摘要:

In general, developments in the design of rotary drill bits have proceeded in three main directions dictated largely by the properties of the materials that were being drilled and by the materials that were available for constructing the bits. Typical examples are firstly, screw point augers and centre bits for drilling relatively soft materials such as woods; secondly, spade bits and twist drill bits, which have more robust cutting edges, for drilling metals; thirdly, diamond bits, roller-cone and fish-tail bits for drilling relatively hard brittle materials such as rocks. New materials are being developed that cannot conveniently be classified under these headings, eg filled plastics, laminates, etc. Consequently production engineers are being called upon to drill such materials, often with drill bits that have not been specifically designed for the tasks they are being called upon to perform.As a consequence of specialization, drill bits and drilling techniques have been developed by engineers in different fields of engineering virtually unknown to each other. In attempting to adopt a completely fresh approach to drill bit design the author was led to consider the various ways in which holes are manufactured and the roles played by drill bits. A brief reference is made to the methods used by animals and plants. This could provide a useful field for research into new hole-making methods.The importance of considering the way in which a drill bit is to be used is emphasised, and some suggestions for definitions are given, in an attempt to clarify some of the confusing terminology found in some of the literature on drill bits. A classification system is described which originated from a collection of information on drill bits.

DOI:10.1049/tpe.1975.0272

出版商:IEE    

年代:1975

数据来源: IET

摘要:

Advanced programmable desk calculators and mini-computers can provide an invaluable aid to production management. Highly effective systems can be designed at a fraction of the cost associated with conventional computing.The paper describes how a desk-top computer can be used in the process of deriving standard work-measurement data, especially for highly-variable work.Once the standard data has been compiled at known accuracy levels, and the correct degree of precision, then the desk-top computer can be gainfully employed as a tool in the estimating process. Standard data can be applied rapidly and with great accuracy to the various key parameters that affect the cost of a job. This is valuable at the quotation stage, as well as at the shop-floor level.It is not only in the labour content of a job cost that desk computers have apart to play. Two mini-computer systems are described that enable high material productivity to be achieved. The specific examples chosen are semi-standard packages for reducing cutting waste when cutting regular shaped parts, eg rectangles, from sheet stock. Similar approaches can be made when cutting other shapes.

DOI:10.1049/tpe.1975.0273

出版商:IEE    

年代:1975

数据来源: IET

摘要:

The purpose of the investigation recorded in this paper was to find out what, if any, differences exist in the organisational characteristics of firms that use a Group Technology approach and those that use other methods of manufacturing organisation. Four firms, all well-established in the operation of GT systems, were investigated and their organisational characteristics compared with firms of similar product ranges covered in the Woodward surveys. While structural changes in organisation had been made in the Group Technology firms, it was found that these did not take them outside the broad limits of the staff and other ratios of the comparison base. The variations found may be indicative but are not definitive.The investigation shows the need firstly for better identification of socio-technical systems used in firms of all types and the reasons for their adoption, and secondly for recognition that the situation in any efficient firm is dynamic and will change from year to year to meet the needs of the situation with the resources available.

DOI:10.1049/tpe.1975.0274

出版商:IEE    

年代:1975

数据来源: IET