The document discusses tool wear, tool life, and machinability. It defines tool life as the useful cutting time before tool failure or need for resharpening. Tool wear is measured by flank wear and crater wear, and causes include attrition, diffusion, abrasion, and plastic deformation. Machinability is assessed based on surface finish, tool life, cutting forces, and chip control difficulty. Factors like material properties, cutting conditions, tool geometry, and lubrication affect tool wear and machinability.
Unit 2 Machinability, Cutting Fluids, Tool Life & Wear, Tool MaterialsMechbytes
Concept of machinability, machinability index, factors affecting machinability
Different mechanism of tool wear types of tool wear (crater, flank etc.), Measurement and control of tool wear
Concept of tool life, Taylor's tool life equation (including modified version)
Different tool materials and their applications including effect of tool coating
Introduction to economics of machining
Cutting fluids: types, properties, selection and application methods
This presentation contains various aspects of metal cutting like mechanics of chip formation, single point cutting tool, chip breakers, types of chips,etc
Unit 2 Machinability, Cutting Fluids, Tool Life & Wear, Tool MaterialsMechbytes
Concept of machinability, machinability index, factors affecting machinability
Different mechanism of tool wear types of tool wear (crater, flank etc.), Measurement and control of tool wear
Concept of tool life, Taylor's tool life equation (including modified version)
Different tool materials and their applications including effect of tool coating
Introduction to economics of machining
Cutting fluids: types, properties, selection and application methods
This presentation contains various aspects of metal cutting like mechanics of chip formation, single point cutting tool, chip breakers, types of chips,etc
Sheet metal characteristics – shearing, bending and drawing operations – Stretch forming operations – Formability of sheet metal – Test methods –special forming processes-Working principle and applications – Hydro forming – Rubber pad forming – Metal spinning– Introduction of Explosive forming, magnetic pulse forming, peen forming, Super plastic forming – Micro forming.
Sheet metal characteristics – shearing, bending and drawing operations – Stretch forming operations – Formability of sheet metal – Test methods –special forming processes-Working principle and applications – Hydro forming – Rubber pad forming – Metal spinning– Introduction of Explosive forming, magnetic pulse forming, peen forming, Super plastic forming – Micro forming.
The operation research book that involves all units including the lpp problems, integer programming problem, queuing theory, simulation Monte Carlo and more is covered in this digital material.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
2. Tool Life
Useful cutting life of tool expressed in time
Time period measured from start of cut to failure
of the tool
Time period b/w two consecutive resharpenings
or replacements.
3. Ways of measuring tool life
No. of pieces of work machined
Total volume of material removed
Total length of cut.
Limiting value of surface finish
Increase in cutting forces
Dimensional accuracy
Overheating and fuming
Presence of chatter
4. Modes of tool failure
1. Temperature failure
a. Plastic deformation of CE due to high temp
b. Cracking at the CE due to thermal stresses.
2. Rupture of the tool point
a. Chipping of tool edge due to mechanical impact
b. Crumbling of CE due to BUE
3. Gradual wear at tool point
a. Flank wear
b. Crater wear
5. Tool wear
Tool wear causes the tool to lose its original
shape- ineffective cutting
Tool needs to be resharpened
7. Attrition wear
At low cutting speeds
Flow of material past cutting edge is irregular and
less stream lined
BUE formed and discontinuous contact with the
tool
Fragments of tool are torn from the tool surface
intermittently
High
Slow and interrupted cutting
Presence of vibrations
Found in carbide tools at low cutting speeds
8. Diffusion wear
Diffusion of metal & carbon atoms from the tool
surface into the w/p & chip.
Due to
High temp
High pressure
Rapid flow of chip & w/p past the tool
Diffusion rate depends on the metallurgical
relationship
Significant in carbide tools.
9. Abrasive wear
Due to
Presence of hard materials in w/p material.
Strain hardening induced in the chip & w/p due to
plastic deformation.
Contributes to flank wear
Effect can be reduced by fine grain size of the
tool & lower percentage of cobalt
10. Electrochemical wear
When ions are passed b/w tool & w/p
Oxidation of the tool surface
Break down of tool material @ chip tool interface
15. Flank Wear
Tool slides over the surface of the work piece and
friction is developed
Due to Friction and abrasion.
Adhesion b/w work piece & tool- BUE
Starts at CE and starts widening along the
clearance face
Independent of cutting conditions and tool / work
piece materials
Brittle and discontinuous chip
Increases as speed is increased.
16. Primary stage rapid
wear due to very high
stress at tool point
Wear rate is more or
less linear in the
secondary stage
Tertiary stage wear
rate increases rapidly
resulting in
catastrophic failure.
