Condition monitoring of belt based motion transmission systems

A key asset of Royal Mail Group consists of a nationwide network of sorting offices that forms a constituent component of the means through which the organisation provides an efficient nationwide postal service within the United Kingdom. It may be argued that the efficiency currently possessed by modem sorting offices is due to the utilisation of machines that automate the process of sorting items of mail. The modem letter-sorting machine possessed by Royal Mail can sort up to 30,000 letters per hour; such machines serve as an example of an achievement of the application of Mechatronics. The maintenance of letter sorting machines constitutes a large overhead for the organisation. In the face of competition from pervasive electronic media within the personal communications market and the prospect of deregulation, Royal Mail seeks to streamline its operation in part by the reduction of the overheads incurred through maintenance of letter sorting machinery. The adoption of condition based maintenance techniques and predictive maintenance, for letter sorting machine components such as belts and bearings, forms part of the strategy through which Royal Mail seeks to reduce this overhead. Utilisation of flat belts and timing belts for the implementation of key functions in letter sorting machinery, such as the transportation of items of mail within the mail sorting process, results in the use of many such components within letter sorting machinery. A direct link exists between the maintenance of peak performance of a sorting machine and the maintenance of belt drives; as such the maintenance of belt drives forms a substantial component of the maintenance overhead. The focus of this thesis consists of the condition monitoring of belt based motion transmission systems and in particular, flat belts. The research that forms the basis of this thesis consists of three elements. Firstly, consideration of current knowledge of belt based power transmission such as knowledge of the mechanics of the belt based power transmission process within the context of condition monitoring... [cont'd

Variation between manufacturers’ declared vibration emission values and those measured under simulated workplace conditions for a range of hand-held power tools typically found in the construction industry

Tool manufacturers are required to declare the vibration emission of their hand-held power tools in order to sell them within Europe. To enable comparison between different manufacturers, tests are carried out in accordance with the relevant test code (such as those defined in the ISO 8662 and EN 60745 series). These tests may be carried out in artificial circumstances which do not necessarily correctly predict the vibration emission that would be obtained in the workplace and often underestimate the magnitude of the vibration. In practice, tools are used with a range of inserted tools on different materials, resulting in a range of vibration emission values for a given tool. CEN Technical Report, CEN/TR 15350 provides multiplication factors to enable an estimate of the workplace vibration emission to be obtained from the manufacturers’ data. This paper compares the manufacturers’ declared vibration emission values with those measured for the public-domain OPERC HAVTEC database. The OPERC measurements have been made according to ISO 5349 using simulated workplace conditions, with a range of inserted tools for each machine tested. A total of 656 tool/attachment combinations are presented from 105 different tool models, covering a wide range of applications typically found within the construction industry. The measured data is compared with the manufacturers declared emission value, with and without the multiplication factors given in CEN/TR 15350. It was found that, in general, the manufacturers’ declared values underestimated the workplace vibration emission, whereas the multiplication factors given in CEN/TR 15350 overestimated the workplace vibration emission