Lecture 1

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Lecture 1 2Processes Tooling

• Overview to Computer Aided Manufacturing -
  ENGR-2963 - Fall 2008
• Class Manager - Sam Chiappone

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Featured Processes For This Class

• Milling
• Turning
• Drilling

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Milling Processes

• Milling is one of the basic machining processes.
  Milling is a very versatile process capable of
  producing simple two dimensional flat shapes to
  complex three dimensional interlaced surface
  configurations.

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The Process

• The milling process
• Typically uses a multi-tooth cutter
• Work is fed into the rotating cutter
• Capable of high MRR
• Well suited for mass production applications
• Cutting tools for this process are called milling
  cutters

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Classifications

• Milling operations are classified into two major
  categories
• Peripheral (side)
• Generally in a plane parallel to the axis of the
  cutter
• Cross section of the milled surface corresponds
  to the contour of the cutter
• Face
• Generally at right angles to the axis of rotation
  of the cutter
• Milled surface is flat and has no relationship to
  the contour of the cutter
• Combined cutting action of the side and face of
  the milling cutter

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Related Operations

• Thread milling - milling treads using the
  capability of a three axis contouring CNC
  machine.

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Operating Parameters

• Rpm
• CS converted into Rpm based on cutter diameter
• Feed rate
• Feed per tooth
• Table feed rate

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Operating Parameters

• Feed direction -- Conventional vs. Climb
• Conventional milling
• Most common method of feed
• Feed work against the rotation of the cutter

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Operating Parameters

• Feed direction - Conventional vs. Climb
• Climb milling
• Load of the cutter tends to pull the work into
  the cutter
• This results in a small feed force and about 20
  less Hp than conventional milling
• Downward motion increases the load on the table
  ways
• This method can pull the work into the cutter
  and scrap the work and/or damage the fixture and
  tool.
• Machine must be very ridged to safely utilize
  climb milling(CNC machines)
• USE CAUTION!

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Operating Parameters

• Conventional vs. Climb Milling

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Operating Parameters

• Depth of cut
• Horsepower

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Milling machines

• Two Major Classifications - Knee Column and Bed
• Knee Column (Bridgeport type)
• Basic job shop type mill
• Column mounted to the base which is the major
  support frame.
• Construction provides controlled motion of the
  worktable in three mutual perpendicular
  directions.
• Knee moves vertically on the ways in the front of
  the machine
• Table moves longitudinally on the ways on the
  saddle
• Saddle moves transversely on the ways on the knee
• Quill moves parallel in Z axis or, if head is
  rotated, X axis
• Versatile general purpose machine

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Milling Machines

• Bed
• Used extensively in production milling operations
• Rigid construction capable of heavy cuts
• Table is mounted directly to the bed
• Spindle head moves vertically to set depth of cut
• Head locks into position for cut
• Base of machine functions as a coolant reservoir

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Machines
Conventional
Computer Numerical Control
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Milling Machines
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Milling Machines
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Milling Machines
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CNC Machines

• CNC
• Horizontal, Vertical,and Planner (up to 5 axis)

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Process Accuracy

• Accuracy of milling machines
• Factors to consider
• Fixture
• Rigidity of machine tool
• Accuracy of the spindle
• Cutter condition
• Coolant
• Type
• Delivery method
• Material condition

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Process Accuracy

• /- .0005 - Optimum situation
• /- .001-.002 - Typical
• /- .001 - Flatness

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Milling Cutters Holding Systems

• Cutter Types
• 2 to 4 Lip Cutters
• Face Mills
• Ball End Mills
• Collect Holding Systems
• Direct Mount Holders
• Face Mill Holders

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Milling Cutters
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Workholding Devices for CNC Milling Machines

• Vise
• Chucks
• Special fixtures
• Modular fixturing systems
• Clamp work to table

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Workholding Devices
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Turning

• Turning is the process of machining external
  cylindrical and conical surfaces. The process
  uses a machine tool called a lathe.

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Turning Processes

• Turning typically involves roughing procedures
  followed by a finishing operation.

