A new exchangeable-tip drill may promise fewer complete-tool replacements, while a solid-carbide drill may simplify setup for a particular hole. Neither statement tells a purchasing team which solution is cheaper per accepted hole. Compare matched applications and include the body, heads, machine time, rework and inventory—not only the unit price of a cutting edge.
Seco’s September 2026 X-Tip announcement describes one modular body with multiple interchangeable carbide tips for different materials and depths. It is a manufacturer product claim, not evidence that every modular drill outperforms a solid-carbide alternative. Seco X-Tip announcement
Do not mix three architectures
| Architecture | What is replaced when the edge wears? | Buyer question |
|---|---|---|
| Solid-carbide drill | Whole drill, unless economically reconditioned under an approved process | What is the usable life and feasible regrind allowance for this geometry? |
| Exchangeable-tip drill | Detachable cutting head or tip; body reused subject to its condition and manufacturer’s limits | How many head changes can the body support, and what is the interface inspection method? |
| Indexable-insert drill | One or more discrete inserts, often with indexable edges | Are insert seats and the body inspected for wear or damage? |
These are not interchangeable terms. Sandvik Coromant discusses solid-carbide, exchangeable-tip and indexable designs as separate options with overlapping application ranges; the limits depend on the actual product family. Sandvik Coromant drilling overview
Define the trial before calculating price
Specify workpiece grade and condition; hole diameter, depth, tolerance, finish and through/blind status; machine, spindle, holder, alignment and coolant; and the exact failure or acceptance criterion. Use the same definition of an accepted hole for both options. If one process needs a secondary finish operation, include it. If a reconditioned solid drill is being compared with a new tip, record that difference rather than hiding it in an average.
The body and tip are a matched system. Verify compatible diameters, depth-to-diameter range, interface key and coolant configuration with the maker. Do not assume a tip from one brand fits another body. After several changes, measure hole quality, not just whether the drill still cuts.
A practical cost-per-accepted-hole model
For a comparable production batch, use:
Cost per accepted hole = (cutting-tool purchases + body consumption + allocated regrind/maintenance + change/setup downtime + machining time + scrap/rework attributable to drilling) ÷ accepted holes.
Avoid counting the initial exchangeable drill-body purchase twice: allocate body consumption over its verified useful life, or count bodies actually consumed by the batch. Use the same accounting period for both alternatives. Track in a worksheet:
| Input | Solid-carbide trial | Exchangeable-tip trial |
|---|---|---|
| Accepted holes / rejected or reworked holes | Measured | Measured |
| Complete drills used, regrind cost and usable cycles | Measured | Not applicable unless approved for this system |
| Tips/heads used; bodies consumed or allocated body wear | Not applicable | Measured |
| Minutes per hole, change events and downtime cost | Measured | Measured |
| Additional operations, inspection or scrap | Measured | Measured |
| Safety stock of sizes and any dedicated accessories | Recorded separately | Recorded separately |
For example, a lower-priced tip does not establish a lower per-hole cost if its change time, interface damage or rejected-hole rate is higher. Conversely, charging the full reusable body to a single short trial unfairly penalises the modular option. A break-even estimate is only as good as the assumed body life and observed acceptable-hole count.
Decide what evidence the supplier must provide
Ask for a drawing and operating envelope; tip-to-body compatibility; body/interface inspection and replacement criteria; hole-quality results after repeated tip changes; consumption measured on your material; and the reorder availability of each tip and body size. Clarify whether the quotation includes starter bodies, keys, spare tips, coolant hardware and reconditioning services. A published claim of “lower inventory” should be checked against the buyer’s actual material mix and diameter demand.
Our general drill-bit cost-per-hole guide explains the overall cost concept. This worksheet is narrower: it compares two distinct constructions under matched, measurable conditions. If your current application calls for a solid-carbide drill, do not substitute a modular design solely because its replacement tip appears inexpensive; confirm hole tolerance, machine compatibility and complete batch cost first.