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Product Design Year 10 Exam - Coggle Diagram
Product Design Year 10 Exam
Timbers
Types of Timber
Hardwood trees are deciduous, broad-leafed trees. These trees typically grow at a much slower rate than softwood trees, meaning that growing and obtaining the wood is much more difficult; meaning the tree is significantly more expensive to purchase. Examples include oak and mahogany.
Softwood trees are evergreen, they bear leaves or needles and grow much quicker than hardwood trees, meaning they are typically more profitable for manufacturers as they can be grown and farmed in masses. Examples include pine and cedar.
Manufactured boards are man-made, they are formed from wood fibres or stacked veneers. Because these boards are extremely easy to manufacture, they are often very cheap for the consumer to purchase. Examples include MDF or chipboard.
Stresses and Forces
Types of Stresses:
Bending
Tension (Pulling)
Torsion (Twisting)
Compression (Squishing)
Shearing (Rubbing)
Ecological and Social Footprint
An
ecological footprint
is the
impact
that someone or
something
has on the
natural environment
by the
quantification of the resources they use
. This is usually measured by the amount of CO2 it emits.
A
social footprint
is the
impact
that a company's
social policies
have on its
consumers/employees/society
as a whole.
Biology of a Tree
From centre to outermost component
: Pith, Heartwood, Sapwood, Annual Rings, Outer Bark
A tree begins its life cycle in
seed form
, this
seed takes in water
and mineral ions that reside within the soil.
After some time, the
seed germinates
and the first root
begins to extend from the seed.
Next, the
seedling stage
begins and the seed just
rises above the earth's surface.
Next, the seed will reach its
sapling stage
(above 3ft tall) at which point it may be
vulnerable to fauna and weather
; the trunk of the sapling is often
malleable with smooth bark
, not able to produce fruit or flora.
A tree reaches the
"mature" stage
when it is able to grow
fruit or flora
, hardwood trees typically remain in this stage for much longer than softwood trees.
A tree classed as
"ancient"
often has a
hollow trunk
,
small canopy
and
missing branches.
A tree classed as decaying is often the dwelling place of bacteria rich eukaryotes such as fungi
Using and Working with Timbers
Plane
: Planes are used to smooth surfaces by removing thin layers of the material by running a sharp blade across the surface.
Method
: Place the plane on the material's surface, slide the tool across the surface, making strict and powerful forward motions. Planes have a tendency to slip if not properly handled.
Chiseling
: Chisels are used to remove material next to a cut or between two cuts, can be used to produce dovetail joints.
Method
: A mallet can be used to enhance the capabilities of a chisel, hitting the handle of the chisel with the mallet when it is aligned with the material you would like to remove.
Sanding
: Used achieve a profiled shape or smooth surface finish by removing fine particles. This can be done by hand, with an orbital or with a sanding disk.
Method
: (Using a sanding disk) Once the machine is operating, adjust the table so that it is at the desired angle, push the material across the table into the rotating disk. (Using sand/glass paper) Simply rub the paper vigorously against the material at the angle that you desire.
Timber Joints
A finger joint is a joint in which two pieces of material are joined together perpendicularly via complementary teeth carved on both materials. Often, adhesive will be used to ensure that these pieces will stick together.
Mitre joints are constructed via cutting slants into two pieces of material, joining them together with adhesive to form a 90 degree angle. These joints are not particularly strong.
Lap joints are formed by carving an indent into a (or multiple) piece of material(s); these pieces are stuck together with adhesive (typically) and connected perpendicularly.
Dowel joints use the dowel stock form. This joint involves the cylindrical hollowing of two pieces of material and the insertion of a dowel to connect the materials together.
A butt joint is simply a direct connection of two piece of material through the use of adhesive, it involves sticking two piece of material together end-to-end at a 90 degree angle.
Specialist Techniques and Processes
Steam bending involves the softening of wood with heated water (steam). This steam allows the timber to be distorted and shaped into a unique form that would be otherwise impossible to create. An apparatus such as a jig will often be used following the softening to keep the wood in the desired shape.
Lamination involves the stacking of thin, timber sheets onto each other, holding the sheets together with adhesive, this process can be used during the manufacturing of desks or table-tops.
Veneering involves the use of a rotating lathe to slice a trunk into extremely thin sheets of timber, these sheets are applied to a surface using adhesive.
Inlays are specially cut pieces of wood that are slotted into a corresponding, identical groove within a surface. The groove will often be created via the use of a laser cutter or chisel. Once the inlay has been inserted into the groove, it will often be stuck there with an adhesive and sanded to ensure the surface is smooth.
A jigs is a type of apparatus used to maintain the position of a material. A former will often be used in processes such as vacuum bending, the material involved with the process will be bent over a former, giving it the desired curve/shape.
Surface Finishing Techniques
Finishing oil is a blend of oils used in woodworking to nourish and enhance the colour of timber; commonly applied with a brush or cloth.
Wax is common finish used to provide timber with a layer of protection. Some waxes may have to be re-applied.
Wood varnish is a mixture of a oils and resin used to provide a glossy coating to a piece of timber. Varnish will also provide a level of water protection or protection from UV rays.
Using a paint finish is a less practical but more ornamental finish. It is typically applied with a brush.
