A QUEUEING ORIENTED DECISION PROCESS FOR CAPACITY PLANNING IN A JOB SHOP ENVIRONMENT

Abstract

A queueing oriented decision process for capacity planning was discussed m this thesis to show how queueing systems models can be a pplied in capacity plan ning to reduce the waiting time for all work orders (demand) and as a resul t, reduce the cost. This was done using a mathematical model for capacity planning in a job-shop environment under the constraints of the total produ ction cost a nd through a gi ven time period. This leads to savings in the capaci ty, and thus reducti on in the total production cost.

This subject was discussed through th e follow ing :

l . Using k nown mathematical models for queueing systems to obtain the wai ting time for every prod uct separatel y and design the necessary produ ction capacity to achieve these products within limited time period. Different serv ice policies were used in every case separately. The mathematical model is composed of:

a) Objective function: the total production cost (setting - production­

storage- fi xed-...- etc).

b) Deci sion variables: the production batch size, the inventory level, and the number of setting times. c) Constraints: the production capaci ty.

2. Devel opment of a mathematica l model m case of multi-server senes queues where the product is produced in more tha n one step. This is done for di fferen t number of production batch si zes. 3. Design of a software program a nd using this program to solve the m athematical models and to get the results of the queueing systems models.