NZQA Expiring unit standard
21621 version 3
Page 1 of 6
Title
Control all MD and CD warp during paper changes for fibreboard
manufacture
Level
4
Credits
10
Purpose
People credited with this unit standard are able to: define
diagonal warp and describe its causes; demonstrate knowledge
of the actions needed to remove or reduce diagonal warp;
control machine directional (MD) and cross directional (CD)
warp at changes of paper; take proactive measures at the
times of paper changes to minimise warp occurring; rectify MD
and CD warp; work in collaboration with other corrugator crew
in accordance with workplace practices; and follow safety
requirements for the equipment being used.
Classification
Fibreboard Packaging > Fibreboard Manufacture
Available grade
Achieved
Entry information
Critical health and
safety prerequisites
Unit 340, Demonstrate knowledge of safe working practices in
the printing and graphic pre-press industries, or demonstrate
equivalent knowledge and skills.
Recommended skills
and knowledge
Unit 21620, Correct faults in a single face web for fibreboard
manufacture, or demonstrate equivalent knowledge and skills.
Explanatory notes
1
All workplace practices must meet any applicable and recognised codes of practice,
and documented workplace health, safety, and environmental procedures for
personal, product, workplace health, safety, and environmental matters, and the
obligations required under current law including the Health and Safety in Employment
Act 1992, Hazardous Substances and New Organisms Act 1996, Resource
Management Act 1991, Privacy Act 1993 and their subsequent amendments.
2
Workplace practices refer to the documented procedures for the equipment and/or
workplace.
3
‘Cross Directional’ and ‘Machine Directional’ are abbreviated to CD and MD where
these terms occur.
4
Diagonal warp is referred to in some workplaces as ‘twist warp’ or ‘propellor warp’.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21621 version 3
Page 2 of 6
5
‘S warp’ is not diagonal warp, but is a variant of cross directional warp where differing
degrees of warp are present across the one board width. ‘S warp’ is not addressed
in this unit standard.
6
As equipment configuration and sophistication varies between workplaces, general
control over warp is achieved by varying proportions of direct control over the
different corrugator work stations, and by co-ordinating the efforts of other operators
at these work stations.
7
The process for defining and calculating warp percentages for the purposes of
assessment is as follows: when a warped board is laid on a level surface so as to
form a shallow arch, the maximum vertical deviation from the horizontal is expressed
as a percentage of the board dimension that forms the arch. Warp is assessed at
take-off, and thus excludes ‘post warp’.
8
Actions and measures available as listed at explanatory note 10, and referred to
elsewhere may be taken in any combination or sequence which is in accordance with
workplace practices and equipment specifications and configuration.
9
Where referred to, ‘plant listed maximum speed’ is that determined by each
workplace as appropriate for specific production conditions taking into account paper
grades, flutes, run length and chop length.
10
Actions available to prevent, minimise or rectify warp are as follows:
(For CD warp)
Adjustments to:
–
adhesive application levels
–
wraps at bridge single face pre-heater
–
wraps at double backer liner pre-heater
–
hot plates temperature
–
platen section pressure
–
wraps at single facer liner pre-heater
–
wraps at single facer medium preconditioner
–
amount of loops on bridge.
Use of:
–
double backer water sprays
–
main belt steam showers
–
single facer medium steam showers
–
single facer water sprays.
(For MD warp using double backer and platen section) Tension control actions:
–
cleaning hot plates
–
adjustment at any or all of double backer liner pre-heater brake, bridge single
face pre-heater brake, bridge brake, double backer liner brake
–
changes to paper lubrication systems, paper guides, bridge single facer vacuum
level.
(For MD warp using single facer)
Adjustments to:
–
amount of loops on bridge
–
single face liner brake.
Outcomes and evidence requirements
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21621 version 3
Page 3 of 6
Outcome 1
Define diagonal warp and describe its causes.
Evidence requirements
1.1
Diagonal warp is defined in terms of the axis of the warp running diagonally
across the board.
1.2
The conditions of reel stock that might cause diagonal warp to occur are
described.
Range
1.3
Tension inequalities that might cause diagonal warp are described.
Range
1.4
includes but is not limited to – slack edges in reel, reel stands out
of line, wrap arms not level, rollers not parallel, misalignment of
top belt, uneven pressure roller pressures.
Moisture variations that might cause diagonal warp are described.
Range
1.5
includes but is not limited to – fibre orientation, slack edges in reel,
paper grammage or calliper not within specification.
includes but is not limited to – varying moisture levels across the
paper width, uneven adhesive application, uneven heat
application.
