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Process design-analysis - Coggle Diagram

- - - - states that the average number of things in the system is the product of the average rate at which things leave the system and the average time each one spends in the system
  - - - restricts the concept of work content to only those tasks that are literally adding value to whatever is being processed, which often eliminates activities such as movement, delays and some inspections
- - - - Variability in the demand for processing at an individual stage within the process – usually expressed in terms of variation in the inter-arrival times of items to be processed
      - Variation in the time taken to perform the activities
- - - - this makes the adjustments that allow the operation to achieve the objectives that the plan has set, even when the assumptions on which the plan was based do not hold true
  - - - This is the amount of work that is allocated to a work centre
      - Finite and infinite loading
        
        FL = allocates work to a work Centre (a person, a machine, or perhaps a group of people or machines) only up a set limit
        
        IL = loading work that does not limit accepting work but instead tries to cope with it
    - - decisions must be taken on the order in which the work will be tackled
      - Types of priorities are
        
        Physical constraints
        
        Customer priority
        
        Due date
        
        Last in, first out
        
        First in, first out
        
        Longest operation time
      - Sequencing performance objectives
        
        Meeting due dates promised to the customer (dependability)
        
        Minimising the job spent in the process, also known as flow time (speed)
        
        Minimising work-in-progress inventory (an element of cost)
        
        Minimising idle time to work centres (another element of cost)
    - - detailed timetable showing at what time data jobs should start and when they should end
      - Complexity
        
        schedulers must deal with several different types of resource stimulation (equipment will have different capabilities and capacities, and staff will have different skills)
        
        Number of possible schedules = (n!)m
        
        n = number of jobs and m = number of machines
      - Forward and backward scheduling
        
        FS = starting work as soon as it arrives
        
        BS = involves starting jobs at the last possible moment, to prevent them from being late
        
        Advantages of FS
        
        High-labor utilization (workers always start work to keep busy)
        
        Flexible (the time slack in the system allows unexpected work to be loaded)
        
        Advantages of BS
        
        Lower material costs (materials are not used until they have to be, therefore delaying added value until the last moment)
        
        Less exposed to risk in case of a schedule change by the customer
        
        Tends to focus the operation on customer due dates
      - Gnatt charts
        
        a simple device that represents time as a bar, or channel, on a chart
        
        Advantages of GC
        
        provide a simple visual representation, of both what should be happening and what actually happens in the operation
        
        can be used to assess alternative schedules
      - Scheduling work patterns
        
        main task of scheduling is to make sure that sufficient numbers of people are working at any point in time to provide a capacity appropriate for the level of demand at that point in time (staff rostering)
        
        This enables:
        
        Capacity to meet demand
        
        The length of each shift is neither excessively long nor too short to be attractive to staff
        
        Working at unsocial hours is minimized
        
        Days off match agreed staff conditions (e.g., staff prefer two consecutive days off every week)
        
        Vacations and other time-off blocks are accommodated
        
        Sufficient flexibility is built into the schedule to cover unexpected changes in supply and demand
    - - After creating a plan for the operation through loading, sequencing, and scheduling, each part of the process has to be monitored to ensure that planned activities are indeed happening
      - Push and Pull control
        
        Push = activities are scheduled by means of a central system and completed in line with the central instructions
        
        Pull = the pace and specification of what is done are set by the customer workstation, which pulls work from the preceding (supplier) workstation
      - Drum, Buffer, Rope Approach
        
        D = the bottleneck in the process should be the control point of the full process. Therefore, this is called the drum because it sets the beat for the rest of the process to follow
        
        B = Because it does not have sufficient capacity, a bottleneck is (or should be) working all the time. Therefore, it is sensible to keep a buffer of inventory in front of it, to make sure that it always has something to work on
        
        R = All they would do is produce work that would accumulate further along in the process, up to the point where the bottleneck is constraining the flow. Therefore, some form of communication between the bottleneck and the input to the process is needed to make sure that activities before the bottleneck do not overproduce
      - Enterprise Resource Planning
        
        automates and integrates core business processes such as customer demand, scheduling operations, ordering items, keeping inventory records, and updating financial data
        
        This consists of:
        
        Marketing and sales
        
        Field service
        
        Product design and development
        
        Production and inventory control
        
        Procurement
        
        Development
        
        Manufacturing
        
        Quality
        
        Human resources
        
        Finance and Accounting
        
        Information services