Steely holemaking: Drilling Performance

Boosting productivity is all well and good, but Sandvik Coromant Co. finds that high-volume part manufacturers are generally more concerned about enhancing and achieving a predictable tool life, noted John Dotday, drilling product and industry specialist for the toolmaker. That’s especially the case when drilling steel workpieces, which can have slight variations between material batches that cause tool breakage, he added.

Sandvik Coromant developed the solid-carbide CoroDrill 860-PM to enable secure and productive steel drilling, including hardened and softer steels. Soft, gummy, low-alloy steels, such as 1018 and 1020, create the biggest drilling challenge because of built-up edge and chip control problems, according to Dotday. While it is difficult to break chips in those materials, the CoroDrill 860-PM creates small chips with tiny tails, he said.

Courtesy of Sandvik Coromant

The CoroDrill 860-PM is for steel holemaking applications. In cross-hole applications where hole diameters differ, end users should always drill the largest diameter first to minimize burr formation and prevent the drill from walking to one side.

In addition to optimizing the drill’s geometry for steel applications, Dotday explained that the drill’s edge-rounding treatment and reinforced drill corner prevent corner chipping, giving strength and security to the drilling process. The treatment is performed by applying abrasive brushes on a grinding machine.

He added that the new edge-prep reinforced corner and tough 4234 carbide substrate prevent premature tool wear, enabling machinists to hold tight tolerances and impart fine surface finishes. “We want a controlled wear pattern,” Dotday said.

The drill not only provides a predictable tool life but a longer one. Compared to other drills, the Sandvik Coromant CoroDrill 860-PM lasts 20 to 40 percent longer, according to Dotday.