4pManagement Ltd

The client’s brief was to assess an existing wet pouch and to build an action plan to reduce the number of seal failures and decrease the time for incubation prior to the pouches being packed.

Seal integrity is the Achilles heel of Wet petfood pouch production. Whilst the format is great for the purchaser giving single serve portion control and good for manufacturing costs vrs other types of primary packing such as cans. It is notoriously difficult to achieve a low failure rate, comparable to a canning line.

For some product types and countries 100% inspection is required to ensure pouch integrity, but this is costly, space and time consuming.

The majority of Petfood manufactures want single day release, without an incubation time and subsequent inspection.

To achieve this, you need to tackle the problem on three fronts.

• Process control – how repeatable is your recipe do you have a narrow Standard deviation?
• Seal integrity checks – can you predict when you will have a problem?
• Maintenance of sealing heads and mechanical mechanisms on the filling machine that open, fill and close the pouch, what condition are these in?

We also had to establish a base line figure for sealing defects, which required a 100% incubation and sorting for a 2 week period. For this client the worst and best lines were suggested based on their present method of measuring sealing defects.

A maintenance improvement program was put in place, particularly for the ultrasonic sealing heads, on average an ultrasonic sealing head is good for 10 million seals, approx. 1 year to 18 months production on a line.

The fill weight of the chuck was planned to be improved to gain a tighter SD, allowing a lowering of upper limit on the multi-head weigher, this required measurements of emulsion moisture to understand the seasonality and effect of different materials. The key to giving a consistent chunk density.

Viscosity control of the gel was also proposed, a small amount of viscosity circa 500 cps can help to “plug” any micro leaks.

Predictive measurements of the sealing were proposed, such as vacuum decay and Infrared seal mapping.

An action plan was provided together with the capital costs and potential savings for the justification. At this point the client decided to go ahead with the maintenance program and trials for the Infrared system.

As of now they have seen a small improvement, and we are now discussing how to implement the full program in line with some other investments planned for the site.

This is based on two shot fill. If you are using single shot fill, there are other critical parameters to measure such as Viscosity, emulsion moisture & fat. Plus, maintenance regimes for the volumetric and dosing pistons.