Less is more manufacturing productivity

Recollections of an memorable project

Thinking about the concept of “less is more”, takes me back to a small and initially unpromising project that a maverick boss of mine persuaded me to get involved in many years ago. It provides an interesting example of counter-intuitive optimisation.

The scene…

There was a manufacturing plant which produced credit cards. The plastic cards were manufactured in sheets; this involved a lamination process which started with a “layup” of three plastic sheets and ended up with them laminated together as one sheet. The lamination was done in a press which was heated and then cooled; this caused the plastic sheets to melt slightly and to become welded together as one.  To produce cards with flat and clean surfaces, each layup also had shiny metal plates on either side to produce a smooth finish.

The instinct …

In the interests of productivity, for each cycle of the press, more sheets of cards could be produced by laminating multiple layups in the press at once. For the people operating the process, this seemed the obvious thing to do; so they put multiple layups into the press, and were happy to see large numbers of sheets being produced on each cycle. If they could have put in more, they probably would have done, but there were other practical limitations.

The stimulant …

Then, one day, along came an “engineer” from the Central Research Laboratories of the company; he started measuring things: temperatures, times, quantities, etc.. The staff at the plant were very friendly and helpful; but, to be honest, he was getting in everyone’s way. He had chart recorders and tangles of wires which, not surprisingly, would break when subjected to the forces of a large hydraulic press. Then he started asking the staff to make odd changes in their processes; cards would emerge from the press melted or, even, burnt; or they would not be laminated at all. And when he started scribbling mathematical formulae on scraps of paper, they knew something strange was happening. As you might have guessed, that “engineer” was me.

The insight …

Many measurements were generated and various, more or less appropriate, theories were considered; but, as is the way with these things, if one keeps plugging away and looking at the thing from different angles, sooner or later a picture emerges.The crucial aspect was that the time required to laminate multiple layups was not only longer than for fewer layups, it was much longer.

A simple thermal conduction model was sufficient to confirm it: the process time depended on the thickness … squared. Laminating ten layups did not take ten times longer than one layup; in theory, it took a hundred times longer.  Once the penny had dropped, I realised that I could have worked that out in two minutes without any measurements; but, until one has dug into the detail of these things, it is usually not clear what to work out.

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The reaction …

Anyway, as you can imagine, radical experimental changes in the parameters of the production process ensued. We dropped from twelve layups to two layups (one layup would have been even better, but again those fiendish practical limitations come into play). Due to this and some other minor changes, process times for each cycle dropped from about forty minutes to about forty seconds; this gave the press operators a lot of work to do, and fewer cups of tea were being drunk. Incidentally, this also led to us providing an automated control system, not long afterwards.

The result …

Everything seemed to make sense experimentally, but would it work operationally? They had no real choice but to try; and, before long, not only the press operators but also everyone else involved in the process was under pressure too. The people who prepared the layups for the press and the people who separated them afterwards could not keep up! Why was this? The reason was that the productivity of the whole plant had increased by a factor of between four and five.

So what had happened? The plant operators were thinking that “more is more” (more quantity leads to more productivity); when, in reality, “more is less” (more quantity leads to less productivity). It was quite a shock for them to be informed of this and, also therefore, that “less is more” (less quantity leads to more productivity). My recollection is that their conversion was not immediate; and I am even not convinced today, more than thirty years later, that it will have been a permanent.

This was simple!

This is no major disruptive change. This was not a case of a process being optimised globally in conflict with the imperatives of localised optimisation. There were no silos being broken down or business models being inverted. This was simply a case of a misunderstanding of the effect of the parameters of a process on its productivity.

Looking back on this project, the idea of “less is more” had played itself out in a very simple way. Before the changes that we made, it is as if greed for more had led to less productivity. After the changes, a lighter weight process with less material consumed on each cycle led to more productivity. If I had had my way, we’d have tried to throw out the press altogether by designing a continuous process using rollers or ovens or both; but that was well beyond my remit!

And, it worked!

Nevertheless, in retrospect, it still seems most unlikely that this little project which, initially at least, involved no investment apart from the time and braincells of a junior research engineer and the considerable efforts of production staff should result in the productivity of a manufacturing plant increasing by a factor of four or five.

Considerable credit for this must also go to the maverick nature of my boss at the time; he had a strong intuition for areas into which it was worthwhile to poke his nose in search of opportunities. In this case, however, it was my nose that he poked into this situation, and I think that we were all very glad that he did!

Less is more!

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