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Advanced Manufacturing Choices

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Title: PowerPoint Presentation Author: Marc Madou Last modified by: Marc Madou Created Date: 3/30/2010 10:09:37 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Advanced Manufacturing Choices


1
Advanced Manufacturing Choices
  • ENG 165-265
  • Spring 2014, Dr. Marc Madou
  • Class 2

2
Table of Content
  • Manufacturing types Primary, secondary and
    tertiary manufacturing
  • Mechanical machining definition
  • Recognized categories of mechanical machining
    turning, milling, drilling and grinding.
  • CNC machining
  • Precision machining
  • Ultraprecision and nanotechnology
  • Desk top factory (DTF)

3
Manufacturing Types
  • Manufacturing dominates world trade. It is the
    main wealth creating activity of all
    industrialized nations and many developing
    nations. A manufacturing industry based on
    advanced technologies with the capability of
    competing in world markets can ensure a higher
    standard of living for an industrial nation
    (McKeown, 1996).
  • Where primary manufacturing processes involve
    casting and molding, secondary manufacturing
    processes constitute the main mechanical removing
    techniques involving turning, drilling and
    milling. Abrasive processes to super-finish a
    work-piece are called tertiary manufacturing
    processes. Casting/molding The act or process
    of making casts or impressions, or of shaping
    metal or plaster in a mold the act or the
    process of pouring molten metal into a mold.

4
Manufacturing Types
  • The difference between casting and molding is
    that in "traditional" casting processes, the mold
    is destroyed/ consumed when removing the
    work-piece from it while in molding, the mold is
    re-used multiple times(this difference is not
    often respected in naming different processes).
  • Lost wax casting process see video
  • Sand casting see utube

5
Mechanical Machining
  • In mechanical removal processes, stresses induced
    by a tool overcome the strength of the material.
  • The process produces complex 3D shapes, with very
    good dimensional control, and good surface
    finishes.
  • The method is wasteful of material, and expensive
    in terms of labor and capital.
  • How well a part made from a given material holds
    its shape with time and stress is referred to as
    the dimensional stability of the part and the
    material.

6
Mechanical Machining
  • To maximize dimensional stability, the machine
    design engineer tries to minimize the ratios of
    applied and residual stress to yield strength of
    the material.
  • A good rule of thumb is to keep the static stress
    below 10 to 20 of yield strength.
  • Increased heat at the work-piece causes uneven
    dimensional changes in the part being machined,
    making it difficult to control its dimensional
    accuracy and tolerances. Thermal errors are often
    the dominant type of error in a precision
    machine, and thermal characteristics such as
    thermal expansion coefficient and thermal
    conductivity deserve special attention .

7
Mechanical Machining
  • In mechanical subtractive machining, physical
    removal of unwanted material is achieved by
    mechanical energy applied at the work piece.
  • Mechanical material removing technologies are
    also categorized as single point machining or
    abrasive machining i.e., multi-point machining.
  • Mechanical removal processes can be broken down
    into four commonly recognized categories
    turning, milling, drilling and grinding.

First lathe as depicted in an Egyptian bas
relief about 300 B.C. Shown here in a line
drawing. The man at left is holding the cutting
tool. The man at the right is making the
workpiece rotate back and forth by pulling on a
cord or thong.
8
Mechanical Energy Based Removing
  • What is milling? The use of a rotating
    multi-point cutting tool to machine flat
    surfaces, slots, or internal recesses into a
    work-piece.
  • Milling is one of the more versatile machining
    processes. There are three degrees of freedom
    associated with milling. The tool can move up and
    down, left to right, and front to back. In this
    process the tool spins while the part remains
    stationary. Although milling is a more versatile
    process than turning or grinding, it is not as
    accurate and tends to leave a rougher surface
    finish than the other two processes.
  • What is turning ? Turning is the machining
    operation that produces cylindrical parts. In its
    basic form, it can be defined as the machining of
    an external surface with the work-piece rotating
    and with a single-point cutting tool.

9
Mechanical Energy Based Removing
  • The main difference between turning and milling
    is that in turning the work-piece spins while the
    tool remains stationary. Because of this, turning
    can be used to create a great surface finish on
    cylindrical parts.
  • Turning is done on a machine called a lathe. The
    lathe spins the workpiece, while the lathe
    operator can position the tool to remove the
    material. The work-piece is held in the chucks of
    the lathe.

10
Mechanical Energy Based Removing
  • Drilling can be defined as a rotary end cutting
    tool having one or more cutting lips, and having
    one or more helical or straight flutes for the
    passage of chips and the admission of a cutting
    fluid.

11
Mechanical Energy Based Removing
  • Grinding is a finishing process that is used to
    remove surplus material from the work-piece
    surface. It is usually used on almost any
    surface that has been previously rough machined
    and is among the most expensive process for it is
    generally quite slow in removing material.

12
Mechanical Energy Based Removing
  • By 1977, highly precise instruments such as
    servomotors, feedback devices, and computers were
    implemented, paving the way for computer
    numerical control machining, commonly called CNC
    machining, which is now standard in many types of
    machine shops. At the start, the smallest
    movement these machines could reproducibly make
    was 0.5 µm.
  • The resolution of the steps a machine can make,
    of course, is a determining factor for the
    manufacturing accuracy of the work-piece.
  • Numerical control is a method of automatically
    operating a manufacturing machine based on a
    code of letters, numbers, and special characters.

