28 November 2011

Sumitomo Super Multi-drill XHT boosts penetration rate in deep hole drilling of steel

Sumitomo has developed an HT cutting geometry for its latest drill range which, it says, reduces the thrust required, creates smaller chips and improves chip flow in deep hole applications. The latter is further aided by a special fluting design.

The Super Multi-drill XHT also boasts a multi-layer nano coating that helps extend in-cut life, while also achieving faster penetration rates in steel, without pecking, than conventional drills.

Development of the Super Multi-drill XHT focused on the creation of the Sumitomo–HT cutting edge geometry. This enables very short chips to be created, while reducing the level of thrust required.

The geometry of the tool also introduces a 'double margin' concept, where the clearance in the body diameter leaves more than one margin on each land of the tool. Margins are also featured on the leading edge and on the heel of the tool's land, which help to optimise stability during the cutting process. The fluting of the tool range also breaks new ground by introducing specialised pocketing to positively influence chip management from the cutting zone and can be very effective across a wide range of materials.

The Super Multi-drill XHT range features Sumitomo's latest Super ZX low-friction, multi-layer nano coating. This coating provides a 40% higher hardness value and an increase of 200ºC in the level of oxidation resistance to over 1,000ºC. The TiAlN / AlCrN PVD coating also requires minimal levels of coolant supply during the drilling operation, even on deep hole applications up to 30:1.

In customer trials undertaking drilling of forged steel automotive crankshafts, Sumitomo Super Multi-drill XHT cutting geometry was used to produce four oil feed holes 5.7 mm diameter by 83 mm deep in each component. With the tool running at 100 m/min with a feedrate of 873 mm/min, tool life was 200 parts.

In further trials in the production of cutting tool bodies in 42 Cr Mo4 steel (35-38 HrC), the Sumitomo drill enabled tool life to be doubled to 60 components in the processing of three holes 7 mm diameter by 90 mm deep in each part. High speed steel tools were used previously, but for the Sumitomo XHT Multi-drill, feedrates were increased from 20 mm/min to 227 mm/min, while the drill was also run much faster, at 50 m/min against 15 m/min previously, reports Sumitomo.

Now available through Sumitomo Electric Hardmetal, the Super Multi-drill XHT solid carbide drill range is available as standard in 0.5 mm diameter steps from 3 to 12 mm and in-hole depth ratios of 10, 15, 20, 25 and 30 times diameter.

The drill range is used in conjunction with the appropriate Sumitomo MDW-PHT pilot hole drill to ensure precise positioning of the deep hole drill and provide, in effect, a bush to stabilise the initial penetration, while accommodating the acceleration of the tool to the recommended cutting speed.

A regrind and recoating service is available through Sumitomo, as well as special versions of the drill to meet specific customer applications.

Author
Celia Cadwallader

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Sumitomo Electric Hardmetal Ltd