SOURCE:

Faculty: Engineering
Department: Electronic And Computer Engineering

CONTRIBUTORS:

Ezema C. Nnaemeka
Okezie C. C.
Okafor E. C.

ABSTRACT:

This work is an implementation of modified JIT manufacturing technique in Juhel Drug Processing Plant. It is a shop floor framework for optimal Common Frequency Routing (CFR) of a Just-in-Time (JIT) system with time-varying demand and flexible production capacities. JIT systems are kanban-controlled production systems where the flow of material is controlled by the presence or absence of a kanban, and where kanbans travel in the system according to certain rules. Problems encountered by the Drug Process Plant include long lead time to customers, no visual method to observe the work in process and extra storage held to anticipate rapid changes of demand. Furthermore, the manufacturing operations face considerable uncertainty and were considered stochastic due to uncertainty in timing customer orders, variability in the processing time, scrap rate and rework, inaccuracy of demand forecasting and uncertainty of equipment failure. The objectives of the study among others were to design computer based production control system, develop a discrete event simulation model for a JIT production line (Juhel Drug Process Plant), deduce the effect of JIT manufacturing system alternative on average throughput- time, demand fill rate, and/or net operating income for a given level of product mix complexity and a given manufacturing overhead level. The study also investigated the effect of trigger point on cycle time / Work in Process (WIP) and the effect of number of kanbans on flow time / orders satisfied. In this work, ARENA / SIMAN and TECNOMATIX simulation software were used to investigate the effects of dominant factors in the implementation. Several factors such as number of buffers, location of buffers and scheduling rules are investigated. This study utilized a modified version of ARENA’s existing “Electronic Assembly and Test System with Part Transfers” as a baseline model. Results reveal that the JIT system implemented at the Drug Process Plant led to inventory reduction at the end buffer, shorter customer lead time and better visual control. The new system after physical implementation on the shop floor recorded 26.7% increase in Net Operating Income (NOI), 39.4% increase in Demand Fulfillment Rate (DFR), 39.5% increase in inventory turn-over and 36.8% increase in WIP. It also recorded 19.2% decreases in cycle time, 32.7% drop in Throughput Time and 20.9% cut in Flow Time. This shows that the new system (JIT manufacturing system) was effective in reducing Cycle Time, Throughput Time, Flow Time and consequently led to increased NOI, DFR and WIP. Results also indicate that NOI differs significantly for manufacturing system (F(2, 1593)=1704.381, p=.000, ήp2=.682), manufacturing overhead level (F(2, 1593)= 31768.716, p=.000, ήp2=.976), and product mix complexity (F(2, 1593)=20449.024, p=.000, ήp2=.963). Manufacturing overhead level did not have a significant impact on DFR (F(2, 1593)=.038, p=.962, ήp2 =.000) or average cycle-time (F(2, 1593)=.014, p=.986, ήp2 =.000), nor do any of its interactions significantly affect DFR or average cycle-time.