Packaging manufacturers are studying ways to further reduce the weight of bottles, without affecting its performance

In recent years, many bottles, carbonated soft drinks and water, have reduced its weight. As a result, preform them for these bottles also have reduced his weight between 20 and 30 per cent. In a constant effort to improve profit margins, packaging manufacturers continue studying ways to further reduce the weight of the bottle, this made affecting the performance of the same.

Is it possible to manufacture lighter bottles? The answer depends on the implementation of the bottle. Certain factors that should be taken into account, as well as the resources available to evaluate the new lightweight packaging are detailed below.

Resin costs are those that influence the total cost of production of a container.

Figure 1, below, shows the usual breakdown of the Total productivity of the team (PTE), taking as an example application of moulding by conventional injection.

This figure shows that a reduction of 5 per cent of the weight of a piece can bring a saving of 4.4 per cent in the cost of the product, while a reduction of 5 per cent of the costs of equipment translates only 0.26% of savings in the cost of the product.

The key to increasing profitability might invest in a program of prototyping to investigate about possible solutions for the reduction of weight of the packaging.

Figura1: Breakdown of the Total productivity of the team in the case of a conventional application (source: Husky Injection Molding Systems)

Figure 2: Savings by reductions in weight in grams depending on the volume of preform them planned (source: Husky Injection Molding Systems)

Figure 2 shows clear reductions in weight in grams and the cost savings associated with the volume of production.

Following the consolidation of certain high-volume production of PET containers, there is an increase in the activities of the packaging weight reduction. For example, in recent years, the individual bottle of 0.5 liters of water has been an important activity in order to go below the barrier of the 15 grams of weight. In the same way, he has worked with 1-1.5 liter water bottles to reduce cycle times through reductions in pesos. In the case of the carbonated soft drinks, there is scope for reducing the weight and the one-time 500-600 ml packaging cycle times, while the containers of 2 litres, weight is reduced below 48 grams.

Figure 3: Evolution of the weight of the packaging at the time (source: Husky Injection Molding Systems)

The value of a prototype is not only defined an optimum weight. A prototype can also serve, inter alia, to ensure that:

• The relationship between the thickness of the side wall of her it preforms and its length does not require a very high injection pressure.

• Her preform it desmoldea and is correctly transferred to the plate of the robot.

• Preforms them are easily positioned before arriving in the area of blowing.

• Her preform is transferred correctly during the blowing process.

• The window of the blowing process conforms to the equipment and the environmental conditions.

To properly assess the quality of the performance of a bottle lightened before moving on to the stage of production, a prototype is essential.

For applications that require modifications of the stem and cavity, many transformers decide to produce preforms in a plant of prototyping and then test them on the blowing machine used in the production process. This reduces the impact in the rigid production programs and offered to the manufacturer of preform the advantage that the bottles are manufactured in the platform of production-blowing.

In a market as competitive as this, any transformer seeks alternatives to improve profitability. If you are not thinking seriously to reduce the weight of the packaging, probably the competition already will be doing.