For Gypsum Board Aficionados – Deming 4th Principle

I accept this is for a small audience, maybe just for me.

Anyhow, it needs writing, after thirty plus years.

Plasterboard* is a simply made product. Slurried plaster is continuously formed between two sheets of creamy coloured face and less processed back plaster linerboard. These are the key raw materials in manufacture. Gas is the other key cost.

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For the each of the three widths of plasterboard, 900mm, 1200mm and 1350 mm, a face and back plaster linerboard are used to suit. The cream faced plaster linerboard is wider in each case to allow the formation of an envelop to contain the slurried plaster. A narrower back plaster linerboard is glued to the face plaster linerboard forming the envelop.

Thus six different sizes on plaster linerboard are used for making the three different widths of plasterboard.

The plaster linerboard width, both face and back are made by the paper manufacturer on a paper machine of fixed width. The sizes needed are cut at the end of the paper making process, the side trim being recycled. Recycling the trim reduces the strength of the paper. The set up costs monthly for the paper maker are huge.

I thought, what if we, the plasterboard manufacturer was to reduce the amount of trim the paper maker incurred.

Face paper making typically required slitting of the jumbo paper rolls into 3 customer rolls and a waste trim. For back paper the jumbo roll was cut into 4 plus a waste trim, The waste trim was between 10 and 13 percent of wasted jumbo roll.

What if the jumbo roll was cut in integer rolls of the machine width? For face paper this would be an exact three rolls and for back paper rolls four. Change overtimes at the slitters would be significantly reduced. Run times for a single width increased.

Simple mathematics easily demonstrates this principle.

However, the look of plasterboard would be changed. Instead of a minimal glued overlap, the overlap would be wider. The plane of weakness at plasterboard edges would be eliminated and a stronger and less curl sensitive product would result.

These superior quality outcomes and operational possibilities was demonstrated in a trial of two 60 sheet pallets made at our factory in by Dale Seeto and me.

Stock sizes of plaster linerboard would be reduced from six to two. Freight and stocking costs could be reduced.

The paper maker could reduce the number of paper makes from 13 per annum to 10 or 11. This is not insignificant considering the paper maker set up costs and the saving of a makes worth of trees. The paper is arguably stronger with less degraded recycle in it.

On presentation, the paper maker technical folk wondered how such an idea hadn’t come up before.

The quality folk at the plasterboard manufacturer were impressed by the improved edge strength and smoothness of the sheet.

For reasons better left unsaid, the idea was not adopted. What can be said is that haggling over price with paper manufacturers had become de rigeuer, rather than working collaboratively for mutual benefit. Likewise sharing good ideas for everyone’s betterment least of all the consumer was anathema.

W Edwards Deming 4th principle “Use a single supplier for any one item…” was ignored.

The two pallets we made were stored in a corner somewhere some thirty years ago.

I took a sheet of it with me on my subsequent travels. That sheet got smaller and smaller. All that’s left is the scraps below, a framed back, face and edge, and this post

Perhaps one day?

Yes that’s Samson showing the interest most reader’s will have.

Interested? Comment or email, I think I still recall enough technical details!


*Plasterboard is also known as Gypsum Board.

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