Stock forms, types and sizes
All designers need to know the The standard size material is processed to. that metals and An alloy is a mixture of two or more elements, at least one of which is a metal. are available in. If stock sizes are known, designs can be manufactured more economically to reduce waste. Metal is available as a stock form in A way to describe that a material is normally much thinner than it is long or wide., A solid cylindrical form., A solid shape that is longer in length than width. and A hollow cylindrical form., and it is sold by length, width, thickness and diameter.
Steel rod is a solid round piece of metal, and the A straight line which joins two points on the circle and passes through the centre is a diameter. and length are needed when ordering. Steel bar can come in many An end view or area of a 3D form., such as square and rectangle, and the dimensions of the cross section and the length are needed when ordering.
Using A ferrous metal composed of iron with small amounts of carbon to increase the strength. as an example: the thickness of sheet steel is also measured using the A way of measuring the thickness of steel sheet and wire. scale. Conversion tables allow the purchaser to understand SWG sizes in millimetres (mm), eg a 2 mm- thick piece of sheet steel has a SWG size of 14. When buying steel tube, the The thickness of the outer wall of a hollow form. is measured using the SWG scale and the outer diameter and length are needed when ordering.
When buying sheet metal, the SWG size gives the thickness measurement, but the length and width measurements are also needed. Bulk buying metal, as with most items, can save money.
Example
1 m2 aluminium at 3 mm thick (SWG 11) = £29.00 per m2
Twice the thickness would cost:
1 m2 aluminium at 6 mm thick (SWG 4) = £44.00 per m2
The percentage increase in the cost for the thicker aluminium can be calculated:
Increase in cost = £44.00 - £30.00 = £14.00
This needs to be calculated as a percentage of the thicker aluminium:
(14 ÷ 44) x 100 = 32%
This shows that 100% more steel has been bought for just 32% of the cost.
Question
1 m2 steel at 2 mm thick (SWG 14) = £45.00 per m2
Twice the thickness would be:
1m2 steel at 4mm thick (SWG 8) = £57.00 per m2
What is the percentage increase in the cost for the thicker steel?
Increase in cost = £57.00 - £45.00 = £12.00
Calculate £12.00 as a percentage of the thicker steel:
(12 ÷ 57) × 100 = 21
So it is 21% more expensive.
Each material group has its own preferred set of standard components to fasten and join them together - metal is no exception. A metal plug used to hold sheet material together. They expand when the central plug is pulled upwards through the body of the rivet., nuts, bolts and screws are all common standard components to fix metal into place.
A rivet is often used to hold sheet material to another metal structure, eg some ‘off-road’ cars have their body held to the structure using a rivet. Nuts and bolts work by tightening a nut along a threaded bolt so that the sheet material is Made smaller by squeezing together. in place. Screws work in a very similar way - as a screw is turned it drives deeper into one material as it compresses another in place.
