REVIEW STUDY ON INCREASING THE CUTTING TOOL SERVICE LIFE
This paper is to review the different techniques to increase or extend the cutting tool life. Cutting tools plays a vital role in machining process and surface finishing. Cutting tool has to be strong enough to withstand the wear resistance. When comparing to uncoated cutting tools the coated tools increases tool hardness and increases life of the tool. There are two methods for coating cutting tools are physical- vapor deposition (PVD) and chemical-vapor deposition (CVD) methods. Some of the coatings proved to be better performance than others. The coatings like TiN, TiC, TiCN, Al2O3, TiAIN, and ZRN respectively are in use. The coating thickness must be in the range of 2-10um.The coated tool performs lower surface roughness when compared to uncoated tool. Coated tool can improve tool life by as much as 10 times of uncoated tools. Heat generation in cutting tool is performed by various cutting parameters like cutting speed, feed rate, and depth of cut respectively. It is also investigated that sudden changes in feed and cutting speed results tool failure or braking. Thus coated tool improves the overall performance and productivity.
Key words:- cutting tool ,Tool geometry, Tool wear, Tool, life, coating, heat, manufacturing.
Machining process is one of the metal removal process in which the unwanted material from the work piece is removed by cutting tool in the form of chips. The cutting tool rake angle plays an important role in surface finish and wear. Heat is generated at the tip of the tool during the machining process that affects the tool geometry and properties. Therefore proper material selection with accurate rake angles is provided to tool in order to overcome the failure of tool.
It is also determined that any sudden change in cutting speed, feed rate and depth of cut has the maximum effect on increasing cutting temperature, wear and surface roughness. Hence any improvement in tool life will have a direct impact on the cost of production. The cutting tool geometry includes back rake angle, end relief angle, side cutting edge angle, end cutting edge angle, lip angle, side rake angle and side relief angle.
During machining operation enormous amount of heat and friction is developed between tool and work piece. In order to overcome this problem coolant is provided. Coolant supplying during the machining operation is also plays an important role to overcome the tool failure and it acts an lubricant.
Tool wear describes the failure of cutting tool due to continuous machining operation. The different types of tool wears are flank wear, crater wear and nose wear. The tool failure occurs due to the following reasons
Mechanical breakage due to excessive forces.
If proper material with composition is not selected.
Sudden overfeed, cutting speed & depth of cut.
Not supplying coolant while performing machining operation.
EFFECTS OF TOOL WEAR:-
Increasing the cutting forces.
Increased cutting temperature.
Poor surface finish.
Fig: – Tool wear
1.2 TOOL LIFE
The tool life may be defined as maximum time that tool spends to make desired satisfactory parts. The various factors that affect the tool life are cutting speed, feed rate, and depth of cut, tool nomenclature, and chip thickness respectively.
The relationship between tool life (T) in minutes & cutting speed (V) in m/min is as follows. By the Taylor’s equation.
VTn = C
Where V- Cutting speed
T- Tool life
n- Taylor’s tool life exponent
C- Intercept on speed axis
PROPERTIES OF CUTTING TOOL:-
The material of the tool must be at least 30-50% harder than the work piece material.
Tool must have high hot hardness temperature.
Ability to withstand high temperature and wear.
High wear resistance.
High thermal conductivity.
Low co-efficient of friction.
Good corrosive resistance.
1.3 CUTTING TOOL MATERIALS
The general cutting tool materials used are as follows.
High speed steels
Ceramics and cermets
Cubic boron nitride(CBN)
Coating is provided on the surface of the cutting tool in order to improve the life span of the tool. The two different techniques like physical vapor deposition and chemical vapor deposition are extensively in use. The wide varieties of coatings available are TiN, TiCN, TiC, Al2O3 ,etc. The performance of the tool after coating increases 10 times than uncoated tool.
BENEFITS OF COATING:-
The following are the benefits achieved if cutting tool is coated with proper material.
It can reduce the friction & heat generation during machining operation.
The chips can easily flow from the surface of the cutting tool.
Prevents corrosive resistance.
High service life to tool compared to uncoated tool.
Increase oxidation resistance.
2. LITERATURE REVIEW
Safal A. shambharkar. 1, studied that the while performing machining operation the maximum stresses and heat is developed near the tip of the cutting tool, which causes failure of the tool. Sudden changes in the cutting speed, feed rate and depth of cut also the one of the reason for failure of the tool. Due to this the complete geometry of the tool gets damaged and becomes unusable. In order to prevent this failure proper tool radius and speed is maintained constant while performing machining operation.
