A moulded PVC component has to meet the physical and performance requirements set for the finished product. The PVC injection moulding process puts those requirements back onto the material being fed into the machine. PVC pellets are softened in a heated barrel before being injected into a mould, cooled and removed as a finished component. When you source compounds from Innovative PVC, requirements such as hardness, flexibility and resistance inform the grade formulated for your application.
PVC injection moulding uses heat, mechanical action and pressure to turn PVC pellets into components shaped by a mould. When an existing PVC grade cannot deliver the hardness, flexibility or resistance required for a moulded product, the compound specification itself can be changed. That gives you another route to achieving the required product properties without treating the available material specification as fixed.
For the PVC injection moulding process, we formulate around both the finished-product requirements and the way the compound will be processed. Decades of PVC compounding experience at Innovative PVC give us a deep working knowledge of how changes to a formulation affect the compound in processing and in the finished product. We use that knowledge when a specialised application requires a new grade or an existing formulation needs further development.
PVC Compound Specification
A flexible gumboot sole and a rigid electrical component are both PVC injection moulding applications, but the material requirements differ substantially. Our PVC pellets for injection moulding are available as flexible, semi-rigid and rigid compounds, while specialised grades address requirements such as hardness, colour, oil resistance and UV stability. The formulation therefore reflects what the finished component has to do and the manufacturing process used to make it.
The British Plastics Federation explains that PVC resin is combined with additives to produce customised compounds with different physical properties. Additives also influence characteristics including flexibility, weather resistance and processing behaviour. This gives a compounder scope to work on the material specification when a standard grade does not satisfy a particular product requirement.
PVC Injection Moulding Process
During PVC injection moulding, pellets enter a heated barrel where heat and mechanical action from a rotating screw soften and work the compound. The softened PVC is then pushed under pressure into the mould cavity, where it takes the required shape before cooling sufficiently for removal. An injection moulding plastic PVC compound needs sufficient flow to fill the required geometry while remaining suitable for the heat and mechanical work applied during processing.
The familiar PVC injection moulding sequence shows where those requirements come into play:
- PVC pellets feed into the heated barrel.
- Heat and mechanical action from the screw soften and work the compound.
- Injection pressure drives the material through the injection point into the mould cavity.
- The material fills the required geometry under the moulder’s processing conditions.
- Cooling gives the component sufficient stability for removal from the mould.
PVC is sensitive to heat and shear during processing, which is why heat stabilisers form part of PVC formulations. The correct PVC moulding temperature therefore depends on the particular compound and processing requirements rather than one universal setting.
Mould Requirements and Custom Formulation
PVC mould design establishes the geometry the compound must fill, including the flow path into the cavity. Compound formulation does not correct unsuitable mould design or machine settings. It gives the moulder material formulated to perform within the specified application and processing requirements.
A specialised product requirement can involve several properties that still need to work within the same compound. Increasing oil resistance, specifying a particular hardness or adding UV stability cannot be treated in isolation from the rest of the formulation and its processing requirements.
Our experience lies in working through those relationships to develop a grade that meets the required combination of properties. The PVC injection moulding process gives the component its form; the formulation is where we engineer the material for the job it has to do.
Need the right compound for your PVC injection moulding process? Talk to Innovative PVC about your product and performance requirements.
FAQs
What is the PVC injection moulding process?
The PVC injection moulding process feeds PVC pellets into a heated barrel, where heat and mechanical action soften the compound. The material is then injected under pressure into a mould cavity, where it takes the required shape before cooling sufficiently for removal.
What are PVC pellets for injection moulding?
PVC pellets for injection moulding are compounded materials formulated for processing into moulded components. Their formulation can vary according to requirements such as flexibility, hardness, colour, UV stability and other performance characteristics.
Is there one correct PVC moulding temperature?
A: No single PVC moulding temperature applies to every compound and application. Appropriate processing conditions depend on factors including the particular PVC formulation, component requirements, mould and manufacturing setup.
What products can be made using PVC injection moulding?
PVC injection moulding applications can include products such as footwear components, seals and other flexible, semi-rigid or rigid moulded components. The compound specification depends on the physical and performance requirements of the finished product.
