The evidence guide provides advice on assessment and must be read in conjunction with the performance criteria required skills and knowledge range statement and the Assessment Guidelines for the Training Package.

Overview of assessment

A person who demonstrates competency in this unit must be able to take a systematic approach to testing a new aluminium extrusion die, including carrying out any required finishing off, conducting trial extrusions, identifying reasons for any faults in the trial extrusions and determining the appropriate action to remedy the fault.

Critical aspects for assessment and evidence required to demonstrate competency in this unit

Assessors must be satisfied that the candidate can competently and consistently:

comply with relevant WHS, regulatory requirements and risk management

correctly identify bearings, apertures, and critical measurements and tolerances on die drawing

supervise and conduct trial extrusions

use workshop machines and hand tools to finish off a die to design specifications

identify cause of extrusion faults from both hollow and solid die extrusions

identify appropriate action to take to remedy extrusion faults

report and document results.

Context of and specific resources for assessment

This unit must be assessed on the job with access to the extruder for which a new die has been designed.

Assessment must cover the testing of both solid and hollow dies across a range of extrusion shapes.

Assessment should cover sufficient trial extrusions to ensure that both shape and surface faults related to die performance are observed.

The competencies covered by this unit would usually be demonstrated by an individual working in a team environment that includes extruder operators and die designers and die makers. The assessment environment should not disadvantage the candidate.

This unit may be assessed in conjunction with any other units addressing the safety, quality, communication, hand tools, machine operation, recording and reporting associated with testing a new aluminium die.

Method of assessment

Assessment must satisfy the endorsed Assessment Guidelines of the MEM05 Metal and Engineering Training Package.

Assessment methods must confirm consistency and accuracy of performance (over a number of extrusions and at least one new solid and one new hollow die) together with application of underpinning knowledge.

Assessment methods must be by direct observation of tasks and include questioning on underpinning knowledge to ensure correct interpretation and application.

Assessment must confirm a reasonable inference that competency is not only able to be satisfied under the particular circumstance, but is able to be transferred to other circumstances.

Assessment may be in conjunction with assessment of other units of competency where required.

Guidance information for assessment

Assessment processes and techniques must be culturally appropriate and appropriate to the language and literacy capacity of the candidate and the work being performed.

Required skills

Required skills include:

interpreting of die design drawings

supervising trial extrusions to ensure trial is conducted to die design specifications

diagnosing faults on solid and hollow dies

diagnosing faults on aluminium extrusions, including:

shape distortions

out of specification wall thickness

serrations or castellations on flanges

surface faults

shape changing from start to end of runout

liaising with die designers, die makers and extruder operators on performance of new die

Required knowledge

Required knowledge includes:

aluminium extrusion die construction

aluminium extrusion process

the effects of nitriding and re-nitriding on tool performance

requirements of AS/NZS 1866:1997 Aluminium and aluminium alloys - Extruded rod, bar, solid and hollow shapes

techniques for correcting solid and hollow dies

die support system, including role and types of feeder plates, bakers, bolsters and spacers

extruder components, including:

container

container liner

billet

die slide

pressure rings

platen

hollow die components, including:

weld chamber

mandrel

die holder

weld feeds

bridges

ports

die and extruder performance and adjustment records

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Die support

Die support is the specified toolstack dimensions that will support dies, according to the force the extruder can exert.

Container

The container is the part of the extruder that holds the billet and billet support components.

Support tooling

Support tooling is the name given to the various pieces of tooling (e.g. bolsters that provide stiffness to the die during extrusion).

Die holder

Die holders accommodate the diesets (feeder plate, die plate and backer). Die holders are the first components in toolstacks.

Bolster

Bolsters are deep discs of steel that provide stiffness in the toolstack to allow the die to remain flat and thus do its work properly. The term bolster includes any inserts designed to cut the cost of support tooling.

Die slide

The die slide is the part of the extruder that accommodates the dies and other tooling that makes up the toolstack.

Toolstack

The toolstack is the assembly of die, feeder plate and backer, holder and support tooling that fits into the die slide.

Die

The die is the part of the tooling that creates the extrusion shape as the metal is pressed through it.

Bearing

The die contains bearings of various lengths. Bearings are lands that act as frictional controls on metal flow. The bearing is an outline of the extrusion shape cut through the die to the highest precision possible.

Feeder plate

The feeder plate precedes the die and provides an additional degree of flow control. It is also described as a control plate. It is bolted to the die and backer, forming the dieset.

Backer

The die must be given support against the force needed to make metal flow. The first item of this support is the backer. Backer profiles are usually slightly larger than die apertures (precision cut) and are not high precision items.

Platen plate

The platen plate or pressure ring is set into the front wall of the extruder as a replaceable feature. Platen plates take up the forces applied to the toolstack and transmit them to the extruder structure.

Primary and secondary bolsters

Some larger extruders operate with a combination of single, one piece bolsters for special shapes and a split system of primary and secondary bolsters.

The primary bolster is usually deeper than the secondary and provides the main support. It is cut closer to the die aperture than the secondary bolster which closely follows the primary aperture so as to back it up.

Secondary bolsters are likely to be shared by several primary bolsters.