13
Mechanical Energy Based Removing
  • Point-to-point control systems cause the tool to
    move to a point on the part and execute an
    operation at that point only. The tool is not in
    continuous contact with the part while it is
    moving.
  • Continuous-path controllers cause the tool to
    maintain continuous contact with the part as the
    tool cuts a contour shape.

14
Mechanical Energy Based Removing
  • These continuous operations include milling along
    any lines at any angle, milling arcs and lathe
    turning.

15
Mechanical Energy Based Removing
  • CNC milling machines can perform simultaneous
    linear motion along the three axis and are called
    three-axes machines.
  • More complex CNC machines have the capability of
    executing additional rotary motions (4th and 5th
    axes).

16
Mechanical Energy Based Removing
  • Machining Centers, equipped with automatic tool
    changers, are capable of changing 90 or more
    tools. Can perform milling, drilling,boring
    turning, on many faces. Boring is the process
    of using a single-point tool to enlarge a
    preexisting hole.
  • Process flow
  • Develop or obtain the 3D geometric model of the
    part, using CAD.
  • Decide which machining operations and cutter-path
    directions are required (computer assisted).
  • Choose the tooling required (computer assisted).
  • Run CAM software to generate the CNC part
    program.
  • Verify and edit program.
  • Download the part program to the appropriate
    machine.
  • Verify the program on the actual machine and edit
    if necessary.Run the program and produce the
    part.

17
Mechanical Energy Based Removing
  • In an integrated CAD/CAM system, the geometry and
    tool motions are derived automatically from the
    CAD database by the NC program (Pro/E,
    Unigraphics, .)

CNC milling is a cutting process in which
material is removed from a block of material by
a rotating tool using a computer numerically
controlled program or code to achieve a desired
tool path to machine very accurate parts
precisely and efficiently. 
18
Precision Machining
  • Mechanical engineers define precision machining
    as machining in which the relative accuracy
    (tolerance/object size) is 104 or less of a
    feature/part size
  • For comparison, a relative accuracy of 103 in
    the construction of a house is considered
    excellent. It is important to realize that, while
    IC techniques and silicon micro- and
    nano-machining can achieve excellent absolute
    tolerances, relative tolerances here are rather
    poor compared to those achieved by most
    mechanical machining techniques.
  • The decrease in manufacturing accuracy with
    decreasing size is rarely mentioned in
    discussions of Si micro-machines this probably
    is because Si micromachining originated from
    electrical engineering practice rather than
    mechanical engineering.

19
Precision Machining
  • In the 1980s advanced machine tools became
    equipped with precision metrology and control
    tools. These machines used laser interferometer
    and capacitance probe feedback controls,
    temperature control and hydrostatic bearings, and
    featured accuracies better than 0.1 micrometers.
    Precision manufacturing methods were extended for
    industrial use for cutting aluminum, which was
    used for making components for scanners,
    photocopying machines and computer memory disks.
    Also in the 1980s, cutting with very small
    diamond tools (e.g., 22 µm diameter) was
    developed in Japan.

20
Ultra Precision Machining-Nanotechnology
  • Taniguchi coined the term nanotechnology and in
    1974, used the term to define ultra-precision
    machining.
  • Taniguchi defines ultra-precision machining as
    the process by which the highest possible
    dimensional accuracy is achieved at a given point
    in time.
  • Norio Taniguchi predicted accuracies along with
    the processes or tools used to achieve it (next
    page)

Norio Taniguchi (????) (27 May 1912 - 15 November
1999) was a professor of Tokyo Science
University.
21

Precision and ultra-precision machining
22
Ultra Precision Machining-Nanotechnology
  • By 1993, 0.05 µm became possible, and today there
    is equipment available featuring 0.01 µm and even
    nanometer step resolution 10 (http//www.fanuc.co.
    jp/eindex.htm).
  • This evolution closely follows the predictions
    sketched in the Taniguchi curves showing a
    machining accuracy for ultra-precision machining
    of sub-nanometer resolution for the year 2008
    (see previous slide) .
  • Fanucs the ROBOnano Ui an ultra-precision
    micromachining station (cost 1 million) and a
    Noh mask made with this machine
    (http//www.fanuc.co.jp/en/product/robonano/index.
    htm).

23
Desk top factory
  • The fact that it often takes a two-ton machine
    tool to fabricate micro parts, where cutting
    forces are in the milli- to micro-Newton range is
    a clear indication that a complete machine tool
    redesign is required for the fabrication of
    micro-machines.
  • One approach is the desk-top factory.

24
Desk top factory
  • Desktop factories (DTF) constitute a rather
    interesting new manufacturing philosophy
    involving flexible and modular table-top-sized
    automated factories that feature minimal human
    participation in the manufacturing process.
  • An example of such a factory is shown below.
    Since the early nineties progress has been made
    towards making such desktop factories (DTF) a
    reality. A desktop factory as shown here has the
    potential of becoming the factory of the future
    a totally self-contained, robotic, desktop-size
    machine tool that only requires materials, power
    and water as outside inputs, and out come the
    finished machined products. The first RD desktop
    factories incorporated lathes, cleaning, gluing,
    punching and drilling stations. The workpiece is
    transported between these different machining
    functions by a cart moving from station to
    station.

25
Desk top factory
  • An example of a desktop factory at AIST, Japan.
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