Stackable containers

Target

The target was to design square stackable large size containers in PET in order to save space and to reduce palletizing cost.
In order to keep the same packaging standards as with HDPE jerry cans (most common material conversion) the container must be vertically stackable also with a neck handle. Conversion is possible also from tinplate cans.
Stackable containers need to have the right design combination between customized base and neck/shoulder. It is important to choose the right neck finish and preform design and stretching ratios (radial and specially axial) have to be within certain limits to ensure an optimum thickness/material distribution and blowability of the container. Special attention must be paid on bottom design: special pattern, special vents, special cooling. The particular shape of the base must be high and wide enough to contain the capped neck (and handle, if present) of the lower container.

Development & challenges

The development was done on different features:

• Special shoulder design to increase the resistance of vertical top load, i.e. force resistance due to the load of other containers stacked above; several vertical ribs have been added to the bottom shoulder in order to avoid permanent deformation when the containers are piled up. The containers need to resist also to the dynamic top load during transportation.
• Suitable bottom design to optimize bottle stability when stacked. A dedicated design plus special mould base cooling and venting were needed. In case of inserted handle on the neck, the bottom of the container must be specially designed to get enough room to accommodate neck with cap and handle of the container below. 
• Dedicated preform design, to have certain stretching ratios (optimized radial stretching, preform diameter, and axial stretching ratio).

The most challenging aspects are:

• Shoulder design;
• Neck diameter, preform design;
• Base design and formation;
• Special ribs to improve stability;
• Overall blowability;
• Filled vertical resistance, top load behavior;
• Drop resistance.

Results & packaging features

We have developed different designs and performed several blowing trials. To produce a good container, it is necessary to respect some limitations:

• The weight range depends on the complexity of the container and on customer specifications;
• A larger neck finish (i.e. 77mm vs 63 or narrower) improves the blowability, enhances stretching ratio by using optimum preform drawing and facilitates lightweighting;
• Handles and closures availability must be evaluated.

Long preforms manufacturing solution

Long preform manufacturing solution: XFORM 500 GEN 3
The 500-ton machine has been engineered to deliver the  highest platform durability along with an unprecedented mold life.
SPECIAL FEATURES FOR THIS APPLICATION:

• Cavity & pitch: 16 C 110V 360 H tooling
• Take-out plate: 3 EOAT cooling positions
• Dedicated pin design for reliable preform extraction
• Dedicated belt lifting system to prevent preform denting
• Up to 350 mm preform length
• Up to 8˙200 g shot size

 
Preforms features and applications:

• Ø neck max: wider neck diameter, up to 77mm
• L max: Long preform, 350mm (up to 16cavity mould)
• Number of cavities: 8 - 16
• L min: 60mm, 6-7 g/preform
• High productivity/output
• Shot size: 6˙000 - 8˙200 grams
• Possibility to use colour up to 4% with NO throughput drop using right mixer device

Advantages

The new XFORM 500 GEN 3 preform system features:

• Up to 144C tooling;
• Fully compatible with legacy tooling;
• New GEN3 Hot Runner delivers high fill rate and outstanding balancing;
• LongLife™ feature for 8 million-cycle guarantee on mold life (only on high cavitation mould);
• Extremely robust clamp design for durable high-performance;
• Best-in-class platen parallelism for extended mold life;
• New cooling robot: reducing preforms cost & increase quality;
• No ID TAG = open system to allow using third-party tooling with no restrictions;
• Highly energy efficient.