Published 2026-06-18 · Practical guides · Holemaking
Choosing a Modular Drill
Specify the body, cutting unit and machine connection together, then compare the complete assembly and replacement costs.
A modular drill quote needs more than a diameter. Specify the drill body, replaceable cutting head or insert, and holder needed to run them. A cutting unit alone is not a complete tool.
Start with the hole
Give the supplier the material and condition, finished diameter and tolerance, depth, and blind or through-hole requirement. Flag angled entry, cross-holes, an uneven exit and any bottom-form requirement. Include the drawing revision.
State whether drilling finishes the hole or prepares it for reaming, boring or tapping. The next operation determines what the drill needs to leave behind.
Match the body and cutting unit
Ask for both part numbers and confirmation that they are compatible. Check the cutting-unit geometry and grade, the body's usable drilling depth, shank connection and assembled projection. Include required screws, keys and adapters.
Kennametal's KSEM system, for example, pairs a drill body with a replaceable carbide insert and offers material-specific point geometries. Select the exact combination, not just the family name.
Check the coolant supply
Tell the supplier whether the machine has through-tool coolant and provide the available pressure and flow. Confirm that the holder and drill connections support it. Internal coolant carries fluid to the cutting zone and helps remove chips; external flood coolant may not reach effectively in deeper holes.
Use the selected tool's application instructions for cutting data, entry method and any pilot-hole requirement.
Price the setup and the repeat purchase
Ask for separate prices for the initial assembly and spare cutting units, plus stock and delivery. Confirm whether the holder and hardware are included. If reconditioning is offered, ask about cost and turnaround.
For a trial, record hole size, finish, cycle time and accepted holes per cutting unit. Compare cost per accepted hole, including tool changes and downtime, rather than the replacement insert price alone.
Sources
Kennametal: KSEM modular drill system
Sandvik Coromant: coolant delivery and chip removal in holemaking