Stackable containers

Stackable containers

Main features:

These containers give you the following advantages:

Conversion advantages from HDPE or metal jerry-can:

  • Lightweighting: less weight vs HDPE/metal bottle;
  • Less machines = PET output is higher than HDPE;
  • Lower cost vs metal container;


PET solution advantages:

  • Lighter packaging: lower packaging cost;
  • Aesthetics: attractive design vs other material solutions;
  • Stacking possibility, handle positioned on top; easy to transport;
  • Perfect sealing: safer;
  • Lower production costs;
  • Palletizing improvement, space saving, interlayer do not needed; stackability permits


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.
Results & packaging features
Volume: from 10 to 25 l
Color: transparent/opaque, clear/colored
Neck finish: 77mm, MIN 66mm
Applications: bulk water, edible oil, engine/motor oil, housekeeping products, etc
Results & packaging features
Container Range
Volume: 10ℓ
Weight: 140 to 250g
Volume: 20ℓ
Weight: 330 to 450g
Volume: 25ℓ
Weight: 400 to 550g

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.
  • 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
Long preforms manufacturing solution
Long preforms manufacturing solution
Long preforms manufacturing solution
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
Preform features:
L ≈ 220-270 mm
Ø ≈ 75-78 mm
Neck finish diameter: 77mm
Weight: 385g
Volume: 20ℓ
Weight: 445g
Volume: 25ℓ


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.

These are the most significant machines for this application

SIPA's products include a wide range of solutions for the manufacture of preforms and containers, filling, process and secondary packaging, able to satisfy all the needs of the mineral water market in terms of bottle shapes, products and productivity.