Equipment faults that might cause conditions leading to diagonal warp are
described.
Range
includes but is not limited to – reel stands, wrap arms, rollers, top
belt.
Outcome 2
Demonstrate knowledge of the actions needed to remove or reduce diagonal warp.
Evidence requirements
2.1
Tension control actions are listed and their effects described in accordance with
workplace practices and equipment configuration.
2.2
Moisture control actions are listed and their effects described in accordance
with workplace practices and equipment configuration.
2.3
Knowledge that switching single facer and double backer paper reels may
sometimes cure diagonal warp is explained.
2.4
Machine specification checks, where diagonal warp is persistent, are explained
in terms of their importance.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
2.5
21621 version 3
Page 4 of 6
Procedures to be followed where diagonal warp is persistent are described in
terms of workplace practices.
Range
to include the workplace practices for requesting an equipment
specifications check by engineers.
Outcome 3
Control MD and CD warp at changes of paper.
Range
paper grade, paper type, paper width, or any combination.
Evidence requirements
3.1
Corrugator is operated ensuring that MD Warp does not exceed 4% at any
stage or meets requirements if job specification is less than 4%.
3.2
Corrugator is operated ensuring that CD Warp does not exceed 4% at any
stage or meets requirements if job specification is less than 4%.
3.3
Corrugator speed is not reduced below 40% of plant listed maximum, except
where slitter changes enforce a greater speed reduction or when making splices
on tight web corrugators.
Outcome 4
Take proactive measures at the times of paper changes to minimise warp occurring.
Range
paper grade, paper type, paper width, or any combination.
Evidence requirements
4.1
Awareness of forthcoming paper changes is demonstrated.
Range
check production documentation, communicate with other crew
members.
4.2
Proactive corrective measures to minimise the risk or effect of MD and CD warp
are taken in anticipation of paper changes using actions available (see
explanatory note 10).
4.3
Proactive measures available to be taken are explained in terms of workplace
practices.
4.4
The effects of the various proactive measures available are explained in terms
of workplace practices.
Outcome 5
Rectify MD and CD warp.
Evidence requirements
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21621 version 3
Page 5 of 6
5.1
Action is taken immediately notification is received that warp has occurred.
5.2
Any warp within the control of the operator that occurs following a paper change
is reduced to 2% or less within the specified period following notification.
Range
specified period is –
(a) for workplaces operating a ‘stop order change’, 200 lineal
metres of produced board, plus a further three minutes of
corrugator running time;
(b) for workplaces not operating a ‘stop order change’, 100 lineal
metres of produced board, plus a further three minutes of
corrugator running time.
5.3
The procedures to be followed in the event of failure to reduce warp to 2% or
less within the specified three minutes period are followed in accordance with
workplace practices.
5.4
Following a paper change, any required reduction of warp to 2% or less is
achieved at not less than 40% of plant listed maximum speed.
5.5
Following the reduction of warp to 2% or less, no MD warp or CD warp
exceeding 2% is experienced before the next paper change.
5.6
The actions available to control MD and CD warp to 2% or less between paper
changes are followed in accordance with workplace practices.
5.7
The effects of the actions available to control MD and CD warp to 2% or less
between paper changes are explained in terms of workplace practices.
Outcome 6
Work in collaboration with other corrugator crew in accordance with workplace practices.
Evidence requirements
6.1
Communication with other crew is made ensuing there are no delays to
production.
6.2
The situation requiring action is identified and the joint action required is
explained.
6.3
Cooperation with other crew is demonstrated in jointly reducing MD and CD
warp within the required time periods.
Outcome 7
Follow safety requirements for the equipment being used.
Range
operating manual, workplace practices.
Evidence requirements
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
21621 version 3
Page 6 of 6
7.1
Equipment start up, shutdown and emergency procedures in the workplace are
explained.
7.2
Hazard control measures, as circulated by the company, are described and
followed.
7.3
Hazards or potential hazards in the workplace are identified and reported in
accordance with workplace practices.
Replacement information
This unit standard, unit standard 3779, and unit standard
3786 have been replaced by unit standard 27811.
This unit standard replaced unit standard 3782 and unit
standard 3785.
This unit standard is expiring. Assessment against the standard must take place by
the last date for assessment set out below.
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
27 April 2005
31 December 2015
Review
2
20 September 2012
31 December 2019
Rollover
3
10 December 2015
31 December 2019
Consent and Moderation Requirements (CMR) reference
0005
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR also includes useful information about special requirements for organisations wishing
to develop education and training programmes, such as minimum qualifications for tutors
and assessors, and special resource requirements.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2016