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Turning Insert Tool Life Log Worksheet

Tool life is the cheapest process data a turning shop can collect and one of the least recorded. This worksheet turns insert changes into parts per edge and tooling cost per part, so you can compare grades and speeds with evidence.

Download:

Date	Job	Insert / grade	Change reason	Parts per edge	Insert price	Edges per insert	Cost per edge	Tool cost per part
							$2	$0
							$2	$0
							$2	$0
							$3	$0
							$3	$0

Total parts logged

413

Average tool cost per part

Worst cost per part

Edge changes logged

Average parts per edge

82.6

Log the edge that was removed, not the one installed. Edges per insert depends on geometry: negative inserts such as CNMG commonly give 4 useful edges, 80 degree trigon types often give 3, positive inserts often 2.

Link tool consumption to work orders

Optional: ask us how tool issues from the crib could post to work orders in your ERP.

Optional. The tool and every export work without this. No spam.

How to use the log

Add one row each time an edge is changed. Enter the number of parts the edge made, the insert price and the usable edges per insert. The sheet computes cost per edge and tooling cost per part. Add rows as needed, remove the examples, and export to Excel to keep a running history by part number or by machine.

Count parts, not minutes, if cycle times are fixed
Pick a reason from the list every time
Log breakage as a change even if the count is low
Review monthly by grade

Reading the results

A low parts-per-edge figure with a cheap insert may still beat a premium grade, and the cost per part column shows that directly. Watch for patterns in the reason column. Frequent flank wear points to speed or grade, chipping points to rigidity or interrupted cuts, built-up edge points to speed too low or the wrong coating for the material, and size drift often means offsets being chased instead of the tool being changed.

Tool life versus speed

Taylor's relationship says tool life falls steeply as cutting speed rises, so a speed increase of ten percent can cut life by far more than ten percent depending on material. Log life at each trial speed on separate rows with the job note, then compare cost per part, not just cycle time. The cheapest part is often between the fastest and the longest-lasting setup.

Common mistakes

Do not mix different materials on one grade comparison. Do not count scrapped parts as good parts unless you want the scrap included in the tooling cost. Avoid recording life only when it is good. Honest records include early failures, because those events drive the real average. Keep the unit consistent and note coolant condition when results swing.

Frequently Asked Questions

How many edges does an insert have?

It depends on shape and design. Double-sided negative rake inserts such as CNMG commonly offer 4 edges, trigon WNMG often 3 per side on a double-sided insert depending on design, and positive single-sided inserts usually 2. Check the catalog for your item.

Should I track tool life in minutes or parts?

Parts per edge is simplest for repeat jobs. Minutes in cut is better when part lengths vary or you compare different jobs. If you log minutes, convert to parts before comparing cost per part.

What is a good parts-per-edge number?

There is no universal figure. It depends on material, depth of cut, speed and part length. Use the log to set your own baseline for each job, then try one change at a time and compare cost per part.

Can I import last year's data?

You can type or paste rows into the worksheet, and exports go to Excel and CSV. For long histories, keep one export per quarter and compare averages rather than loading everything into one sheet.

If your ERP tracks tool issues and crib stock, Netray can help link insert consumption to work orders so cost per part builds itself.

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