If you have to put a consumables number in a budget, you have probably asked a supplier how many cutters a machine gets through in a year.
You will not have got a straight answer. There is a reason for that, and it is not evasion.
Why nobody can tell you
There is no independent standard for testing how long an annular cutter lasts.
Manufacturers publish comparisons between grades of steel. Almost nobody publishes hole counts for a specific cutter in specific material, and when they do it is their own test.
So any figure you are quoted is either a marketing number or a guess. Neither belongs in a budget.
What actually moves the number
Four things, and they move it by multiples rather than percentages.
- Plate thickness. A cutter going through 30 mm is doing three times the work of one going through 10 mm, per hole.
- What the steel is. Mild steel, weathered structural steel and stainless are three different jobs for the same cutter.
- Coolant. Dry cutting on anything but the thinnest material shortens tool life dramatically. This is the single biggest avoidable factor.
- Feed discipline. Too light and the cutter rubs instead of cutting, which work-hardens the steel and finishes the edge. Too heavy and you stall the machine.
Two shops buying the same cutter can be a factor of three apart on consumption, and both be running properly.
The method: count holes per job, not holes per cutter
Nobody will reliably tally holes against a specific cutter while they are working. Do not ask them to. Count at the level the paperwork already exists.
- Take one month of job sheets. Any representative month.
- Count the holes drilled. Most job sheets already carry hole counts, or a drawing you can count off.
- Count the cutters issued from the store that month. Your stores system already knows this.
- Divide. Holes ÷ cutters = your rate.
That number is worth more than any published figure, because it is true for your steel, your machines and your people.
A worked example
Say a month of job sheets shows 4,200 holes, and the store issued 14 cutters. That is 300 holes per cutter. Multiply by twelve for the year, cross-check against last year’s spend, and you have a defensible budget line.
Those numbers are illustrative. Yours will be different, and that is exactly the point.
Split it by diameter if you can
A 12 mm cutter and a 40 mm cutter have very different lives and very different prices.
If your job sheets carry hole sizes, run the sum per size band. It takes an extra half hour and tells you which size is quietly eating the budget.
When to re-check
Your rate is not permanent. Re-run it when any of these change:
- A new steel grade or a materially different plate thickness on a contract
- New machines, or old machines coming back from repair
- A change of operators, or a period of heavy overtime
- A change of cutter brand or grade
What to do with the answer
Two things.
- Budget properly, instead of carrying last year’s figure forward with a percentage on top.
- Use it as a baseline. If consumption jumps 30% with no change in workload, something is wrong upstream – usually coolant, usually feed – and you now have the evidence to go and look.
We will do the sum with you
Send us a month of job sheets and your cutter issue figures and we will work out your rate. If it looks high we will say where we think it is going, and we will tell you when the answer is not a different cutter.
Email info@neweratools.com or call +65 6241 0908.