Annual Drill Program Audit: A Shop's Year-End Checklist

The end of the fiscal year is the most valuable time to review your drilling program. You have twelve months of data — tool spend, quality records, cycle times, scrap rates — and the opportunity to set different parameters for the coming year before habits calcify. Most shops skip this review entirely and wonder why their tooling costs are the same year after year. Here is a structured process that takes two to three hours and consistently surfaces actionable improvements.

Step 1: Pull the Numbers

The first step is collecting the raw data. You need four categories of numbers:

Tool spend: total dollars spent on new drills, broken down by size and material. Your purchasing records have this. If you can also extract resharpening costs separately, do so — the ratio of resharpening spend to new drill spend tells you how aggressively you are recycling versus replacing.

Volume drilled: total holes drilled by size, or by machine/cell if you track at that level. CNC control logs have this data if someone is pulling it. Estimated from production counts and typical holes per part if not tracked directly.

Quality events: scrap and rework incidents attributable to drilling — oversized holes, positional errors, broken drills in parts, surface finish failures. Pull these from your quality records or NCR log.

Unplanned downtime: machine stops attributable to drill breakage, tool changes outside the normal schedule, or chip problems. Even a rough estimate from operator logs is valuable.

Step 2: Calculate Drill Cost Per Operation

With tool spend and volume data in hand, calculate the fully-loaded cost per hole drilled. This is: (total drill spend + resharpening spend + quality event cost + downtime cost) divided by total holes drilled.

The resulting number — dollars per hole — is your benchmark. Compare it to the prior year if you have it. Compare it across drill sizes to find outliers. A size that costs 3× the average cost per hole is telling you something important: either it runs in unusually difficult material, or the process for that size is not optimized, or you are buying inferior tooling for that size.

Outliers deserve investigation, not just acknowledgment. If 3/8" drills in your stainless cell cost five times more per hole than 3/8" drills in your mild steel cell, the stainless process may need re-evaluation — different grade, different geometry, different coolant, or different speeds and feeds. The cost-per-hole calculation surfaces this in a way that qualitative shop observation never would.

Step 3: Review the Resharpening Program

How much of your drill spend went to resharpening versus new drill purchases? A healthy program typically resharpen 60-80% of eligible drills (those that are dull but not broken or too short) rather than discarding them. If your resharpening-to-new ratio is below 50%, you are likely discarding drills that could have been resharpened — either because the rotation system is not capturing them, or because operators are binning marginal drills rather than sending them out.

Review the quality of resharpened drills versus new drills. If you track hole quality or tool life post-regrind (as described in our benchmarking article), compare the average holes-per-regrind across vendor batches. Consistent vendors produce consistent results. If you see wide variation in post-regrind performance, the resharpening quality is inconsistent and worth addressing.

Step 4: Evaluate Inventory Levels

How often did drilling operations stop or slow because the right drill was not available? Any stockout event — no matter how brief — is a sign of inadequate safety stock or a process that is not signaling restocking needs early enough. Conversely, if you are carrying inventory of drill sizes that have not moved in six months, you have capital tied up in slow-moving stock that could be freed.

Set minimum and maximum inventory levels for each active drill size based on your actual annual consumption and resharpening lead time. Sizes used infrequently should be reviewed: do you still need them, or has the work that required them moved or changed?

Step 5: Set Next Year Targets

Based on the analysis, identify two or three specific improvements with measurable targets. Examples: reduce cost per hole in the stainless cell by 20% through optimized speeds and feeds and a trial of M42 drills; reduce unplanned drill breakage events by 50% through tightened tool life limits; increase resharpening capture rate from 55% to 75% through a better dull-bin process.

Keep targets specific, measurable, and tied to actions that someone owns. "Improve drill program" is not a target. "Reduce stainless cell cost per hole from $0.42 to $0.34 by Q2 through the M42 trial and feed rate optimization" is a target. The annual review creates the targets. The quarterly check-in tracks progress. The next annual review measures whether you hit them.

Two to three hours once a year on this process consistently returns more value than any single tooling upgrade decision made without data. Your numbers already know what needs to change — the audit is just the discipline to look at them systematically.