Ninety-degree milling: Part 1- The right squareshoulder milling cutter

 A milling cutter with a ninety-degree entering angle provides most versatility in being able to perform practically any milling operation. This, in addition to that square shoulder milling represents the largest share of milling operations performed today, makes the ninety-degree cutter well worthy of extra attention. In this issue of International Metalworking News for Asia, we feature the first part of a fulllength article on ninety-degree milling from Sandvik Coromant to help provide solutions to a multitude of metalworking operations manufacturers in Asia perform.
 There are a few types of operations that cannot be considered for using the ninety-degree cutter, in the form of a square-shoulder facemill or as an endmill. This is especially the case when versatility is required, as it is in many machining centres and multi-task machines where low-volume manufacturing dominates. Obviously, when optimising large-volume production or operations targeting highfeed, extensive plunging, mirror finishing or heavy-duty face milling, then dedicated milling cutters benefit from a smaller entering angle. Performance optimisation, however, is now as important for versatilityoriented applications involving ninety-degree cutters.
 Certain milling operations can only be carried out with ninety-degree square shoulder, radial cutting edge and perpendicular edges. And often, the cutter is also the best choice for slot and circular milling. In addition, there are numerous operation, which the cutter can do well in, such as general face milling, turn-milling, ramping, peck milling, even plungemilling and even helical interpolation.
 A ninety-degree milling cutter is almost included in all set-up, through its operational flexibility, it often saves tool positions in the machine magazine and minimises any additional tooling cost. With its radial and axial cutting edges, the ninety-degree cutter is also advantageous in many operations because of the direction of the cutting forces produce during machining. Where the minimal axial force created lends itself to face milling on thin-plated work piece. It also allows relatively large depth of cut and contributed in achieving maximum axial tool reach. The capability of the tool in these operations, however, is hugely dependent upon the design of the indexable insert, the milling cutter and rigidity of the tool holding. Moreover, the ninety-degree cutter usually has different sizes of insert to select from, in order to optimise the radial milling capability. This makes the available cutter suited for either light to heavy machining, profiling and large corner radii capability.

 Radial milling
 When an extended long radial edge is required, the longedge milling cutter (representing a modern version of the traditional shell and slab cutters) is often the best solution. The solid carbide endmill is the conventional long radial-edge cutter but indexable insert technology has provided advantageous solutions also for small tool diameters (down to 12mm). For really deep workpiece shoulders and wide edges, especially when material removal is the priority, the long-edge milling cutter is in a league of its own. Even for slot and circular milling, as needed on many housings, this type of cutter is often the best choice. Today's long-edge cutters are also not as power and stability hungry as its predecessors and surface finishing capability has improved. Even to the extent that the indexable inser t concept has been adapted to be a dedicated finishing cutter, achieving results that close to what solid carbide and brazed carbide cutters can achieve.

 Titanium machining
 The ninety-degree, long-edge miAdidas