Materials revision
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Materials Revision. Metals, Plastics, and Woods This powerpoint runs through materials and their properties, fixing methods (temporary and permanent), and finishing techniques. Categories of metals. Metals can be broken down into two main categories: . Ferrous Metals. contain iron

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Materials Revision

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Materials revision

Materials Revision

Metals, Plastics, and Woods

This powerpoint runs through materials and their properties, fixing methods (temporary and permanent), and finishing techniques


Materials revision

Categories of metals

Metals can be broken down into two main categories:

Ferrous Metals

  • contain iron

  • will corrode unless protected

  • attracted by a magnet.

  • don’t contain iron

  • aluminium, copper, tin and lead are all non-ferrous.

Non-ferrous Metals


Materials revision

Categories of metals

Alloys

  • A mixture of two or more metals

  • Brass is an alloy of 65% copper and 35% zinc

  • High tensile steel is an alloy of low carbon steel and nickel

  • Stainless steel is an alloy of steel, chromium, nickel and magnesium.


Materials revision

Joining metals

Materials can be joined temporarily or permanently. Three methods of joining metals are shown below.

Riveting

Nut, bolt &

washer

MIG Welding


Materials revision

Working with metals – finishing techniques

Several surface finishing techniques can be used on metals. The most common ones are detailed below:

Paint

Lacquering

  • Helps to prevent corrosion after polishing

  • A layer of cellulose or varnish is applied

  • Often used on jewellery.

  • Surface must be smooth & de-greased

  • Primer required

  • Hammerite is a good one-coat metal paint.

Plastic Coating

Enamelling

  • Suitable for most metals

  • Object is heated and dipped in a tank of powder paint

  • Object is returned to oven to ensure a smooth, glossy finish.

  • Powdered glass is melted onto the metal surface

  • Provides a hard (but brittle) finish with different colours and textures.


Materials revision

Categories of plastics

Plastics can be broken down into two categories:

thermoplastics and thermosets.

  • Soften when heated

  • Can bereshaped

  • More commonly used in schools

Thermoplastics

  • Initially set byheat

  • Cannot be reshaped once set

  • Extremely stronganddurable

Thermosets


Materials revision

Uses of plastics (thermoplastics)

Plastics have an extremely wide range of uses. Here are some common products made from thermoplastics.

Polystyrene

High Density

Polyethene

ABS

Low Density

Polyethene

Polypropene

Acrylic


Materials revision

Uses of plastics (thermosets)

Thermosets have different qualities to thermoplastics. Here are some uses for thermosets.

Epoxy

resin

Urea

formaldehyde

GRP

Melamine formaldehyde

Phenol formaldehyde


Materials revision

Working with plastics – other processes

Plastics can also be worked in other ways.

Hot wire

strip heater

Oven

Scroll Saw

Drill

Buffer


Materials revision

Joining plastics

Materials can be joined temporarily or permanently. Three methods of joining plastic are shown below.

Riveting

Adhesive

Nut, bolt and

washer


Materials revision

Working with plastics – finishing techniques

Plastics have excellent surface qualities. As they are self-finishing, plastics require little or no surface finish. However, when designers want a specific colour or texture, spray paints can be used.

  • Use wet and drypaper (wet) to smooth the surface down and create a ‘key’ for the primer to grip to.

  • Primer is used to create an undercoat to protect the plastic and provide a good surface finish for the top coat. The primer should be rubbed down using wet and dry paper between coats.

  • Top coat is applied once the primer has completely hardened. There are different surface textures: gloss, matt and metallic being the most common. Top coat is applied in several layers to build up a thick, tough surface layer on the top of the primer.


Materials revision

Categories of timbers

Timbers can be broken down into three categories:

  • available in sheet form

  • user friendly.

Manufactured boards

  • come from deciduous trees

  • can be very expensive.

Hardwoods

  • come from coniferous trees

  • grow in colder climates.

Softwoods


Materials revision

A closer look at hardwoods


Materials revision

A closer look at softwoods


Materials revision

A closer look at manufactured boards


Materials revision

Wood Lathe

Scroll Saw

Belt Sander

Working with timber – other processes

Timber can also be worked in other ways.

Drill


Materials revision

Joining timbers

Materials can be joined temporarily or permanently. Two methods of joining timbers are shown below.

Nails

Screws

Can you think of any other methods?


Materials revision

Working with timber – finishing techniques

Timbers can be treated with several surface finishes. They have different purposes and are chosen depending on where the product is going to be used and what type of visual appearance is desired:

Paint

Wax

  • Gives a dull gloss shine

  • Enhances the grain

  • Surfaces must be sealed

  • Indoor and outdoor use

  • Wood is sealed with a primer first

  • Coats the surface of timber

  • Cost effective

Stain

Varnish

  • Enhances the grain

  • Penetrates the surface of timber

  • A variety of colours is available

  • Tough surface develops

  • Resistant to heat and water

  • Can be coloured


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