Module WOOL-482-582-08

Topic 01: Overview of Early Stage Processing

This topic provides an overview of the steps involved in Early Stage Wool Processing (ESP), the costs and value adding aspects of the industry, the major players in the Australian industry, recent changes in the industry and impediments to future growth.

On completion of this topic you should be able to:

• Outline the main wool processing systems
• Understand the value adding aspects of the Australian early stage processing industry
• Describe the major players in the Australian early stage processing industry
• List factors affecting the growth of the early stage wool processing industry in Australia.

Topic 02: Overview of Wool Yarn Manufacture

To make almost all wool products the wool must first be scoured and impurities such as vegetable matter removed; then the fibres are made parallel and mostly spun into yarn, and finally the yarns are interlaced by weaving or knitting to form the product. The type of processing route and the range of products that can be made depends largely on the properties of the wool. For fine wools which are destined for high quality apparel, the worsted system is the preferred route. This is the most complex of the three main routes. To achieve the required yarn quality, there are generally stringent requirements on the raw material. On the other hand, the woollen system, which is the most common route for coarser wools, can accept a wide range of wool types. The resulting yarn has quite different properties to a typical worsted yarn, but is well suited for carpets and heavy apparel. Between these two routes is the semiworsted system, which is essentially a shortened version of the worsted route and produces a yarn that is intermediate in properties between worsted and woollen yarns.

On completion of this topic you should be able to:

• Describe the essential features of the worsted, woollen and semiworsted processing routes, using an appropriate flow diagram
• Explain the similarities and differences between these routes with respect to (a) the raw material requirements, (b) complexity of each route, and (c) the properties and uses of the yarn produced by each.
• Outline the functions of the key processing steps involved in converting scoured wool into yarn
• Sketch the layout of a simple, single-swift card and name the key parts.

Topic  03: An Overview of Wool Scouring

This topic provides an overview of the wool scouring process, placing it in an historical context and presenting the principal objectives and functions of the modern industry. Wool scouring is the only operation, other than carbonising, which is unique to the early stage processing of wool fibre. Synthetic fibres are not contaminated to any significant extent, and are not scoured.

On completion of this topic you should be able to:

• Describe the nature of the main contaminants of raw wool
• Outline the changes that have occurred in woolscouring from its beginnings in the mid 19th century
• Describe the developments that have occurred in wool scouring in the past 50 years
• List the objectives and key functions of wool scouring.

Topic 04: Aqueous Scouring and Detergents

This topic outlines the principles of aqueous wool scouring, in particular the role of the detergent in grease removal by the formation of an emulsion.

On completion you should be able to:

• Explain how grease may be removed from wool
• Describe the conditions under which liquids may, or may not, mix, and the role of the interface
• Explain how surface active agents behave
• Differentiate between anionic, cationic, non-ionic and amphoteric surfactants
• Outline the key stages in the removal of grease from wool in a scouring bowl
• Describe, by means of a sketch, the types of detergent mostly used today for wool scouring
• Explain how entanglement and felting occurs with wool
• Explain the role of the squeeze press and the factors that affect its performance.

Topic 05: Control and Instrumentation

This topic covers the principles of industrial control systems and their application to the modern woolscouring industry. The gradual introduction of these systems in the last few decades of the twentieth century has enabled woolscours to operate increasingly efficiently with fewer staff, to maintain required performance with respect to production and quality, and to meet increasingly stringent environmental requirements.

On completion of this topic you should be able to:

• Explain the terms that apply to the principles of process control
• Differentiate in simple terms between the various types of feedback control methods
• Outline the applications of process control to a range of woolscouring operations, in particular the control of feed rate, liquor quality and wool drying.

Topic 06: Scoured Wool Quality and Testing

This topic looks at the full range of certificated tests that are routinely carried out on scoured wool consignments in Australia and New Zealand – yield, vegetable matter content and solvent extractables, fibre diameter, colour, regain and length after carding. In addition, the in-scour tests for quality are included – the rapid tests for grease (solvent extractables) and regain, and the use of NIRA technology. Tests are also available for woolgrease and effluent quality.

On completion of this topic you should be able to:

• Explain why testing is important to the industry
• Describe the sampling techniques appropriate to scoured wool testing
• Outline the yield test procedures, in particular the determination of wool base, ash content, vegetable matter content and solvent (i.e. ethanol and DCM) extractables
• Explain why and how various yield calculations are carried out, for presentation on a test certificate
• Describe briefly the modern instruments used for fibre diameter measurement, their operating principles and the results they produce
• Outline the colour measurement techniques applicable to wool, including preparation, instrument requirements and the form in which results are reported
• Explain the sampling, preparation and testing steps for the Length After Carding test
• Calculate the regain of a wool sample, given the original mass and the dry mass
• Outline the rapid tests used in the scour for moisture and residual grease measurement
• Describe how NIRA techniques have revolutionised in-scour quality management.

