In order to overcome the challenges of chip formation and evacuation when drilling non-ferrous metals, Halesowen-based Sandvik Coromant has introduced its CoroDrill 880 CVD diamond-coated insert grades GCN124 and GCN134.

The super-hard properties of the diamond coating provide long tool life and are combined with special chip-breaker and geometry designs to increase machining performance when drilling materials such as aluminium.

The ductility and softness of this material cause it to make constant and prolonged contact with a drilling insert’s cutting edges (www.sandvik.coromant.com).

As a result, aluminium creates a built-up edge (BUE) that makes chip formation and evacuation difficult. GCN124 and GCN134 diamond-coated insert grades are designed to offer low cost per hole in most ISO-N (non-ferrous) materials.

Increased productivity can be gained from ‘elevated cutting data’, as well more machine up-time thanks to fewer insert changes.

Further advantages include enhanced surface finish inside the hole — a result of the ability to resist BUE and smearing effects.

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 gain to any company producing ISO-N parts — as well as those 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 (90-100HB), CoroDrill 880 mounted with the new N124 (peripheral) and N134 (central) inserts extended the tool life from 700 to 3,024 pieces.

Moreover, the inserts allowed the use of higher cutting speeds for a 33% gain in productivity and a 23% reduction in the overall cost per hole.

Similar success was achieved when through-drilling a 22.5mm-diameter hole in a 20mm-thick automotive front control arm made from AISi1Mg-T6 aluminium (150HB).

Here, the new CoroDrill 880 diamond-coated inserts helped extend tool life from 3,000 to 30,000 pieces.

Productivity also improved by 10% as a result of less machine down-time for insert indexing, while the cost per hole was reduced by 17%.