File Name: fundamentals of production planning and control .zip
- Elements of Production Planning and Control in an Organization
- 6 Basic Principles of Production Planning
- Production Planning and Control
Reflections on production planning and control PPC. The paper examines the current state of Production Planning and Control PPC , identifies some technical and systems changes that have occurred over recent years and links these with the requirements being placed on companies by the market.
Elements of Production Planning and Control in an Organization
Reflections on production planning and control PPC. The paper examines the current state of Production Planning and Control PPC , identifies some technical and systems changes that have occurred over recent years and links these with the requirements being placed on companies by the market. PPC is being asked to respond effectively to these internal and external changes by being more dynamic and providing better control of resources and delivery performance.
Some of the requirements to be satisfied by the new PPC systems are identified. To meet these requirements it is suggested that better understanding is required of how different factors affect PPC systems performance and that administrative systems need improving.
The quantitative, administrative and behavioural aspects of PPC are discussed. A framework for developing an agenda for action and research is provided. Key words: production planning, production control, overview. Many technical and systems changes have occurred in manufacturing industry over recent years. The requirements being placed on companies by the market are also changing. Production Planning and Control PPC is being asked to respond effectively to these internal and external changes by providing a faster response and better control of resources and delivery performance.
The paper examines the current state of PPC. The discussion then reviews recent developments in the market, manufacturing and manufacturing systems and relates these changes to our understanding of production planning and control.
The description brings together many threads associated with PPC and identifies some areas where there are deficiencies in our understanding. Some thoughts are then presented on how PPC systems need to respond to the changing technology, changing market needs and individual customer's expectations. All papers are personal in the sense that they reflect the interests and priorities of the authors. However personal opinions have deliberately been given greater weight in this paper than is conventional.
Indeed, several sections of the paper contain ideas that have been partially tested but not fully evaluated. In that category are the personal classification and organisation of PPC described in section 4, the concurrent engineering views and figures in section 7, the framework for production management in section 8.
How the tabular representation leads to a possible research agenda also needs further evaluation. The paper uses some general principles which, although not proven, have been reinforced over the years by personal experience and research investigations. Hopefully these principles will also be useful to you.
They include:. The conjectural nature of some aspects of the paper has been highlighted to encourage readers to be critical of the content and to ask whether the interpretations are consistent with readers' experiences.
Feedback on whether the generalisations stand up to international scrutiny and apply to different systems will be useful. Companies wish to satisfy market demands expressed in terms of real or forecast demand. To do this companies in general produce a Master Production Schedule MPS that states the number of each product to be made over some planning horizon and a Sales Programme that states the number of each product to be sold.
The PPC function and its associated systems aim to plan and control production so that a company meets the production requirements as effectively as possible. PPC systems are hierarchical. A hierarchical planning process is used for PPC to help a manager understand and control the operations for which he is responsible. A high-level plan sets the context within which the next lower level plans operate. The different levels in the hierarchy operate on different time scales.
Typically aggregate planning is associated with long planning horizons and detailed planning is associated with short planning horizons. A common operational starting point for planning production is the Master Production Schedule from which the requirements of materials, parts, machines and labour are derived. Modifications may be made to the plans if the derived requirements are thought to be inappropriate. The consequences of the chosen plans, usually expressed as a list of requirements of made-in and bought-out parts, become the basis of the work schedules placed on individual men and machines and orders placed on suppliers.
The prime objective of production planning and control is to ensure that parts and products are produced so as to achieve the Master Production Schedule MPS in a way that is consistent with meeting the company's other performance measures. The MPS states the number of each product to be produced period by period over some time into the future known as the planning horizon. The MPS, in conjunction with the sales programme, is the company's planned response to the demands of the market.
In particular, the MPS, company production and inventory policies and knowledge of inventory levels, are used to determine the number of items to produce, the planned inventories of raw material, work-in-progress, finished parts and finished products and the manufacturing resource requirements such as machines and labour. Plans should be realistic and avoid asking for the impossible. The British Standards document BS Part states that the Production Control function comprises three inter-related stages: programming, ordering and dispatching.
It also states that production control occupies a central position in the exchange of information between the functional departments within a manufacturing organisation. A common representation of PPC includes the following characteristics:. BS also makes the points that 'there is a tendency when designing production control systems to make them over-complicated. Some of these are discussed later.
PPC systems consist of inputs, transformations, outputs and appropriate control systems. Traditionally it has been difficult to plan and control production because of limitations in the planning methods and because unplanned changes occur in demand, supply and resources.
In recent years further complexity has arisen because the emphasis of PPC has shifted from controlling individual plants to co-ordinating the complete supply and delivery chains. The production units may therefore be geographically dispersed and the systems in the different units, which are not necessarily part of the same company, may not integrate easily with the others.
The consequence is that many companies find it difficult to provide the service required by the market. They also find it difficult to produce items according to their plans despite major developments in computer aided production planning and control and better systems understanding. Difficulties of planning and control arise when there is a mismatch or incompatibility between various parts of the total system i. There is frequently a gap between the theory and practice of PPC. Academics try to improve understanding of PPC systems by analysing the mutual impact of influential PPC factors whereas practitioners try to obtain usable results from a mix of non-ideal softwareand ad hoc manual systems.
