Double-stage PET in containers for water coolers

Double-stage PET in containers for water coolers

Alkam has designed an extremely innovative blowing machine specifically for large capacity PET containers (from 5 to 25 litres): based on double- stage technology, model BM1 combines the precision and flexibility of electric drive with ease of use and simple maintenance.
The widespread proliferation of water distributors is arousing the interest of companies supplying equipment and/or machines for bottling and the production of containers. Although the item most commonly found on the market is still the multi-use 5-gallon (18.9 l) "decanter" made in polycarbonate through single-stage technology, research is moving apace in other directions, to provide more flexible and competitive solutions.

These new developments foresee the production of disposable PET containers, which completely satisfy the need for cleanliness, more streamlined distribution and logistical handling, ease of recycling and, not least, excellent economies of scale. The containers, obtained by the blowing of a pre- mould, are shiny, transparent and recyclable, They also permit a substantial reduction in weight and impact on the environment.

The pre-moulds have features which allow the production of 5- gallon containers weighing between 350 g and 750 g depending on the user's requirements. Among the first to produce a disposable PET pre-mould/container for water-coolers were IMPET and PDC.

In this field, the adoption of double-stage technology has proved competitive compared with single-stage. In fact, the system allows the blowing of the pre-mould and the despatch of the containers obtained straight to the bottling line, limiting the risk of possible contamination and at the same time reducing the need for large areas for the storage of empty containers.

A technological response
Alkam (Cordignano, TV) considered it a strategic move to invest in this sector, and has designed a blowing machine (the BM1 in figure 1) specifically for containers from 5 to 25 litres, achieving production speeds between 400 and 250 pieces per hour respectively, that is added to an already broad range of double-stage systems. Based on knowhow obtained in the bottling sector, Alkam has combined its own electric stretch technology with an electrically-driven shell-type blowing mould (2 and 3). Particular attention as been paid to the heating stage of the pre- mould, whose thickness (up to 10 mm) has required significant changes to the methodology traditionally adopted.

The ovens are arranged so that the pre-mould is subjected to a heating cycle, followed by conditioning stages, before arriving at the correct temperature, which is then maintained by retroaction in a closed ring. Alkam's research has also focussed on establishing the optimum quantity of air to be introduced into the ovens, to find a balance between radiant and convection heat exchange systems. Every functional parameter of the machine is easily controlled by touch screen with a supervision system which uses an intuitive, multilingual menu (4), while an internal modem allows remote control.

The advantages in practice
Unlike the situation with polycarbonate containers which, being made by external converters, are subject to different handling and transportation operations before being filled, the BM1 allows the bottling company to produce its own containers in the line.

This results in:
- a greater guarantee of cleanliness;
- a reduction in the area required for storing empty containers;
- more flexible control over the production of the containers, in line with bottling requirements;
- simplified production process.

The equipment also has advantages from the point of view of economy, given that:
- the initial investment in equipment is lower than, for example, that for single-stage equipment;
- on average, the hourly output of containers is three times that produced by single-stage technology, this results in a considerable reduction in unit costs;
- the weight of each container can also be reduced (by up to 50%), depending on the user's requirements, thus allowing further savings;
- by acquiring the pre-moulds, the bottling company increases tenfold the number of pieces transported per load, with obvious economies during the transportation stage.