Simulation in manufacturing: A regression metamodel approach

A simulation modelling, using a simulation language SIMPLE++, was used to study the personnel capacity utilisation in a maintenance department. Input data included work orders with different throughput times, different personnel profile based on work order requirements, and different prioritisation rules. A decentralised maintenance department was assumed, whereby each department had its own maintenance unit. The effects of personnel organisational policies on the capacity utilisation of the personnel and on the throughput time of maintenance work orders were studied. The results of the simulation show that the best utilisation of the personnel and the best throughput time of maintenance work orders is obtained if the maintenance personnel are allowed to function across the borders of their department (here termed as exchangeability of personnel). Likewise, if there were universal maintenance personnel (i.e. who could take both electrical and mechanical work orders), then there would have been an optimum staffing of the maintenance department.

An analysis of personnel capacity requirement in the maintenance department by using a simulation method

In this paper we introduce a model to determine the maintenance float needed to maximize the availability of an operating system with N number of circulating units. An implicit enumeration algorithm is used as a solution technique to the closed queueing maintenance network with two types of repairs: minor and major repairs. It is shown that when there is no differentiation of repair type, this special case is obtained as a by-product of the two-repair-centre model. This paper assumes exponential failure times and exponential repair times with load-independent servers. The approach followed in this paper provides an approximate and simple way to solve the maintenance-float problem of this complex closed-network system.

A Closed Queueing Maintenance Network with Two Repair Centres

This paper applies Buzen's algorithm to the problem of determining the maintenance float needed to support an operating system with N circulating units. A maintenance network with load-independent servers is assumed. The operating system availability and maintenance floats are obtained using this iterative algorithm. It is shown that the normalizing constant used in the algorithm can easily be computed for the maintenance float problem by using geometric series. This result is further used to obtain a simple model for the expected number of operating units, thus making it easy to compute the operating system availability for any given N. Buzen's algorithm therefore provides a simple solution to the maintenance float problem.

Determination of maintenance floats using Buzen’s algorithm.

Polynomial metamodelling and Taguchi designs in simulation with application to the maintenance float system

This paper describes an operational system composed of a number of independent but similar units. A given number N must be in service and to ensure this a maintenance float is provided. The float comprises units under repair and in an equipment reserve. Float factors are estimated using a Weibull distribution for failures and a log-normal function for repairs. Both functions are applied to an engineering case study and the estimated float levels are compared with a simulation of the field data. Optimum float levels are developed using a simple cost model.

W. Lewis

Papers

Reliability analysis based on the Weibull distribution: an application to maintenance float factors