KHS has set an impressive new benchmark by engineering one of the world’s lightest PET bottles for still beverages to date. Under the working title of Factor 101, in close cooperation with Canadian-based injection molding technology equipment and services provider Husky Technologies, a container has been produced that uses just 5.89 grams of material to hold 591 milliliters of product. This is equivalent to the 20-ounce size common in the United States.
At drinktec 2017 KHS presented its Factor 100 concept as a feasibility study that featured a PET bottle weighing approximately five grams with a capacity of 500 milliliters. A number of optimizations have now been made to the further development, as KHS packaging designer Fabian Osterhold in Hamburg explains. “With such extreme lightweighting, what’s known as the top load is especially important. This value tells us how sturdy the bottle is from a vertical perspective. It determines whether the container can be stacked or not and survive transportation undamaged.”
Extremely robust lightweight
To increase stability, the shoulder design of Factor 101 has been modified and the bottle body reinforced with functional webbing. Moreover, Osterhold and his colleagues have developed a base with a pop-in effect. Here, the base pops inwards to a certain degree when a top load is applied, increasing the internal pressure and therefore the stability of the bottle.
Two hundred newtons is a common top load threshold in the industry; at 220 newtons, the Factor 101 exceeds this. In order to achieve this high value for a PET bottle used for still beverages, adapting just the container shape wasn’t enough. “The preform design also needed to be developed further,” emphasizes Osterhold. This is why KHS joined forces with the specialists at Husky. The company has a wealth of expertise as the world’s leading equipment supplier of PET preform injection molding systems and services and has been in cooperation with KHS for many years.
Challenging coordination
Technically speaking, the stretching factors from blank to bottle and the resulting preform dimensions were especially important here. The relation of length to wall thickness is particularly relevant to injection molding. In this context, KHS addressed the specifications and feasibilities of the stretch blow molder and bottle design, while Husky made the necessary modifications to the preform. “The focus here was on the exact profiling of the preform made possible by KHS technology,” Osterhold ascertains. “Focus lamps in the heater on our InnoPET Blomax Series V, for example, make for extremely precise temperature profiling directly under the bottle neck ring. This ensures that no material stays unstretched. In turn, this considerably reduces the amount of plastic used.”
30% less material
Compared to the standard lightweight PET container holding 500 milliliters of still water that usually weighs seven grams on the US market, the joint KHS/Husky product requires 30% less material. It can also be manufactured entirely from rPET.
However, bottle geometry is just one factor. “Line compatibility in the high- capacity range of up to 90,000 bottles per hour was a key challenge,” says Osterhold. “The main issues here were conveying, labeling and the secondary packaging. In the shrink tunnel, for instance, special attention had to be paid to the bottle shoulder – and the bottle of course shouldn’t fall over during conveying.”
