Production planning and control


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Production planning and control

  2. 2. Decision Making in POM • What to Produce  Product Planning and Development including product design • How to Produce Process Planning, Material Planning, Tool equipment Planning • Where to Produce  Facilities Planning, Capacity Planning and Sub-contracting Planning • When to Produce  Production Scheduling and machine Loading • Who will Produce  Manpower Planning • How much to Produce  Planning for quantity, economic batch size etc.
  3. 3. 3 POM - Critical Decisions 1. Managing quality 2. Design of goods and services 3. Process and capacity design 4. Layout design 5. Human resources 6. Location strategies 7. Supply-chain management 8. Inventory management 9. Scheduling 10. Maintenance
  4. 4. 4 The Critical Decisions - 1 • Quality management – Who is responsible for quality? – How do we define quality? • Goods and services design – What product or service should we offer? – How should we design these products and services?
  5. 5. 5 The Critical Decisions - 2 • Process and Capacity design – What processes will these products require and in what order? – What equipment and technology is necessary for these processes?
  6. 6. 6 The Critical Decisions - 3 • Layout design – How should we arrange the facility? – How large a facility is required? • Human resources and job design – How do we provide a reasonable work environment? – How much can we expect our employees to produce?
  7. 7. 7 The Critical Decisions - 4 • Supply chain management and JIT “Just-in- time” Inventory, Material Requirements Planning – Should we make or buy this item? – Who are our good suppliers and how many should we have? – How much inventory of each item should we have? – When do we re-order?
  8. 8. 8 The Critical Decisions - 5 • Immediate, short term, and project scheduling – Is subcontracting production a good idea? – Are we better off keeping people on the payroll during slowdowns? • Maintenance – Who is responsible for maintenance? • Location – Where should we put the facility – On what criteria should we base this location decision?
  9. 9. PRODUCTION PLANNING AND CONTROL • Once the entrepreneur has taken the decisions regarding the product design and production processes and system, his next task is to take steps for production planning and control, as this function is essentially required for efficient and economical production
  10. 10. Objectives of PPC • Optimum Utilization of Capacity • Inventory control • Economy in production time • Ensure quality • to establish routes and schedules for work An effective PPC contributes to time, quality and cost parameters of entrepreneurial success.
  11. 11. Production Planning and Control Functions • Process Planning (Routing) • Loading • Scheduling • Combining Functions • Dispatching • Reporting or Follow – up • Corrective Action • Re-planning
  12. 12. • The determination of where each operation on a component part, subassembly, or assembly is to be performed results in a route for the movement of a manufacturing lot through the factory. • Prior determination of these routes is the job of the manufacturing engineering function. Production Planning and Control Functions- Process Planning (Routing)
  13. 13. • Once the route has been established, the work required can be loaded against the selected machine or workstation. The total time required to perform the operation is computed by multiplying the unit operation times given on the standard process sheet by the number of parts to be processed. • This total time is then added to the work already planned for the workstation. • This is the function of loading, and it results in a tabulated list or chart showing the planned utilization of the machines or workstations in the plant. Production Planning and Control Functions- Loading
  14. 14. • Scheduling is the last of the planning functions. It determines when an operation is to be performed, or when work is to be completed; the difference lies in the detail of the scheduling procedure. • In a centralized control situation - where all process planning, loading, and scheduling for the plant are done in a central office- the details of the schedule may specify the starting and finishing time for an operation. • On the other hand, the central schedule may simply give a completion time for the work in a given department. Production Planning and Control Functions- Scheduling
  15. 15. • While it is easy to define “where” as process planning, “how much work” as loading, and “when as scheduling, in actual operations these three functions are often combined and performed concurrently. • How far in advance routes, loads, and schedules should be established always presents an interesting problem. Obviously, it is desirable that a minimum of changes be made after schedules are established. • This objective can be approached if the amount of work scheduled for the factory or department is equal to or slightly greater than the manufacturing cycle. • For optimum control, it should never be less than the manufacturing cycle. Production Planning and Control Functions- Combining Functions
  16. 16. Production Planning and Control Functions- Dispatching • Authorizing the start of an operation on the shop floor is the function of dispatching. • This function may be centralized or decentralized. • Again using our machine-shop example, the departmental dispatcher would authorize the start of each of the three machine operations – three dispatch actions based on the foreman’s routing and scheduling of the work through his department. This is decentralized dispatching.