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Turning Operations

• Turning operations performed on a lathe include
• Straight turning
• Taper turning
• End facing
• Facing

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Turning Operations

• Shoulder Facing
• Contour Turing
• Grooving
• Form turning
• Parting-off

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Turning Operations

• Threading
• Internal / External
• Knurling
• Drilling
• Reaming
• Milling-CNC turning centers

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Process Calculations

• Rpm calculation
• RPM
• CS

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Process Calculations

• Feed is typically a given distance per
  revolution. This value is dependent on the
  operation, depth of cut, cutting speed, tool
  material, surface finish----etc. Units are---
  in. per rev (in./rev)

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Machine Classification

• Size designation
• Swing - maximum diameter that can be rotated on
  the lathe
• 2xs distance from spindle center line to ways
• Maximum distance between centers

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Conventional and CNC Lathes

• Engine
• Most frequently used lathe
• Heavy duty
• Power drive for most tool movements
• Size range 12x24 to 24x48 - can be larger
• CNC
• Computer controlled
• Wide variety of process capability
• Multiple axis
• Indexing and contouring head
• On- line and off- line programming available

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Other Types of Lathes

• Tracer
• Hydraulic attachment used to copy the shape of a
  part from a master.

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Types of Lathes
1
2
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Types of Lathes
Combination Conventional / CNC
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Cutting Tools for Lathes

• External
• Right hand turning
• Left hand turning
• Round nose turning
• Cut-off
• Left hand facing

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Cutting tools for Lathes

• External (cont)
• Broad nose finishing
• Right hand facing
• Threading
• Form
• Internal
• Boring
• Threading
• Grooving
• Form

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Typical Carbide Insert Holder
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Workholding on a Lathe

• Between centers
• Live-tailstock
• Dead-headstock
• Face plate
• Drive dog

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Workholding on a Lathe

• Chuck
• 3,4, or 6 jaw
• Soft jaws

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Workholding on a Lathe

• Collect system

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Workholding on a Lathe

• Others
• Face driver system
• Sub-spindle system

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Drilling Related Hole Making Processes

• Basic hole making processes account for
  approximately 50-70 of all the metal removal
  processes utilized today.
• Holes
• Casting
• Sand, die, molding
• Punching
• Machining,
• Drilling, milling, EDM, AWJ, etc.
• Burning

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Processes

• Standard hole making processes include
• Drilling - Drilling is the process of producing
  or enlarging a hole. This is accomplished by
  rotating the tool and/or workpiece.
• Reaming - Enlarging an existing hole with a
  multi-edged tool (reamer) for dimensional
  accuracy and/or surface finish
• Spot facing - Smoothing, squaring, and/or
  flattening a surface

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Processes

• Counter sinking - operation or producing a
  tapered feature at the end of a hole. Most
  popular application is a feature for a flathead
  screw (82 degrees) to sit flush with a surface.
• Counter boring - Enlarging of an existing hole at
  one end. This enlarged hole is concentric with
  the existing hole and is flat at the bottom. One
  application of this process is a feature to set
  the head of a bolt below a surface.

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Process Parameters

• Cutting speed
• Rpm
• Feed (in/rev ---- in/min) (Rpm x in/rev)

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Process Parameters
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Drill Variations
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Reamers
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Machine Tools

• Machine tools used in this process include drill
  presses, lathes, milling machines, and special
  purpose machines. One of the most popular is the
  drill press.

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Drill Presses

• Upright Drill Press
• Larger than the sensitive
• Can be equipped with a gearbox and variable speed
  head
• Hand and automatic feed mechanism
• Automatic coolant system
• Table can move on a rack and pinion system

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Drill Presses

• Gang Drilling Machine
• Equipped with more than one spindle
• Multi-head arrangement
• Single table
• Used for production set-up
• Multiple operations at one location (drill, ream,
  tap, csink, cborte etc.)

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Drill Presses

• CNC Turret (Conventional)
• 2 axis motion
• Computer controlled
• Series of operations
• Turret indexes to different tools
• Individual speeds / feeds

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Tool Holding Devices

• Drill chucks
• Key type or keyless
• Drill Sleeves
• Collet

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Lecture 2 Tooling Tools

• Overview to Computer Aided Manufacturing -
  ENGR-2963 - Fall 2008
• Class Manager - Sam Chiappone

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Process Basics

• Components
• Speed Feed Calculations
• Carbide Insert Specifications

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Process Basics

• Tools
• Refers to devices used to cut or deform the
  metal.
• Cutting tools - examples include end mills,
  carbide inserts, drills, grinding wheels, shell
  mills, etc.

