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Manufacturing Systems Modeling, Analysis and Design IME 452 IME 545 Modeling and Analysis of Manufac

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Modeling and Analysis of Manufacturing Systems. Amy Thompson. Instructor. 7/30/09 ... There are six people going to a drive through window of a McDonald (i.e., N = 6) ... – PowerPoint PPT presentation

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Title: Manufacturing Systems Modeling, Analysis and Design IME 452 IME 545 Modeling and Analysis of Manufac


1
Manufacturing SystemsModeling, Analysis and
DesignIME 452 / IME 545Modeling and Analysis
of Manufacturing Systems
Amy Thompson Instructor
2
Chapter 1 Manufacturing Models
  • The anatomy of manufacturing operations
  • Product design
  • Process planning
  • Tools and fixtures
  • Operating conditions, ...
  • Production planning
  • What type of process
  • Facility layout
  • Material flow
  • Production scheduling
  • Operations
  • Production monitoring and control
  • Quality control, ...
  • Role of information
  • Drives the interrelated functions
  • Measures compliance to corporate objectives

3
Chapter 1 Manufacturing Models
  • Manufacturing Classifications
  • Discrete parts or continuous processing
  • Manufacturing Operations
  • Fabrication or Assembly
  • Manufacturing process and manufacturing system
  • manufacturing process deals with machinery such
    as stamping press, CNC machining center,
    injection molding machine,
  • manufacturing system it is an integration of
    various machinery with material handling,
    network, control, ...
  • Manufacturing process and manufacturing system is
    often inseparable today.

4
Chapter 1 Manufacturing Models
  • A step back from the level of individual
    processing, in this course, we will focus on
    manufacturing systems how to make them
  • better (more reliable)
  • faster (more efficient)
  • cheaper (more cost-effective)

5
Types of Manufacturing Systems According to
Factory Layout
  • Product (production line)
  • Process (job shop)

materials
product
materials
products
6
Types of Manufacturing Systems According to
Layout Group/Cell
Machines
Material handling system
7
Group Technology History
  • In 1925, R.E. Flanders use product oriented
    departments to make standardized products
  • In 1937, A.P. Sokolovski parts with similar
    features manufactured together
  • In 1960s J.L. Burbidge developed a systematic
    approach based upon these concepts
  • Complete History see Snead (1989)
  • Currently evolved into small focused factories

8
Group Technology
  • Group Technology is a Management Theory
  • The basic principle of GT
  • many problems are similar, and that by grouping
    similar problems, a single solution can be found
    to a set of problems and thus saving time and
    effort

9
Group Technology on theManufacturing Floor
  • Cellular Manufacturing
  • Divide manufacturing facility into small cells
    that manufacture a specified set of part types
  • Cells usually contain no more than 5 machines,
    but can have only one or two machines
  • Configuring machines with different capabilities
    into a cohesive group is an alternative to
    process layout
  • Larger groups departments with many cells
  • Lessons to be gained from GT for all
    manufacturing Small is beautiful?

10
Group vs. Other Organization
  • Group vs. process for medium-volume,
    medium-variety products
  • If volumes large, pure item flow line
  • If volumes are small and only slight similarities
    exist, then less gained by grouping
  • Method for gaining advantages of flow line in
    shops previously organized by process
  • GT can be used for
  • Design whenever possible, new parts should be
    designed to be compatible with the processes and
    tooling of an existing part family
  • GT is an attempt to standardize products and
    process plans.
  • Items with similar geometric features should have
    similar designs
  • SKU reductions, partial SKUs

11
Group vs. Other Organization
  • Setup time reduction is an important benefit of
    cellular manufacturing on the shop floor
  • Work center produce similar products with similar
    features which allows development of generic
    fixtures and tools.
  • Tools can be stored locally, reducing retrieval
    time.
  • Some machines can be loaded with all the tools
    for all the products in the families, so tool
    change is only required due to wear, not
    production changes.
  • The same universal fixture can be designed to
    hold any part in the family by simple adjustment
    to the fixture.
  • Reduced setup time allows for smaller batches to
    be produced, which significantly reduces WIP,
    thus throughput time.
  • Lower setup time and lower WIP inventory, smaller
    batch sizes allow products to be made JIT. This
    in turn, reduces finished product inventory.
  • Less floor space, less inventory cost, shorter
    lead times.

