An Equipment Replacement Decision Model that Lets You Review Your Equipment Replacement Strategies and Make Sound Equipment Replacement Decisions
Download a Microsoft Excel based modelling tool used to select optimal equipment replacement or refurbishment time periods
Optimize equipment replacement decision making with an Excel Spreadsheet for Weibull modelling equipment replacement intervals that minimise both maintenance costs and the number of equipment failures.
The replacement modelling tool allows you to use historic equipment failure mode data to model a Weibull distribution plot for the equipment. The equipment replacement interval optimisation tool lets you use site specific information to conduct ‘what-if’ analysis for minimising your equipment operating life maintenance costs.
The Modelling Software Optimizes by Using Actual Equipment Maintenance Costs and Equipment Failure History
The equipment modeled in the image below had five failures to-date during its operating life. It had also been overhauled periodically between the recorded failures. A new equipment item, or an ‘as good as new’ rebuild would cost $10,000. The business-wide costs of a breakdown are $25,000. The failure data points (noted as non-parametric) are plotted over a Weibull distribution and the fit is workable for the situation being investigated. Based on the failure data the model advises the optimal period to replace the equipment with new, or completely overhaul it with new parts throughout, is every 26 months (2.2 years). Over time this strategy would minimise business-wide breakdown costs to about $8,000 per year with the least number of failures.
The necessary requirement is that the equipment is always replaced with new equipment, or totally rebuilt ‘as good as new’ and not merely overhauled and returned to service. Overhauls mix old and new parts during the refurbishment and the old parts, already having had a prior life, failure prematurely. That is why overhauled equipment always fails sooner than new equipment in the same service. Complete ‘as good as new’ replacement ensures all parts start in a brand new condition with maximum operating life.
This equipment restoration/replacement optimization modelling tool was developed by Howard Witt, a professional reliability engineer with over 25 years hands-on industry experience, including nuclear facilities and industrial process plants.
View a PDF document showing the use of the Equipment Replacement Optimization Model
Plant and Equipment Replacement Optimization Model Example
View a PDF document of the first few pages from the User Guide for the Equipment Replacement Optimization Model
Extract of Equipment Replacement Optimization User Guide
Because it is unknowable how applications will be used, their Developer and Lifetime Reliability Solutions take no responsibility for correctly modelling the situation, or for the outcomes of using an application.
It is recommended that you understand well the theory behind the application you use, so you can confidently judge whether it applies to the situation under investigation and if its output is sufficiently accurate in the circumstances. Remember the warning that applies to all equipment replacement decision modelling methods — ‘garbage in, garbage out’.