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Process Basics

• Tooling
• Refers to holding devices
• Examples include- vises, fixtures, jigs...etc.

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Process Basics

• Cutting fluid
• Act as a coolant and lubricant
• Reduce friction between chip and tool face
• Extend tool life
• Help to remove chips from cutting area

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Metal Removal RelatedCalculations

• To efficiently use these components, different
  input parameters have to be calculated. They
  include
• RPM of cutter
• Milling or drilling operation Rpm for cutter
• Turning operation Rpm for part
• Basically the rotating component
• Feed
• The distance in inches, feet, or millimeters per
  minute that the work advances into the cutter.

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Metal Removal RelatedCalculations

• Input parameters (cont)
• Cutting speed(CS)-the surface feet per minute or
  meters per minute, at which a metal can be
  machined efficiently. This variable has a direct
  relationship to the diameter of the cutter, in a
  milling or drilling operation, or the diameter of
  the work piece in a lathe operation.
• Example - When machining(using a milling machine)
  a medium grade steel, the cutter must achieve a
  surface speed of about 90 ft/min. The diameter
  of the cutter will have a direct relationship to
  the rpm calculation.

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Metal Removal RelatedCalculations

• Input parameters (cont)
• Depth of cut - Amount of material being removed.
• Horsepower required for cut
• Material removal rate (MRR) - volume of material
  being removed per unit of time
• In a milling operation, you also have to take
  into account the thickness of the chip each tooth
  will remover per revolution as it advances into
  the work. This value is expressed in feed per
  tooth.

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Metal Removal Problem
1.
Cutting Tools
4.
2.
3.
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Metal Removal Problem
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Factors Effecting Calculations

• Set-up conditions
• Machine conditions
• Tooling conditions
• Material conditions
• Cutting fluid

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Tool Selection Process
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Tool Materials

• Wide variety of materials and compositions are
  available to choose from when selecting a cutting
  tool

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Tool Materials

• They include
• Tool steels - low end of scale. Used to make
  some drills, taps, reamers, etc. Low cost equals
  low tool life.
• High speed steel(HSS) - can withstand cutting
  temperatures up to 1100F. Have improved hardness
  and wear resistance, used to manufacture drills,
  reamers, single point tool bits, milling cutters,
  etc. HSS cutting tools can be purchased with
  additional coatings such as TiN which add
  additional protection against wear.

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Tool Materials

• Cobalt - one step above HSS, cutting speeds are
  generally 25 higher.
• Carbides - Most widely used cutting tool today.
  Cutting speeds are three to five times faster
  than HSS. Basic composition is tungsten carbide
  with a cobalt binder. Today a wide variety of
  chemical compositions are available to meet
  different applications. In addition to tool
  composition, coatings are added to tool materials
  to incerase resistance to wear.

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Tool Materials

• Ceramics - Contain pure aluminum oxide and can
  cut at two to three times faster than carbides.
  Ceramic tools have poor thermal and shock
  resistance and are not recommended for
  interrupted cuts. Caution should be taken when
  selecting these tools for cutting aluminum,
  titanium, or other materials that may react with
  aluminum oxide.

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Tool Materials

• Cubic Boron Nitride(CBN) - This tool material
  maintains its hardness and resistance to wear at
  elevated temperatures and has a low chemical
  reactivity to the chip/tool interface. Typically
  used to machine hard aerospace materials.
  Cutting speeds and metal removal rates are up to
  five times faster than carbide.
• Industrial Diamonds - diamonds are used to
  produce smooth surface finishes such as mirrored
  surfaces. Can also be used in hard turning
  operations to eliminate finish grinding
  processes. Diamond machining is performed at
  high speeds and generally fine feeds. Is used to
  machine a variety of metals.

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Carbide Inset Selection
M1-Fine M2-Medium M3-S.S M4-Cast iron M5-General
Purpose
A.N.S.I. Insert Identification System ANSI -
B212.4-1986
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Carbide Inset Selection