ABSTRACT
Today the basic method of equipment scheduling in the surface mining industry is to determine the equipment required to maintain the desired tonnage and to then schedule only the required equipment to do the job. In the event of a breakdown, production is maintained by the crew picking up another machine on standby or just out of repair. In order to properly schedule and size the overall equipment fleet, knowledge of a number of factors dealing with machine availability and utilization are needed. In this regard, one or more of the following terms are used:
• availability • operational availability • mechanical availability • physical availability • utilization • use of availability • working efficiency • job efficiency • operating efficiency • effective utilization The calculation of useful hours or minutes is accomplished by applying these factors to
various periods of time. Time expressions such as • scheduled hours • annual hours • total hours • working hours • shift hours • operating hours • efficiency hours
may be used. Unfortunately there is little consistency with which most of these terms are used and their values calculated in the mining industry today. ‘Availability’ to one mining company may not have the same meaning to another mining company or to a supplier of mining equipment. In this section, the authors have attempted to provide a consistent set of definitions and formulate an overall logical framework for these important concepts.
A number of different information sources have been drawn upon in this effort and some new terms have been applied. It is hoped that confusionwill be reduced rather than increased with this approach.
