more production stuff Flashcards
what are production aids
tools and techniques used to aid production, often speeding up or simplifying a process
what is a reference point
a point where measurements are made from
- helps control accuracy
what is a datum point
the point where x, y and z meet at (0,0,0)
why are reference points important
- they align CAM machines with the materials they are operating on
- they reduce measurement errors
what do CAM machines use reference points for
to guide the tool being used
how to use a reference point for scaling the size of something like a drawing
- choose a reference point
- figure out how far away each point on the drawing is from the point
- multiply these coordinates by a scale factor
- plot your new coordinates
what is a template
a shaped piece of rigid material used as a pattern for processes such as cutting out or drawing around
advantages of templates
- quicker and easier than measuring out the dimensions of the shape eac time
- useful in quality control, as you can check your components against the template
- using a template makes the procure consistent
features of templates
- need to be strong
- need to be hard wearing
- so that they can be used repetitively without getting damaged or worn
what are patterns
templates that are used to cut out pieces of fabric - these pieces are then sewn together to make a textiles pridgcb
what are patterns normally made from
tissue paper which are then pinned to a fabric so that you can cut around them
- can be made from materials such as resin wood and metal
how are patterns made using CAM
- CAM cutting machines are used to cut the fabric
- The patterns are drawn out using CAD. the coordinates of the patterns outline are then used to tell the machine how to cut the pieces of fabric
what does casting involve
forming a material into a particular shape - determined by a pattern
what can patterns be used to make
moulds that are used in the casting process and make products that are a consistent shape
what is a jig
a device that guides the tools that are working on a component, or makes sure that the workpiece is positioned in the right place for machining
what does a drilling jig do
- guides the drill, which helps cut down errors and makes sure that components are consistent
- using this means you don’t have to mark out exactly where you want to drill, saving time and effort
what does a dovetail jig do
allows complex, dovetail joints to be cut easily and quickly, with minimal measuring and marking out
potential disadvantage of using jigs
although they can be really useful, they can take a long time to make, so not worthwhile using one if you’re only gonna make a few products
what are paper and board made from
cellulose fibres
how is board/paper made
- trees are cut down and taken by lorry to a paper mill
- the bark is stripped off. The wood is then cut into small pieces by a chipper
- these small bits of wood undergo chemical or mechanical pulping to turn them into a mushy brown pulp
- The pulp is then washed and bleached to make it white, hen it’s pressed clay between rollers, dried and cut to size
why is pulping an important stage in paper and board making
it converts the wood into individual cellulose fibres (pulp)
what does mechanical pulping involve
grinding down the wood to separate out fibres
what does chemical pulping involve
heating the wood with chemicals - this dissolves other parts of the wood, leaving just the fibre behind
where else can cellulose fibres come from
other plants like grasses - the process is similar to wood but theres no debarking or chippung
examples of types of board that may have an extra stage in production
corrugated cardboard needs its fluted middle layer sticking to the outer layers to form a laminate
How is wood made
- Trees are felled (cut down)
- the bark is removed and the trunk is sawn up
- the wood is the seasoned by drying it
what does the way a trunk is sawn affect
how the plank looks and how much its likely to bend or warp (twist)
ways wood can be seasoned
air drying or kiln drying
summarise air drying
involves stacking up wood outside or in sheds and allowing air to circulate around it
summarise kiln drying
similar to air drying but its done in a heated chamber with fans to circulate the air
pros and cons of kiln drying
- quicker
- ## but conditions have to be carefully controlled to avoid the wood drying too fast (which can damage it)
how is MDF made
using wood that has been processed into cellulose fibres
how is chipboard made
using a mixture of dried wood chips, shavings and saw dust
whats the long name for glue
urea formaldehyde
what is added to mixtures such as chipboard and mdf
glue
how is plywood made
using wood that has been softened, either through soaking it in hot water or steaming it
- a thin sheet is peeled from the softened wood, cut to a suitable size and dried
- the cut wood can then be arranged into stacks of three or more layers (each with a grain direction of 90 degrees)
- glue is then added between each layer and the sheets are heated and pressed
where do metals come from
the ground as a metal ore
what is a metal ore
a rock with enough metal locked up in it to make it profitable for the metal to be extracted from the rest of the ore
how are metals made
- metal is mined from the ground as a metal ore
- metal is then extracted using displacement or electrolysis
- impurities are removed from the metal in a process called refining
- the refined molten metal is usually cast
describe the two ways of extracting metals
- some metal ores can be crushed then heated in a furnace with other materials such as charcoal. the metal separates out and will often sink to the bottom where it can be tapped off
- electrolysis uses electricity to extract a metal from its ore
why are metals refined
because when they’ve been extracted from their ores, they will contain impurities
what are impurities
small amounts of other substances
what is casting
a process which involves pouring metal into a mould and allowing it to cool and solidify into the required shape
Examples of metal ores that have to be prepared before extraction takes place
bauxite is heated under pressure with chemicals to separate aluminium oxide
what are most plastics made from
crude oil
how are plastics made
- crude oil is extracted from the ground and taken into a refinery
- here, its heated using a process called fractional distillation, which separates it into different chemicals called fractions
- some of these fractions can be linked together to make polymers and some need cracking
- these plastics can then be used
what is cracking
a process where you heat fractions and break them down into smaller molecules