Topic 07: Wool Scouring Systems

The main aim of woolscouring is to remove as many contaminants as possible from greasy wool, thus leaving the wool in the best possible condition (i.e. clean and free of contaminants) for further processing. This may be achieved with different levels of performance and cost by solvent scouring or aqueous scouring. Today the aqueous process is the dominant method.

On completion of this topic you should be able to:

• Describe the following and compare the advantages and disadvantages of:
  • Solvent scouring versus aqueous wool scouring
  • Traditional scouring versus mini-bowls
  • Standard scouring versus suint scouring
  • Two stage and three stage scouring systems
  • The scouring of coarse wools and fine wools
• Explain the main innovations contained in the Wool Research Organisation of New Zealand (WRONZ) Comprehensive Scouring System and sketch a simple diagram of the bowls, flowback paths and effluent treatment flows
• Describe the design of a typical mini-bowl
• Outline the requirements of fine wool scouring for topmaking, and how these are achieved in modern scouring systems such as Siroscour.

Topic 08: Carbonising

Carbonising is the chemical process which is used to remove vegetable matter (VM) from wool. The VM, which may be seeds, burrs, grass etc., is predominantly made up of cellulose, hemicellulose and lignin whereas the wool is principally protein. The carbonising process makes use of the difference in the stability of proteins and cellulose to the effects of mineral acids.

On completion of this topic you should be able to:

• developed an understanding of why certain wools need to be carbonised
• an understanding of the basic principles involved in the carbonising process
• an understanding of the parameters to be controlled during the process
• an awareness of the problems which can be encountered and the adverse affect they can have on the final product.

Topic 09: Principles of Wool Carding

Irrespective of which of the three routes (woollen, worsted or semiworsted) is used to process wool into yarn, the card (or carding machine) plays an essential part. It separates the entangled clumps of fibres into a web of individual fibres by working them between a series of closely spaced moving surfaces which are covered with pointed wire, pins or teeth (the card clothing). Important considerations in carding are the processes of fibre individualisation, formation of the web, the extent and configuration of the fibres in the web, and the degree of fibre damage occurring during carding. These are important because, in processing stages after to carding, excessive fibre breakage and poor fibre configuration (i.e. straightness) may lead to unacceptable yarn irregularity and imperfections.

On completion of this topic you should be able to:

• Name the key rollers in a card and explain their functions
• Describe the various card roller interactions and their purposes
• Explain how fibres gain a hooked configuration in card sliver, and how these hooks are  subsequently removed
• Describe the process of fibre  breakage on a card and the factors that influence the level of breakage
• Sketch how the fibre length distribution changes in carding
• Explain the terms collecting fraction and delay factor, and their relevance to the mixing ability of a card
• Describe, with the use of a suitable diagram, the effect on carding production of a rapid change in feed rate.
• Describe a nep, and outline the factors that contribute to nep formation.

Topic 10: Drafting and Gilling of Fibrous Assemblies

Gilling improves the straightness and alignment of the fibres in a sliver, while drafting reduces its linear density (or count) by the desired amount. Both processes may be carried out by the same machine, a gillbox (or pin drafting machine), but drafting is also employed to attenuate slivers, tops and rovings in other spinning operations.

On completion of this topic you should be able to:

• Explain the principles of roller drafting and the devices used to achieve this
• Define the terms associated with the drafting process and distinguish between calculated and actual drafts
• Describe the purposes and method of doubling
• Explain how periodic irregularities are introduced into slivers during roller drafting and pin drafting, and the factors that may influence this.
• Describe the various methods of controlling fibre in drafting
• Explain the purpose of autolevelling of slivers and the devices used for this process
• Describe the essential features of a gillbox, comparing the screw drive, chain gill and pinned roller mechanisms
• Explain the interaction of the faller pins with the front and back rollers to improve the fibre alignment and straightness in gilled slivers
• Outline how faller bar marks occur in gilled sliver.

Topic 11: Wool Combing

Wool combing is a comprehensive term when used in its widest sense, and it embraces all the operations carried out in a topmaking plant. It includes the processes of raw wool scouring, drying, carding, backwashing and preparer gilling. Then follows the actual combing operation, and the sequences of topmaking processes concludes with two gilling steps called top finishing (or finisher gilling). Combing is not included in the semiworsted or woollen processing routes.

