# Tool Life (Taylor Equation) and Cost Per Part Calculator

> Source: https://netray.co/tools/tool-life-taylor-equation-cost-per-part-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

See how a speed change shifts tool life, then find the speed that minimises total cost per part including insert cost and tool change time.

## Category

cost-finance

## Industry

Precision Machining

## Audience

- Process engineer
- Manufacturing engineer
- Cost accountant

## Tool

**Kind:** calculator

**Currency:** $

**Inputs:**

#### Reference cutting speed

**Key:** v1

**Type:** number

**Default:** 200

**Min:** 5

**Step:** 5

**Unit:** m/min

**Help:** Speed at which you know the tool life.

#### Tool life at reference speed

**Key:** t1

**Type:** number

**Default:** 15

**Min:** 0.5

**Step:** 0.5

**Unit:** min

#### Taylor exponent n

**Key:** n

**Type:** select

**Default:** 0.25

**Help:** Typical ranges: HSS 0.08 to 0.2, carbide 0.2 to 0.4, ceramic 0.4 to 0.6.

**Options:**

##### HSS (about 0.125)

**Value:** 0.125

##### Coated carbide (about 0.25)

**Value:** 0.25

##### Carbide, stable cut (about 0.35)

**Value:** 0.35

##### Ceramic (about 0.5)

**Value:** 0.5

#### New cutting speed

**Key:** v2

**Type:** slider

**Default:** 250

**Min:** 60

**Max:** 450

**Step:** 5

**Unit:** m/min

#### Cutting time per part at reference speed

**Key:** tc1

**Type:** number

**Default:** 2

**Min:** 0.1

**Step:** 0.1

**Unit:** min

#### Cost per cutting edge

**Key:** edge

**Type:** number

**Default:** 3

**Min:** 0

**Step:** 0.25

**Unit:** $

**Help:** Insert price divided by usable edges.

#### Machine and labour rate

**Key:** rate

**Type:** number

**Default:** 60

**Min:** 1

**Step:** 1

**Unit:** $/hr

#### Tool change time

**Key:** tchg

**Type:** number

**Default:** 1.5

**Min:** 0

**Step:** 0.1

**Unit:** min

**Outputs:**

#### Taylor constant C

**Key:** c

**Expr:** v1 * pow(t1, n)

**Format:** decimal

**Description:** From V x T^n = C.

#### Tool life at new speed

**Key:** t2

**Expr:** pow(c / v2, 1 / n)

**Format:** decimal

**Primary:** true

**Description:** Minutes.

#### Speed change

**Key:** dspeed

**Expr:** (v2 / v1 - 1) * 100

**Format:** percent

#### Tool life change

**Key:** dlife

**Expr:** (t2 / t1 - 1) * 100

**Format:** percent

#### Cutting time per part at new speed

**Key:** tc2

**Expr:** tc1 * v1 / v2

**Format:** decimal

**Description:** Minutes.

#### Parts per cutting edge

**Key:** parts

**Expr:** t2 / tc2

**Format:** decimal

#### Total cost per part

**Key:** cost_part

**Expr:** rate / 60 * tc2 + (edge + rate / 60 * tchg) / parts

**Format:** currency

**Primary:** true

**Description:** Machining time plus insert and tool-change cost per part.

**Chart:**

#### Cost per part vs cutting speed

**Type:** line

**X:** v2

**From:** 60

**To:** 450

**Steps:** 40

**Series:**

- cost_part

**Disclaimer:** Taylor's equation is an empirical fit valid near your test speeds. Do not extrapolate far outside the speed range you have data for.

## Content

**Intro:** Running faster cuts cycle time but burns tools quicker, and the cheapest speed is rarely the fastest one. This calculator uses Taylor's equation to predict tool life at a new speed and then finds the speed with the lowest cost per part.

**Sections:**

#### How to use it

**Body:** Enter one known point: the speed you ran and the tool life you got. Choose an exponent n for your tool material. Then slide the new speed and watch tool life, parts per edge and cost per part change. Add insert cost per edge, machine rate and tool change time to capture the real economics. The chart makes the cost-minimum speed obvious: it is the bottom of the curve.

**Bullets:**

- Measure tool life as minutes of actual cutting to a fixed wear limit, such as VB 0.3 mm.
- Use edge cost, not box cost.
- Include the time to index and re-touch off.

#### Formulas

**Body:** Taylor's equation is V x T^n = C. Given a reference pair, C = V1 x T1^n, and life at a new speed is T2 = (C / V2)^(1/n). Cutting time per part scales inversely with speed. Cost per part is machine rate times cutting time, plus the cost of one edge and one tool change divided by the number of parts per edge. Because n is small, a modest speed increase cuts tool life sharply: with n of 0.25, 25 percent more speed cuts life by about 60 percent.

#### Worked example

**Body:** With 200 m/min giving 15 minutes of life, n of 0.25 and a 2 minute cut, going to 250 m/min drops life to about 6.1 minutes while cutting time falls to 1.6 minutes. With a 3 dollar edge, 60 dollar per hour rate and 1.5 minute tool change, cost per part is about 2.20 dollars at 250 versus about 2.31 dollars at 200. Sweeping the chart shows the true optimum for your numbers.

#### Common mistakes

**Body:** The biggest mistake is extrapolating far from tested speeds, where the power law breaks down. Others include ignoring that feed and depth also change tool life, mixing minutes of cut with minutes of part cycle, and treating the optimum as fixed when machine rates or insert prices change. In production, optimise for the minimum cost speed only if the machine is not a bottleneck; if it is, choose the maximum production rate speed instead.

**Bullets:**

- Re-measure n when you change grade or coating.
- Check for edge breakage, not just wear, at high speed.
- Bottleneck machines favour higher speeds than the cost optimum.

**Cta:** If tooling usage and cost per part are tracked in an ERP, Netray can help bring actual insert consumption into your costing so these models use real numbers.

**Faq:**

#### What is the Taylor equation?

**Answer:** It is the empirical relation V x T^n = C between cutting speed V and tool life T, where n and C depend on the work material, tool grade and conditions. It lets you predict life at another speed from one test point.

#### What exponent n should I use?

**Answer:** Typical values are about 0.1 to 0.2 for HSS, 0.2 to 0.4 for carbide, and 0.4 to 0.6 for ceramics. Better still, derive n from two of your own tests at different speeds.

#### Why is the lowest cost speed lower than the fastest?

**Answer:** Increased speed shortens cutting time but disproportionately reduces tool life, so insert and tool change costs per part rise. The cost curve has a minimum, usually at a moderate speed.

#### Should I always run the minimum cost speed?

**Answer:** Not on a bottleneck machine. If capacity limits throughput, the maximum production rate speed, which is higher, may earn more. Compare the cost saved with the revenue from extra output.

## Search terms

taylor tool life equation calculator, tool life vs cutting speed, economic cutting speed, cost per part machining calculator, insert cost per part, VT^n = C, optimum cutting speed minimum cost, tool change time cost

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