  17. 17. • The manufacturing activity of a plant is said to be “in control” when the actual performance is within the objectives of the planned performance. • When jobs are started and completed on schedule, there should be very little, if any, concern about the meeting of commitments. • Optimum operation of the plant, however, is attained only if the original plan has been carefully prepared to utilize the manufacturing facilities fully and effectively. Production Planning and Control Functions- Reporting or Follow – up
  18. 18. • This is the keystone of any production planning and control activity. • A plant in which all manufacturing activity runs on schedule in all probability is not being scheduled to its optimum productive capacity. • With an optimum schedule, manufacturing delays are the rule, not the exception. Production Planning and Control Functions- Corrective Action
  19. 19. • Re-planning is not corrective action. • Re-planning revise routes, loads, and schedules; a new plan is developed. • In manufacturing this is often required. Changes in market conditions, manufacturing methods, or many other factors affecting the plant will often indicate that a new manufacturing plan is needed. Production Planning and Control Functions- Re-planning
  20. 20. Factors Affecting Production Planning and Control • Type of Product • Type of Manufacturing
  21. 21. Production Planning Functions • Estimating • Routing • Scheduling • Loading Production Control Functions •Dispatching •Expediting/Follow –up/Progressing
  22. 22. Role of PPC in Different Types of Manufacturing • Mass Production • Batch Production • Job Production
  23. 23. 23 Process Types - Products Project Job Batch Mass Continuous Volume VarietyLowHigh Low High
  24. 24. Production planning • Production planning may be defined as the technique of foreseeing every step in a long series of separate operations, each step to be taken at the right time and in the right place and each operation to be performed in maximum efficiency. It helps entrepreneur to work out the quantity of material manpower, machine and money requires for producing predetermined level of output in given period of time.
  25. 25. Routing • Under this, the operations, their path and sequence are established. To perform these operations the proper class of machines and personnel required are also worked out. The main aim of routing is to determine the best and cheapest sequence of operations and to ensure that this sequence is strictly followed.
  26. 26. Routing procedure • An analysis of the article to determine what to make and what to buy. • To determine the quality and type of material • Determining the manufacturing operations and their sequence. • A determination of lot sizes • Determination of scrap factors • An analysis of cost of the article • Organization of production control forms.
  27. 27. Scheduling • It means working out of time that should be required to perform each operation and also the time necessary to perform the entire series as routed, making allowances for all factors concerned. It mainly concerns with time element and priorities of a job.
  28. 28. Production schedule It takes into account following factors. • Physical plant facilities of the type required to process the material being scheduled. • Personnel who possess the desired skills and experience to operate the equipment and perform the type of work involved. • Necessary materials and purchased parts.
  29. 29. Master Schedule • Scheduling usually starts with preparation of master schedule which is weekly or monthly break-down of the production requirement for each product for a definite time period, by having this as a running record of total production requirements the entrepreneur is in better position to shift the production from one product to another as per the changed production requirements.
  30. 30. Manufacturing schedule • It is prepared on the basis of type of manufacturing process involved. It is very useful where single or few products are manufactured repeatedly at regular intervals. Thus it would show the required quality of each product and sequence in which the same to be operated
  31. 31. Scheduling of Job order manufacturing • Scheduling acquires greater importance in job order manufacturing. This will enable the speedy execution of job at each center point. • As far as small scale industry is concerned scheduling is of utmost importance as it brings out efficiency in the operations and reduces cost price. The small entrepreneur should maintain four types of schedules to have a close scrutiny of all stages namely an enquiry schedule, a production schedule, a shop schedule and an arrears schedule out of above four, a shop schedule is the most important most suited to the needs of small scale industry as it enables a foreman to see at a glance. • The total load on any section • The operational sequence • The stage, which any job has reached.
  32. 32. Loading The next step is the execution of the schedule plan as per the route chalked out it includes the assignment of the work to the operators at their machines or work places. So loading determines who will do the work as routing determines where and scheduling determines when it shall be done. Gantt Charts are most commonly used in small industries in order to determine the existing load and also to foresee how fast a job can be done. The usefulness of their technique lies in the fact that they compare what has been done and what ought to have been done.
  33. 33. Production control • Production control is the process of planning production in advance of operations, establishing the extract route of each individual item part or assembly, setting, starting and finishing for each important item, assembly or the finishing production and releasing the necessary orders as well as initiating the necessary follow-up to have the smooth function of the enterprise.
