R. Leonard

Designing a material-requirements-planning system to meet the needs of low-volume, make-to-order companies (with case study)†

SUMMARY This paper considers the factors affecting the design of material-requirements-planning (MRP) systems for make-to-order companies. It shows how key elements of MRP, such as bills of material, design change control, master production scheduling (MPS) and order entry, can be made to function effectively within this type of business environment. The work is based on a major research programme between Simon Container Machinery Ltd and the UMIST, Total Technology Scheme. †Science and Engineering Research Council grant awarded under the Total Technology Industry/University Programme.

Predicting future developments in flexible manufacturing technology

The ability to evaluate flexible manufacturing (FM) in the context of the relationship between manufacturing and the total company shows that, using the nature of the financial benefits as the criteria, FM can be divided into four categories. By identifying the potential benefit of each category, predictions are made about those future developments which are required to increase the scope and viability of FM.

Designing the closed loop elements of a. material requirements planning system in a low volume, make-to-order company (with case study)

Abstract This paper describes how material requirements planning (MRP) can provide a working solution to job shop scheduling problems. In particular, the critical factors relating to resource and capacity management are examined within a low volume, make-to-order company. A rough cut capacity planning (RCCP) module is described which, when used with a detailed capacity management methodology, has enabled the collaborating company to achieve substantial savings in work-in-progress (WIP), a marked reduction in machining lead times and viable control over customer lead times. Finally, an MRP production methodology is described, which allows such concepts as unit cost justification and machine utilisation to be re-examined.

Reappraising cutting tool economics within the bounds of accountancy theory

SUMMARY Current research in cutting tool technology i9 based on absorption costing; within this paper however, this is shown to be an incorrect technique to use. When variable costing, together with DCF, is correctly used, the traditional assumptions which typically result in a 15 minute tool life are found to be erroneous, with the optimum cutting conditions being markedly different from those recommended within existing literature. It is also demonstrated that by. using a correct financial methodology, the viability -of advance processes such as CNC and FMS are improved because the cutting conditions for such machines should differ greatly from those for inexpensive machine tools.

Elements of cost-effective CIM

Abstract The paper initially describes the creation of an investment analysis program whose use enables all the factors surrounding a CIM or AMT project to be quantified, including such important ‘intangible’ aspects as improved manufacturing flexibility or enhanced product quality. Following an historical review of the constituent elements of CIM, and a projection of these technologies into the near future, CAD, CAM, MRP and FMS are subsequently discussed in terms of overall system economics. From this base, it is shown that by analysing each sub-set of CIM with respect to its economic impact on a company, the appropriate level of investment for a specific situation can be correctly determined, and it becomes possible to predict how emerging technologies will develop. The paper concludes by discussing a selection of future research areas which must be successfully investigated if CIM is to become a working reality.

The Application of Investment Appraisal to Aid the Evaluation and Implementation of Material Requirements Planning Systems

This paper describes the application of the discounted cash flow (DCF) techniques for MRP evaluation, as discussed in the companion paper (1), by means of an ‘in-depth’ case study of a medium sized, small batch engineering company. The results demonstrate that the benefits of material requirements planning (MRP) are company-wide, and that when these benefits are quantified, the financial case for MRP is greatly strengthened. The paper also shows that MRP should not be viewed within the restricted concept of a technique which only improves shop floor efficiency. The use of the evaluation techniques within a number of major companies reveals that the ‘company-wide’ return on investment is much greater than has been previously suggested, and that the greatest potential benefits of MRP accrue outside production.

Production control strategies within multi-product batch manufacturing companies

Abstract In response to increased international competition many companies are searching for a means to improve their competitive positioning, mainly through the strategic management of manufacture. Within the multi-product batch manufacturing environment, effective control is a highly complex task, as short-term fluctuations in sales volume and product mix must be met by the manufacturing system in response to business and marketing requirements. In this paper the authors consider typical production control strategies within this environment and apply an analytic investigation incorporating steady-state queueing theory to illustrate the variations in scheduling effectiveness, plant layout and work-in-progress costs affecting production performance.

A Methodology for Incorporating the ‘Company-wide’ Benefits of Material Requirements Planning within a Discounted Cash Flow Investment Analysis

Although companies can obtain major benefits from material requirements planning (MRP) serious difficulties are usually encountered during the implementation phase. This paper highlights these difficulties and then goes on to show how they can be overcome if MRP is viewed as a ‘standard’ investment decision with quantifiable objectives. The financial evaluation techniques developed at UMIST are described and a comprehensive list of costs and benefits relating to MRP is given, with 76 factors being listed. These factors, selected to prevent double counting, ensure that each potential benefit is directly quantifiable, rather than being simply described as ‘positive but intangible’. The paper then goes on to describe a systematic method of defining and quantifying the benefits listed. Finally, because MRP represents a major investment decision, it is shown that the ability to conduct a comprehensive discounted cash flow (DCF) analysis enables the main savings to be identified, thereby ensuring that the implementation strategy can be designed to optimize both the operational and financial advantages.

The role of automated guided vehicles within cellular manufacturing as a shop floor contribution to CIM

Abstract Edbro plc is o medium-sized manufacturer of hydraulic rams, and the company has made many investments in advanced manufacturing technology (AMT), including shop floor data collection to provide closed-loop MRP. In the factory AMT has resulted in islands of automation and the company now wishes to integrate these islands using automated guided vehicles (AGVs). The case study relates to transforming a process-oriented approach into a product form of organization with respect to material flow in the system. The paper gives an analysis of the constraints which traditionally generate process forms of material flows within an MRP production planning and control system. It also shows that in the case of Edbro plc, a functional layout of facilities, and complex part routings using MRP, does not give sufficient financial benefits to justify the use of AGV units to assist the material handling system. Conversely, when the organization of material flow is based on a product principle, then the correct usage...

Bridging the gap between production management and economics Part 1 A micro production model

This paper attempts to bridge the gap between where economic theory leaves the concept of the production function and where the pragmatic production manager stands, devoid of an adequate theoretical understanding of the multivariate, compounding set of real-time factors associated with manufacturing systems. The mathematical approach has been changed from calculus to topology in an attempt to provide a more visual vehicle for everyday use. Essentially the topological building block is a three-dimensional vector space which is used to model both the microeconomic and the microproduction function. As the number of dimensions in the model increases to match practical needs, so a new method of defining the production function was evolved.