Category Archives: Math

Posts including calculations and formulas.

How to Measure Cycle Times – Part 1

Quadracycle 1886
The good old cycle times …

The cycle time of a process is a key to match the supply with the demand in lean manufacturing. Everybody working on a shop floor knows the term. Yet, I still find that people sometimes confuse what exactly it means. The cycle time is the fastest repeatable time in which you can produce one part. Hence, in this post as part of a series on manufacturing speed measurements I would like to dig deeper into what cycle times really are, and how to best measure them. As it turns out, there is actually quite some detail on how to measure cycle times, hence I split this post into two parts (second part How to Measure Cycle Times – Part 2), with an additional third post focusing on the details of manual cycle times. Continue reading How to Measure Cycle Times – Part 1

Pitfalls of Takt Times

UCLA Marching BandThe customer takt (or takt time) is one of the fundamentals for determining the speed of a production system. After my post on How to determine Takt Times,  this second post on takt times gives a bit of history, and then goes into more details about possible pitfalls and problems when calculating the customer takt. I also added an example for easier understanding. Continue reading Pitfalls of Takt Times

How to determine Takt Times

The rhythm of your system
The rhythm of your system

The customer takt (or takt time) is one of the fundamentals for determining the speed of a production system. It represents the average demand of the customer during a time period. Whenever you design a new production system or change an existing system, one of the early data inputs you need is the customer takt. While the customer takt can be simply calculated by dividing the demand by the time available for production, there are many more details needed to understand it fully. Continue reading How to determine Takt Times

On the Different Ways to Measure Production Speed

Harold Lloyd – Safety Last!
Trouble with Times…

The speed of your production system is a key aspect of your manufacturing system, and controlling it is important for the success of your organization. Unfortunately, there are many different and confusing ways to measure the manufacturing speed. Even a simple question on how to call a speed is often confused, with many practitioners using the same term for different measurements, or different terms for the same measurements. This post aims to give an overview of what is out there, and what it is good for. Continue reading On the Different Ways to Measure Production Speed

A Eulogy for Little’s Law

Water Tank Littles LawOne of the most significant fundamental relations in lean manufacturing is the relation between the inventory, the throughput, and the lead time. The inventory and the throughput are usually easy to measure. The lead time, however, is more difficult. You would need to take the time when a part enters the system and then take the time again when a part leaves the system. Luckily, the lead time can easily and accurately be calculated using Little’s Law, one of the most fundamental laws in lean manufacturing (and also many other places). Continue reading A Eulogy for Little’s Law

The FiFo Calculator – Determining the Size of your Buffers

FiFo LaneIn my previous post, I discussed how to Determine the Size of Your FiFo Lane – The FiFo Formula. My preferred method is still an expert estimate. However, if you are interested in the math, here is a small JavaScript calculator that estimates a FiFo size for two processes. Continue reading The FiFo Calculator – Determining the Size of your Buffers

Determining the Size of Your FiFo Lane – The FiFo Formula

FiFo Lanes
How long should it be?

FiFo lanes are an important tool to establish a pull system. They are often combined with kanban. However, while there is a lot of information on how to calculate the number of kanban (the Kanban Formula), there is very little information available on how large a FiFo should be. In my last post I talked about why we need FiFo lanes. In this post I want to discuss how large a FiFo should be.  Continue reading Determining the Size of Your FiFo Lane – The FiFo Formula

How Many Kanbans? – Estimation Approach and Maintenance

Number of Kanban
How many Kanban?

In my previous two posts, I described how to calculate the number of kanbans (Post 1 and Post 2). However, this calculation is complex, and the result is nothing more than a very rough estimate. Hence my preferred method for determining the number of kanbans is, broadly speaking,  “just take enough, and then see if you can reduce them.” In this post, I would like to explain this approach and also discuss how and when to update the number of kanbans. Continue reading How Many Kanbans? – Estimation Approach and Maintenance