Reduction of the wall thickness is a constant topic with the pack-aging and PET preform industries. Less raw material means to both of them shorter cycle times, lower costs and less weight. No wonder airlines favour the highly developed thin-wall technology in the production of their packaging products.

Small saving, big effect.
A little numbers game to start with: Thanks to the thin-wall technology of Otto Hofstetter AG a weight saving of 0.5 grams was achieved in the drinking cup of Emirates Airways. Projected to the annual total consumption, the weight saving amounts to 40 tons. Considering that the payload of an aircraft is always seen in relation to the kerosene consumption, 40 tons of material saved correspond to almost 13,000 gallons of fuel. If we take an A 380 with 550 passengers on board, the countervalue of the saved polystyrene corresponds to a flight from Zurich to Boston.

Convincing advantages.
A constructed calculation, we admit. But even from a purely factual point of view the thin-wall technology of Otto Hofstetter AG is a high-flyer. In the case of the 8-cavity mould the original cycle time of six seconds has been halved. With a production around the clock and 95 % efficiency, approximately 80 million parts are produced per year – this is twice the original output. The clearly higher procurement cost hasn’t deterred the customer from buying the high-output moulds from Otto Hofstetter AG.

« The thin-wall technology of Otto Hofstetter AG doubles
the production capacity and guarantees a rapid

Security thanks to own experience and tests.
Otto Hofstetter AG draws from its more than 50 years expe-r-i-ence in thin-walled products also in the field of PET. The proverbial stability of Hofstetter moulds was the decisive factor for the implementation of thinner walls in the preform. All existing preform designs can be subjected to a feasibility study concerning a reduction of the wall thickness. If neces-sary, test series can be run on the test moulds of Otto Hofstetter AG. A decisive factor in the development was the axial stretching ratio between preform and, for example, bottle, which may be maximum 3. To establish the conditions exactly, the newly developed preforms were tested on Hofstetter’s own test moulds.

Well proven in everyday production.
Enterprises such as Resilux, PDG, Köksan and Sunpet
already use the new thin-wall technology in the production of their preforms. A total of 17 systems with up to 128 cavities each are in operation and produce wall thicknesses of less than 2 millimetres. And first tests with even further reduced wall thicknesses have already yielded positive


Basis for further development.
Initial experience with the new technology shows that the injection moulding machine must provide more locking force and a higher plasticizing capacity. An unchanged high quality of the preform as regards even wall thickness and freedom from flash calls for yet higher precision in mould making. Efficient venting of the mould is a must and the wear parts need to stand up to higher
strains. Design measures must be introduced to make the bottle
more rigid and give it the usual handling stability.

Thinner still in future.
Otto Hofstetter’s hunger for further innovation in the thin-wall technology is not yet satisfied. In the case of long preforms, the thickness must be further reduced to achieve the minimum specified weight. Yet higher locking forces and injection pressures are unavoidable. The specialists of the development department keep at it.




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