Search

Many materials machine in either a ductile or brittle manner depending on the cutting conditions. This paper identifies the conditions which allow perspex to be machined in a ductile manner. A quantitative assessment is made of the effects of cutting speed and feed rate on the ductile-brittle transition when turning with a tool having a 30degrees rake angle. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Production Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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 arid method are comparable to the one used in the study. [ABSTRACT FROM AUTHOR]

An original procedure for the determination of the optimum value of tool life criterion of cutting tools tooled with throw-away carbide tips is described in this paper. The procedure has the character of an iterative method, on the basis of which one can reach the optimum value of tool life criterion with respect to attaining the minimum machining cost. The algorithm of the given method is represented in a bar chart, where we can see two calculation cycles, their purpose and other relationships. A practical example closes the paper. [ABSTRACT FROM AUTHOR]

The paper suggests that the factors which limit the development and use of work measurement and work design in practice are those features of the organization which cause distortion of the measurements and restrict the application of the results. Some directions for changing this situation are given. Current industrial techniques both for visually observable working activities and for process type jobs, lag behind research practices in several notable areas. Most industrial techniques are very old and used by modestly trained technicians. The fear of mis-use of more sophisticated techniques, it is suggested, inhibits their introduction in practice.
The paper then continues by discussing four areas where techniques are needed or available. Some recent developments in each area are briefly discussed. Finally, some points regarding how the research worker should view the problems of their possible misuse are introduced. [ABSTRACT FROM AUTHOR]

Optimization is rightly claimed to be the most significant factor distinguishing the modern approach to machining processes from the orthodox one. Practical results can be obtained from the application of mathematical modelling and optimization techniques.
The paper presents a procedure for solution of machining process optimization problems, with the use of theory of graphs and Bellman's optimum principle.
The finite graph G=(N, A) (where N denoted a set of nodes and A the set of arcs) here presents the set of feasible solutions. Each arc represents a corresponding machining operation and each path the feasible machining process.
A number can be associated with each are the increment of criterion for optimality. Using the optimum principle we can find the shortest possible path in the graph, thus solving given problems of choice for the optimal machining process.
There is a variety of ways in which the performance criterion can be formulated. In this paper only those performance measures having sufficient economical justification are considered. We may minimize the costs of machining processes, or optimize economical effectiveness of capital engaged.
The method presented can be applied with every additive criterion, as well as with some non-additive ones. A practical example illustrates the field of possible application of this method. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Production Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

The paper describes an electrical analogue for aiding the solution of the classical transportation problem. It is based on the Simplex method of solution due to Dantzig. Two simple basic circuits, a feasibility circuit and a cost comparison circuit, are provided for each source and destination pair. Switching enables the feasible routes to be selected and then explored for comparative costs. The procedure is iterative. By not being self-optimizing but aiming to eliminate the routine hand calculation a flexible machine is provided with simple components. [ABSTRACT FROM AUTHOR]

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 conventional 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 quantities 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. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Production Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The work reported in this paper deals with the mechanism of metal removal in electrothermic machining. An empirical relation between the metal removal rate and the current has been established. The effect of tool materials and polarity on metal removal rate has also been analysed. [ABSTRACT FROM AUTHOR]

Two experiments were carried out to examine the effects on the comprehension by a drawing reader of linear dimension tolerance information when it was presented in different ways. The presentation methods studied are those outlined in B.S. 308: 1953.
In the first experiment 12 students and 12 school children with no previous knowledge of engineering drawings had to check whether a given value, representing an actual dimension, was inside or outside tolerance as indicated on a drawing. Significant differences in time taken and errors made were associated with different methods of presenting tolerance information. Explicit indication of upper and lower dimension values was superior. The error behaviour of subjects suggested that spatial stereotypes were operating in their interpretation of two of the three tolerance presentation methods and that, because of this, they were making mistakes.
In the second experiment 20 experienced engineering workshop machine operators had to state what final machining aiming point they would use if they were working to a presented drawing of part of an engineering component. Various sizes of tolerance values and ways of presenting them were used on different drawings. The results showed that the chosen aiming point was dependant on size of tolerance but not on method of presentation of tolerance. Also the nominal or 'design' dimension was most valuable to the machine operator in preference to explicit indications of the upper and lower dimension limits.
The paper concludes with a suggestion for and discussion of a compromise method of tolerance presentation which might be more error free and more generally acceptable for all types of reader. [ABSTRACT FROM AUTHOR]

The paper gives a qualitative treatment of a new approach to the synthesis of sequential control systems. Complex sequential control systems can be assembled from a relatively small number of standard sequence packages. These have useful sequential properties in their own right, but the methods for coupling them together to form larger sequential systems are described by the authors. Additional benefit is gained by using the machine actuators alone as memory devices. This removes any possibility of unintentional disturbance of the state of the memory function in the control system. Three examples are chosen to illustrate the design process. [ABSTRACT FROM AUTHOR]

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 drifted, 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. [ABSTRACT FROM AUTHOR]

This paper discusses the use of the geometric programming technique to determine the cutting speed and feed 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper describes the development of a cutting force equation for single-point orthogonal cutting which incorporates cutting speed, feed, depth of cut and side-rake angle. Additional cutting force equations are then developed using smaller levels of the machining variables resulting in reduced experimental costs but retention of reliable predictive equations. [ABSTRACT FROM AUTHOR]

In this paper the Filon's transformed equations have been applied successfully to evaluate the chip-toot 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. [ABSTRACT FROM AUTHOR]

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 2.0 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 0.06 sec. at a very high speed of 342 ft./min. to 1.4 sec. at 11.2 f.p.m. [ABSTRACT FROM AUTHOR]

Apart from the conventional theory of the minimum-cost or maximum-production cutting speed, a new concept of the machining conditions for maximizing the profit for the manufacturing enterprise was presented. Based upon this concept, a n analysis of the maximum-profit cutting speed was made and the theoretical expression for it was deduced.
The first step for economical machining is to select the most suitable type of machine tool for the production purpose. The next problem is to discuss the economics of machining itself, and high-production and low-cost tooling should be considered. Regarding the optimal machining conditions, Gilbert and other investigators analyzed the minimum-cost cutting speed at which the production cost per piece of products is minimum and the maximum-production cutting speed at which the rate of production is maximum.
In this paper, apart from the above concepts, the authors present a new concept of the maximum-profit machining conditions at which the profit for a manufacturing enterprise becomes maximum. Based upon this concept, the economics of machining was analyzed and developed. The expression for the maximum-profit cutting speed was deduced theoretically. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Production Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents an optimization approach for machining for a fixed demand. Determination of the cutting conditions for minimum overall machining cost; Emphasis on the technological constraints related to each operation in machining; Economic effects of batch- and machine-idle time and of other disturbing events.

Analyzes total cost optimization for a single pass turning operation for a given feed and depth of cut. Emphasis on penalty cost for due date violation; Focus on in-process inventory cost; Implications for machining economics.