Wood stain is applied to a section of timber to saturate and colour the wood, stain reaches into every chasm of the woods surface, appearing to give the wood a greater level of detail.
Distressing of wood is a process in which the wood is slightly burned/singed with a torch. This appears to give the wood a weathered, older appearance.
Burnishing is a finishing technique which leaves a section of timber with a texture similar to that of a sanded piece. Burnishing is often undergone through the use of friction generated by steel wool.
Stock Forms
Stock Forms Used for Timbers:
Square section board
-
Rectangular section board
-
Moulds
-
Sheet
-
Dowell
Polymers
Types of Plastic
Thermoplastics are one of two types of plastics, they are able to melt and be reshaped due to their chemical structure. Some examples include polypropelene and acrylonitrile butadiene styrene.
Thermosetting plastics are not easily melted or reshaped and are often much less flexible than thermoplastics. This is due to more bonds between monomers. Examples include bakelite.
Polymer Alternatives
Bioplastics are bio-degradable plastics; they consist of natural matter such as plants or animal remains. These plastics are able to be produced in a renewable manner and are non-toxic to produce.
Forces and Stresses
A force can cause an object to do several things: change speed, change direction, stop moving and change shape. The two main categories of forces are contact and non-contact. Some contact forces include friction and normal contact force. Examples of non-contact forces include electrostatic and gravitational.
Sources and Origins
Common plastics are made from crude oil, cellulose or salts. Fossil fuels are often used during the production of plastics.
Fractional Distillation
:
This process involves the separation of crude oil into several hydrocarbons, each with a differing boiling point.
-
Naptha is the hydrocarbon mixture used to produce plastics,
-
The stronger the covalent bonds within these hydrocarbons and the longer the polymer chains; the larger the amount of energy required to overcome these forces.
-
There are varying temperatures throughout the distillation chamber, this allows the crude oil to be separated. As the substances with a lower boiling point manifest as a gas more quickly; travelling to the top of the chamber.
-
Combustion is necessary for the distillation process.
Cracking
:
A process in which alkanes (long hydrocarbons) are broken down into more useful hydrocarbons.
-
The alkanes are heated to titanic temperatures; at this point they are passed over a catalyst and "cracked" into smaller hydrocarbons.
-
The cracking of hexane produces butane and ethene.
Polymerisation
:
This process forms polymers from constituent monomers.
-
Ethene can form polyethene via polymerisation.
Using and Working
A coping saw can be used to cut curved lines in thin materials
-
A bandsaw can be used to make incredibly accurate cuts (straight or curved).
-
A vinyl cutter is a computer operated cutter; it is often used to create shapes and letters from thin sheets of vinyl.
-
A laser cutter is a computer operated cutter; it is one of the most accurate ways of cutting plastics. The shape of this cut is determined by a CAD program.
-
Some abrasion techniques for polymers include: metal filing and abrasive pads
-
A pillar drill can be used to create accurate holes within plastics.
Stock Forms
Sheet
- Sheets are most commonly used in processes such as vacuum forming, laser cutting and line bending.
-
Rod
- Rods are commonly used to fix together pieces of material (similarly to a dowell).
-
Tube
- Tubes are commonly used for plastic piping/plumbing. Using plastic tubing for plumbing eliminated the likelyhood of rusting or staining.
-
Granules
- Necessary for processes such as injection moulding, extrusion and dip coating.
-
Film and Foam
- Film is a stock form commonly used for vinyl or food packaging. Foam is a stock form commonly used for packaging and can easily be manufactured through recycling.
Scales of Production
One off (expensive, large amount of time to manufacture).
-
Batch (set quantities, products that may go out of style, lower costs).
-
Mass (large quantities made, not suitable for commonly redesigned products).
-
Continuous (low manufacturing costs, automated, suitable for products that will not change).
-
Just in time (relies on shipping company, order materials just in time for manufacturing).
Processes
Line bending is a process that involves the use of a strip heater and a plastic sheet. A mark will first be made on the sheet; then, it will be secured with a jig and left on the heater for an allocated amount of time.
Vacuum forming involves a plastic sheet being clamped on a vacuum former, suspended over a mould. The sheet is heated until a dip in the material can be seen. At which point it is lowered towards the mould, the vacuum is then switched on. The mould should be tapered to allow it to slow from the mould.
Blow moulding involved a heated plastic tube being pumped with air; expanding the tube to fit the mould that it resides within.
Extrusion involves melted polymer granules being forces through a die to create a specific shape. Similar to injection moulding but is continuous.
Injection moulding involves a set quantity of melted plastic granules being pushed through a die into a mould. The granules are heated in a chamber with heating elements and then pushed into the mould through the use of an Archimedes screw.
3D printing involves a 3D printer stacking layers of thermoplastic filament in a pre-decided shape. This is incredibly accurate process but the printer itself is expensive.
Joining Methods
Lamination (bonding strips or material together to reinforce or make flexible), welding (using heat or chemicals, applied with a hot air gun), plastic rivets (cheap alternative to screws), heat sealing (via a bag sealer used to seal thermoplastic bag or tubing).
Finishing Techniques
Spray paint and primer (aesthetics, UV protection), vinyl decal (aesthetics, graphics), flocking (fluffy finish), embossing (aesthetics), heat transfer printing, hydro-graphic printing, electroplating and electroless plating, rubberising spray.