This PET bottle for still water offers the best in user comfort for an ultra-lightweight package – less than 10g for a 500-ml bottle – thanks to its reinforced foundation using the overstroke base technology.
Lighter, yes, but not at just any price. On supermarket shelves, ultra-lightweight water bottles increasingly suffer from deformations of their base, which alters not only package appearance but also stability. Sidel has found a solution for this issue: SmartWeight™, a lightweight 500-ml PET water bottle weighing less than 10 g, with a much stiffer base that ensures better mechanical performance and appearance. Due to the overstroke base technology, these benefits open the door for the lightweighting of premium water bottles.
Stiff base for ultra-lightweight bottles
The overstroke base technology consists in synchronizing the blow molding process with the rise of the bases. It increases the lengthwise stretching rate of the PET preform. It therefore helps to decrease the quantity of material used for the base of the SmartWeight™ bottle and to ensure more uniform distribution. The savings made on base weight can therefore be redistributed throughout the bottle body.
In addition, the most fragile part of an ultra-lightweight bottle, its standing ring, is located between the base and body. With the overstroke base, this area displays better mechanical resistance, since the lifting of the base leads to the formation of a fold with smaller radii of curvature than those obtained with a traditional blow molding process. The SmartWeight™ bottle illustrates Sidel’s know-how in process sequencing through optimal management of mechanical controls and automation on Sidel blow molders.
Better bottle stability
The bottle base diameter is about 10% greater than standard therefore the bottle stability is greater on conveyor lines, which makes it possible to increase speeds. During packing and stretch wrapping, film shrinkage exerts forces between the bottles. But even when pressed together, the bases of SmartWeight™ bottles retain their shape, which ensures bottle integrity. During transport on palettes, the pivot effect (bottle twisting, which exerts stress on the base) is considerably less, which preserves better pack quality. In the end, on supermarket shelves, the consumer gets a perfectly intact and stable bottle for everyday use.
Pressure decreased to 20 bar
The formation of the base helps to reduce blow pressure to 20 bar, instead of the average pressure of 25 bar that is used to produce standard water bottles and which is necessary for the formation of the stiffness ribs on the standing ring diameter. This decreases air consumption by 20% for SmartWeight™ bottle production.
This proven technology is currently in industrial development on Sidel blow molders, thus benefiting from their high-speed performance. It will also be possible to adapt it to most Sidel blow molders currently in service at customer sites. Available initially for 0.5-liter bottles, this technology will soon be extended to 1.5-liter bottles.
In addition to package integrity when it reaches the consumer, the overstroke base offers another marketing benefit: it creates greater freedom of shapes for lightweight water bottles. The ribs needed to reinforce the dome, which generally continue onto the body, are no longer used. This solution is enabling the development of premium bottles at just 10 g, a weight that previously had been limited to lower-end bottles.