Production planning and controlPresentation Transcript
DEPARTMENT OF BUSINESS ADMINISTRATION & RESEARCH Shri Sant Gajanan Maharaj College of Engg., ShegaonPRODUCTION PLANNING AND CONTROL L B Deshmukh
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.
POM - Critical Decisions1. Managing quality2. Design of goods and services3. Process and capacity design4. Layout design5. Human resources6. Location strategies7. Supply-chain management8. Inventory management9. Scheduling10. Maintenance 3
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? 4
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? 5
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? 6
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? 7
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? 8
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
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.
Production Planning and Control Functions• Process Planning (Routing)• Loading• Scheduling• Combining Functions• Dispatching• Reporting or Follow – up• Corrective Action• Re-planning
Production Planning and Control Functions- Process Planning (Routing)• 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- Loading• 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- Scheduling• 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- Combining Functions• 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- 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.
Production Planning and Control Functions- Reporting or Follow – up• 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- Corrective Action• 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- Re-planning• 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.
Factors Affecting Production Planning and Control• Type of Product• Type of Manufacturing
Production Planning Functions • Estimating • Routing • Scheduling • Loading Production Control Functions•Dispatching•Expediting/Follow –up/Progressing
Role of PPC in Different Types of Manufacturing• Mass Production• Batch Production• Job Production
Process Types - Products ProjectHigh Job BatchVariety Mass ContinuousLow Low Volume High 23
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.
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.
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.
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.
Production scheduleIt 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.
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.
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
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.
LoadingThe next step is the execution of the schedule plan as per the route chalkedout it includes the assignment of the work to the operators at their machinesor work places. So loading determines who will do the work as routingdetermines where and scheduling determines when it shall be done. GanttCharts are most commonly used in small industries in order to determinethe existing load and also to foresee how fast a job can be done. Theusefulness of their technique lies in the fact that they compare what hasbeen done and what ought to have been done.
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.
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
Dispatching is an important step as it translates production plans into production.
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.
Inspection• This is mainly to ensure the quality of goods. It can be required as effective agency of production control.
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.
Work CenterDefined• 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
Types of Manufacturing Scheduling Processes and Scheduling Approaches Type of Process Typical Scheduling ApproachContinuous Finite forward of process, machineprocess limitedHigh-volume Finite forward of line, machined limitedmanufacturingMed-volume Infinite forward of process, labor andmanufacturing machined limitedLow-volume Infinite forward of jobs, labor and somemanufacturing machine limited
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
Work-Center Scheduling Objectives• Meet due dates• Minimize lead time• Minimize setup time or cost• Minimize work-in-process inventory• Maximize machine utilization
Priority Rules for Job Sequencing1. First-come, first-served (FCFS)2. Shortest operating time (SOT)3. Earliest due date first (DDate)4. Slack time remaining (STR) first5. Slack time remaining per operation (STR/OP)
Example of Job Sequencing: First-Come First- Served Jobs (in order Processing Due DateSuppose you have the four of arrival) Time (days) (days hence)jobs to the right arrive for A 4 5processing on one machine B 7 10 C 3 6 D 1 4What is the FCFS schedule? Do all the jobs get done on time? Answer: FCFS Schedule No, Jobs B, C, and D are Jobs (in order Processing Due Date Flow Time going to be late of arrival) Time (days) (days hence) (days) A 4 5 4 B 7 10 11 C 3 6 14 D 1 4 15