  34. 34. Dispatching Dispatching involves issue of production orders for starting the operations. Necessary authority and conformation is given for: 1. Movement of materials to different workstations. 2. Movement of tools and fixtures necessary for each operation. 3. Beginning of work on each operation. 4. Recording of time and cost involved in each operation. 5. Movement of work from one operation to another in accordance with the route sheet. 6. Inspecting or supervision of work
  35. 35. Dispatching is an important step as it translates production plans into production.
  36. 36. Follow up • Every production program involves determination of the progress of work, removing bottlenecks in the flow of work and ensuring that the productive operations are taking place in accordance with the plans. • It spots delays or deviations from the production plans. It helps to reveal detects in routing and scheduling, misunderstanding of orders and instruction, under loading or overloading of work etc.
  37. 37. Inspection • This is mainly to ensure the quality of goods. It can be required as effective agency of production control.
  38. 38. Corrective measures • Corrective action may involve any of those activities of adjusting the route, rescheduling of work changing the workloads, repairs and maintenance of machinery or equipment, control over inventories of the cause of deviation is the poor performance of the employees. Certain personnel decisions like training, transfer, demotion etc. may have to be taken.
  39. 39. Operations Scheduling
  40. 40. Work Center Defined • A work center is an area in a business in which productive resources are organized and work is completed • Can be a single machine, a group of machines, or an area where a particular type of work is done
  41. 41. Capacity and Scheduling • Infinite loading (Example: MRP) • Finite loading • Forward scheduling • Backward scheduling (Example: MRP)
  42. 42. Types of Manufacturing Scheduling Processes and Scheduling Approaches Continuous process Type of Process Typical Scheduling Approach High-volume manufacturing Med-volume manufacturing Low-volume manufacturing Finite forward of process, machine limited Finite forward of line, machined limited Infinite forward of process, labor and machined limited Infinite forward of jobs, labor and some machine limited
  43. 43. Typical Scheduling and Control Functions • Allocating orders, equipment, and personnel • Determining the sequence of order performance • Initiating performance of the scheduled work • Shop-floor control
  44. 44. Work-Center Scheduling Objectives • Meet due dates • Minimize lead time • Minimize setup time or cost • Minimize work-in-process inventory • Maximize machine utilization
  45. 45. Priority Rules for Job Sequencing 1. First-come, first-served (FCFS) 2. Shortest operating time (SOT) 3. Earliest due date first (DDate) 4. Slack time remaining (STR) first 5. Slack time remaining per operation (STR/OP)
  46. 46. Example of Job Sequencing: First-Come First- Served Jobs (in order Processing Due Date Flow Time of arrival) Time (days) (days hence) (days) A 4 5 4 B 7 10 11 C 3 6 14 D 1 4 15 Answer: FCFS Schedule Jobs (in order Processing Due Date of arrival) Time (days) (days hence) A 4 5 B 7 10 C 3 6 D 1 4 Suppose you have the four jobs to the right arrive for processing on one machine What is the FCFS schedule? No, Jobs B, C, and D are going to be late Do all the jobs get done on time?
  47. 47. Example of Job Sequencing: Shortest Operating Time Jobs (in order Processing Due Date of arrival) Time (days) (days hence) A 4 5 B 7 10 C 3 6 D 1 4 Answer: Shortest Operating Time Schedule Jobs (in order Processing Due Date Flow Time of arrival) Time (days) (days hence) (days) D 1 4 1 C 3 6 4 A 4 5 8 B 7 10 15 Suppose you have the four jobs to the right arrive for processing on one machine What is the SOT schedule? No, Jobs A and B are going to be late Do all the jobs get done on time?
  48. 48. Example of Job Sequencing: Earliest Due Date First Jobs (in order Processing Due Date of arrival) Time (days) (days hence) A 4 5 B 7 10 C 3 6 D 1 4 Answer: Earliest Due Date First Jobs (in order Processing Due Date Flow Time of arrival) Time (days) (days hence) (days) D 1 4 1 A 4 5 5 C 3 6 8 B 7 10 15 Suppose you have the four jobs to the right arrive for processing on one machine What is the earliest due date first schedule? No, Jobs C and B are going to be late Do all the jobs get done on time?
