Wool Processing

Current Version

WOOL-382 was originally issued in 2008 as WOOL-482-582. It was created with funding provided by the Sheep CRC supported by AWET. UNE, charged with creating the unit, initially presented the material with lecture notes in DOC and PDF format, and included copies of of many of the references appended to the lectures. Presentations in Powerpoint format were also provided for each topic. There were 29 topics in the original module.

Funded by AWET, the original and subsequent versions of this module have been substantially edited to remove a considerable amount of detail in order to provide a broader overview of this important topic.

This module includes 15 topics.

Topic 1: Overview of Early Stage Processing

On completion of this topic you should be able to:

• Outline the main wool processing systems, from greasy wool through to finished yarn
• Describe the essential features of the worsted, woollen and semi-worsted 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
• Describe the essential differences between a woollen and worsted card


Topic 2: Wool Scouring Principles and Methods

On completion of this topic you should be able to:

• Describe the nature of the main contaminants of raw wool
• List the objectives of wool scouring
• Describe sequence of operations in a scouring plant
• Explain how a detergent removes grease from wool fibres
• List the factors that affect the quality of scouring
• Explain the following:
– Preparations of wool for scouring (ie, opening, blending, and cleaning
– The parts of a minibowl and their role
– How the various contaminants are removed in aqueous scouring
– Post-scouring operations (drying, cleaning, packaging)
– How scouring effluent is treated to minimise waste and extract wool grease
• Explain the different requirements in the scouring of fine and coarse wools, and the scouring lines used for each type

Topic 3: Wool Carbonising

On completion of this topic you should be able to:

• explain why certain wools need to be carbonised
• outline the basic principles involved in the carbonising process
• describe the parameters to be controlled during the process
• discuss the problems which can be encountered in carbonising and the adverse effects they can have on the final product


Topic 4: Principles of Wool Carding

On completion of this topic you should be able to:

• Identify the key rollers in a card, explain their functions and compare their speeds
• 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
• 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 in carding

Topic 5: Drafting and Gilling of Fibrous Assemblies

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 slivers

Topic 6: Wool Combing

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 7: Fundamentals of Yarn Technology

On completion of this topic you should be able to:

• understand and apply the definitions for different yarn count systems
• convert between yarn count systems
• explain the effect of moisture on yarn count results
• describe the effect of twist on certain yarn and fabric properties
• explain the importance of surface twist angle and of selecting the right twist factor for different yarns
• calculate the twist contraction
• apply the basic rules that apply to twist measurements

Topic 8: Spinning

On completion of this topic you should be able to:

• Describe the preparation of the materials required for the three main 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 role 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 purpose of the false twist device in woollen spinning
• Explain the purpose and means of drafting in worsted and semiworsted spinning
• Describe the methods used to dye wool yarns
• Outline the steps required after spinning to ready a wool yarn for weaving or knitting, in
particular winding, clearing and twisting

Topic 9: Latest Developments in Spinning and Non-wovens

On completion of this topic you should be able to:

• Describe the latest developments in worsted spinning including ring, collapsed balloon, and compact spinning
• Outline bicomponent yarns, two-folding, winding and clearing
• Outline developments in non-woven processing
• Describe cross-lapping, and compare bonding systems such as needle punching, stitch and hydroentanglement

Topic 10: Weaving technologies and structures

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

• Briefly explain the basic stages in the weaving of fabric
• Draw a diagram of a basic loom, showing the key parts
• Outline the warping and drawing-in steps
• Explain why yarn sizing is required and how this is carried out
• Outline the sequence of steps in the weaving cycle and the purpose of each step
• Describe 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
• Discuss the main yarn interlacing structures in woven fabrics, their characteristics and uses

Topic 11: Machine Knitting

On completion of this lecture you should be able to:

• Outline the fibre and yarn requirements for machine knitting, with an emphasis on the
suitability of wool yarns
• Describe and explain the function of key parts of a knitting machine
• Explain the features, operation and products of the main types of knitting machine and compare their advantages
• Compare knitted and woven fabrics, in particular their respective advantages and
• Briefly describe the purposes and methods of finishing treatments commonly used with
• Describe, using simple diagrams, the most common knitted loop

Topic 12: Wool Carpet Manufacture

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
• Describe the wool components of a typical carpet yarn blend
• 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
• Explain the purpose of yarn setting and how it is carried out
• Define the terms used to describe the constructions of tufted 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
• Briefly outline the methods of making Axminster, Wilton and face-to-face woven carpets
• Discuss the advantages and disadvantages of the various production methods for machine-made wool carpets, including construction, production rate, and patterning options

Topic 13: Wool Dyeing Principles and Techniques

On completion of this topic you should be able to:

• Compare the features of the four main classes of dyestuff used for dyeing wool
• Explain the roles of dyeing auxiliaries and assistants
• Describe what occurs at the molecular level during the five phases in the dyeing process
• List the factors that affect the effectiveness of dyeing and explain the reasons
• Describe the machines used for the dyeing of loose fibre, tops, yarns and fabrics, and compare their advantages and disadvantages

Topic 14: Principles of Wool Fabric Finishing

On completion of this topic you should be able to:

• Explain the various types of dimensions change that can occur in fabrics
• Describe the finishing methods used to remove contaminants from greige state wool fabrics
• Outline the finishing methods used to stabilise the dimensions of wool fabrics
• Describe the methods used for drying wool fabrics
• Describe the finishing processes employed to modify the handle and appearance of wool fabrics

Topic 15: Effect of Fibre Properties on Processing Greasy Wool into Worsted Yarn

On completion of this topic you should be able to:

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