Wool combing, the single process, is indispensable in the manufacture of a worsted yarn.

On completion of this topic you should be able to:

• Outline the objectives of wool combing
• Describe the design of a typical rectilinear comb
• Explain the steps in rectilinear combing – feeding, initial combing, final combing and drawing off, and sliver formation
• Discuss the means by which noils are removed, and the balance required in setting the amount to be removed
• Explain the purpose of re-combing
• Calculate: tear ratio, noil(%), romaine, regain and combing production
• Discuss the factors that affect the combing quality of fine wools.

Topic 12: Spinning

While the term spinning is commonly used to describe the entire yarn-making process, in this topic the more specific meaning applied, i.e. the formation of yarn by drafting, the insertion of twist and forming a package. The ultimate aim of spinning is to produce a coherent and cohesive strand of fibres (i.e. a yarn) of the required linear density (count) and which has good evenness, tensile properties and a minimum number of faults.

On completion of this topic you should be able to:

• Describe the preparation of the materials required for the three spinning systems
• Explain the purpose and device used for drawing to form a roving
• Outline the principles of ring spinning, in particular the functions of the key parts of a spinning frame
• Explain the purpose of the traveller and the parameters that control its performance
• Describe what an end-break is, and why it occurs
• Outline the process of package formation
• Compare the essential features of worsted, semiworsted and woollen ring spinning frames
• Explain the role of the false twist device in woollen spinning
• List the features provided with modern ring spinning machine.

Topic 13: Fundamentals of Yarn Technology

A yarn is a relatively strong and flexible assembly of fibres or filaments with or without twist. It is an important intermediate product between fibres and fabrics.

On completion of this topic you should be able to:

• understand the definitions for different yarn count systems
• know the conversion between yarn counts
• appreciate the effect of moisture on yarn count results
• understand the effect of twist on certain yarn and fabric properties
• appreciate the importance of surface twist angle and of selecting the right twist factor for different yarns
• know how to calculate the twist contraction
• know the basic rules that apply to twist measurements.

Topic 14: Ring Spinning Systems

This topic covers the most widely used means of producing a wool yarn, the ring spinning technique, which is common to all three wool processing routes.

On completion of this topic you should be able to explain the principles of ring spinning and the roles of the components of a spindle assembly in all three machinery versions.

Topic 15: Advanced Ring Spinning

Insertion of twist is very expensive. Ring spinning is more expensive than the total cost of all the processes from scouring up to the spinning frame but it produces a yarn with the desired attributes. A lot of effort has gone into improvements to ring spinning in order to increase production and performance (quality) or to reduce costs. These include methods to avoid the need for two-folding of yarns in order to make them weavable (Sirospun, Solospun) and to allow higher spinning speeds (Compact and collapsed-balloon spinning). Blending of wool with synthetics during spinning particularly to provide stretch in woven fabrics is briefly considered. Recent improvements are covered in this lecture together with the other steps involved in preparing a yarn for use in weaving or knitting.

By the end of this lecture, you should have:

• an appreciation of why ring spinning is so slow and expensive
• an understanding of improvements to reduce costs, including Sirospun, Solospun, Compact and collapsed-balloon spinning, and their benefits and limitations
• a knowledge of the post-spinning steps needed to prepare a yarn for weaving or knitting
• an awareness of the way synthetics can be added during spinning.

Topic 16: Latest Developments in Spinning and Non-wovens

Spinning is the conversion of fibre or filaments into a continuous strand by the insertion of twist. If you have ever observed a hand spinner, you will have noted that the fibres are gradually teased out between the thumb and forefinger of one hand from a bulk fibre supply held in the other hand. In order to hold the teased out fibres together to make something useful out of the fibre assembly, the fibres are twisted together by the rotating action of a spinning wheel or some other rotating device, hence the term spinning.

On completion of this topic you should be able to:

• Describe the latest developments in worsted spinning including ring, collapsed balloon, air condensed and compact spinning
• Outline bicomponent yarns, two-folding, winding and clearing
• Compare the latest developments in ring spinning including open-end or rotor spinning, air-jet spinning, DREF friction spinning
• Describe developments in non-woven processing
• Outline the physical limitations of processing non-wovens
• Describe cross-lapping, and compare bonding systems such as needle punch, stitch and hydroentanglement.

