Injection molding: Timely tips for drilling in pre-hardened steel

One supplier, Sweden’s SSAB (Oxelösund, Sweden), has been working with metalworking tool supplier Botek and French moldmaker and metalworking specialist René Devaux to determine the optimal parameters for drilling deep holes in pre-hardened steel. SSAB’s Toolox 44 grade of steel has a hardness of 45 HRC, which it claims is the pre-hardened steel with the highest toughness and hardness that is currently commercially available. According to SSAB, although the metal’s low carbon content and high degree of homogeneity make it readily machinable, customers still occasionally experience difficulty, especially on their first use of the steel.

In one test at René Devaux , five 12-mm diameter holes were drilled to a depth of 650 mm, giving a combined total depth of 3250 mm, reportedly without any complications and no re-sharpening of the drill needed. According to Botek, which provided the bits used, critical to successful boring on these steels is a complete absence of vibration during drilling, as well as the use of coated tools with the correct carbide type. Crucial, says Botek, is to have the recommended angle on the drill tip (which should not be too sharp). Also important is that pure drilling oil (no mixture) is used. For drilling of holes with a depth:diameter ratio higher than 40, support of the drill is needed.

Moldmakers who are willing to share their own tips are welcome to contact the editor at [email protected] or [email protected].