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The multivariate extension of control charts for process dispersion is not as straightforward as that for the process mean. A general model and techniques that would encompass a wide range of problems encountered in practice is not available. In most cases, particular problems need to be handled in a specific manner. In this paper we consider several special cases of a process displacement affecting the covariance matrix and we develop control charts (both Shewhart-type and CUSUM) to detect these process changes.

SUMMARY This paper presents some general relations for the selection of speed, feed and depth of cut to achieve optimum economic conditions in machining. The relations are based on the assumptions that a power law relates the machining rate variables to tool life and to cutting power. Consideration is given to single point tools removing material in both one and two passes, and to operations involving more than one tool. Methods of establishing numerical data for practical application of the relations, are outlined briefly.

SUMMARY Studies of the effectiveness of management control have usually been based on observations of inter-personal or inter-departmental relationships within an organisation. This paper suggests that a new approach would be to observe what happens to plans, decisions and tasks, from inception to completion. It discusses the application of scientific methods for analysing management control, with particular emphasis on research techniques for measuring and evaluating the effectiveness of control procedures.

SUMMARY This paper is a progress report on a study of an actual decision-making system. It scrutinizes the demands made on a manufacturing organization and the responses of the organization to these demands The study focuses on the ways the organization got a particular job done, namely the job of production scheduling and work-flow smoothing in the box-making plants of a manufacturer of shipping containers. The complete system can be factored into two parts. One sub-system places orders in sequence and prepares an advance production schedule. The second subsystem controls the flow of work through the actual manufacturing operations, making final adjustments in the sequence and speed of the work-flow.

SUMMARY Tests were run with high strength thermal-resistant work materials selected by surveying U.S. aircraft engineering companies to find representative types of materials presenting problems in convential machining. Each material tested had two different heat treatment procedures. Tests were conducted in orthogonal and conventional turning, in milling and in drilling operations using different methods of workpiece heating. Information was obtained on tool life—cutting speed relationships, tool temperatures and forces, chip formation and related quantites for a range of work temperatures. Metallographic studies of hot-machined parts were carried out and the effects of the process on workpiece geometry are discussed. Assessment of workpiece heating methods will be the subject of a further paper.

SUMMARY Random errors in inspection may lead to good products being rejected and defective products being accepted by inspectors. If the cost involved in rejecting good products is high, the supplier may be tempted to send back the rejects for re-inspection, in spite of additional costs involved in such a procedure (called “re-circulation” of rejects). This paper analyses several models to indicate under what conditions such a re-circulation policy is worthwhile.

SUMMARY Optimal power balance in complex systems such as natural gas refineries has been studied by Gignoux, Littauer & Starr for a model of interconnected units whose energy consumption or production is constant and where the system's power requirements fluctuate owing to failure of various units. In the present paper the distribution functions of power requirements are obtained for a similar discrete model and also for a continuous model where the quantities of power consumed or produced are themselves random variables. The optimal balance between power self generated and power purchased from an outside source is derived by application of the distribution functions and illustrated by a numerical example. The method is general and applicable to other systems of power generation.

SUMMARY This paper reviews research on frequency distributions of operation cycle and element times. Preliminary findings are given of comparative studies of experienced and trainee workers on repetitive paced and unpaced tasks.

The difficulties encountered when using a stop-watch for the measurement of basic time are well known and the authors of this paper suggest a new and more efficient method for such measurement without a stop-watch. A portable apparatus (consisting of a transistorized signal generator with a mechanical clock driven, hand wound, recorder) has been designed and is described The authors wish at this stage to give interested persons the opportunity to comment upon the principle involved and hope that similar or alternative types of instruments will be constructed, utilizing the principle, and then subjected to practical testing in real work situations. The authors have communicated the results of a first test in this paper but the task of comparing the instrument with standard methods of time study has still to be carried out.