Topic 17: Preparation for Textile Weaving

While the term ‘weaving’ is mostly used for the process of interlacing yarns on a loom to form a woven fabric, it is actually a series of processes which convert yarn into fabric which is suitable for tailoring.

On completion of this topic you should be able to:

• Describe and explain the differences between fabrics made from (a) solutions, (b) directly from fibres, (c) from yarns and (d) composite/multi-component fabrics
• Outline the history of weaving from its traditional roots to the modern high speed looms
• Briefly explain the basic steps in weaving
• Describe the requirements for (a) warp yarns and (b) weft yarns
• Describe the sectional warping and beam warping procedures
• Outline the drawing-in process
• Explain why yarn sizing is required and how this is carried out.

Topic 18: Weaving Technologies and Structures

Shuttle looms have been the traditional machines for weaving, and are still widely used around the world today, especially in developing countries. However, over the past three decades, shuttle-less looms have taken the lead position in weaving machinery. Speed and versatility have been the main thrust of the developments.

By the end of this lecture, you should be able to:

• Draw a diagram of a basic loom, showing the key parts
• Outline the steps involved in the weaving cycle and the purpose of each step
• Explain the different shedding mechanisms and the advantages and disadvantages of each
• Describe and compare the various mechanisms used for weft insertion, both shuttle and shuttleless weaving
• Explain the purpose and method of selvedge formation
• Define and compare the main yarn interlacing structures used for woven fabrics.

Topic 19: Principles of Yarn Requirements for Knitting

This lecture covers the fibre and yarn requirements for knitting, and explains the formation of knitted structures.

Knitting as a method of converting yarn into fabric begins with the bending of the yarn into either weft or warp loops. These loops are then intermeshed with other loops of the same open or closed configuration in either a horizontal or vertical direction. These directions correspond respectively to the two basic forms of knitting technology – weft and warp knitting.

On completion of this lecture you should be able to:

• Describe the general methods of forming textile fabrics;
• Outline the fibre and yarn requirements for machine knitwear
• Describe the steps in manufacturing and preparing yarn for knitting

Topic 20: Formation and Properties of Knitted Structures

Knitted structures are progressively built up by converting newly fed yarn into new loops in the needle hooks. The needles then draw these new loops head first through the old loops which they have retained from the previous knitting cycle. The needles at the same time release (‘cast off’ or ‘knock over’) old loops so that they hang suspended by their heads from the feet of the new loops whose heads are still held in the hooks of the needles. A cohesive, flexible structure is thus produced by a combination of the intermeshed loops and the yarn joining those loops together.

On completion of this lecture you should be able to:

• Describe, using simple diagrams, common knitted structures (eg, jersey stitch, rib stitch, purl stitch)
• Compare the features the of various types of stitch
• Explain how designs can be  introduced into knit fabrics using the various types of stitches
• Discuss the factors that influence the cover factor of a woven fabric
• Describe the types of faults that can occur in knitwear, and their origin
• Compare the respective advantages and limitations of knitted and woven fabrics.

Topic 21: Fibre and Yarns for Carpets

A carpet is a textile floor covering that combines an attractive appearance with warmth, and comfort for standing, walking or reclining on. Carpets bring many diverse benefits to homes and public spaces. Today’s carpets come in a huge range of combinations of constructions, textures, colours and patterns.

On completion of this topic you should be able to:

• List the key attributes of an ideal carpet fibre
• Briefly outline the properties of wool that make it a good fibre for carpets
• Compare the advantages and disadvantages of wool with the other major carpet fibres
• Outline the raw material requirements for the various types of tufted and woven carpets
• Describe the main route by which wool carpet yarn is produced
• Briefly discuss the colouration options for carpets
• Outline the yarn requirements and characteristics for the various types of tufted and woven carpets.

Topic 22: Wool Carpet Manufacture

This lecture examines the various technologies that are used to make wool carpets today, from the simple hand-knotting loom to the highly sophisticated face-to-face weaving loom.

By the end of this lecture, you should be able to:

• Define the terms used to describe the constructions of tufted and woven carpets
• Explain the hand-knotting method of making a carpet
• Describe the tufting method of making a carpet, including the machine features required to produce loop pile and cut pile constructions
• Outline the features of Axminster, Wilton and face-to-face woven carpets
• Compare the advantages and disadvantages of the various production methods for machine-made wool carpets, including construction, production rate, and patterning options.

Topic 23: Overview of Non-wovens Manufacturing

This lecture will focus on nonwovens fibres and processing systems that are widely used and the subsequent lecture (Mechanical felting processes and products) will concentrate on the production of nonwoven fabrics by the carding and needlepunching route. This route offers the best opportunities for wool in nonwovens, currently a small but promising product area.

