This product is a 4.0 mm cobalt stub drill conforming to DIN 1897, designed for short, accurate drilling where rigidity and hole quality are important. Its primary use is producing precise small-diameter holes in difficult-to-machine materials such as stainless steels, heat-treated alloy steels and other high-temperature alloys where ordinary HSS drills blunt quickly.

The flute and cutting geometry are provided as a two-flute twist design with a straight cylindrical shank to suit standard three-jaw chucks, collets and drill holders. The drill is manufactured from HSS-E (cobalt) tool steel, typically M35 grade (approx. 5% cobalt), giving enhanced red-hardness and wear resistance compared with conventional HSS. The tool is supplied in a bright, ground finish for accurate diameter control and smooth chip evacuation. The item is produced to DIN 1897 dimensional and length standards for stub drills, ensuring interchangeability with other DIN-compliant tooling.

Typical applications include through and blind drilling in a production or maintenance environment where stiffness and repeatable hole position are needed: component drilling in aerospace and automotive sub-assemblies, engineering workshops, toolroom, oil and gas fabrication and general mechanical engineering. The cobalt alloy is particularly effective when machining austenitic and martensitic stainless steels, case-hardened steels and some nickel-based alloys; use of cutting fluid is recommended to extend tool life and reduce built-up edge.

Key benefits are the M35 strength grade offering improved hot hardness and longer life in abrasive or heat-generating cuts, the stub length which reduces flex and improves positional accuracy compared with standard-length drills, and DIN 1897 compliance which guarantees fit and length for assembly-line and tooling jigs. Note that the bright cobalt finish gives limited corrosion resistance compared with coated variants, so drills should be stored dry or oiled if required.

Duchy Fasteners holds a broad stock of DIN 1897 cobalt stub drills in metric sizes and offers individual items and multi-packs; contact us for current size availability, pack quantities and any split-point or coated alternatives.