Scheduling Terminology

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					Course Part 3

           Various Topics




11/15/04     SJSU Bus. 140 - David Bentley   1
    Course Organization
   Part 3
       Scheduling
       Project Management
       Product and Service Design
       Process Selection and Layout
       Design of Work Systems
       Facility location


04/13/05            SJSU Bus. 140 - David Bentley   2
Chapter 15 - Scheduling

       Terminology, lead time, priority
         rules, theory of constraints
         (discussed in Capacity),
           volume considerations

Rev. 11/04/04    SJSU Bus. 140 - David Bentley   3
  Volume considerations
      High volume (repetitive, cont. flow)
           Flow-shop scheduling (rate based)
      Intermediate volume (job/repetitive)
           Mixed model scheduling
      Low volume (job)
           Operation scheduling (forward/backward/
            midpoint)
           Synchronized scheduling

Rev. 11/15/01        SJSU Bus. 140 - David Bentley   4
Low Volume Scheduling

           Job Shops




11/12/03   SJSU Bus. 140 - David Bentley   5
  Elements of Lead Time
      Queue – job waiting to be worked on (jobs
       with higher priority are ahead)
      Setup – Making the machine or workplace
       ready to work on a job
      Run – performing the required action to
       complete an operation on a job
      Wait – awaiting a move to the next
       operation / work center or the stockroom
      Move (transit) – time moving to next
       operation / work center or stockroom
Rev. 09/06/01     SJSU Bus. 140 - David Bentley    6
   Lead time elements


    Queue         Setup        Run Wait Move
|----------------|--------|------------|------|-----|




 11/11/02         SJSU Bus. 140 - David Bentley    7
  Scheduling Terminology
      Operation – a discrete step or task, one of a
       number required to make an item
      Workstation – a specific machine or
       employee work space
      Work center – a machine grouping or work
       grouping used for scheduling and costing
      Routing – a sequenced list of operations,
       with associated work centers
      Job – an order to produce a specific quantity
       of an item with a specific start and/or due
       date
Rev.11/11/02       SJSU Bus. 140 - David Bentley   8
    Sequence of operations

   Q     S    R W M
|-----|----|------|---|---| Q S         R     W M
        Seq 010           |-----|----|-------|---|---|
                                  Seq 020



  Rev. 05/04/05    SJSU Bus. 140 - David Bentley    9
  Loading and Scheduling
      Loading – assigning jobs to work centers
      Infinite vs. finite loading and scheduling
           Infinite – ignored capacity constraints
           Finite – considers capacity constraints
      Forward vs. backward scheduling (+midpt)
           Forward – start with start date, determine due
            date
           Backward – start with due date, determine start
            date
           Midpoint – from current date, determine revised
            due date
Rev. 11/11/02           SJSU Bus. 140 - David Bentley     10
  Sequencing and Dispatching
      Sequencing – determining the sequence of
       processing jobs at a work center
      Priority rules – rules used in sequencing
       (see later overhead)
      Dispatch list – authorized sequence list
      Input-Output Analysis – monitoring the
       flow of work into and out of work centers to
       assure a steady flow and to identify problem
       areas

Rev. 11/11/02      SJSU Bus. 140 - David Bentley   11
  Sequencing & Priority Rules
      FCFS – first come, first served
      SPT – shortest processing time
      EDD – earliest due date
      CR – critical ratio
           (time remaining / processing time)
           Time remaining = (due date – “now” date)
      S/O – slack per remaining operation
      ESD – earliest start date
      Other – favorite customer, “hot” job, etc.
Rev. 11/07/05          SJSU Bus. 140 - David Bentley   12
        Charts
   Gantt – visual (bar chart) representation of
    schedule and actual performance
       Load – Gantt chart showing load and idle time
        for a machine or work center by time period
       Schedule – Gantt chart showing the progress
        of jobs by time period




    Rev. 11/12/03     SJSU Bus. 140 - David Bentley   13
  Performance Measures
     Job Flow Time
           Time at a workstation, work center, or plant
           Includes Q,S,R,W,M
     Average Flow Time (group of jobs)
           Sum of flow times for n jobs / n
     Job Lateness
           Expected due date – original due date
     Makespan (group of jobs)
           From start of first job to end of last job
     Average number of jobs (group of jobs)
           Total flow time / Makespan
Rev. 11/07/05            SJSU Bus. 140 - David Bentley     14
    Other Related Activities - 1
   Dispatching
   Expediting
       Queue compression
       Lot splitting
       Job overlapping
       “Stop what you’re doing and work on this!” BAD!!
   Synchronized scheduling
       Timing of production meshed with use rate
       Example: bakery oven


Rev. 11/12/03         SJSU Bus. 140 - David Bentley    15
  Other Related Activities - 2
      Input-Output Analysis
           Monitoring the flow of work into and out of
            work centers to assure a steady flow and
            to identify problem areas
           Reports the following:
                   Input for the period
                   Output for the period
                   Queue change


Rev. 04/17/02               SJSU Bus. 140 - David Bentley   16
High Volume Scheduling

       Repetitive and Continuous Flow




11/12/03         SJSU Bus. 140 - David Bentley   17
  Rate Based Scheduling
     Schedule by quantity per
              Month,
              Week,
              Day,
              Shift
     Limited number of items
     Seek to achieve flow

11/12/03                SJSU Bus. 140 - David Bentley   18
Intermediate Volume
Scheduling

           Bridge Between Job Shop and
               Repetitive Operations



11/12/03            SJSU Bus. 140 - David Bentley   19
  Mixed Model Scheduling
     Interspersing different models
              Alternative to producing longer runs of
               each model
     Look for:
              Lowest ratio and
              Most repetitive mix
     Bicycle example

11/12/03                 SJSU Bus. 140 - David Bentley   20
  Service Operations
     Appointment book (e.g., dentist)
     Reservations (e.g., airlines)
     Scheduling multiple resources
     Managing capacity




11/12/03        SJSU Bus. 140 - David Bentley   21

				
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