Moisture control in the plastics forming industry

Within the processes carried out in the plastic industry, the presence of ambient moisture directly influences the quality of the finished product. This is especially significant in the injection and moulding of the raw material for its transformation.

Injection: presence of moisture

The raw materials, whether thermoplastic or resin, go through a process of having their temperature raised to increase plasticity in order to achieve the required shape in the mould.

The moisture content of the hygroscopic raw material, which has a high affinity to absorb moisture, is vaporized with this increase in temperature, causing both structural damage and aesthetic imperfections in the finished product. This means that a percentage of production is, therefore, lost.

Moulding: condensation

Most moulding processes introduce cold water cooling, to reduce the temperature of the mould. This reduces manufacturing times and increases production volumes, in general, the colder the mould is, the faster the manufacturing cycle. However, operating with low-temperature cooling can create condensation problems in the mould, especially in summer. This can cause deformations in the finished product.

A relatively simple alternative to avoid condensation, is simply to increase the temperature of the mould surface, however, an increase in mould temperature leads to longer manufacturing cycles and reduces production volume.

The optimal solution used in the industry for these circumstances is the implementation of  a desiccant dehumidification system which enables the dew point on the surface of the mould to be controlled. This will allow manufacturing to operate with lower mould temperatures without risk of condensation formation and therefore increase production volumes while maintaining the quality of the finished product.

Moulds: corrosion

Corrosion can affect moulds both during the production process and during storage:

  • During production, due to the formation of condensation.
  • During storage, due to environmental humidity.

In both cases, if humidity is controlled it allows preservation regardless of temperature. This prevents the need for repair or replacement of moulds and the consequent cost involved.

Steel corrosion curve

Success story

The excellent waters of the Solán de Cabras Spa in Cuenca (Spain) also stand out for the refined design of their container. It’s bottling plant is able to maintain quality and increase productivity throughout the year thanks to the Fisair DFRB series dehumidifiers installed there.

Deshumificadores compactos DF DF air dehumidifiers

Related applications

Some outstanding references:

  • Valeo 
  • Faurecia 
  • Jovi 
  • APPE 
  •  Solan de Cabras 
  • La Casera 
  • Aguas de Mondariz 
  • Coca-Cola 

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