Practitioners often believe that academics are not investigating the 'right' problems and are touched by the arrogance of ignorance whereas academics are frequently unhappy about the apparent lack of understanding that production control managers have of straightforward concepts. As an illustration, practitioners need to agree lead-times at the time of accepting orders so as to be able to quote dates for delivery and to co-ordinate the availability of parts for assembly.
Selecting a delivery date is usually achieved by assuming that the lead-time is fixed and deterministic. This may be a reasonable approximation provided that the load on resources stays fairly constant or fairly light. However, queuing theory clearly demonstrates that highly loaded resources, in the presence of demand and service both subject to variability, create long and variable delays. Actual lead-times are thus a consequence of the load on the system together with random effects arising from problems of quality, reliability of the machines and processes, deliveries, people and the demand.
Rather obviously the quoted lead times affect the load, the level of stock and the probability of delivering on time. However, companies frequently adopt simultaneously the contradictory strategies of varying load while fixing the quoted lead-time. This may be one reason why many plans are unrealistic. There are many systems of production control. In general, PPC systems have originated within industry although the major system software producers now have a great influence on their detailed content.
Although some companies have local objectives such as keeping groups of individual men and machines busy, formal descriptions of PPC systems usually sub-divide them into make-to-order and make-for-stock systems.
Make-to-order systems, of which jobbing production is the purest manifestation, respond directly to customer's demands. On the other hand, make-for-stock systems, including base stock, re-order cycle ROC and sometimes re-order point ROP systems, attempt to bring stock up to pre-defined levels. Many systems, of which MRP is one, are a combination of make-to-order and make-for-stock.
Conversely the MPS is chosen so that orders that have already been accepted will be produced. Of recent years, Just-in-time JIT , which according to APICS , is usually considered to be a philosophy based on the 'planned elimination of all waste and continuous improvement of productivity', has become fashionable and sufficiently important to become an objective of many companies. JIT is usually a make-for-stock base stock system suitable for repetitive manufacturing, but it has two features: demand pull and the minimisation of stock that together allow the system to respond effectively to customer orders.
JIT has had some important successes but it has not been universally successful. Indeed the effectiveness of JIT systems has frequently been somewhat different from that expected even in companies that have claimed success in its implementation e.
MRP is still the most used production planning and control system. However, the basic system embedded within these extensions, is still MRP, an approach that has been heavily criticised partly because its centralised nature requires a large amount of data handling and the need to maintain highly accurate stock records.
Nevertheless, it is essential for companies to co-ordinate deliveries and a wide range of other activities and so MRP has continued to be used even though the data handling may preclude responsiveness. The choice of parameters available within an MRP system and the differences between companies and their markets mean that it is unlikely that any two MRP systems are identical even if the companies use the same software.
JIT and kanban systems also have great variety in the way that they have been implemented. In practice the same label, whether MRP or JIT, may be used to describe systems with different structures, different parameter values and very different performance.
More confusing, but less frequently recognised, is that the labels, push and pull, that are commonly used to describe MRP and JIT systems are also defined in many different ways. Thus not only can different systems be described in the same way but the same systems may also be described in contradictory ways. The simulation indicates that under some specific conditions, push systems, appropriately defined, have similar potential for stock reduction as pull systems.
The lack of precision with definitions has led to confusion within the literature and among production control practitioners. This suggests that to improve understanding it is essential to represent systems with clarity and desirable to represent them consistently. PPC systems in companies frequently progress through a series of stages. In the early stages most company PPC systems are administrative systems built up ad hoc to deal with the housekeeping aspects of planning, ordering, receiving, issuing, making and storing items.
Instructions are issued and transactions related to materials, men and machines are recorded. Unless resources are lightly loaded, it is common to find that order acceptance is not compatible with the resources available. This introduces uncertainty into the delivery times on top of the uncertainty that arises from changing customers' requirements, machine breakdowns, absenteeism, quality problems, etc. The consequence is likely to be a set of dissatisfied customers.
To try to overcome these problems, procedures are introduced to perform actions such as master scheduling, lot sizing, setting safety stocks, rescheduling, setting time fences and extending planning horizons. Computer systems are introduced to handle the required data more effectively. While these methods help, they do not completely meet the needs of the companies and they frequently do not meet the needs of the users.
Together the procedures used for planning and control make PPC systems surprisingly complex. Since the earliest days of computerised production control, an objective of companies has been to develop Integrated Data Processing IDP systems.
In those early days bespoke PPC systems and modular packages both existed. TATE showed that the early modular packages were not as successful as bespoke systems.
6 Basic Principles of Production Planning
Production Planning and Control draws on practitioner experiences on the shop floor, covering everything a manufacturing or industrial engineer needs to know on the topic. It is written in an approachable style, thus making it ideal for readers with limited knowledge of production planning. End of chapter questions help readers ensure they have grasped the most important concepts. MSc students and researchers working on manufacturing and industrial engineering topics, manufacturing engineers and others working in factories in roles related to PP and C. Elements of Production Planning and Control 2.
Production Planning and Control
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Solution Manual for Fundamentals of Production Planning and Control
Planning refers to deciding in advance what is to be done in future. A separate planning department is established in the organisation which is responsible for the preparation of policies and plans with regard to production to be undertaken in due course. While explaining the concept of scientific management, F. Taylor emphasised the need of separating planning function from the function of actual operation in an organisation. For successful implementation of production control, production planning is of utmost importance. The planning department prepares various charts, manuals production budgets etc.