Siapi Expands Wide-Mouth Jars with the Blow-Trimming Technique

This is how Siapi developed a system of blowing which allows using the same machine to obtain - starting from a small-neck preform (30-38 mm) - both wide-mouth bottles and jars (60-85 mm).

Dec 8 2011 --- Siapi has expanded its offer industrializing the "blow-trimming" technique for the production of wide-mouth jars and containers.

The development of this technology stems from the specific requirements of a client who needed to blow using the same machine and the same preform both jars (with a neck in diameter from 60 to 85 mm) and bottles (with a neck from 30 - 38 mm) and to maintain a high level of productivity, from 8000 to 9000 bph.

The typical production of wide-mouth preforms foresees that the neck is injected and, as such, due to the overall dimensions of the neck itself, makes it possible to only enter a limited number of cavities in the mold injection, losing production capacity per hour (a reduction of about 2/3rds of the productivity). In addition, this type of wide-mouth performs, due to their current limited volume and a low level of standardization of the neck, are still difficult to find on the market. Both of these situations represent, in fact, an important limit to
the diffusion of wide-mouth jars in PET.

This is how Siapi developed a system of blowing which allows using the same machine to obtain - starting from a small-neck preform (30-38 mm) - both wide-mouth bottles and jars (60-85 mm).

This process is called "blow-trimming" as it foresees a first blowing phase in which the neck is made widemouth (below the narrow neck one obviously already present in the preform) and, subsequently, a phase in which a cut is made at the top of the container (dome) which has the narrow neck, thus obtaining the results of a wide-mouth jar with its neck blown from a narrow neck preform. This approach requires a detailed study of the preform and of the process in order to:

- Minimize the weight of the neck and the dome to facilitate the cutting phase and reduce the amount of material cut
- obtain a good formation of the thread in order to ensure the seal with the cap
- ensure high consistency of the thread with the appropriate weight of the neck to allow for a perfect grip and neck resistance.

The result is a new application for SIAPI and increased versatility of their blowing machines that allows the production of containers from 250 ml to 1000 ml, with the diameter of the neck which can range from 30-85 mm.