17. Crater wear
Direct contact of tool and w/p
Forms cavity
Ductile materials – continuous chips
Initiates rapid rupture near to nose
Leads to
weakening of the tool
Increase in cutting temp
Cutting forces & friction
18. Measurement of tool life
Time for Total destruction in case of HSS or time to
produce 0.75 mm wear for carbide tools
Tool life expressed by Taylor’s eqn
VTb = C
V = cutting speed in cm/min
T= tool life in min
b= const= 0.1 for HSS
C= 50 for HSS
Cemeted carbide : b=0.125, C=100
Tool life expressed in volume of metal removed
L = TVfd
19. Measurement of tool life
Diamond indentor technique
Radioactive techniques
Test at elevated cutting speeds
Facing tests
Test with low wear criterion
20. Factors affecting tool life
1. Cutting speed
2. Physical properties of w/p
3. Area of cut
4. Ratio of feed to depth of cut
5. Shape and angles of tool
6. Tool material and its heat treatment
7. Nature and quantity of coolants
8. Rigidity of tool and wp
21. Machinability
Machinability is defined in terms of:
1. Surface finish and surface integrity
2. Tool life
3. Force and power required
4. The level of difficulty in chip control
Good machinability indicates good surface finish and
surface integrity, a long tool life, and low force and power
requirements
Machinability ratings (indexes) are available for each type
of material and its condition
22. Factors affecting machinability of
metals
1. Material of w/p- hardness, tensile properties,
strain hardenability
2. Tool material.
3. Size and shape of the tool.
4. Type of machining operation.
5. Size, shape and velocity of cut.
6. Type and quality of machine used
7. Quality of lubricant used in machining
8. Friction b/w chip & tool
9. Shearing strength of w/p material
23. Evaluation of machinability- factors
Tool life
Form and size of chip and shear angle.
Cutting forces and power consumption
Surface finish
Cutting temperature
MRR per tool grind
Rate of cutting under standard force
Dimensional accuracy
24. Evaluation of machinability
Machinability decreases with increase in tensile
strength and hardness
Machinability of a material is assessed by any of
the following.
Tool life
Limiting MRR at which the material can be
machined for standard short tool life.
Cutting force
Surface finish
Chip shape
25. Relative machinability
Mg alloys
Bearing bronze
Al alloys
Zn alloys
Free cutting sheet brass
Gun metal
Silicon bronze, Mn bronze
S.G Cast iron
Malleable cast iron
Gray CI
Free cutting steel
Sulphur bearing steel
Cu-Al alloys
Low carbon steels
Nickel
Low alloy steels
Wrought iron
HSS
18-8 SS
Monel
White CI
Stellite
26. Machinability index
Machinability index= Vt/Vs x100
Vt – cutting speed of metal for 1 min tool life
Vs – cutting speed of standard free cutting steel
for 1 min tool life.
Material MI
SS 25
Low carbon steel 55-65
Cu 70
Red brass 180
Al alloys 300-1500
Mg alloys 500-2000
27. Machinability:
Machinability of Ferrous Metals
Steels
If a carbon steel is too ductile, chip formation can produce built-up
edge, leading to poor surface finish
If too hard, it can cause abrasive wear of the tool because of the
presence of carbides in the steel
In leaded steels, a high percentage of lead solidifies at the tips of
manganese sulfide inclusions
Calcium-deoxidized steels contain oxide flakes of calcium
silicates (CaSO) that reduce the strength of the secondary shear
zone and decrease tool–chip interface friction and wear
28. Machinability:
Machinability of Ferrous Metals
Effects of Various Elements in Steels
Presence of aluminum and silicon is harmful, as it combine with
oxygen to form aluminum oxide and silicates, which are hard and
abrasive
Thus tool wear increases and machinability reduce
Stainless Steels
Austenitic (300 series) steels are difficult to machine
Ferritic stainless steels (also 300 series) have good machinability
Martensitic (400 series) steels are abrasive
29. Machinability:
Machinability of Nonferrous Metals
Aluminum is very easy to machine
Beryllium requires machining in a controlled environment
Cobalt-based alloys require sharp, abrasion-resistant tool
materials and low feeds and speeds
Copper can be difficult to machine because of builtup edge
formation
Magnesium is very easy to machine, with good surface finish and
prolonged tool life
Titanium and its alloys have very poor thermal conductivity
Tungsten is brittle, strong, and very abrasive
30. Cutting fluids
Decreasing power requirement
Increasing heat dissipation
Neat oils+ extreme pressure additives
Water emulsions