Production Scheduling – Every Part

This post is part of our series discussing the 7 lean manufacturing guidelines. In this post we’ll discuss the every part every interval – EPEI – metric.

Post 1: The 7 Lean Manufacturing Guidelines
Post 2: Building to Takt Time
Post 3: Developing Flow
Post 4: Supermarkets & Pull
Post 5: The Pacemaker Process
Post 6: Leveling the Mix
Post 7: Leveling the Volume

The last of the seven guidelines for designing a lean future state is to develop the ability to make “every part every day” (then every shift, then every hour, or pallet or pitch) upstream of the pacemaker process.

The EPE & EPEI Lean Manufacturing Metric

Every Part Every (EPE) or Every Part Every Interval (EPEI) is a key lean metric especially for high mix manufacturers where machine changeover times are critical to determine available capacity. In brief, EPEI is the length of time that it takes to cycle through all the members of the product family including the changeovers between products. Or looking at it another way, EPEI sets your production batch sizes and therefore buffer inventory levels. The math for an EPEI calculation can be a bit daunting. See my blog series on EPEI for all the details on both the math and the meaning.

Calculating EPEI

EPEI should be calculated for every machine-based process and then used to establish the targeted stock level for all of your intermediate inventories replenished by these machine-based processes. That’s why the guideline is specific to upstream of the pacemaker.

Note carefully that the guideline is not to just calculate and know your EPEI but to work to continuously reduce that EPEI. In doing so, you continue to free up inventory and reduce overall lead time. In fact, EPEI is an excellent candidate for an overall lean metric that you should want to track over time to ensure that your EPEI is continually reducing.

Since this series is focused on production scheduling, it’s worth noting that EPEI is not directly related to any new production scheduling technique. It’s useful in helping to set your targeted stock levels for all of your upstream inventory supermarkets.

Future State Design Requires EPEI

Your future state design isn’t complete until you have calculated EPEI for each machine-based process and have compared to your targeted stock levels in supermarkets.

I hope that this series has been helpful to explore the various methods of lean production scheduling and how the future state design guidelines help you to identify opportunities to continually reduce lead time and reduce waste in your operations.

In future posts we’ll look at how production scheduling using lean principles is implemented in Microsoft Dynamics AX Lean Manufacturing.

Written By:  Phil Coy