Is there an ace in the hole?

“Making holes in aluminium can be a challenging task,” explained Patrik Pichler, Global Product Manager, Indexable Drilling Tools at Sandvik Coromant.

“Ductility and softness cause the material to make constant and prolonged contact with the insert’s cutting edges. As a consequence, the aluminium adheres to the cutting edge and creates a Built-Up Edge (BUE) that makes chip formation and evacuation difficult.”

GCN124 and GCN134 diamond-coated insert grades are designed to offer the lowest cost per hole in most ISO-N materials thanks to long lasting insert tool life and/or greater productivity. The increased productivity could be gained from elevated cutting data as well as a result of less machine downtime thanks to fewer insert changes.

Further advantages available to customers include easier handling in production due to the reliability and longer life of the inserts, and enhanced surface finish inside the hole, which results from the ability to resist BUE and smearing effects. Reduced insert consumption will also help lower stock levels and environmental impact.

Among those set to benefit are automotive manufacturers drilling and boring aluminium components such as cylinder blocks, cylinder heads, knuckles, housings, brake calipers, control arms, transmission cases, steering-column covers and yokes. However, the diamond-coated inserts will also offer competitive gains to any company producing ISO-N parts, as well as those performing niche composite applications such as drilling GFRP rotors/blades for the wind turbine industry.

To highlight the potential of the new grades, when drilling a 22mm diameter blind hole to a depth of 84.1mm in a cylinder head made from 6061-T6 aluminium (90-100 HB), CoroDrill 880 mounted with the new N124 (peripheral) and N134 (central) inserts extended tool life from 700 to 3024 pieces; an impressive 332% increase. The new insert permitted increased cutting speed, allowing productivity to increase by 33%. In total, some 300 hours of production time were saved, while overall cost per hole was reduced by 23%.

Similar success was achieved when performing through-hole drilling (22.5mm diameter) in 20mm thick automotive front control arms made from AISi1Mg-T6 aluminium (150HB). Here, the new CoroDrill 880 diamond-coated inserts helped elevated tool life from 3,000-30,000 pieces. Productivity also improved by ten percent as a result of less machine down-time for insert indexing, while cost per hole was reduced by 17%.

GCN124 and GCN134 are now the first choice insert grades for ISO-N materials. They complement the existing H13A, uncoated insert from Sandvik Coromant, which remains recommended in applications involving shorter production runs and/or difficult interrupted cuts.

The standard CoroDrill 880 range features indexable insert drills from 12-84mm (0.472-3.307") in diameter, with drill lengths of 2, 3, 4 and 5xD. With Sandvik Coromant’s Tailor Made offering it is possible to order intermediate diameter and length combinations as well as different connection types and sizes such as HSK, Coromant Capto or cylindrical shank. One of the Tailor Made options includes the ability to design customised step and chamfer drills for specific components.