Performance Analysis of a System in a Underproductive State
It is very common during industrial processes that failures
in a system’s parts can lead to a underproductive state. In a situation like this
production doesn’t stop complelety but impact for company’s income can be severe.
RAM products give needed tools for examining of this kind of a misfunctional
In the given fault tree above we can see some situations
where a system doesn’t work at the optimal level. Failures in the motors or the
belt can cause underproduction. System uses the two motors at the same time and
failures in the more powerful motor lead to 75% underproduction and failures in
the smaller capacity motor lead to 50% underproduction. System breakdowns
completely if both the motors are in a failure state simultaneously or if the
belt loosens. When we give failure probabilities to the motors and the belt it
is possible to calculate every part’s (including TOP) failure probability. After
doing this it is possible to solve eg. which part is the bottle neck of the
system and how much the system will be improved after making the critical part
First thing to do during cost
accounting is to give separate repair expenses for the motors and the belt. Then
we can give costs for each underproductive state (50%, 25%, 0%). The tree should
contain NOT-conditions in order to avoid unwanted overlapping of costs. Thus the
system cannot be at two states simultaneously (eg. the system operates at
capacity of 50% and the system operates at capacity of 25%).
described above can be fulfilled with help of the ELMAS program. If more
versatile results are needed we can use RAMoptim for achieving this goal. In
that case we can give (eg. the motors and the belt) failure tendencies and
distributions of failure times for parts. Also parts’ operation restrictions (eg.
should part be stopped during repair of another part), maintenance programs and
different costs (eg. personnel, spare part) can be given. The RAMoptim software
calculates the system’s true availability, maintenance costs and personnel
demand after the required inputs have been given.