In the manufacture of metal cans tinplate is a major cost item and when the scale of output of cans, say, in the food industry, is considered, it is obvious that efficient utilization of material is a factor of considerable economic importance. The first part of this paper analyses in some detail the parameters which determine the optimal H/D ratio when trim losses are taken into account and makes a comparison with actual can dimensions used in the food industry. Having stated the optimal dimensions for an individual can, this study first attempts to estimate the sensitivity of these optimal conditions, that is to say what material wastage is expected to occur if deviations from optimal dimensions; are considered. Secondly it was felt that the optimal solutions should be subjected to consumer tests so that some indication might be given as to customers' preferences, and to whether these are compatible with the theoretical optimal dimensions. Thirdly a solution is suggested for a multi-can program...

This paper describes briefly the context in which a portable system for recording certain aspects of drilling performance is being developed. Particular emphasis is placed on a time recording channel in which a sensing element attached to the quill of the machine conveys signals from the translatory feed motion to a sequential-event timer and recorder (SETAR—after the design of N. T. Welford).Some discussion is devoted to indicating how the reliability of such a system is largely dependent on the method of collecting, transmitting and recording for subsequent analysis the excitation signals.

SUMMARY This paper gives the results of computations, for a chosen production control model, yielding the extra costs incurred when information about a change in mean demand level becomes available at some time relative to the time of the change. These extra costs are zero if the information is available from prehistoric times and increase monotomcally as the detection moment shifts to later points of time. Only “jumplike”changes of mean demand level are considered. It is found that the extra costs as a function of the detection moment N approach a linear asymptote for high N. The points of contact of these results with control chart theory, especially the optimization of control charts as a link between predictors and production control, are mentioned.

SUMMARY The London School of Economics have, since 1959, studied the jobs of supervisors in a number of plants to demonstrate their range and variety and the relation of supervisory systems to technology. A previous article (see below) on the first part of the research argued that there was no straightforward relationship between the two, but that organizational and human factors could also greatly determine supervisory jobs. This paper describes the last part of the research which was devoted to a far deeper and more detailed analysis of supervisory jobs in one large firm in an attempt to find more concrete evidence of different influences on supervisory jobs. The results show that the nature of the product, the technical situation, the factory organization, the supervisory training programme and the supervisor's personality all affected both his behaviour and the demands made on him. A supervisor was seen to be reacting to a continuous succession of pressures, some of which ran counter to others. The re...

SUMMARY This paper reports a D.S.I.R. experiment in the application of programmed instruction to craft apprentice training An instructor at an apprentice school was trained to convert parts of the normal syllabus into auto-instructional programmes, such programmes being progressively reshaped in the light of the success of the programmes as a teaching device. It was found that, in addition to providing a teaching method fitted to the apprentice's needs, the system (when in operation for the ninety-day pre-apprenticeship period) also allowed an instructor to give much more time to personal tuition of individual apprentices. This proved a dual aid to pre-apprenticeship training and, in some cases, shortened the teaching time required, thus permitting extended production experiences under controlled workshop conditions before transference to the main works.

SUMMARY A previous investigation proposed general definitions of some screw thread elements. Further study of one of these elements (the effective diameter equivalent of flank angle errors) has shown that certain ambiguity was left unexplained. This paper gives clarification and the choice already made is justified The new method for the determination of the effective diameter equivalent of flank angle errors for triangular parallel screw threads has been generalized to the complex case of taper screw threads When the results obtained are applied to some standard threads, certain appreciable divergencies are noticed It is expected that the results of this study will lead to more rational use of the effective diameter tolerances and may be exploited towards more accurate procedure of measurement of taper threaded elements.

SUMMARY This paper uses the statistical tool of analysis of variance to look at the recommended operating values for chemical machining. The results obtained agree in general with those published by The Chem-Mill Division of Turco Products Inc., except that there was an indication of some deterioration of surface finish when using sodium aluminate in the solution. The results obtained should not be used in general, but only applied where the material and method are comparable to the one used in the study.