On completion of this topic you should be able to:

• Explain the benefits and limitations of the nonwoven route for textile manufacture
• List the main fibres used in nonwovens and their features that make them suitable for this application
• Outline
  • the various approaches to the formation of a fibrous web
  • the various methods used for the consolidation and bonding of fibrous webs
  • chemical and mechanical finishing treatments and their purposes.

Topic 24: Principles of Wool Fabric Finishing

This lecture provides an overview of the principles of wool fabric finishing. The topic of wool fabric finishing is a very extensive one, and therefore can only be dealt with quite briefly here. Wet finishing and dry finishing are dealt with in more depth in Topic 25.

On completion of this topic you should be able to:

• Outline the use of wool fabric finishing flow charts
• Describe the various contaminants that may be present in greige state wool fabrics
• Describe the finishing methods employed to remove contaminants from greige state wool fabrics
• Describe the various forms of dimensional change that take place in wool fabrics
• Outline the finishing methods employed to control the dimensions of wool fabrics
• Describe the finishing processes employed to modify handle and appearance of wool fabrics.

Topic 25: Wet Finishing of Wool Fabrics

The objects of the wet finishing of wool fabrics are firstly to remove contaminants from the wool by scouring and, if necessary, by carbonising. The latent stresses and strains the fabrics must then be relaxed, and the fabric set, in a process known as crabbing. Special qualities can then be developed in the wool fabrics by processes known as milling, shrink proofing, bleaching and dyeing. These so called wet finishing processes are grouped together, the aim being to minimise water consumption and to dry the fabric only once.

This lecture provides details on the topics of wool setting, scouring, crabbing, carbonising, milling, shrink proofing, bleaching, hydroextraction, scutching and back-rolling.

By the end of this lecture, you should be able to:

• Outline the various levels of set that can be achieved in wool fabrics.
• Describe the various machines used to scour wool fabric.
• Understand the principles of wool fabric carbonising.
• Outline the objects of crabbing.
• Describe the process of milling.
• Outline the various methods available for the shrink proofing of wool fabrics.

Topic 26: Dry Finishing of Wool Fabrics

The so called dry finishing processes for wool fabrics follow on after hydroextraction and scutching, beginning with drying. One of the objects in wool fabric finishing is to dry the fabric only once, thereby making substantial energy savings.

By the end of this lecture, you should be able to:

• Describe the various methods that are available for the drying of wool fabrics.
• Understand the need for conditioning wool fabrics after drying.
• Outline the methods used in the brushing of wool fabrics.
• Describe the process of shearing.
• Outline the principles involved in the decatising of wool fabrics.
• Explain the need for the steaming of wool fabrics.

Topic 27: Dyeing Principles and Dyes for Wool Fabrics

This lecture provides and overview of wool dyeing with particular reference to the dyeing of wool fabrics. The topic of wool dyeing is a very extensive one, and therefore is only dealt with quite briefly.

By the end of this lecture, you should be able to:

• Outline the classes of dyes suitable for the dyeing of wool fabrics.
• Explain the purposes of dyeing assistants and auxiliaries used in the dyeing of wool fabrics.
• Describe the mode of action of levelling agents.
• Outline the various factors that affect the dyeing performance of wool fabrics.
• Describe the various methods employed for the determination of the colourfastness of wool dyeings.

Topic 28: Effect of Fibre Properties on Processing Performance – greasy wool to top

This topic describes the effect of fibre properties on performance in early stage worsted processing. The effects of greasy wool properties on performance in topmaking are examined in this topic.  Following this, in Topic 29, the effects of the measured top properties on yarn properties and spinning performance are examined, with some reference back to greasy wool properties.

On completion of this and Topic 29 you should be able to:

• understand how and why greasy wool fibre properties affect topmaking
• understand how and why top properties affect yarn properties and spinning performance
• appreciate the key drivers of specifications for tops and greasy fibres
• understand the reasons for and the relative importance of fibre properties in early stage processing.

Topic 29: Effect of Fibre Properties on Processing Performance – top to yarn

Following this, in Topic 29, the effects of the measured top properties on yarn properties and spinning performance are examined, with some reference back to greasy wool properties.

On completion of this and Topic 28 you should be able to:

• understand how and why greasy wool fibre properties affect topmaking
• understand how and why top properties affect yarn properties and spinning performance
• appreciate the key drivers of specifications for tops and greasy fibres
• understand the reasons for and the relative importance of fibre properties in early stage processing.