27 Kasım 2007 Salı

Materials for textile engineers

Materials for engineers

Materials
Types of fibre
Fibres are the basis for all textiles. You need to know the difference between natural and synthetic fibres, how each fibre is used, and which fibres can be combined together.

1)Types of fibre
Textile materials are made in three stages:
.Spinning fibres into yarns
.Weaving or knitting yarns to make fabrics
.Finishing fabrics to make them more useful
There are two types of textile fibres: natural fibres and synthetic or man-made fibres.
Synthetic fibres are continuous filament fibres, while natural fibres are usually short staple fibres. The exception to this rule is silk - a natural fibre whose continuous filaments are up to one kilometre in length!
Where fibres come from
Natural fibres come from plants and animals: cotton from the cotton plant, linen from the flax plant, wool from sheep, silk from silkworms.
Synthetic fibres are manufactured using plant materials and minerals: viscose comes from pine trees or petrochemicals, while acrylic, nylon and polyester come from oil and coal.
Natural fibres
1. Natural fibres from plants:
Cotton
is used for making jeans, t-shirts and towels. It is cool to wear, has a soft handle, a good drape, and is durable. It can be washed and ironed, but it creases easily, is very absorbent and dries slowly.
Linen is used for summer clothing, tea towels and tablecloths. It is fresh and cool to wear, has a stiffer handle, and a good drape. It is durable, but can be washed and ironed. It creases badly and is very absorbent, but is also fast drying.
2. Natural fibres from animals:
Wool
is used for jumpers, suits and blankets. It is warm to wear, absorbent, dries slowly, is breathable repels rain and can be soft or coarse to handle. It does not have good drape, and is not durable; however, creases tend to drop out. If it is not dry-cleaned it may shrink.
Silk is used for evening wear and ties. It is warm to wear, absorbent, has a soft handle and a good lustre and drape. It is durable and creases drop out. It needs to be dry cleaned.

Synthetic fibres
The main synthetic fibres are:
Viscose
is used for shirts, dresses and linings. It has a soft handle, a good drape and can be washed and ironed. However it has low warmth, and is absorbent and slow-drying. Viscose is not durable and creases easily.
Acrylic is used for jumpers, fleece jackets and blankets. It is warm to wear, non-absorbent, and fast-drying, with a soft handle like wool, and a good drape. It is easy to care for, durable and crease-resistant.
Polyester is used for raincoats, fleece jackets, children's nightwear, medical textiles and working clothes. It has a soft handle, a good drape, is very durable, crease-resistant, easy-care, non-absorbent, and fast drying. It can be recycled, but has low warmth.
Nylon (Tactel) is used for active sportswear, fleece jackets, socks and seat belts. It has a soft handle, a good drape, is non-absorbent, fast drying, very durable, crease-resistant and easy-care. However it has low warmth.
Modern fibres
Microfibres:Polyester or nylon microfibres are 60-100 times finer than a human hair (the diagram below shows what they look like up close):
Microfibres can be blended with other synthetic or natural fibres.
Microfibres are used for outdoor-pursuits clothing and active sportswear.
Thermoplastic polyester or nylon microfibres can be heat-treated to give them coils, crimps and loops, which makes these textured yarns stretchy and warm. They are used for underwear, sportswear, knitwear and carpets.
Fibre blends:Blending different fibres together produces yarns that have the combined properties of each component fibre. Using fibre blends improves the appearance, performance, comfort and aftercare of fabric. Blending can also reduce the cost of an expensive fibre.
A shirt made from polyester / cotton blend is more easy-care and crease-resistant than a shirt made from 100 per cent cotton.
Cotton / Lycra blend jeans are more comfortable, stretchy and fit better than cotton jeans.
Acrylic / wool blend trousers are less expensive than 100 per cent wool trousers.
Two key modern microfibres:
Elastane (Lycra). This is always used in a blend with other fibres. It is used to make sportswear, body-hugging clothes and bandages. It has good handle and drape, is durable, crease-resistant, stretchy (more comfortable) and is easy-care. It has low warmth and is absorbent
Tencel. This is a 'natural' microfibre made from cellulose derived from wood-pulp. It is used for shirts and jeans. It has soft handle, good drape, is breathable, durable, crease-resistant, easy-care and biodegradable. It is absorbent and has low warmth.
Exam tip:Make sure that you know the properties and end-uses of fibre blends such as polyester / cotton. You'll get extra marks for being able to a fibre's properties to the product it's used for.
For example, Tencel fibre is suitable for denim jeans because it is soft, drapes well and is easy to care for

Fibres test

1 . Textile materials are made by spinning fibres into fabrics: false
2 . What are continuous filaments?
Continuous filaments are usually long filaments of synthetic fibres that run the whole length of the yarn
3 . The passage explains about blended fibres. Pick the correct words out of the list below and insert them into the text:cost
materials
properties
performance
yarns
appeal
Blending different types of fibres together produces yarns that have the combined properties of each component fibre. Using fibre blends improves the appearance, performance, comfort and aftercare of fabric. Blending can also reduce the cost of an expensive fibre.
4 . The passage outlines why particular fabrics are used for certain types of clothes. Pick the correct words out of the list below and insert them into the text:
warm
cool
dyes
absorbent
lustre
Cotton is used for T-shirts because it is cool to wear and dyes well. Linen is used for tea-towels because it is very absorbent. Wool is used for jumpers because it is warm to wear. Silk is used for evening wear because it has good lustre and drape
5 . Why is polyester suitable for children's nightwear
Polyester has a soft handle.
6 . Why is Tencel fibre suitable for denim jeans
it has good drape
7 . Which fabric is a good choice for body-hugging clothes
Elastane
8 . The passage explains some of the key terms used in textiles. Pick the correct words out of the list below and insert them into the text:
comic
perspiration
flexible
comfortable
hangs
behaves
feels
fashionable
Handle is how a textile when touched, such as soft, rough, smooth, warm or cool. Drape is the supple and character of a fabric - how it or behaves when pleated or folded. Breathable is how a fabric allows to evaporate, making it to wear.

