Two mills quoted within a few thousand dollars of each other can differ by considerably more than that over 3 years. The purchase price is the number everyone compares because it is the number on the quote. Here are the five that are not.
1. Tooling
The largest recurring cost and the easiest to underestimate. Tool consumption scales with material hardness and with how aggressively your CAM strategies run. A lab milling mostly zirconia goes through carbide substantially faster than one milling mostly PMMA.
Estimate it by units, not by months. Take your expected monthly unit count, divide by your tool life in units, multiply by tool price. Do it per tool diameter, because the fine tools wear fastest and cost most.
2. Extraction and filtration
Dry milling requires extraction, and extraction requires filters. Filters are consumable and their replacement interval is measured in months, not years. A lab that does not budget for this discovers it as gradually declining suction and a dusty bench.
3. Spindle service
Spindles are the wear item that costs real money. Service intervals are published in operating hours, and a mill running unattended overnight accumulates hours far faster than one running a single shift. Ask for the interval and the price of a rebuild before you buy, not after.
4. Power and compressed air
A 2.5 kW spindle plus extraction plus a compressor is a real electrical load. If the machine needs 220V and your bench does not have it, that is an electrician before the machine can be commissioned.
Compressed air is the one labs forget entirely. Some machines need a dedicated compressor with specific air quality and drying, which is a second purchase.
5. Downtime
The number nobody quotes. A machine down for a week outsources every case in that week at full price. Remote diagnostics and local support change this number more than any specification does, because they change how long a fault takes to resolve.
How to compare two quotes properly
Build the 3 year total for each: purchase, plus tooling at your unit volume, plus filters, plus one spindle service, plus commissioning. The gap between two machines usually reverses.
Building the 3-year number
Write down six lines for each machine you are comparing. Purchase price including commissioning. Tooling at your real unit volume. Filters and consumables. One spindle service. Electrical and compressed air installation. An allowance for downtime.
The last one is the one people leave out because it feels speculative. Estimate it as one week per year outsourced at your normal outsourcing rate. That is conservative for most labs and it puts a real number on support quality.
Total the six. The ranking of two machines quoted within a few thousand dollars of each other frequently reverses once this is done.
Tooling, worked
Take your expected monthly unit count. Divide by your measured tool life in units, per diameter. Multiply by tool price. Sum across the diameters you actually use.
Then multiply by 12 and by 3. For a lab running meaningful zirconia volume, this line is often a substantial fraction of the purchase price over 3 years, which is why tool cost and tool life belong in the machine decision rather than being treated as a separate consumable question.
The support variable
Two machines with identical specifications can differ enormously in what happens when one stops. Ask three concrete questions before purchase.
What is the typical response time for a fault. Are spare spindles held locally or shipped from the manufacturer. And can the supplier diagnose remotely, or does every fault require a visit.
Remote diagnostics turns a large class of faults from a multi-day wait into a same-day resolution. That is worth more than most spec-sheet differences.
Residual value, briefly
Mills hold value unevenly. Platforms with a wide installed base and available parts sell on. Orphaned platforms do not, and a machine you cannot sell is a machine you keep running past the point where it makes sense.
It is a minor line in the calculation and it is not zero.
Go deeper
Power, air, extraction and space: milling requirements. Cross-brand comparison: milling units compared for 2026.
Pricing
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The DEPRAG W5 PRO milling unit is quoted per configuration — voltage, software, extraction and freight all change the number.