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Lecture 1

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... on the operation, depth of cut, cutting speed, tool material, surface finish ... Refers to devices used to cut or deform the metal. ... – PowerPoint PPT presentation

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Title: Lecture 1


1
Lecture 1 2Processes Tooling
  • Overview to Computer Aided Manufacturing -
    ENGR-2963 - Fall 2008
  • Class Manager - Sam Chiappone

2
Featured Processes For This Class
  • Milling
  • Turning
  • Drilling

3
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.

4
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

5
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

6
Related Operations
  • Thread milling - milling treads using the
    capability of a three axis contouring CNC
    machine.

7
Operating Parameters
  • Rpm
  • CS converted into Rpm based on cutter diameter
  • Feed rate
  • Feed per tooth
  • Table feed rate

8
Operating Parameters
  • Feed direction -- Conventional vs. Climb
  • Conventional milling
  • Most common method of feed
  • Feed work against the rotation of the cutter

9
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!

10
Operating Parameters
  • Conventional vs. Climb Milling

11
Operating Parameters
  • Depth of cut
  • Horsepower

12
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

13
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

14
Machines
Conventional
Computer Numerical Control
15
Milling Machines
16
Milling Machines
17
Milling Machines
18
CNC Machines
  • CNC
  • Horizontal, Vertical,and Planner (up to 5 axis)

19
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

20
Process Accuracy
  • /- .0005 - Optimum situation
  • /- .001-.002 - Typical
  • /- .001 - Flatness

21
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

22
Milling Cutters
23
Workholding Devices for CNC Milling Machines
  • Vise
  • Chucks
  • Special fixtures
  • Modular fixturing systems
  • Clamp work to table

24
Workholding Devices
25
Turning
  • Turning is the process of machining external
    cylindrical and conical surfaces. The process
    uses a machine tool called a lathe.

26
Turning Processes
  • Turning typically involves roughing procedures
    followed by a finishing operation.

27
Turning Operations
  • Turning operations performed on a lathe include
  • Straight turning
  • Taper turning
  • End facing
  • Facing

28
Turning Operations
  • Shoulder Facing
  • Contour Turing
  • Grooving
  • Form turning
  • Parting-off

29
Turning Operations
  • Threading
  • Internal / External
  • Knurling
  • Drilling
  • Reaming
  • Milling-CNC turning centers

30
Process Calculations
  • Rpm calculation
  • RPM
  • CS

31
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)

32
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

33
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

34
Other Types of Lathes
  • Tracer
  • Hydraulic attachment used to copy the shape of a
    part from a master.

35
Types of Lathes
1
2
36
Types of Lathes
Combination Conventional / CNC
37
Cutting Tools for Lathes
  • External
  • Right hand turning
  • Left hand turning
  • Round nose turning
  • Cut-off
  • Left hand facing

38
Cutting tools for Lathes
  • External (cont)
  • Broad nose finishing
  • Right hand facing
  • Threading
  • Form
  • Internal
  • Boring
  • Threading
  • Grooving
  • Form

39
Typical Carbide Insert Holder
40
Workholding on a Lathe
  • Between centers
  • Live-tailstock
  • Dead-headstock
  • Face plate
  • Drive dog

41
Workholding on a Lathe
  • Chuck
  • 3,4, or 6 jaw
  • Soft jaws

42
Workholding on a Lathe
  • Collect system

43
Workholding on a Lathe
  • Others
  • Face driver system
  • Sub-spindle system

44
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

45
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

46
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.

47
Process Parameters
  • Cutting speed
  • Rpm
  • Feed (in/rev ---- in/min) (Rpm x in/rev)

48
Process Parameters
49
Drill Variations
50
Reamers
51
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.

52
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

53
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.)

54
Drill Presses
  • CNC Turret (Conventional)
  • 2 axis motion
  • Computer controlled
  • Series of operations
  • Turret indexes to different tools
  • Individual speeds / feeds

55
Tool Holding Devices
  • Drill chucks
  • Key type or keyless
  • Drill Sleeves
  • Collet

56
Lecture 2 Tooling Tools
  • Overview to Computer Aided Manufacturing -
    ENGR-2963 - Fall 2008
  • Class Manager - Sam Chiappone

57
Process Basics
  • Components
  • Speed Feed Calculations
  • Carbide Insert Specifications

58
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.

59
Process Basics
  • Tooling
  • Refers to holding devices
  • Examples include- vises, fixtures, jigs...etc.

60
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

61
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.

62
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.

63
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.

64
Metal Removal Problem
1.
Cutting Tools
4.
2.
3.
65
Metal Removal Problem
66
Factors Effecting Calculations
  • Set-up conditions
  • Machine conditions
  • Tooling conditions
  • Material conditions
  • Cutting fluid

67
Tool Selection Process
68
Tool Materials
  • Wide variety of materials and compositions are
    available to choose from when selecting a cutting
    tool

69
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.

70
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.

71
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.

72
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.

73
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
74
Carbide Inset Selection
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