fabric test
1 What is twill-weave fabric?
Twill-weave fabric has a diagonal pattern on its surface. It is strong and drapes well.
2 Non-woven fabric is made by bonding. What are bonded fabrics made from?
Bonded fabrics are made from webs of synthetic fibres bonded together with heat or adhesives.
3 What is the key advantage of bonded fabrics, such as Vilene? .
they are bonded fabrics such as Vilene are crease-resistant.
4 The passage explains some of the key terms used in textiles. Pick the correct words out of the list below and insert them into the text:
fray
hats
non-woven
animal hair
underwear
strength
smell
woven
Wool felt is a non-woven fabric made from animal hair or wool fibres matted together using moisture, heat and pressure. Felt has no strength, drape or elasticity, but is warm and does not fray. Wool felt is expensive. It is used for hats and slippers.
5 A smart fabric responds to the needs of the manufacturer in an environment: false
6 What are micro-encapsulated fabrics used for?
Micro-encapsulated fabrics are used for underwear, anti-bacterial socks and medical textiles.
7 Fabrics should be chosen that ensure a product will suit the target market and do the job it is intended to do: true
8 Aesthetic properties of a product relate to the appearance of a material.
including drape
9 Functional properties relate to the performance of a material.
including the strength, cost, water-resistance and aftercare of the material.
10 Comfort properties relate to how comfortable the material is to wear.
including the softness, elasticity, stretchiness and warmth of the material.
11 Women's jumpers are usually made from a fabric that is:
soft, colourful, stretchy, warm and easy-care.
12 Seatbelts, airbags or conveyor belts are normally made from fabric that is:
strong, durable, flame-resistant materials.

Design considerations

Product analysis and evaluation test
1 Market research is used to find out the taste, values and lifestyle of a random section of the community: false
2 Designers and manufacturers use product analysis to help them develop ideas for new or improved products: true
3 The fitness for purpose of a product is evaluated by studying the product performance, price and aesthetic appeal: true
4 Quality of design means that textile products are well-designed, so they sell successfully. Which of the following is true?
A well-designed textile product should be all of these
5 Quality of manufacture means textile products are well-made, so they sell successfully. Which of the following is NOT a characteristic of a well-made textile product
The product is made as quickly as possible
6 One way of evaluating the quality of a product is to apply product-design specification criteria to your analysis. Which of the following is NOT likely to be included in a product-design specification? e- All these items should be included in a product-design specification.
7 When evaluating the manufacturing quality of the product, you don't need to examine the seam allowance, stitching or fastenings:false
8 Which of the following is NOT necessary when you analyse a product?
to work out and sketch the pattern section.
9 The quality assurance [QA] system uses quality control to test and monitor the quality, accuracy and fitness for purpose of the product from the design stage right through to manufacture. Which of the following are involved in the QA system?
manufacturing specifications; work schedules; prototypes; and sealed samples are all part of the QA system.
10 The passage explains the quality-assurance system in the textiles business. Pick the correct words out of the list below and insert them into the text:
tolerance
used
breaks
points
specification
manual
stitch
raw
Quality-control checks take place at critical control points in a product's manufacture. This includes checking the following. First, that the raw materials are the correct width, colour, weight and fibre content. Second, depending on the product end-use, the fabric may be tested for strength, durability, crease-resistance, stretch, shrinkage or water-repellence. Third, during production there are checks for stitch and seam strength. The seam allowances are tested to check that they meet the tolerance stated in the manufacturing specification.
11 The final product is inspected for which of the following
the final product is inspected for size and fit

Textiles production

Systems and practices test
1 Whose role is it to identify the need for a product, using market research and set a design brief set the price and set product deadlines?
Client
2 Whose role is it to research the market, trends, materials, social, cultural, moral, environmental and safety issues to ensure the product is right; then produce a product-design specification, produce costing for product, and help to plan product manufacture?
Designer
3 Whose role is to analyse the product prototype, produce a production plan and a work schedule; then make sure that production, material and labour costs are kept to a minimum, while producing a high-quality, safe product on schedule.
Manufacturer
4 Whose role is it to demand a high-quality, value-for-money product that meets requirements and is safe?
User/consumer
5 Which stage of production includes adding decorative or functional details and final pressing?
Finishing
6 Which stage of production includes the spreading, cutting, labelling and bundling of the fabric pieces?
Processing
7 Which stage of production includes the labelling, hanging, folding and covering the product ready for transport to the retailer?
Packaging
8 Which stage of production includes fusing, joining and pressing the separate product parts?
Assembly
9 Which stage of production includes working out the amount of materials to buy in and the preparation of patterns, templates and lay plans?
preparation
10 Which production method is the most likely for producing black socks and other products that change slowly with fashion?
Mass production
11 What type of computer systems are used in the design and manufacture of textiles?
Computer Numerical Control [CNC].
12 ICT is used to plan the 'just in time' ordering of materials and components, so they arrive at the factory
Just before they are needed

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