12
Group vs. Other Organization
  • Management Orientation Changes
  • Process-based department
  • In a process based department, the blueprint and
    written specifications are the target, and the
    focus of work is placed directly on the part
    being made.
  • Customers are rarely consulted
  • The final use of the part is rarely understood,
    there are too many different types of parts going
    through the area to understand the purpose or
    problems of each type.
  • Cellular-based department
  • Focused product type means smaller group of
    suppliers, producers, and customers.
  • Communication can be verbal and personal.
  • More common for customers to visit supply cell
    group and better understand requirements.

13
Group Technologyon the Manufacturing Floor
  • For manufacturing systems, the basic steps of GT
    include
  • Coding assigning a symbolic or a numerical
    description to the parts based upon product
    characteristics
  • Classification (group formation) use the part
    code and other information to assign parts to
    families based upon similarities
  • Layout group machines to produce the parts with
    best efficiency. (Assign families to groups.)
    Part routings must be known.

14
Characteristics of Successful Groups
  • Size is important. Group must be small enough to
    act as a close-knit structure good
    communication, good cooperation. Social
    scientists have determined that groups of 6 to 12
    best, 7 being optimal.
  • Level long-run utilization between groups to
    match production plans. What major/typical
    problems could this cause?
  • Consider safety when combining operations into a
    cell.
  • Layout machines in cell to minimize material
    movement.
  • Physically separate cells within a facility with
    an input and output buffer. (Establish
    independence/autonomy.)
  • Reside group tooling locally.
  • All documents and drawings reside locally.
  • Organize business around groups.
  • Workers must be empowered.
  • Independent profit center.

15
Introduction to a Flexible Manufacturing System
(FMS)
  • The definition of the FMS
  • Flexible Manufacturing System (FMS) refers to a
    set of computer numerically controlled (CNC)
    machine tools and supporting workstations that
    are connected by an automated material handling
    system and are controlled by a central computer.

16
  • A sample of flexible manufacturing systems

Parts loading and unloading
Machines
Material handling system
17
Introduction to a Flexible Manufacturing System
(FMS)
  • The basic components of FMS
  • Machines
  • they are the backbone of the FMS
  • various machines can be used, such as vertical
    and horizontal machining centers
  • machines must be programmable
  • Supporting workstations
  • they are used for loading, unloading, storage and
    inspection (such as gages and Coordinate
    Measurement Machine (CMM))
  • Part transportation system
  • it is used to transport the parts between
    workstations
  • commonly used transportation devices include
    conveyors, tow cars, rail cars, and AGV
    (automated guided vehicle)
  • System controller
  • it is a computer that controls the entire system

18
Introduction to a Flexible Manufacturing System
(FMS)
Plant
Shop 2
Shop 1
  • Control in FMS
  • Five-level control hierarchy
  • plant
  • shop
  • cell
  • workstation
  • equipment

Cell 2
Cell 1
Cell 3
Station 2
Station 1
Station 3
Robot
Machine
I/O
19
Introduction to a Flexible Manufacturing System
(FMS)
  • Problems to be solved
  • System design problems
  • Is FMS beneficial?
  • Capacity of the FMS
  • Hardware machining centers, tool changers,
    pallet and pallet loaders, cutting tools,
    fixtures, and etc.
  • Software computer language, communication
    protocol,
  • System setup problems
  • Part selection
  • which parts are to be made by the FMS
  • which part shall be made by which machine
  • Tooling assignment
  • Machine setup and operation sequencing
  • Task assignment
  • Operation sequencing

20
Chapter 1 Manufacturing ModelsCharacteristics
of Mfg. Systems
21
Chapter 1 Manufacturing Models
  • Application examples (production line)
  • Product layout shops automobile assembly line
  • Process layout shops tool and die shop
  • Applications can also be found in our daily life
  • Product shop McDonalds
  • Process shops Make-to-order restaurant.
  • New McDonalds stores change to a Process Shop,
    Why?
  • Different manufacturing systems require different
    ways to organize and to run.

