CoroDrill 870 chamfer drill, recently introduced by Sandvik Coromant, improves chamfered hole operations.
CoroDrill 870 chamfer drill, recently introduced by Sandvik Coromant, improves chamfered hole operations.

The new tool allows machine shops to produce chamfered holes in a single operation, thus reducing tool/insert cost per hole and/or machine cost per hole, while at the same time achieving extended tool life.

According to Sandvik Coromant, it is suitable for ISO P (steel) and ISO K (cast iron) materials. CoroDrill 870 is an exchangeable tip range that now offers an insert-based 45° chamfer drill as part of the Tailor Made D275 family.

In tests on an automotive wheel hub machined from P1 low alloy steel (190 HB), performed using a vertical machining centre with emulsion coolant, the new tool was used to produce 12.6 mm diameter holes with a 45° chamfer through a 14 mm thick workpiece. Up against a comparable competitor product, the CoroDrill 870 chamfer drill achieved 100% greater tool life, delivering a total drilled length of 60 m before tolerance limits were exceeded, compared with just 30 m using the competitor tool.

The CoroDrill 870 chamfer drill has one or two chamfer inserts depending on requirements. The use of two chamfer inserts produces thinner chips, and as a result is recommended for medium or high feed applications, in unstable conditions or where a large chamfer width is needed. Conversely, a single chamfer insert delivers a thicker chip and thereby gives better chip breakage in stable, low feed or small chamfer width applications. A range of insert sizes is available.

Sandvik Coromant recommends that the same feed rate be used when the chamfer insert is cutting. This is important, especially when drilling a blind hole, because a reduction in feed can result in undesirable long chips from the drilling operation.