  49. 49. Example of Job Sequencing: Critical Ratio Method Jobs (in order Processing Due Date of arrival) Time (days) (days hence) A 4 5 B 7 10 C 3 6 D 1 4 Suppose you have the four jobs to the right arrive for processing on one machine What is the CR schedule? No, but since there is three- way tie, only the first job or two will be on time In order to do this schedule the CR’s have be calculated for each job. If we let today be Day 1 and allow a total of 15 days to do the work. The resulting CR’s and order schedule are: CR(A)=(5-4)/15=0.06 (Do this job last) CR(B)=(10-7)/15=0.20 (Do this job first, tied with C and D) CR(C)=(6-3)/15=0.20 (Do this job first, tied with B and D) CR(D)=(4-1)/15=0.20 (Do this job first, tied with B and C) Do all the jobs get done on time?
  50. 50. Example of Job Sequencing: Last-Come First-Served Jobs (in order Processing Due Date of arrival) Time (days) (days hence) A 4 5 B 7 10 C 3 6 D 1 4 Answer: Last-Come First-Served Schedule Jobs (in order Processing Due Date Flow Time of arrival) Time (days) (days hence) (days) D 1 4 1 C 3 6 4 B 7 10 11 A 4 5 15 No, Jobs B and A are going to be late Suppose you have the four jobs to the right arrive for processing on one machine What is the LCFS schedule? Do all the jobs get done on time?
  51. 51. Scheduling Low-Volume Systems • Loading - assignment of jobs to process centers • Sequencing - determining the order in which jobs will be processed • Job-shop scheduling – Scheduling for low-volume systems with many variations in requirements
  52. 52. Gantt Load Chart • Gantt chart - used as a visual aid for loading and scheduling Work Center Mon. Tues. Wed. Thurs. Fri. 1 Job 3 Job 4 2 Job 3 Job 7 3 Job 1 Job 6 Job 7 4 Job 10 Figure 15.2
  53. 53. • Infinite loading • Finite loading • Vertical loading • Horizontal loading • Forward scheduling • Backward scheduling • Schedule chart Loading
  54. 54. Sequencing • Sequencing: Determine the order in which jobs at a work center will be processed. • Workstation: An area where one person works, usually with special equipment, on a specialized job.
  55. 55. Example of Job Sequencing: Johnson’s Rule (Part 1) Suppose you have the following five jobs with time requirements in two stages of production. What is the job sequence using Johnson’s Rule? Time in Hours Jobs Stage 1 Stage 2 A 1.50 1.25 B 2.00 3.00 C 2.50 2.00 D 1.00 2.00
  56. 56. Example of Job Sequencing: Johnson’s Rule (Part 2) First, select the job with the smallest time in either stage. That is Job D with the smallest time in the first stage. Place that job as early as possible in the unfilled job sequence below. Drop D out, select the next smallest time (Job A), and place it 4th in the job sequence. Drop A out, select the next smallest time. There is a tie in two stages for two different jobs. In this case, place the job with the smallest time in the first stage as early as possible in the unfilled job sequence. Then place the job with the smallest time in the second stage as late as possible in the unfilled sequence. Job Sequence 1 2 3 4 Job Assigned D AB C Time in Hours Jobs Stage 1 Stage 2 A 1.50 1.25 B 2.00 3.00 C 2.50 2.00 D 1.00 2.00
  57. 57. Shop-Floor Control: Major Functions 1. Assigning priority of each shop order 2. Maintaining work-in-process quantity information 3. Conveying shop-order status information to the office
  58. 58. Shop-Floor Control: Major Functions (Continued) 4. Providing actual output data for capacity control purposes 5. Providing quantity by location by shop order for WIP inventory and accounting purposes 6. Providing measurement of efficiency, utilization, and productivity of manpower and machines
  59. 59. Input/Output Control Input Output • Planned input should never exceed planned output • Focuses attention on bottleneck work centers Work Center
  60. 60. Principles of Work Center Scheduling 1. There is a direct equivalence between work flow and cash flow 2. The effectiveness of any job shop should be measured by speed of flow through the shop 3. Schedule jobs as a string, with process steps back-to-back 4. A job once started should not be interrupted
  61. 61. Principles of Job Shop Scheduling (Continued) 5. Speed of flow is most efficiently achieved by focusing on bottleneck work centers and jobs 6. Reschedule every day 7. Obtain feedback each day on jobs that are not completed at each work center 8. Match work center input information to what the worker can actually do
  62. 62. Principles of Job Shop Scheduling (Continued) 9. When seeking improvement in output, look for incompatibility between engineering design and process execution 10. Certainty of standards, routings, and so forth is not possible in a job shop, but always work towards achieving it
  63. 63. Personnel Scheduling in Services • Scheduling consecutive days off • Scheduling daily work times • Scheduling hourly work times
  64. 64. Thank You