Twist drill for stainless steel HSS-E Cobalt 5% BOHRCRAFT 1140-red, reduced shank, for drilling stainless steel, acid-resistant and heat-resistant steel

Twist drill for stainless steel HSS-E Cobalt 5% BOHRCRAFT 1140-red, reduced shank, for drilling stainless steel, acid-resistant and heat-resistant steel serves large-diameter holes on machines with small chucks. The diameter range runs from 11.0 mm to 20.0 mm, while the shank is reduced to only 10 mm or 13 mm. The drill body is manufactured to DIN 338 from HSS-E alloyed with 5% cobalt.

The 135° split point grind lets the drill self-centre and reduces walking when entering the workpiece. The type N flute geometry suits materials of medium to high toughness. The reference drilling depth is 5xD. The cobalt alloy increases the hot hardness of the cutting edges, limiting the loss of hardness as cutting temperature rises. Because of this, article 1140-red handles stainless steel, acid-resistant steel and heat-resistant steel well.

Twist drill for stainless steel HSS-E Cobalt 5% BOHRCRAFT 1140-red, reduced shank
for drilling stainless steel, acid-resistant and heat-resistant steel

The cylindrical shank is reduced relative to the cutting diameter, with a shank length of 30 mm or 35 mm depending on size. The entire range keeps the same DIN 338 standard and 135° point angle. The steel surface is bright ground, uncoated. The split point cutting edge reduces axial force and vibration at large diameters.

• Standard: DIN 338, type N flute
• Material: HSS-E alloyed with 5% cobalt (Co5)
• 135° point angle, split point grind, DIN 1412 C
• Cutting diameter Ø d1: 11.0 – 20.0 mm
• Cylindrical shank Ø d2: 10 mm for sizes 11.0 – 16.0 mm; 13 mm for sizes 16.5 – 20.0 mm
• Shank length L3: 30 mm or 35 mm
• Overall length L1: 142 – 205 mm; flute length L2: 94 – 140 mm
• Reference drilling ratio 5xD, packed in 1 piece

The reduced shank design allows a Ø 20.0 mm drill to be mounted in a 13 mm chuck. This is a familiar approach when a bench drill or hand-held machine is limited by clamping size. The article group 1140 03 11100 to 1140 03 12000 covers 0.5 mm increments from 13.5 mm upwards. Users select the exact hole size without changing the machine.

Material machining capability

The material table in the catalogue places article 1140 in groups P, M, K, N and S. The high hot hardness of the HSS-E base steel keeps the cutting edges stable when drilling stainless steel, which generates considerable heat and work-hardens at the surface. A steady feed rate and continuous coolant supply are required conditions for achieving drill life.

• Group P: material codes 1.1 – 2.1; 3.1 – 4.1; 5.1
• Group M: 1.1 – 2.1
• Group K: 1.1 – 4.2
• Group N: 1.1 – 1.6; 2.1 – 2.6; 4.2
• Group S: 1.1 – 2.6
• Usage orientation: stainless steel, acid-resistant steel, heat-resistant steel

The VA INOX marking on the catalogue page confirms the main usage direction for the stainless steel group. With cast iron and non-ferrous metals, the drill still works according to the K and N group tables. When drilling large holes, a pilot hole should be drilled first to reduce the load on the chisel edge.

Common applications

This article is often used in stainless steel structural fabrication, tank and vessel assembly, and food and chemical piping. Mechanical workshops use it to drill flanges, gusset plates, base plates and stainless steel supports. The reduced shank version is convenient for small bench drilling machines. Maintenance technicians working on boilers and thermal equipment also choose the type for drilling stainless steel when they have to open holes in heat-resistant components.

Determine the hole diameter first, then check the chuck size of the machine. Sizes 11.0 – 16.0 mm use a 10 mm shank; sizes 16.5 – 20.0 mm use a 13 mm shank. The workpiece thickness should stay within the flute length L2 of the corresponding drill.