Example of Job Sequencing: Shortest Operating Time Jobs (in order Processing Due DateSuppose you have the four of arrival) Time (days) (days hence)jobs to the right arrive for A 4 5processing on one machine B 7 10 C 3 6 D 1 4What is the SOT schedule? Do all the jobs get done on time? Answer: Shortest Operating Time Schedule Jobs (in order Processing Due Date Flow Time No, Jobs A of arrival) Time (days) (days hence) (days) and B are D 1 4 1 going to be C 3 6 4 late A 4 5 8 B 7 10 15
Example of Job Sequencing: Earliest Due Date First Jobs (in order Processing Due DateSuppose you have the four of arrival) Time (days) (days hence)jobs to the right arrive for A 4 5processing on one machine B 7 10 C 3 6 D 1 4What is the earliest due datefirst schedule? Do all the jobs get done on time? Answer: Earliest Due Date FirstJobs (in order Processing Due Date Flow Time No, Jobs C of arrival) Time (days) (days hence) (days) and B are D 1 4 1 going to be A 4 5 5 late C 3 6 8 B 7 10 15
Example of Job Sequencing: Critical Ratio Method Jobs (in order Processing Due DateSuppose you have the four of arrival) Time (days) (days hence)jobs to the right arrive for A 4 5processing on one machine B 7 10 C 3 6 D 1 4What is the CR schedule? Do all the jobs get done on time?In order to do this schedule the CR’s have be calculated No, but sincefor each job. If we let today be Day 1 and allow a total of there is three-15 days to do the work. The resulting CR’s and order way tie, onlyschedule are: the first job orCR(A)=(5-4)/15=0.06 (Do this job last) two will be onCR(B)=(10-7)/15=0.20 (Do this job first, tied with C and D) timeCR(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)
Example of Job Sequencing: Last-Come First-Served Jobs (in order Processing Due DateSuppose you have the four of arrival) Time (days) (days hence)jobs to the right arrive for A 4 5processing on one machine B 7 10 C 3 6 D 1 4What is the LCFS schedule? Do all the jobs get done on time? Answer: Last-Come First-Served Schedule Jobs (in order Processing Due Date Flow Time of arrival) Time (days) (days hence) (days) No, Jobs B D 1 4 1 and A are C 3 6 4 going to be B 7 10 11 late A 4 5 15
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
Figure 15.2 Gantt Load Chart • Gantt chart - used as a visual aid for loading and scheduling Work Mon. Tues. Wed. Thurs. Fri. Center 1 Job 3 Job 4 2 Job 3 Job 7 3 Job 1 Job 6 Job 7 4 Job 10
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.
Example of Job Sequencing: Johnson’s Rule (Part 1)Suppose you have the following five jobs with time requirements in twostages 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
Example of Job Sequencing: Johnson’s Rule (Part 2)First, select the job with the Time in Hourssmallest time in either stage. Jobs Stage 1 Stage 2That is Job D with the smallest A 1.50 1.25time in the first stage. Place that B 2.00 3.00job as early as possible in the C 2.50 2.00unfilled job sequence below. D 1.00 2.00Drop D out, select the next smallest time (Job A), and place it 4th in the jobsequence.Drop A out, select the next smallest time. There is a tie in two stages fortwo different jobs. In this case, place the job with the smallest time in thefirst stage as early as possible in the unfilled job sequence.Then place the job with the smallest time in the second stage as late aspossible in the unfilled sequence. Job Sequence 1 2 3 4 Job Assigned D B C A
Shop-Floor Control: Major Functions1. Assigning priority of each shop order2. Maintaining work-in-process quantity information3. Conveying shop-order status information to the office
Shop-Floor Control: Major Functions (Continued)4. Providing actual output data for capacity control purposes5. Providing quantity by location by shop order for WIP inventory and accounting purposes6. Providing measurement of efficiency, utilization, and productivity of manpower and machines
Input/Output Control Work Input Output Center• Planned input should never exceed planned output• Focuses attention on bottleneck work centers
Principles of Work Center Scheduling1. There is a direct equivalence between work flow and cash flow2. The effectiveness of any job shop should be measured by speed of flow through the shop3. Schedule jobs as a string, with process steps back-to-back4. A job once started should not be interrupted
Principles of Job Shop Scheduling (Continued)5. Speed of flow is most efficiently achieved by focusing on bottleneck work centers and jobs6. Reschedule every day7. Obtain feedback each day on jobs that are not completed at each work center8. Match work center input information to what the worker can actually do
Principles of Job Shop Scheduling (Continued)9. When seeking improvement in output, look for incompatibility between engineering design and process execution10. Certainty of standards, routings, and so forth is not possible in a job shop, but always work towards achieving it
Personnel Scheduling in Services• Scheduling consecutive days off• Scheduling daily work times• Scheduling hourly work times