Following Sumitomo Electric Hardmetal’s (www.sumitool.com) application success with its range of Flat MultiDrill series (MDF) high-rigidity coated-carbide drills, the range has now been extended.

The drills are used for spot-facing and counter-boring features on horizontal, curved or inclined surfaces of a component that would normally put uneven and excessive side loading on the tool and machine spindle.

The MDF series now includes length-to-diameter ratios up to 10:1, a long shank, external coolant supply (L2D) and through-coolant feed (H3D/H5D) variants.

With its 180deg point angle, true flat-bottoming can be achieved, while pre-tapped holes can be produced in thinner plate or sheet material; and with high length-to-diameter ratios, these tools can be used to access component features that are deep — within housings, for example.

Significant to the high-rigidity MDF tool series is Sumitomo’s ‘RS’ thinning development, which creates a “greater wall thickness at the tip of the drill”.

Swarf evacuation is very effective, due to wider pockets (that accommodate chips) with high levels of flute finishing and a specific shape applied to the rake face.

A special high-strength cutting edge helps to resist impact damage when interrupted cutting is involved; this also maximises the overall stability of the tool.

Due to the design, minimal burr formation is a further benefit.

The extended line-up of MDF drills can be used on general steels, stainless steels, alloy steels and hardened steels up to 50 HRC; grey and ductile cast irons and aluminium can also be drilled.

Standard tools can be used with pilot holes and are available in diameters between 3 and 20mm for a 2:1 depth-to-diameter ratio; with oil feed holes, depth-to-diameter ratios of 3:1 and 5:1 ratio in diameters between 3 and 16mm.

Recent MDF applications resulted in a 400% increase in tool life when producing counter-bores within a 34CrMo4 steel gear frame.

The MDF tool was run at 65m/min with a 0.1 mm/rev feed rate.

Meanwhile, on a C35 automotive component featuring a starting surface of 60deg, MDF significantly reduced cutting-edge damage and chipping compared to existing competitor tool methods. The MDF was run at 80m/min and 0.45mm/rev.

The latest additions to the MDF series further expand the higher-performance Sumitomo drill solution offering, where both the SumiDrill SDP and SDM Power Series enables higher-productivity drilling for holes between 3 and 16mm
diameter to depths of 7xD.

In addition, the Super MultiDrill XHGS and XHGA types are for deep-hole drilling applications up to 30:1 ratio and can be applied across the spectrum of materials from aluminium to steel.