Anna University - Mechanical Engineering - Abstract notes (not so detailed)
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FOUNDRAY, FORMING AND WELDING
METAL CUTTING AND MACHINE TOOLSFull description
FOUNDRAY, FORMING AND WELDINGFull description
FOUNDRAY, FORMING AND WELDING
FOUNDRAY, FORMING AND WELDING
A summary and comparison of various traditional and non-traditional machining processes for manufacturing aerospace components
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ME 2252 – MANUFACTURING TECHNOLOGY – II II year Mechanical Engg. B-Sec Notes on Lesson
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UNIT – I : THEORY OF METAL CUTTING
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Material removal process
Types of machine tools Turning machines
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Drilling machines
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Boring machines
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Milling machines
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Grinding machines
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Shaping and planing machines
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Gear cutting machines
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Unconventional machining machines
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Special machines like automats, copy turning machines, reaming ,
Provides movement of the spindle in three directions
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Several holes can be drilled on a work piece without moving the same.
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UNIT-IV : ABRASIVE PROCESS, SAWING, BROACHING AND GEAR CUTTING Grinding wheel – specification and selection
Aluminium oxide
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Silicon carbide
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Cubic boron carbide
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Diamond
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Abrasive types
Fine
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Medium
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Coarse
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Vitrified
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Silicate
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Synthetic resin Rubber
Shellac
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Bond
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Grain size
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Metal
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Soft
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Medium
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Hard
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Grade
Structure •
Open
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Medium
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Dense
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Grinding wheel types
Wheel balancing
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Dressing and truing
Cylindrical grinding
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Surface grinding
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Centreless grinding
The main parts are
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Cylindrical Grinding Machine
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Types of grinding machines
Base
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Tables – lower and upper table
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Head stock
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Tail stock
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Wheel head
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Surface grinding machine
Horizontal spindle and reciprocating table
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Vertical spindle and reciprocating table
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Horizontal spindle and rotating table
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Vertical spindle and rotating table
Centreless grinding machine The main parts are •
Grinding wheel
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Regulating wheel
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Types of feed in centreless grinding Infeed
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Through feed
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End feed
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Honing
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Honing is a low abrading process which uses bonded abrasive sticks for removing stock from metallic and non-metallic surfaces. The advantages of honing are
Out of roundness
Taper
Axial distortion
Dimensional accuracy
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Correction of geometrical accuracy
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Lapping
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Lapping is generally the final finishing operation done with loose abrasive grains. The process is employed to get
Extreme accuracy of dimension
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Correction of minor imperfection of shape
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Refinement of the surface finish
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Close fit between mating surfaces
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Super finishing
Super finishing is another abrasive process which utilizes either a bonded
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abrasive like honing for cylindrical surfaces or a cup wheel for flat surfaces. It is generally used for •
Removing surface fragmentation
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Reducing surface stresses and burns and thus restoring surface integrity
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Correcting inequalities in geometry 13
Polishing and Buffing Polishing is done with a very fine abrasive in loose form smeared on the
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polishing wheel with the work rubbing against the flexible wheel. A very small amount of material is removed in polishing. In buffing the abrasive grains in a suitable carrying medium such as grease are applied at suitable intervals to the
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buffing wheel. Negligible amount of material is removed in buffing while a very high luster is generated on the buffed surface. The dimensional accuracy of the parts is not affected by polishing and buffing operations.
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Abrasive belt grinding
In this process a continuous moving belt with an abrasive is used for grinding the
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surfaces. The abrasive belt is normally passed between two wheels with one being driven while the other remains idle. The workpiece is oscillated across the
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face of the abrasive belt to obtain a uniform belt wear and surface finish. Sawing machines
The various types of sawing machines used are
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Hack saw •
Manual
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Power
Band saw
Vertical
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Horizontal
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Contour
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Circular saw
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Broaching Broaching is a multiple tooth cutting operation with the tool reciprocating similar to the sawing operations. The similarities end there, since in broaching the
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machining operation is completed in a single stroke as the teeth on the cutting tool called broach, are at a gradually increasing height corresponding to the feed
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per tooth of a milling cutter.
Broaching machines Push broaching machines
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Pull broaching machines
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Surface broaching machines
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Continuous surface broaching machines
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Gear cutting
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Gear shaping
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Gear hobbing
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Gear forming Vs Gear generation
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UNIT-V : CNC MACHINE TOOLS AND PART PROGRAMMING Numerical Control (N.C) It can be defined as a programmable automation in which the process is
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controlled by numbers, letters and symbols. Components of N.C
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o Program of instructions o Machine control unit
N.C. Procedure o Process planning
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o Part programming
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o Machine tool
o Tape preparation o Tape verification
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o Production Components Of CNC A tape reader
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Micro or mini computer
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Computer hardware interface and servo mechanism
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Machine tool
Advantages
Greater flexibility
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High productivity
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Good reliability
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Metric conversions
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Memory functions
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Feed function
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Speed function
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Tool function
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Preparatory functions
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Miscellaneous functions
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Program number
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Tool length compensation
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Cutter radius compensation
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Canned cycles
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Coordinate function
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Manual part programming
Computer assisted part programming
Preparing the part programs for CNC machine tools manually is a viable system for any kind of job. But the assistance of a computer is desirable for part
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programming because of a variety of reasons. The first and foremost in this respect is the complexity of the work piece which makes manufal part programming a very difficult exercise. Close tolerance contouring to some
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mathematically defined, or through a set of points other than a circular arc, is an example requiring too many coordinate calculations making manual part programming too tedious to be practicable.
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APT language
The complete APT part program consists of the following four types of