Elements and Performance Criteria

This competency applies to all work environments and sectors within the plastics, rubber and cablemaking industry. It includes the operation of all relevant equipment.

Standard procedures means all relevant workplace procedures, work instructions, temporary instructions and relevant industry and government codes and standards.

This unit of competency may be designated for one of the following streams where workers use that unit substantially only in that stream area:
cablemaking
blow moulding
blown film
calendering
composites
compounding
extrusion
fabrication
injection moulding
polystyrene
expanded foam polyurethane
rotational moulding
thermoforming
belt splicing
rubber lining
tyre manufacture
tyre retreading
surface coating.

Additives include:
anti-blocking agents
anti-oxidants
anti-static agents
fillers
flame retardants
impact modifiers
lubricating agents
nucleating agents
pigments
plasticisers
release agents
slip agents
UV stabilisers
cross-linking agents
blowing agents
heat stabilisers.

Polymers include:
thermoplastics
thermosets
elastomers
linear, branched and cross linked
crystalline, amorphous.

Physical properties include:
rigidity
clarity
hardness
density
toughness
softening point.

Impurities include:
moisture/water
foreign matter
other polymers.

Corrective actions include drying moisture (e.g. by oven, refrigerated dehumidifier, desiccant bed dehumidifier).

Flow tests include:
melt flow
spiral flow
rheometry
viscometry
as are relevant to the process and materials.

All operations are performed in accordance with standard procedures and work instructions.

Essential knowledge and enterprise requirements:
Knowledge of polymers and how their properties vary and the relevance to these properties to processing and product. Descriptions of polymer molecular shape and arrangement should be limited to commonly accepted diagrammatic representations of these structures.
Knowledge of the enterprise's procedures and relevant regulatory requirements along with the ability to implement them within appropriate time constraints and work standards.

Competence includes the ability for the practical completion of the job to:
apply and/or explain:
type of polymer and polymer structure
impact of additives
the importance of flow and flow properties
the impact of temperature and heating/cooling rate on processing and properties
distinguish between causes of faults such as:
wrong raw materials/additives or wrong grade
incorrect quantity of materials/additives
contaminated materials/additives
out of specification materials
process set-up and/or operation.

Critical aspects
It is essential that the principles of polymers and how these contribute to properties is known and able to be applied to the work. Competence must be demonstrated in the ability to recognise potential situations requiring action and then in implementing appropriate action.

Consistent performance should be demonstrated. In particular look to see that production standards are met consistently.

Language, literacy and numeracy requirements
This unit requires the ability to read and interpret technical specifications and similar information.
Writing may be required to the level of completing workplace reports.
Numeracy is required to the level of understanding the significance of numbers and being able to interpret numerical data.

Assessment method and context
Competence in this unit may be assessed:
on an operating plant allowing for operation under all normal and a range of abnormal conditions
by use of a suitable simulation and/or a range of case studies/scenarios
by a combination of these techniques.

In all cases it is expected that practical assessment will be combined with targeted questioning to assess the underpinning knowledge and theoretical assessment will be combined with appropriate practical/simulation or similar assessment.

Resource implications
This section should be read in conjunction with the range of variables for this unit of competency. Resources required include suitable access to an operating plant or equipment that allows for appropriate and realistic simulation. A bank of case studies/scenarios and questions will also be required to the extent that they form part of the assessment method. Questioning may take place either in the workplace, or in an adjacent, quiet facility such as an office or lunchroom.

Additional resources might include samples of products requiring analysis, particularly products showing processing faults, or potential product specifications requiring the specification of polymer types and polymer compounds.