SUMMARY Determination of time of temperature rise in a cutting tool is of significance in machining of metals. It is particularly so in milling where the cutting is intermittent, thus allowing time for dissipation of heat between successive cuts. Many researches have been directed to this problem but their findings vary widely within the range of 0-2 sec. to 20 min. It would seem that this wide variation is due to the effect of the first revolution where the feed is, in effect, continuously increased. As a result of the research incorporated in this paper, the time of temperature rise was determined, eliminating the effect of the first revolution. It varied from 006 sec. at a very high speed of 342 ft./min. to 1.4 sec. at 11.2 f.p.m.

SUMMARY The paper deals with an error experienced in measuring the cutting temperature by the tool work thermocouple method. The problems when using a high speed steel tool and carbon steel for metal cutting are described. The experimental results suggest that when using high speed steel as part of the thermocouple, error appears in the temperature range when carbide dislocation occurs.

SUMMARY SUMMARY This paper is concerned with a “variable input output” system of inventory control in which both the inventory level and maintenance capacity are intimately connected to arrive at a minimum cost solution. The characteristic of the situation is the closed system formed by an organisation in which specific items which require periodic maintenance are at any time being used, reconditioned and stored. A bus engine inventory network of a transport industry was studied and the optimum cost condition obtained for the total number o spare engines and maintenance channels

SUMMARY SUMMARY In Part I (Glover, 1965) it was shown that the model ∑y+C =a(∑,x)m could be used to describe all cases of learning in industry, whether of individuals learning a particular skill, or of complete factories learning to produce a new product. The development of the CULOG form of learning curve was discussed. In the present paper consideration is given to the selection of trainees and a method of monitoring their progress so that the occurrence of “plateaus” of learning is minimised.

SUMMARY This paper describes a pilot study conducted to investigate the performance of operators under paced conditions in a particular form of conveyor-paced working. The response shown by the operator is reflected grossly by a speeding-up in work rate The study aims particularly at investigating whether the service time for a part, delivered on the conveyor, will depend upon the time available before the next part would be missed and pass unprocessed. The feed rate and the position in the pick-up area in which a part is picked up arc shown to affect the service time with different degrees of magnitude.

SUMMARY The paper describes a study covering 409 workers in the assembly factory of a large Belgian automobile company. It was desired to identify the factors which contributed, in both a positive and a negative way, to the attitudes of the men toward their work. The technique adopted was a free, but standardised, interview with each man whilst working on the line with him, the research worker having previously been trained and having worked on the line as an assembler. The data were subjected to an analysis of variance, and factors at work groups lying at the extremes of the distributions are discussed, reasons for their contribution to the total variance being drawn from the interview data.

SUMMARY The paper is concerned with a special case of the silo problem, namely when it is sought to divide optimally a container into two compartments used for storing two commodities separately. The two compartments are filled to capacity at the beginning of each period and quantities of the two commodities are withdrawn during the period according to two independent demand distributions. There are no storage costs, but penalties are incurred in case of runouts. A solution to the problem is given and the sensitivity of the model is discussed.

SUMMARY Parts I and II of this paper were concerned with a model based on the CULOG form of the learning curve, its comparison with existing functions, and its applications in the training of employees. In the present part it is proposed to discuss briefly the applications of the model in forecasting future production levels of new products (or of products in new plants) and in production control generally.

SUMMARY This paper discusses a method for determining the optimal characteristics for a machine which fabricates two-dimensional products. The machine is a high-speed, high-cost, continuous processing facility. The end products of this continuous operation, called intermediate inventory, are stored and then used as input for a low-speed, low-cost, job-shop operation which finishes them to customers' dimensional specifications. The study is based on a specific problem in the paper industry but problems of the same basic type are encountered in the manufacture of special products of steel, aluminium, plastics, textiles and so forth.

SUMMARY This paper is concerned with the evaluation of tool stresses in the orthogonal cutting process. Theory and elasticity methods are applied to determine these stresses within the elastic region. In this analysis the tool is considered as a wedge with the normal and frictional loading on the rake face. For general conditions of loading it has been found that the equivalent stresses are or the order of a hundred thousand pounds per square inch. It has also been found that the equivalent stresses decrease with positive rake and increase with negative rake.

