Tool Life, Taylor’s Tool Life Equation, Calculation, Factor

Hello, friends today we will learn what is tool lifeTaylor’s tool life equation, what are the factors affecting the tool life and at the last also we will know how to calculate tool life.

The longevity of a cutting tool, known as tool life, holds significant importance as it indicates the duration the tool remains effective. Taylor’s tool life equation is employed for calculating tool life, and we will delve into its details shortly.

What is Tool Life?

Tool life refers to the duration a cutting tool remains effective in machining or cutting operations before it requires reconditioning, re-sharpening, or replacement. It is a crucial parameter in manufacturing and machining processes, indicating the efficiency and longevity of a tool during actual use. Longer tool life is generally desirable as it contributes to increased productivity and reduced downtime associated with tool maintenance. Various factors, including cutting conditions, tool material, and workpiece material, influence the tool life of cutting tools.

Tool life based upon the criterion of the volume of material removed is derived as follows :

The volume of material removed per minute

V = π D × t x f × N (mm^3/min)

V = π D × t x f × N × T mm^3

Cutting Speed

C = [π D N] / 60 m/s 

    = [π DN]/1000 mm/min 

πDN= 1000 C

Then also find out Volume of material

V = 1000 C × t x f × T mm^3

Where, 

D=Diameter of the workpiece in mm 

t= depth of cut in mm 

F= feed in mm/rev 

N=revolution of the workpiece in rpm 

T= time for tool failure in min

V= Volume of material 

Taylor’s Tool Life Equation

Taylor’s tool life equation As per F.W. Taylor, the relationship between Cutting Speed and Tool Life can be expressed as

VT^n = C

If V1, T1 initial condition and V2, T2 second condition then can be written as,

V1 × T1^n = V2 × T2^n

(V1/V2) = (T2/T1)^n

Where,

V= Cutting speed (m/min) 

T= Tool life (minutes) 

n= a constant whose value depends upon the material of the cutting tool & job, called tool life Index. 

(Commonly, n=0.08 to 0.02 for H.S.S tools, n=0.2 to 0.4 for cemented carbide tools, n= 0.5 to 0.7 for Ceramic Tools, n = 0.1 to 0.15 for cast alloys)

C = a constant, called machining constant

Read also: Types of Cutting Tool Materials and Their Properties

Taylor’s tool life equations modified version is,

VT^n × f^n1 × d^n2 = C

Where,

f = feed rate in mm/rev 

d = depth of cut in mm

The cutting speed stands out as a critical parameter impacting both tool wear and, consequently, tool life.

Typically, the relationship between cutting speed and tool life reduction follows a parabolic pattern.

See in the figure when increasing cutting speed then tool life decreases.

Tool Life, Taylor's Tool Life Equation, Calculation, Factor
Cutting Speed Vs Tool Life

 

When plotted on a log-log graph, the relationships between various cutting speeds and their corresponding tool life result in straight lines.

See in figure log-log graph, 

Tool Life Vs Cutting Speed
Tool Life Vs Cutting Speed

So, we can also write as Taylor’s tool life equation in the form of a log.

Taking both side log then we can write it,

log(VT^n) = log C

log V + log T^n = log C

log V + n log T = log C

It reveals that the tool life decreases with the increase in cutting speed.

Read also: Tool Wear: Types, Factor Affecting, Causes and Remedies

Factor Affecting Tool Life

The various parameters affecting the tool life are:

  • Cutting Speed
  • Cutting Temperature
  • Feed and Depth of Cut
  • Tool Geometry
  • Tool Material
  • Workpiece Material
  • Nature and Cutting
  • Use of Cutting Fluids
  • Operator’s Skill

Cutting Speed

As mentioned earlier, an increase in cutting speed invariably leads to a decrease in tool life.

Cutting Temperature

Elevating the temperature of the tool has a detrimental effect on tool life. The increased temperature accelerates the wear and degradation of the tool material, leading to a shorter lifespan. This is a crucial consideration in machining processes, where managing temperature is essential for optimizing tool performance and longevity.

Feed and Depth of Cut

Enhancing the feed and depth of cut intensifies the friction between the tool tip and the workpiece. This heightened friction is a contributing factor to the reduction in tool life. It underscores the importance of carefully managing feed rates and cutting depths to mitigate excessive wear and extend the lifespan of the tool.

Tool Geometry

The life of the tool can be adversely affected if the appropriate rack angle, back rack angle, and other crucial parameters are not accurately configured. Ensuring proper alignment and angles in tool setup is essential for optimizing tool life and performance.

Tool Material

The life of a tool depends on various mechanical properties, and tools are crafted from diverse materials such as carbide, ceramic, high-speed steel, carbon steel, etc. These materials exhibit distinct mechanical characteristics that significantly influence the tool’s durability and performance.

Workpiece Material

The selection of a cutting tool must align with the properties of the workpiece material to ensure optimal performance and longevity. Failure to choose a cutting tool compatible with the specific workpiece material can adversely impact the tool’s lifespan.

Read also: Manufacturing Process of Steel: 6 Methods of Making Steel

Nature and Cutting

The nature of the material being machined and the environmental cutting conditions significantly impact the tool’s lifespan. It’s essential to consider these factors to ensure the tool performs effectively and maintains a longer life.

Use of Cutting Fluids

Inadequate or low-quality usage of cutting fluid can diminish the tool’s lifespan. It is crucial to ensure proper application and quality of cutting fluids to maintain optimal tool performance.

Operator’s Skill

The proficiency of operators in handling machining processes is essential; otherwise, the tool life is prone to reduction.

Calculation of Tool Life

Question

A cutting speed of 80 m/min with a material removal exponent (n) of 0.09 was observed to have a tool life of 50 minutes during machining cast iron at a cutting speed of 100 m/min. Calculate the tool life at the reduced cutting speed.

Solution

Given Data 

T = 50 min

V = 100 m/min

n = 0.09

For finding tool life firstly we have to calculate the machining constant 

As we know,

Taylor’s Tool Life Equation,

VT^n = C

Taking both side log then we can write it,

log V + log T^n = log C

log V + n log T = log C

Putting value,

log (100) + 0.09 log (50) = log C

2 + 0.1529 = log C

2.159 = log C

Then,

C = 144.2

Now we can find tool life at a speed of 80 m/min.

VT^n = C

80 × (T)^0.09 = 144.2

(T)^0.09 = 144.2/80

                = 1.775           

T = 587.31 min

In this article, you have gained insights into tool life, Taylor’s tool life equation, factors influencing tool life, and a practical example demonstrating how to calculate tool life.

I hope you enjoyed this topic.

Frequently Asked Questions about Taylor’s Tool Life Equation

What does the Taylor Tool Life Equation calculate?

The Taylor Tool Life Equation is used to calculate the tool life for various types of cutting tools.

How is the relationship between tool life (t) and cutting speed (v) expressed?

The relationship is expressed as �⋅��=�, where is cutting speed in m/min, is tool life in minutes, and is the Taylor’s tool life index.

What is the modified Taylor’s tool life equation?

The modified Taylor’s tool life equation is expressed as �⋅��⋅��1⋅��2=�, where is feed rate in mm/rev, and is the depth of cut in mm.

What is Taylor’s tool life index?

The constant value in the equation is called Taylor’s tool life index, and its value depends on the material of the cutting tool and the job.

What are the typical values of in Taylor’s tool life equation?

The value of varies for different materials. For HSS tools, it ranges from 0.08 to 0.02, and for cemented carbide tools, it ranges from 0.2 to 0.4. (Rewrite United state language)

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