CoroDrill 881 optimizes small hole drilling

In unfavourable cutting conditions such as where there is turret misalignment, producing holes below 24 mm diameter can prove tricky due to lack of process security, a factor that often leads to poor internal bore finish or out-of-tolerance holes. However, cutting tool and tooling systems specialist, Sandvik Coromant, is offering a solution to this problem with the introduction of its new insert-based CoroDrill® 881.

Featuring strong insert design for improved reliability in unstable conditions, such as when using older or less rigid machine tools, and a shot-peened drill body for improved fatigue resistance, users are assured of increased hole making security and enhanced precision.

This easy-to-use, problem-solving innovation is a particularly good choice for low-to-medium feed applications, as well as lathe-based non-rotating applications. Featuring two cutting edges per insert, general purpose, high performance geometry (GM1) is used to accommodate all material groups to suit a wide range of industries.

Potential parts might include: flanges and slewing bearings for the power generation sector; crankshafts, connecting rods and transmission parts for automotive manufacturers; flanges, reducers and collectors for the oil and gas industry; and housings and security parts for pump and valve manufacturers.

In tests on a stainless steel (CMC 05.21) flange component drilled using a 16 mm diameter drill to 17 mm depth on a vertical machining centre, CoroDrill 881 outperformed a comparable competitor product by 25 per cent (achieving 250 holes against 200) thanks to increased process security. In another VMC application, CoroDrill 881 completed 72 holes in Inconel 825 (CMC 20.2) to 19 mm diameter and 25 mm depth, in comparison to just 56 using a competitor drill.

Among the many possibilities in non-rotating applications, CoroDrill 881 can be used to generate tapered holes, or to make holes larger than the nominal size of the drill by applying a subsequent boring pass. Chamfering and reliefs can also be achieved, while a hole for threading can be prepared in a single pass together with chamfering. It is also worth noting that finishing cuts can be made on the return stroke (back boring).

CoroDrill 881 is available in diameters from 14 mm up to 23.5 mm to suit cylindrical ISO 9766 or Coromant Capto® (C4, C5, C6) coupling type tool holders, although Tailor Made tool options are also available to suit individual customer requirements. Preferred grades for the central insert are GC1044 or GC1144, while for the peripheral insert, GC2044, GC4044 or GC4024 are recommended but final selection is dependent upon material and application. Final selection is dependent upon material and application.