17.07.2007- New short neck finish „PCO Corvaglia“

The "PCO Corvaglia“ neck finish offers unique material savings

The best results in the race for maximum material savings come from a total design concept that includes the neck finish and the closure itself - not forgetting the need to maintain or improve existing filling line performance. Maximum compatibility with existing preform equipment, blowing machines and filling lines is a major consideration.

Dispassionate technical assessment of short neck finishes

With the aim of saving as much costly material as possible in every single PET bottle (which means the PET resin itself and the closure) a number of different so-called short neck finishes have recently been put forward. The number of options does not make it easy for the bottle manufacturer to decide which to use. However, one thing should be clear - the savings in material alone are not a sound enough basis for selecting any particular finish.

In the first place maximum compatibility with existing neck finishes is important, as this will have a direct effect on the cost of converting preform tools, blow moulds and filling/capping lines. The short neck finish developed by the cap design specialists Corvaglia of Eschlikon in Switzerland, known as the "PCO Corvaglia", is the only short neck finish that maintains the distance between the neck ring and the tamper band. This means that existing grippers can be used on the filling line. Furthermore the height of the PCO Corvaglia is identical to the three-start 26.8 mm "Alaska" finish, which means that the cost of adapting existing machinery and equipment is reduced to a minimum. Switching from an Alaska bottle to a PCO Corvaglia on the same filling line is a simple job.

In hot countries, perhaps with rough roads, soft drinks and mineral water with a high CO2 content place high demands on the sealing performance of the closure. The PCO Corvaglia is the only short neck finish with a thread that incorporates more than two full turns. This allows a sealing performance which other caps, that sometimes have only one full turn, simply cannot equal. In addition the PCO Corvaglia finish can be used on bottles of various sizes and on different types of cap.

Releasing the internal pressure when opening a bottle of carbonated beverage must be a controlled process, and yet be fast enough to avoid the cap flying off and hitting the consumer. The 744 ° single-start thread on the PCO Corvaglia neck offers advantages here. All other short neck finishes on offer have less than 2 full turns, and such designs with a 2-start or 3-start thread run a correspondingly higher risk of blow-off.

Material savings

In comparison with the standard PCO 28 the PCO Corvaglia short neck offers material savings of up to 1.5 grams of PET in the bottle neck finish. In addition the material that can be saved on the cap itself is in the order of between 0.7 and 1.2 grams. Corvaglia offer three different caps designs for use on the PCO Corvaglia neck. The lightest, at only 1.8 grams, for still water and other still beverages, a 2 gram cap and a 2.3 gram cap, for lightly carbonated drinks whilst the heaviest, can safely be used even on highly carbonated beverages. Based on current raw material prices the costs that can be saved on material for the PET container and the closure is between 2.9 and 3.5 Euros per 1000.

Full output from the capper

Because of the short distance between the tamper band ring and the thread only the PCO Corvaglia allows the use of all tamper band designs that are used on PCO 28 or PCO 19 necks. With all of the other short neck finishes there are restrictions and, for example, folded tamper bands must be used in order not to affect the capping performance.

PCO Corvaglia for everybody

Although it was developed by Corvaglia the PCO Corvaglia neck finish can be freely used by any bottle manufacturer.

It is only by unrestricted availability of preforms and caps from various suppliers that a new short neck finish will enjoy universal market acceptance. Several independent preform manufacturers in Europe already offer the new neck finish.The caps are also available from several sources.