Conveyor Blog

Update: I recently made some changes to this article. Most assumed that I was in favor of always slowing down to increase throughput, but it’s actually only advisable if you can increase efficiency by a significant amount (10-20%). All the changes are in the last paragraph.

Can you increase efficiency and throughput by slowing down?

I recently had a discussion with a customer and an engineering firm about increasing throughput by slowing down the rate of a labeler from 400/minute to 380/minute. They recorded an improvement in efficiency to justify the change.  I questioned the decision from a thruput standpoint and wanted to come up with a good way to determine if an increase in efficiency actually increased the thruput or not.

Is slower better?

Efficiency is calculated using the following formula:

MTBF / (MTBF + MTR)

MTR = Mean Time to Repair
MTBF = Mean Time Between Failure

A properly buffered line should have capacity to handle the longest MTR on the line. The difference in maximum rates should be such that the table can go from full to empty in less time than the MTBF. For example, if you have a line like this:

Your labeler must have a MTR of 3 minutes or less and an MTBF of 9.9 minutes or more, giving us a minimum labeler efficiency of 77%. So what if I decrease my max rate in an effort to improve efficiency?

My minimum required MTR is the same since I’m still filling the buffer at 330 bpm, but my minimum required MTBF is now 19.8 minutes. This gives us a way to measure whether the decrease in rate has affected throughput. My labeler efficiency must now remain above 87% (19.8 / (3+19.8)) to keep the filler running and maintain throughput.

As the labeler slows down, its efficiency must go up to maintain throughput for the packaging line.

The formula can even more simply be expressed like this:

e = (Fr / Lr)

Where e = the minimum efficiency needed to maintain throughput
Fr = the max rate of the constraint
Lr = the max rate of the machine in question

If I run the labeler at 400 bpm I need to maintain a labeler efficiency of 77%. If I run it at 380bpm, I must maintain an efficiency of 87%. So if slowing the max rate of the labeler resulted in improving the efficiency from under 77% to something over 87%, then yes it will have improved throughput. If they were already running above 77% prior to the rate change, then throughput will be unchanged. If efficiency is under 87% after the rate change, then throughput will decrease.

In practice you have to find the right balance between rate and efficiency. It may be tremendously more difficult to maintain 87% than 77%, due to inconsistent materials or operator error.

Business books come in three types: Great, bad, and awful. Here are my favorites.

The Goal by Eli Goldratt

The Goal by Eli Goldratt: Classic novel about the theory of constraints. I didn’t understand my job until I read this book.

Getting Things Done by David Allen: Read this book if you want to complete projects that have been lingering for years and be productive despite everyday distractions. Can’t recommend it enough.

The Visual Display of Quantitative Information by Edward Tufte: There’s a science to making great charts and graphs and this is the textbook. If you make charts for your job, you absolutely have to read this. See our results.

Priceless by William Poundstone: Before switching to Computer Science I toyed with being an Economics major in college. It’s a fascinating science and helps explain many things in the world. This book helped me understand that when it comes to price, throw economics out the window because psychology is everything.

The Long Tail by Chris Anderson: 20th century mass market products were about producing hits. Distribution and production costs have sunk so low, it’s now about producing anything for anyone. Does this book apply to our business? The constant stream of custom quote requests says yes.

The Toyota Way by Jeffery Liker: The Toyota Production system changed world wide manufacturing and this is probably the best written example of what it is.

The Wisdom of Crowds by James Surowieki: Polls are almost always right and committees are usually wrong. This book explains why.

Rework by Jason Fried and David Heinemeier Hansson: A takedown of standard business practices and ideas for new companies.

Any suggestions?

We have a Garvey twitter account, but I mostly use it for internal communications (read this for an explanation). I spend much more time and effort on my personal twitter account trying to engage customers and the industry right along side friends and strangers. I think the only way social media can benefit our business is by participating as a human being and not a company. PMMI’s Michael Hess put together this video to show how they’re utilizing social media and enhancing our own social media efforts.

So far Twitter has been a fun distraction during the show and has gotten us some free press as an early adopter. It will be interesting to see how it will be used during Pack Expo in Chicago this year.

The best social media mavens aren’t robots spouting their company press releases. They post about whatever interests them and occasionally comment on industry news and events. It should go without saying that their posts may not always represent the views of their respective companies, but I’ll say it anyway. Here are some great industry tweeters:

PMMI
The Packaging Diva
Jake Garvey, Garvey Corporation
Michael Senske, Pearson Packaging
Mike Collins, Federal Mfg Co.
Kate Putnam, Package Machinery Company
Steve Windham, Omron
Marc Ostertag, B&R Automation

My entire packaging list.