22
Chapter 1 Manufacturing Models
  • Production planning
  • What type of process
  • Facility layout
  • Material flow
  • Production scheduling
  • Actual production planning and control process
    takes market demand, production capacity, and
    inventory levels to determine quantities of
    product families to make over different time
    spans. This plan is then disaggregated to
    schedule machines, jobs and resources on a daily
    basis.
  • Designing systems for optimal performance, given
    a production plan, versus learning process of
    production scheduling.

23
Chapter 1 Manufacturing Models
  • Modeling Assumptions in this Text Minimize
    complexity
  • Assume product design and process plans are known
  • An information system is assumed to exist
  • All data is reliable and no inconsistencies exist
  • Why are these assumptions not always true in
    reality?

24
Chapter 1 Manufacturing Models
  • Assume Product Design/Process Plans Exist
  • Product Design Levels of Available Data
  • 3D CAD model with all information available to
    user
  • 3D CAD model available, but designer must access
  • CAM program available, but no other details
  • 2D representational model (orthographic drawing)
  • Written summary of critical design criteria
  • Jigs or tool available
  • No information available. When would this occur?
  • Process Routing/Planning Levels of Data
  • Complete description of processes, equipment, and
    parameters
  • Complete BOM and routing information
  • Routing complexity (alternate routes, FMS, etc.)

25
Chapter 1 Manufacturing Models
  • Data gathering
  • Does the data exist that you need?
  • Where or who has the data?
  • If the data doesnt exist, how do you get it and
    what issues are involved?
  • Type of data available depends upon traditional
    use
  • Aggregated/averaged data
  • What if you cant get the data, what do you do,
    what are the issues?
  • Ignore the data. How important is the data to the
    model outcome?
  • Sensitivity Analysis.
  • What industries are most likely to have the data
    you need?

26
Chapter 1 Manufacturing Models
  • Model components
  • Objectives
  • Efficiency versus effectiveness
  • 7 types of waste (Suzaki, 1987)
  • Waste from overproduction, Waste of waiting time,
    Transportation waste, Processing waste, Inventory
    waste, Waste of motion, Waste from product
    defects
  • Meet customer satisfaction in a profitable
    manner. Think globally.
  • An efficient modeler builds a model that finds an
    optimal solution.
  • An effective modeler builds a model that is used
    to understand the important factors in the system
    and uses it to find a very good/improved solution
    to a real system or an important problem.
  • Not much value in finding optimal solutions to
    trivial sub-problems which ignore system
    interactions on a higher level.

27
Chapter 1 Manufacturing Models
  • Inputs and Outputs to a Production Activity (from
    A. Thompson, Unattended and Lights-Out
    Manufacturing, 2003 adapted and modified from S.
    Nakajima, Introduction to TPM, 1988)

28
Chapter 1 Manufacturing Models
  • Objects in building manufacturing system models
  • Physical Objects
  • Materials
  • Resources (Human, Machine, Tool, Energy)
  • Organizational Objects
  • Tasks
  • Production and Process Plans
  • Events point in time when a resource starts or
    completes a task

29
Chapter 1 Manufacturing Models
  • Model Types
  • In order to understand and then better control
    complicated manufacturing systems, we need models
  • The types of models
  • Physical models prototype, 2D or 3D
  • Mathematical models
  • Set of mathematical or logical relationships
  • Use parameters to define process and system
  • Use decision variables
  • Descriptive models
  • Simulation
  • Prescriptive models
  • Linear Programming
  • Heuristics
  • Analytical and experimental
  • Computer simulation

30
Chapter 1 Manufacturing Models
  • Model Uses
  • insight understanding
  • prediction
  • justification
  • optimization
  • control

31
Chapter 1 Manufacturing Models
  • Model building Process
  • The model building process
  • define the problem
  • define the objectives
  • define the decision variables
  • define the solving method
  • objective functions
  • constraints
  • verification and validation
  • Verification and validation criteria
  • structure
  • operation conditions
  • behavior

