In the modern manufacturing industry, an increase in productivity is always sought after. One of the main requirements is a predictable machining process with high process security. This requirement is further amplified for drilling processes, as they usually are performed late in the manufacturing when previous machining processes have added much value to the component.

One of the main components in achieving high process reliability is efficient chip control. An efficient chip breaking process minimizes the risks of chip jamming disturbances that may lead to off-tolerance holes, broken drills, discarding the workpiece or in worst case a damaged machine, resulting in decreased productivity and additional costs for the manufacturer.

To investigate whether the chip breaking ability of an indexable insert drill may improve through a change in the drill dynamic, three drill holder concepts were developed. The CAD-models were made in Siemens NX 12.0 and evaluated through modal analysis and static structural simulations in Ansys 2021R2. The final designs were then manufactured in the Sandvik Coromant prototype workshop.

The prototypes were paired to the Sandvik Coromant Corodrill indexable insert drill body and evaluated through testing in stainless and low carbon steel, as chip jamming is most commonly occurring in these long-chipping materials.

The static structural simulations made during the design phase show a good correlation against the experimental testing performed on the prototypes to verify the simulations. The modal analysis of the prototypes shows a larger deviation from the simulation, which is expected as the simulations use a simplified setup.

The chip break testing shows a slight decrease in chip length for the Medium prototype and a significant decrease when using High prototype together with cutting data which resulted in a changed sound. The evaluation of the hole quality does not show any major difference in the R_a surface finish. The diametric deviation increases with the hole depth compared to using a standard drill holder.

The decrease in frequency may correlate to excitation of the first torsional mode of the High prototype drill holder through regenerative vibrations, also known as chatter. While this frequency drop seems to correlate with an improved chip breaking performance, there seems to be no correlation between the frequency drop and change in diametric deviation.