stock forms Flashcards
what are the categories of metals
ferrous
non ferrous
alloys
what is low carbon steel
malleable, ductile good tensile strength.
medium carbon steel
these carbons are less ductile, hard, malleable and good tensile strength
grey cast iron
distributes heat evenly and withstands compression and deformation
white cast iron
excellent resistance to abrasion, hard and brittle and good tensile strength
what are the 6 non ferrous metals
-aluminium
-copper
-silver
-gold
-titanium
-tin
list four non ferrous alloys
-bronze
-brass
-duralumin
-pewter
what are the three categories of timber
hardwoods/softwoods and manufactured boards
what range are natural timbers stock forms
-rough sawn
-planed square edge (PSE)
-planed all round (PAR)
what is rough saw timber
-the cheapest stock from
-surfaces are rough from industrial saws
-cheap due to little processing
what is planed timber
-desired to have 90 degrees edge on one or more sides
how much timber is removed from PSE and PAR
around 3mm from original cut
what is the difference between PSE and PAR
PSE has one square edge
PAR is square on all sides (more expensive)
what are mouldings
machined profiles made for functional and aesthetic purposes
what are manufactured boards
boards that have been man made for example chip board or MDF
what are advantages of manufactured boards
-cheaper than natural timbers
-can be cut to larger scales
-can be enhanced with special properties such as water resistance or fire resistance
-can be aesthetically enhanced
name 6 soft woods
-pine
-Douglas fir
-Cedar
-Spruce
-Redwood
-Larch
what are characteristics of softwoods
fast growth
low cost
straight shape
lightweight
easily farmable
name six hard woods
-Oak
-Ash
-Teak
-Beech
-Birch
-Mahogany
what are characteristics of hard wood
slow growing
need more land
expensive
best aesthetic qualities
stronger more durable
how is MDF made
form fine wood dust particles bonded with resin under pressure, where chipboard uses larger chips
qualities of MDF
perfectly smooth finish
uniform density
ideal for CNC milling
what are the main performance characteristics of wood
-grain pattern
-warpage, shrinkage or splitting
-machining qualities
-resistance to decay and moisture
-toxicity
what causes warpage
caused by different moisture levels in different parts of the wood
what is shrinkage
as wood dry its volume decreases
what is splitting
as wood dries the fibres separate, usually when wood dries too quickly
what is wood when it is anistrpoic
when the grain gives natural wood different physical properties in different directions –it is an anisotropic material
what woods arent anisotropic
manufactured woods
what are types of surface defects in woods
-knots
-machining marks
-insects, disease or rot
what is seasoning
it is when the wood is dried to prevent warpage, shrinking and splitting
what are the two different types of seasoning
-air dried
-kiln dried
what are the three types of wood distortion
-diamond shrinkage
-cup shaped
-uniform shrinkage
what causes shrinkage
moisture levels
what are the advantages of seasoning
-makes the wood more stable
-less likely to decay or rot
-less likely to corrode metals
-absorbs preservatives more easily
what types of testing can be used for woods
-strength (tensile)
-toughness
-hardness
-density
-corrosion
-malleability
-elasticity