32
Chapter 1 Manufacturing Models
  • Most models in the real world (and discussed in
    the class) are simple and straightforward.
  • An example job assignment
  • The job costs data
  • The objective find the minimum cost assignment

33
Chapter 1 Manufacturing Models
  • The decision variables machine assignments
  • The solving method
  • A heuristic starting from job 1, find the
    machine with minimum cost and assign it.
  • Evaluation the total cost is 36
  • Question
  • Is there a better assignment?
  • Is there a systematic method by which we can find
    the best assignment?

34
Chapter 1 Manufacturing Models
  • Summary in this course, we will focus on
  • modeling
  • model solving
  • model evaluating
  • Problems
  • Facility layout
  • Material flow systems
  • Process planning
  • Machine setup
  • Operation optimization
  • Scheduling

35
Chapter 1 Principles of Mfg. Systems
  • The first law (Littles law)
  • the formula
  • work_in_process production rate ? throughput
    time
  • an illustration
  • Interpolation the production rate is X, the
    number of part in process in the system is N,
    then the total processing time is
  • T N(1/X) or NXT, and (1/X) is the arrival
    rate to the system.
  • Implication if the production rate is fixed,
    then merely putting more parts into the system
    will only increase throughput time

36
Chapter 1 Principles of Manufacturing Systems
  • An example
  • There are six people going to a drive through
    window of a McDonald (i.e., N 6)
  • The service rate of the clerk is 2
    minutes/customer (X 2)
  • Therefore, the total processing time is (6)(2)
    12.
  • Note that at any give time, there is only one
    customer being served while the other five are
    waiting (assuming they have to leave all
    together).
  • Implications
  • If someone else joins the group the waiting will
    be longer
  • Increase the service rate or add another service
    window can reduce the waiting time

37
Chapter 1 Principles of Manufacturing Systems
  • The second law matter is conserved.
  • The formula material in material out storage
    (disposal)
  • A stable system cannot have storage accumulation.
    In other words, input materials shall equal to
    the output materials. The storage includes
    scraps, chips, wastes, and etc., which must be
    cleared out as well
  • Examples
  • Your garage
  • Just-In-Time Manufacturing (i.e., zero inventory
    manufacturing) in Toyota.

38
Chapter 1 Principles of Manufacturing Systems
  • The third law the larger the system, the less
    reliable it becomes
  • The formula suppose the system has N components
    connected in series and the availability of
    component i is ri, then the system availability
    is
  • An example there are 5 machines connected in
    series, each has an availability (i.e., the
    reliability in operating) of 0.9, then, the
    system availability is (0.9)5 0.59.
  • Solutions of the problem
  • Buffer
  • Parallel system

39
Chapter 1 Principles of Manufacturing Systems
  • The fourth law objects decay
  • The causes of failures
  • wear
  • fatigue
  • Corrosion, etc.
  • Implications conditions may change and
    maintenance is necessary

40
Chapter 1 Principles of Manufacturing Systems
  • The fifth law exponential growth in complexity
  • The formula if a system has N components and
    each component has M states, then the system will
    have NM states in total.
  • Implication consider six components with four
    states 4096 possible system states
  • Limit the number of system components and
  • Limit states of these components

41
Chapter 1 Principles of Manufacturing Systems
  • The sixth law technology advances
  • Implication continuous improvement
  • The seventh law system components may behave
    randomly
  • Implication 1 we may only find the expected
    value
  • Implication 2 be prepared for unusual events

42
Chapter 1 Principles of Manufacturing Systems
  • The eighth law limits of human rationality
  • Human limits
  • Linear thinking concerning a single task at a
    time
  • Short term memory is limited to seven items
  • Difficult to view more than 3D
  • Implication simplify the design, the process and
    the system

43
Chapter 1 Principles of Manufacturing Systems
  • The ninth law combining, simplifying, and
    eliminating tasks will save time, money, and
    energy
  • Note that this is the founding principle of
    scientific management
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