When the label printer and pad supplier change together

Two changes in one month: a new label printer in week one, a new pad supplier in week three. By week five the complaint log has three entries about wrinkled film and one about a wet pack, and nobody can say which change caused what. That is the predictable cost of changing two variables inside one production cycle, and it happens constantly because purchasing runs on annual contracts and maintenance runs on its own timetable.

The individual changes are both sensible. Together they remove your ability to diagnose anything.

Two variables, one month

A new printer changes ink coverage, web tension and the heat applied to the film. A new pad changes thickness, surface texture and how much water it holds. Both affect how a pack looks on the shelf, and both can produce condensation, wrinkling or a loose wrap.

When they happen at once, every symptom has two possible causes. The team picks the one that is easier to blame, usually the pad, because it is the cheaper supplier and the newer relationship.

There is an organisational reason this keeps happening. The printer is an engineering purchase and goes through maintenance, the pad is a consumable and goes through purchasing, and neither team sees the other’s installation date. Both changes are logged, in different systems, by different people. Nobody is being careless. The information simply never meets.

A wall chart with every packaging change on one line solves it for the price of a sheet of paper. If two changes land within a month, one of them moves, and the argument about which one is usually settled by the contract dates.

The three-week chase

A plant we know spent three weeks chasing a pad problem that was not a pad problem. The new film had a lower moisture transmission rate than the old one, so moisture that used to escape through the wrap now stayed inside. The pad was doing its job and taking more water than before, which made it look like the culprit. Two pallets of perfectly good pads were returned before anyone measured the film.

The test that settled it took an afternoon: same product, same pad, two films side by side for five days. The film was the variable all along.

A bridging trial you can run in a day

If the changes cannot be separated in time, separate them in the trial:

• Old pad with new film, six packs.
• New pad with old film, six packs.
• New pad with new film, six packs.
• Old with old, six packs as a control.

Hold all four cells in the same chiller, on the same shelf, and photograph at day one, three and five. Twenty-four packs and one afternoon will tell you which variable is responsible, which is faster than three weeks of guessing.

Photograph from the same spot every day, with a ruler in frame for the wrinkle. A phone on a bracket taped to the shelf gives you comparable images, and comparable images are the difference between a discussion and an argument. Record the chiller temperature at the same time, because a two-degree drift will confound the whole trial and you will not notice it without the number.

What to keep in the change file

One page per change, with the date, the old and new specification, the lot codes, and the person who signed it off. Add the complaint count for the four weeks before and after. When a retailer asks why a pack looks different, that page is the answer, and it takes ten minutes to write.

Keep the physical sample as well, one pack from each cell, labelled and held for the shelf life plus a week. A photograph persuades, a pack settles it.

There is a cheaper option, which is to leave four weeks between the two changes. Most sites can do this if someone owns the calendar, and almost none do, because purchasing and engineering sit in different meetings. Put both dates on one wall chart and the problem mostly disappears. Guidance on how pad thickness and surface affect wrap performance sits in the absorbent pad guide.