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Carry out knitted fabric analysis calculations Level 4

Credits 4 Purpose This unit standard is for senior technical personnel working with any types of

industrial knitting machines, and for quality control/quality assurance personnel in any of the sectors of the knitting industry.

People credited with this unit standard are able to: measure yarns for length

and weight to calculate yarn counts; convert yarn counts between different counting systems; relate yarn counts to machine gauge and stitch density; calculate fabric weights and yields; and calculate percentage fibre-content of knitted fabrics composed of different fibres.

Subfield Industrial Machine Knitting

Domain Knitting Machine Technical Servicing

Status Registered

Status date 20 January 1999

Date version published 24 August 2007

Planned review date 31 December 2008

Entry information Open.

Accreditation Evaluation of documentation and visit by NZQA and industry.

Standard setting body (SSB) Apparel and Textile Industry Training Organisation

Accreditation and Moderation Action Plan (AMAP) reference 0030

This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do. Special notes 1 This unit standard applies to all sectors of the knitting industry. 2 This unit standard relates to the calculations carried out in a knitting plant in respect

of: a yarn counts; b fabric weights and/or yields; c fibre-contents in fabrics.

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3 Technical aspects that are required to be covered in demonstrating competence in this unit standard include:

a yarn measurement, count calculations, count conversions; b relationships of yarn count to machine gauges and stitch densities; c fabric measurements, fabric weights or yield calculations; d calculations of fibre compositions of blended-fibre fabrics. 4 In this unit standard, the term ‘yarn count’ (and related variations) has been used

exclusively for simplicity of description. This is traditional trade usage for all yarn numbering systems in which a length of

yarn and its weight (mass) are related, and covers denier and all indirect counting systems such as metric, YSW (Yorkshire skein), cotton count, worsted count, and so on.

The term ‘yarn count’ is also used here to cover the ISO descriptive of ‘linear density’

and yarns measured under this system in terms of ‘tex’ and ‘decitex’. 5 Formulae of counting systems in common usage include the following: Direct counts – Count Length unit Standard wt unit

Tex 1,000 m No. of grams weight Decitex 10,000 m No. of grams weight Denier 9,000 m No. of grams weight Indirect counts – Standard length unit Count (No. of multiples of) Wt unit Metric 1,000 m 1 kg Cotton count 840 yds 1 lb Worsted count 560 yds 1 lb YSW 256 yds 1 lb (1 lb – 1 Imperial pound = 453.6 grams; 1 yd = 0.9144 metres).

6 Common count conversion factors: Tex → decitex = tex x 10 Decitex → tex = decitex ÷ 10 Decitex → denier = decitex ÷ 1.1 Denier → decitex = denier x 1.1 Tex ↔metric = 1000 ÷ yarn number Tex ↔ cotton count = 590.5 ÷ yarn number Tex ↔ worsted count = 885.8 ÷ yarn number Tex ↔ YSW = 1938 ÷ yarn number.

7 In terms of fabric yield, warp-knitting may use both grey yield and finished yield. 8 ‘Fabric Weight’ is defined as weight of fabric per unit area (e.g. grams per square

metre) or running length (e.g. grams per metre). ‘Fabric Yield’ is length of fabric per unit weight (e.g. metres per kg.).

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Elements and performance criteria Element 1 Measure yarns for length and weight to calculate yarn count. Performance criteria 1.1 The counting system is specified, and defined in terms of its standard units of

length or weight specific to that system. 1.2 A predetermined length of yarn is weighed, and the measured length and its

weight are extended to relate to the standard units of the specified counting system.

1.3 The yarn count is calculated according to the formula relating to the specified

counting system. 1.4 The calculated yarn count is described in the terms applying to that counting

system.

Range the numerical descriptions of singles and folded yarns specific to the counting system.

Element 2 Convert yarn counts between different counting systems. Performance criteria 2.1 The counting system that the yarn count is to be converted into, is specified,

and the conversion factor identified for that calculation. 2.2 Yarn counts are converted from one counting system to another by means of

the specified conversion factor. 2.3 The converted yarn count is described in the terms applying to that counting

system.

Range numerical descriptions of singles and folded yarns specific to the counting system.

Element 3 Relate yarn counts to machine gauge and stitch density. Performance criteria 3.1 The range of yarn counts used on each type and gauge of machine in

production is identified and described according to company practice.

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3.2 The stitch density of fabric produced on each type and gauge of machine is identified in terms of company practice.

3.3 The relationship of yarn count to the stitch density of fabric produced by each

type and gauge of machine in production is identified in terms of company practice.

Element 4 Calculate fabric weights and yields. Performance criteria 4.1 A fabric sample is measured for its dimensions and/or weighed according to

company practice.

Range a sample of predetermined size and a calibrated direct-read balance, or a sample is measured for length and width, weighed, and its weight scaled to specified dimensions.

4.2 The sample weight and dimensions are extended to specified parameters of

fabric weight and/or fabric yield according to company practice. Element 5 Calculate percentage fibre-content of knitted fabrics composed of different fibres. Performance criteria 5.1 The individual components of a sample are separated and weighed according to

company practice. 5.2 The percentage composition of each fibre component of the fabric is calculated

according to company practice. Please note Providers must be accredited by NZQA, or an inter-institutional body with delegated authority for quality assurance, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment. Industry Training Organisations must be accredited by NZQA before they can register credits from assessment against unit standards. Accredited providers and Industry Training Organisations assessing against unit standards must engage with the moderation system that applies to those standards.

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Accreditation requirements and an outline of the moderation system that applies to this standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The AMAP 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. Comments on this unit standard Please contact the Apparel and Textile Industry Training Organisation training@atito.org.nz if you wish to suggest changes to the content of this unit standard.