry, it is also possible to use CoroMill® MR80 as a problem solver in difficult machining situations, even with long overhangs.
“Frequently, due to their intricate shapes, automotive cast stainless components are mounted on a fixture that may not be suitable for higher cutting loads”, says Dash. “And often, in die and mold applications the cutter must go deep into the mold cavity, mounted on a long adaptor. In both cases, the cutting forces must be limited so that vibration can be avoided. Although CoroMill® MR80 is a double-sided negative concept, it works with fairly low cutting forces and is a suitable solution for such applications.”
The CoroMill® MR80 assortment offers cylindrical and arbor cutter bodies, with diameters from 32 to 100 mm, 3–12 cutting teeth, even pitch, and shim protection. All cutter bodies feature internal coolant supply. The double-sided E-L50 inserts offer true and easy indexing (6 + 6), with a 3 mm recommended depth of cut.
In addition, Sandvik Coromant has recently introduced the GC4425 and GC4415 steel turning grades. The new generation grades have been fully refined, delivering an average 25% increase in tool life compared to the previous grades.
”With the introduction of GC4405, we are complementing the steel turning grade chain within the high feed roughing area”, says Torbjörn Ågren, Product Application Specialist at Sandvik Coromant. “We strive to make it as easy as possible to choose and apply the correct grade to match the specific application.” Grade GC4425 delivers wear resistance, heat resistance and toughness in a wide application range, while grade GC4415 complements GC4425 with enhanced performance when more heat resistance is needed. Grade GC4405 should be applied as a high feed productivity optimizer with high metal removal rates in stable conditions with demanding plastic deformation properties.
Among the features offered by the new grade is a new carbide substrate with optimized microstructure, which will reduce plastic deformation in high feed applications. The substantial increase in plastic deformation resistance has enabled a drastic expansion in the application range towards harder steels and higher productivity compared to the existing grade GC4305.
The new grade GC4405 features the second-generation Inveio® technology coating, which is designed specifically to combat crater wear common to P05 applications. What makes second generation Inveio® different from the earlier generation is the alumina coating, where the crystals are aligned even more vertically towards the top surface to improve wear resistance, offering more consistent quality and performance.
The new grade offers a considerable increase in productivity and tool life, particularly when machining steels above 300 HB. The grade is also suitable for machining softer steels — in this case without the need for coolant, offering substantial opportunities from a sustainability point of view.
Comprehensive tests conducted between the existing GC4305 and the next-generation GC4405 steel turning grade indicate an increase in tool life ranging from 30% up to 130%, which is primarily thanks to significant improvements in the plastic deformation and crater wear resistance.
Grade GC4405 is recommended for continuous roughing to semi-finishing in stable conditions and long time in cut. It is suitable for high feed machining with medium, roughing or wiper geometries in harder steels above 300 HB, or for high feed and/or high speed machining in softer steels below 300 HB.
The grade should be applied in ISO application area P05 (P01–P10). It is optimized for P2.5 low-alloy hardened steel, but also recommended for high productivity applications in low-alloy P2.1 and unalloyed P1.2 steel.
Article by: MEGA Tech & Sandvik Thailand Limited << Click Here