SUMMARY This paper presents a theory and related experiments on centrifugal barrel finishing. A calculation for the centrifugal force in the barrel is described. The limitation of the ratio between the rotation speed of the tubs and turrets, and values of polishing efficiency are determined by the calculation and compared with experimental results. It can be understood from the results why the polishing efficiency of the centrifugal barrel is far higher than that of the ordinary rotating barrel. Finally some considerations on design criteria are mentioned.

SUMMARY Standard tests for metal arc welders are based on the quality of the weld, for which many factors are beyond the control of the welder. Therefore tests fail to provide an exclusive measure of the skill of the welder. In this paper, an assessment of the arc length maintained by the welder is proposed as an additional test.

SUMMARY In this paper the Filon's transformed equations have been applied successfully to evaluate the chip-tool interface stresses of a cutting tool from the photo-elastic data. This method is shown to be advantageous over the shear difference method, particularly for negative rake tools. The analysis was carried out to study the effect of rake angle and depth of cut on the stress distribution and total forces on the rake face, involved in the orthogonal machining process.

SUMMARY The design of mechanical feeders is very much a matter for experience. This paper illustrates that by experiment and synthesis better understanding of the behaviour of such devices can be achieved. Although the work specifically relates to a particular feeder handling simple cylinders, the exercise is capable of wider interpretation and the techniques evaluated could be applied in a wider sense.

SUMMARY The work summarised in this paper has been directed to examine the basic requirements of warehouse layouts. Two simple types of layout have been examined and equations derived for the dimensioning of these, given such information as total volume of stock and number of stock lines. A sketch of the layouts is given. Ten factors have been considered in arriving at the theoretical layouts and it is shown that different types of layout are affected by different factors, some layouts being independent of factors to which others are sensitive. Dimensions of a layout can be calculated to minimise handling distance, handling time or space utilisation. Where cost functions are available for these parameters, total cost can also be minimised. The formulae lend themselves readily to computer manipulation, enabling an optimum layout to be determined given only the number of stock lines and volumes stored.

SUMMARY This paper examines the problem of optimally locating a main facility with respect to located ancillary facilities when unit transportation cosis between the main facility and ancillaries are known. Problems of location both in the planar and spatial states are examined, and an electrical analogue solution is proposed and verified. Solutions to problems with non-linear transportation cost functions are discussed and a worked example is included to illustrate the technique.

SUMMARY This paper develops a method for computing the optimal division of a container into any number (N) of compartments when each compartment contains an item which is subjected to an independent demand over some time period. Each of the N compartments is filled at the beginning of the period and the objective is to minimise total runout cost during the demand period.

SUMMARY The advantages of progressive assembly of products have been evident to industry for many years. The problem addressed in this paper is to assign models to several mixed model lines so as to minimize the assembly costs associated with each line. Criteria are developed which represent costs affected by mixed model assembly. These include balance delay, learning, and a type of inefficiency introduced in this paper called sequence delay. When the criteria are combined, the result is a quantitative measurement of assignment effectiveness in terms of predicted mixed model assembly costs. Typical applications are given demonstrating the consequences of the criteria and their scope of utilization. In addition, a heuristic procedure for assigning models to lines is given. Through an actual example, the applicability of the procedure is demonstrated. The solution, while not optimal, yields assembly costs significantly lower than costs resulting from a large group of randomly generated assignments.

SUMMARY The paper summarises theoretical and experimental studies of some problems concerning the realisation of broaching of ring thrust faces. It presents descriptions of devices and investigations into the limits of application of this technology such as tool life, the deformation of rings under cutting forces and the stability of rings under clamping forces. The objectives of this project were to increase the productivity rate and continuity of production and to facilitate automation.