A.Nagarajan. 2 , Investigated that the coated cutting tools perform better than uncoated tool SAE-AISI 1037 carbon steel is selected as a cutting tool coated with titanium nitride (TiN),and Aluminum oxide (AL2O3).coating to the cutting tool is done by physical-vapor deposition technique. Coating to the cutting tool generally increases wear, corrosion and fatigue resistance and also service life of the tool.
Nbv Lakshmi kumara, S Irfan sadaq.3, conducted experiment on the two different materials which are high speed steel and mild steel. As a cutting speed increases the temperature at the tip of the tool also increases. The comparison of the high speed steel vs mild steel is done at different cutting speed, feed rate and depth of cut. When the mild steel work piece is machined at different cutting speed and constant feed is maintained.
S.H Rathod,Mohd Razik .4 , Investigated that experimental measurement of temperature in machining process at slow, medium and high cutting speeds. The main factors which are responsible for increasing the temperature are cutting speed (v) ,feed rate(f),and depth of cut(d) respectively. Here the cutting tool materials are high speed steel and carbide tip tool.
O O. Awopetu, O A. Dahunsi.5, Developed that different cutting tools which are used to turning ?-titanium alloy Bt5 materials are tungsten carbide and cemented carbide. They have longer life with titanium alloy than the steel cutting tungsten-titanium carbide. The material titanium BT5 contains 95% titanium and 5% aluminum by composition. Finally it is turned at 60m/min in a semi-finished operation.
Dr.venkatesh babu.6, suggested that the single point cutting tool wear analysis in cnc turning center is determined. Tool failure occurs when continuous using of cutting tool without time interval. The types of tool wears occurred are nose wear, flank wear and crater wear. Here the cutting tool material used for turning are TNMG 160404 FV CU25 and for finish boring turning TNMG 160404 CQ CA5525.proper coolant supply should be increased from 0.75 to 1.25.the different coatings are also in use to reduce tool wear. Tool wear also reduces productivity rate.
Ananth sidagam.7, Investigated that by varying the rake angle of single point cutting tool the life of the tool increases. The geometry of the cutting tool consists of a five different angles they are side rake angle back rake angle, relief angle, end cutting edge angle & side cutting edge angle respectively. Here the material of the cutting tool used is high speed steel and carbides. The effect of various parameters like cutting speed, feed, and depth of cut occurs during the machining process. Finally concluded that tool life increases by using different rake angles.
Akilesh pratap singh.8, In his research, the effect of rake angles on tool life is studied. He describes a review of basic terms & major components of the cutting tool geometry and lubrication techniques in machining process. The parameters like rake angle, depth of cut, feed rate, cutting speed, temperature, coolant, places an important role on effect of tool life and surface roughness. The different types of rake angles are positive, negative and zero respectively. Finally conclude that rake angle of 200 gives the longest tool life and surface finish
Anil A.chavan,P V Deshmukh.9, Investigated that coatings to the cutting tools improves the performance in machining operation. The different types of coatings used are TiAlSiN and TiAlN which reduces the tool wear and surface roughness. Comparison of tool life at different cutting speeds is also determined.
Roop sandeep Bammidi, Prathyusha.10, In his research he mainly focused on cutting tool geometry, materials and their properties, working conditions and effect on different parameters like feed rate, cutting speed and depth of cut during the machining operation. This paper also includes the designing of single point turning tool under variable commercial angles and analysis of it. The maximum stress is considered as the optimal angle because maximum stress obtained at low cross-sectional area of tool. The cutting speed, feed rate and depth of cut have maximum influence on life of cutting tool during the machining operation.
By studying the above literature reviews the following results are concluded……
Coated tools perform better than uncoated tools and increase a tool life and overall efficiency.
By maintaining the cutting parameters like cutting speed, feed rate, depth of cut respectively there may be chance to improve the service life of tool.
By varying the side rake angles and back rake angles the sharpness of the tool increases. Thus increases the life of the tool.
In order to increase the efficiency and life span of the of cutting tool, material with proper composition is selected.
It is noted that the cutting speed increases tool life decreases.
Changing the cutting edge angles (more than 150) the life of the tool gets increases.
The radius of the nose will also effect on cutting tool life.
In day-by-day modern technology the material alloys are improving.
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