EPEI stands for Every Part Every Interval and is used to calculate the lot size for production over a given time period, such as days or weeks. It indicates how many times a part is produced. Implementing quick changeovers allows companies to reduce lot sizes and EPEI. A lower EPEI means less inventory and shorter lead times. However, this must be balanced with setup costs, which should tend toward zero, and the ability to process completed batches without backlogs. Calculating EPEI involves identifying production equipment, parts, times, and comparing to total available time to determine the minimum runs needed to meet customer demand.

1. EPEI – Every Part Every Interval
Overview of the purpose and
application of the tool
Tiago Lopes, Industrial Engineer/Executive MBA, May 2014

2. What is the EPEI ?
• EPEI stands for Every Part Every Interval. Normally the
interval is then replaced by the time period relative to the
calculation – day(s), week.
• EPEI is the lot size expressed in time.
• It is an indicator to follow the number of times a part is
produced. The primary reason for implementing quick
changeover is to be able to reduce the lot size...

3. “Mind map” on interdependencies of cost
Cost
Materials
Labour
Process
Equipment
Overheads Central
Finished
products
Variances
Volumes
Batch size
Inventory
Availability
space
Obsolecence
Design
Specifications
Suppliers
Delliveries
TAKT
Packaging
Spare parts
Financing
Technical
validation
Efficiency
Cycle timeScrap
SuppliersIT
Facilities
Energy
Maintenance
Marketing
Waste
Utilization
Depreciation
Indirect
Labour
Quality
requirements
Handling
Laboratory
Research
Development
Sales
Rent
Consultancy
Other
Equipments
Building
Tools
These issues are being addressed
directly (but indirectly many others
are impacted )

4. The mechanics…(1/2)
• Identify the equipment (line, machine, etc.) to apply the
study
• Identify all the parts to be produced on the equipment (e.g.
Part A; Part B; Part C)
• Identify the production time and setup time of the parts
(e.g. Total time A = Production time A + Setup time A, etc.)
• Add all the times and compare to total available time for the
equipment. This is the “minimum” required to produce the
customer needs
• The difference can be used to “break” the required
production into smaller lots. Any improvement to the setups
will allow to divide production into more/smaller lots

5. The mechanics…(2/2)
• Start identifying times
(EPEI = 1 per interval)
• Reduce lot (increase
EPEI), «breaking» lot
into two, repeating
setup (EPEI = 2/i)
• Reduce lot even further
with reduced setup
(EPEI = 3/i)
A B C
Free time
Total available time

6. Conclusions
• The goal is to have a lower EPEI - why would we
want this? If we have a smaller EPEI, we can have
less inventory and shorter lead times. If your EPEI
is one week, you will need to have about 5 times
more inventory (and lead time) than if you had an
EPEI of 1 day.
• But this needs to be balanced with the costs of
setup (which we all agree need to tend to zero)...
• … and that produced batches can be evacuated –
meaning that batches are not going to «sit» in the
warehouse

7. Who am I?
• I’m an Industrial Engineer and exec. MBA
• Experienced in
– Management: Plant Management, Business management,
Project Management, VA/VE and other special projects
– Operations: Supply chain, Industrial footpath & Green field
operations, Lean process installation & Ergonomics, Lean 6
Sigma continuous improvement
– Finance: P&L, Cost calculation, Price target strategies
– International footpath,
– Passionate for sci-fi and strategy