Plant efficiency: a value stream mapping and overall
equipment effectiveness study

Abstract: In this Masters Thesis the Overall Equipment Effectiveness, OEE, and Value
Stream Mapping, VSM, were used for measuring and making production more
efficient as part of Lean Manufacturing. The work has been carried out
during the spring and summer of 2004 at some of the foundries of INTERMET
Corp in the USA.
The INTERMET foundries use OEE and VSM tools to report their results to the
company headquarter and to follow up and continuously improve their
effectiveness.
The fact that OEE is used to compare the different factories might lead to
it
not being utilized as well as possible. The OEE number is basically a very
good measure of the effectiveness of the machines, but should primarily be
used for internal supervision of trends. If it is used to compare different
factories, the temptation to adapt the values to the expectations might
reduce its contribution to the real work of making production more
efficient.
VSM is a simple and efficient method used to focus on the path a product
takes through the value adding chain and to generate good ideas for how to
develop, simplify and make this more efficient. The important thing to
think
about when starting VSM work is to be prepared to implement any
improvements
quickly, otherwise the results soon will be forgotten and VSM will lose its
status as a good and efficient tool.
INTERMET should continue their OEE measure for the plants for continuous
improvement of the machines and not as a measure for comparing plants. This
will be misleading as different plants have different machines.
INTERMET should also continue to do VSM mappings on a regular basis to see
if
the plants actually do change their processes in a lean manufacturing way.