To make a circuit board clamp 2 main modern materials are used, these are:
* Low carbon steel
These two materials have many different properties and design issues and in this essay I am going to be looking at what they are and why that certain material has been used.
First I’m going to look at the different properties of Low Carbon Steel.
The properties I’m going to be looking at are the density, weight, machine ability, strength and cost.
Low carbon steel has a carbon content of around 0.05-0.29%, this is less than the other types of carbon steel including medium, high and ultra-high carbon steel therefore it is more ductile.
Firstly i’m going to look at it’s density, this is a measure of how heavy an object is for a given size, for example the mass of material per unit volume. The density of this material is 0.28 lb/in3.
Next is its strength, When strength is not a major concern, low-carbon steels are good choices because they are easy to handle (draw, bend, punch, swage, etc.), the tensile strength of low carbon steel is a maximum of 500 Mpa.
This material is also very cheap so is good for making and selling as the product will not be too expensive.
The main reasons for the use of low carbon steel in the mechanical engineering industry are:
* Strong-the product will not break too easily(high tensile stregnth)
* Heavy-product will be stable(ecsecially important if it will be holding something i.e. circuit board)
* Cost-material is cheap so will not be too expensive to make the product
* Low carbon content-easy to machine/work on
* Ductile and malleable
There a some down falls to this material for example it has a poor resistance to corrosion which means it rusts easily.
This material has many applications for example it is used for nails, screws, bolts, girders, car bodies, boiler plates e.t.c.
This certain material benefits the design by being stable to hold a circuit board and it also might sell better as it will not be expensive.
I am now going to start looking at Nylon (polyamide); this is only used for the clamp bars on the circuit board clamp.
Nylon (Polyamide), invented in 1928 by Wallace Carothers is considered to be the first engineering thermoplastic. Same as the low carbon steel I’m going to look at the properties of nylon.
Nylon is a tough, strong, and impact resistant material and an excellent material for machining it also is Abrasion resistant.
First I’m going to look at its strength; the strength (tensile) of nylon is 5,800 psi, it also has a high melting point as it will not start to melt till it reaches a temperature of 420F 216C. The hardness of the material is measured at R92. The maximum density of nylon is 1.25 g/cc.
Different forms of nylon are used widely all over the world, including for:
* Apparel: Blouses, dresses, foundation garments, hosiery, lingerie, underwear, raincoats, ski apparel, windbreakers, swimwear, and cycle wear
* Home Furnishings: Bedspreads, carpets, curtains, upholstery
* Industrial and Other Uses: Tire cord, hoses, conveyer and seat belts, parachutes, racket strings, ropes and nets, sleeping bags, tarpaulins, tents, thread, monofilament fishing line, dental floss
This material has been chosen to be used for the circuit board clamp as it will make the product more sellable as it will not damage the circuit board that it will be holding.
I’m now going to look at 2 other materials that have not been used in our project and compare them and explain why they haven’t been used.
The two materials I’m going to look are Gold and Aluminium. First I’m going to look at aluminium.
Aluminium is a soft, lightweight, malleable metal with appearance ranging from silvery to dull gray, depending on the surface roughness. Aluminium is nontoxic, nonmagnetic, and nonsparking. Aluminium is a good thermal and electrical conductor, by weight better than copper. Aluminium is capable of being a superconductor, with a superconducting critical temperature of 1.2 kelvins The yield strength of pure aluminium is 7-11 Mpa.
It is ductile and easily machined also corrosion resistance is excellent due to a thin surface layer of aluminium oxide that forms when the metal is exposed to air, effectively preventing further oxidation.
The density of aluminium is a maximum of 2.70 g/cm-3
On the Mohs hardness scale aluminium is 2.75 which is a similar hardness to gold, the standard atomic weight is 26.981538612349936 gmol-1
The melting point of aluminium is lower than gold but is still quite high as it has to reach a temperature of 660.32 C to melt. This material is widely used because of its ability to resist corrosion and its light weight.
Aliminum has many applications including:
* Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles etc.)
* Packaging (cans, foil, etc.)
* Water treatment
* Treatment against fish parasites such as Gyrodactylus salaris.
* Construction (windows, doors, siding, building wire, etc.)
* Cooking utensils
* Electrical transmission lines for power distribution
* MKM steel and Alnico magnets
* Super purity aluminium (SPA, 99.980% to 99.999% Al), used in electronics and CDs.
* Heat sinks for electronic appliances such as transistors and CPUs.
* Powdered aluminium is used in paint, and in pyrotechnics such as solid rocket fuels and thermite.
* In the blades of prop swords and knives used in stage combat.
Next I’m going to look at gold; the chemical symbol for gold is Au.
Gold is a very rare substance making up only five ten-millionths of the Earth’s outer layer. Like most metals gold is very malleable and ductile. The relative density of gold is 19.3 and is 2.5-3 for hardness on the Mohs scale this is quite soft compared to other materials like copper coins, window glass and diamond.
It has an extremely high melting point at 1060C and has an atomic mass of 196.97, atomic mass is the mass of one atom of an element.
Gold is heavy, it weighs over nineteen times more than water, and is almost twice as heavy as lead, Gold, like most metals, can be hammered into thin sheets (malleable) or drawn out into thin wires (ductile).
Gold is not a widely used material but is used for lettering on honour rolls in schools, most jewellery and some ornaments.
The reason this material has not been used for our project is because it would be far too expensive and probably too soft.
I’ve looked at why these materials have not been used and now I’m going to conclude why the two materials that have been used (low carbon steel and nylon) was chosen for our cicuit board clamp.
The main reasons for why we used low carbon steel are because:
* It’s strong
* Easy to machine
* Ductile and malleable
The reasons for using Nylon are because:
* Will not damage the circuit board
* Abrasion resistant