SUMMARY It has been assumed in recent research that the distribution of units on conveyors is a stationary Bernoulli distribution. This paper presents a technique which is used to test the validity of this assumption. The system was simulated using the GPSS 111 language. A statistical run test is used to test the Bernoulli assumption. From the results of this study, the general assumption that the distribution of units on the conveyor is stationary Bernoulli cannot be supported.

This paper reports the use of two techniques which were used to evaluate the important design parameters in a cranking type task. Namely, electromyography served as an indicator of physiological costs for the task, and biomechanical analysis provided quantitative data concerning the mechanical costs for the task. Both these measures were shown to support the importance of handle radius, torque, and working height as critical criteria in design of a cranking task.

This paper treats work variety as a subjective variable rather than an objective attribute of work. The results of several industrial experiments are outlined in presenting a method for measuring perceived variety in terms of a psycho-physical function. A null finding is reported concerning the relationship between variety and work performance.

According to standard handbooks and inspection practice, screw thread roll gauges are set by employing special master set plugs. In the present paper, formulae are developed to enable thread wires and gauge blocks to serve the same purpose. The appropriate exact formulae, as well as approximate, easily applicable ones, are derived for symmetrical triangular and trapezoidal threads and the non-symmetric case deduced from the previous results.

Earlier investigation has shown that, from the point of view of flank wear, tool-life can be predicted by the initial cutting temperature. This paper presents a correlation between the drill temperature with cutting speed and feed while drilling cast iron and derives the tool-life equation on the basis of temperature data. The equation obtained agrees well with that obtained by conventional test.

This paper presents a method of assigning tolerances to components so that (a) assemblies composed of the components meet specified functional requirements and (b) the cost of manufacturing all the components to their respective tolerance is minimised. Methods of obtaining tolerance equations from functional equations are briefly reviewed; the “method of extremes” is explained in detail. A relationship between cost and tolerance is derived, based upon published data. A method of assigning least-cost tolerances to a single tolerance equation is then developed.

SUMMARY This paper discusses the use of the geometric programming technique to determine the cutting speed and Teed which yield minimum production cost. The method provides for simultaneous determination of the cost optimum values of speed and feed and allows for the incorporation of restrictions on the allowable levels of the machining variables.

The paper discusses a deductive strategy for the design of systems in contrast to the more conventional inductive strategy, and indicates the improvements which may be achieved by the use of the Ideals Concept. Practical examples are quoted indicating the effectiveness of the strategy

The paper indicates the limitations on improved performance arising from physical effort and from information handling and outlines the role of training in improving job performance. Changes in jobs indicate that physical limitations will play less and less part but that other areas of job knowledge will be needed. In particular, the developments in job design may call for radically different areas of training than formerly.

This paper describes a, general model for planning work flow through a multiprocess production system and proposes a new practical scheme of control for scheduling. The features of the model are based on experience of a wide variety of industries and a means is considered for resolving the conflicts between different objectives such as meeting due dates and reducing work in progress. The control system presumes that only the inlet times of the jobs into the production system can actually be decided and managed by a production planner, and not the subsequent internal operation start times, as previous studies have often assumed. A method for optimizing the schedule is developed on the basis of this form of control and it is illustrated on a small example. Finally implementation factors and extensions are discussed.

The paper describes experimental investigation into the internal broaching process and deals with three related sections. (i) The tendency of a broach to correct misalignments and surface irregularities of the pilot hole. Split workpieces, clamped in a special fixture for machining, enabled measurements and surface traces to be taken after drilling and after broaching. The effect of hole axis inclination, deliberately introduced at the time of drilling was examined. (ii) The tendency of a broach to drift in a transverse direction was studied by the use of composite workpieces built up of similar and dissimilar materials. ( iii) Work on section ( ii) showed that when broaching a composite workpiece of steel and brass more material was removed from the steel than the brass, i.e. the broach drifterd, transversely, towards the steel. To study this effect further, a broaching dynamometer was used to measure tangential and normal forces during the broaching of composite specimens.