The Following Glossary Is Taken from the State Examinations Commissionwebsite, Rearranged

The following glossary is taken from the State Examinations Commissionwebsite, rearranged in alphabetical order.

Examination material archive – marking schemes

Ordinary Level(2004, ’05, ’07, ’08, ’09, ‘10)

Adhesive bonding Adhesives can be used to join similar or dissimilar materials e.g. metal to metal or metal to plastics by surface attachment. Adhesives are supplied in liquid, paste, solid or power form. Joints, which can be air or water tight, are quick and economical to make. Adhesives can be applied to the surface by hand and allowed to harden. Methods of hardening include the use of a hardener, heat, pressure and the evaporation of a solvent. The use of adhesives is a bonding process. Application: Car break pads to steel shoes.

An alloy is a combination of metals or other elements. Alloys produce metals with improved properties such as resistance to corrosion and the ability to retain hardness and strength at high temperatures.

The metals and or elements added depend on the properties required. Solder - Lead & Tin, Brass - Copper & Zinc

Annealing is carried out to soften metal and to relieve internal stresses. The metal is heated to the required temperature and allowed to cool down as slow as possible. When annealing copper it is heated to a dull red color and allowed to coolin air or water.

Basic Oxygen FurnaceMild Steel is produced in the BOF. The charge consists of scrap iron and steel together with lime and molten pig iron. Oxygen is blown at the surface of the molten charge from a water cooled lance which is lowered through the mouth of the furnace. Impurities in the charge are oxidized and form a slag on the surface. At the end of the blow, the steel is poured off through a tapping hole followed by emptying the slag through the mouth of the furnace.

A belt and pulley drive system. Application: Household machines such as sewing machines, spin driers and washing machines are often driven by round grooved pulleys. Machine tools such

as drilling machines and lathes use vee pulleys and vee belts. Belt and pulley drive systems can also be used to transfer rotary motion from a motor spindle to a drive axle on class projects.

Bevel gauge: A bevel gauge is used for checking inclined faces and marking out lines at given angles. It can be set to the required angle by means of a setting protractor and locked in position by a clamping screw.

Bevel gears are used to change the axis of rotational motion. A mechanical hand drill uses bevel gears not only to change the rotary motion through 90 degs. but also, by using different size gears, to increase the output rotational speed.

A Bimetal strip is made of two dissimilar strips of metal i.e. Copper and Steel riveted together. At room temperature both strips are the same length. When heat is applied the copper will expand to a greater extent than steel. The result is that the bimetal strip bends. A bimetal strip can beused as a thermostat or in fire alarms. If heat is applied to the strip it will bend upwards closing contacts causing an electrical bell to ring. An alloy is a combination of metals or other elements.

Blast FurnacePig Iron is produced in the Blast Furnace. Fed in through the top of the furnace, iron ore, coke and limestone provide the charge. As the coke burns, carbon monoxide is produced, and combines with the oxygen in the ore, leaving iron. The limestone combines with impurities to form slag. The molten iron falls to the bottom of the furnace where it is tapped off from time to time. The slag floats above the molten iron and is tapped off as required.

Blind hole This is a hole that does not go all the way through a part. When it is not practical to have a machine screw going through a part, a blind hole can be drilled and tapped and ascrew used.

In blow moulding a heated thermoplastic tube called a parison is

extruded between the two halves of a split mould. The mould

closes around the parison and air is blown into it forcing the

parison out against the wall of the mould. The component is

allowed to cool before being removed from the opened mould.

Blow Moulding: In blow moulding a heated thermoplastic tube called a parison is extruded between the two halves of a split mould. The mould closes around the parison and air is blown into it forcing the parison out against the wall of the mould. The component is allowed to cool before being removed from the opened mould. Using blow moulding thermoplastic materials like polythene can be moulded into bottles and drums.

Brass. Copper and Zinc

Brittleness: A brittle material will fracture if subjected to an impact or blow. Glass is an example of a brittle material.

A brittle material is very hard and can easily be fractured by an impact. Brittleness is the opposite of toughness. Glass is an example of a brittle material.

Broadband provides high speed internet access by delivering multiple channels of data over single communication mediums such as DSL, Wireless or Satellite. Providing an always on connection, broadband facilitates fast access to data, voice or video.

Browser A browser is a piece of software that is used to view and download the content of webpage’s. Browsers provide users with a graphical interface to explore the web by translating HTML pages into various types of files such as text, audio, video and graphics. Mozilla Firefox and Microsoft’s Internet Explorer are two common browsers in use.

BronzeCopper and Tin produce

Cam and follower A cam is a specially shaped piece of material which is fixed to an axle or shaft. A follower is a device designed to move up and down as it follows the shape or profile of the rotating cam. The shape of the cam controls the movement of the follower. Depending on design, a cam and follower can be used to convert one type of motion into another. The most common design is based on a rotary cam which changes the rotary motion of the cam into reciprocating motion of the follower. The follower is kept in contact with the cam by its own weight or by pressure exerted on it.

CAMComputer Aided Manufacture

CAD Computer Aided Drawing / Design

CAD/CAM: Stands for Computer-Aided-Design and Computer- Aided-Manufacture. Such a system enables us to draw the part on the computer screen, with the aid of a mouse, and then by selectingthe appropriate command the computer will write the part program.

Cam and follower: A rotary cam changes rotary motion into reciprocating motion. A follower in contact with the edge of the cam moves up and down or in and out as the cam rotates. The shape

of the cam controls the motion of the follower. The follower is kept in contact with the cam

by its own weight or by pressure exerted on it.

Capillary action Capillary action refers to the solder being drawn into a joint. The parts to be joined are cleaned fluxed and heated. If the work is hot enough and the gap between metals correct the solder will be drawn into the joint, completely filling it.

A Carburising flame: Excess acetylene is supplied to the neutral flame.

Case hardening: Case hardening is a method of making low carbon steel very hard on the outside while leaving its centre tough. Low carbon steel may be case hardened by first increasing the amount of carbon in the outer surface by carburising. Carburising is carried out by heating the steel to a cherry red and allowing it to cool in a carbon rich material. The steel part will now have a skin or ‘case’ rich in carbon. The part is then heated to a cherry red and quenched, producing a hardened skin with a tough core.

CDRW A compact re-writable disk provides portable memory in the form of a compact disk. Capable of storing very large files it can be written to many times allowing the data to be over written as required.

The Centre drill is used first when drilling round material on the centre lathe. Use of a Centre drill ensures accurate location of the twist drill size required. The Centre drill or ‘Slocomb’drill is also used for drilling holes for lathe centers, which are used for supporting the ends of work pieces.

ChuckFour Jaw Independent: The four jaw independent chuck can be used for eccentric turning and for gripping square, round, rectangular and irregular shapes. The four jaw independent chuck allows the work to be centred more accurately than a three jaw, but takes longer. The jaws can be moved independently of one another, each being actuated by its own screw. The jaws are also reversible and therefore only one set isrequired.

The chuck key is used to open and close the jaws on a lathe chuck.A spring is often fitted to ensure the chuck key is removed from thelathe chuck before operating.

Chuck guard Due to the dangers of high speed moving parts and / or metal cuttings achuck guard is put in place before machining to protect the operator from serious injuries

The Clearance angle ensures that only the cutting edge of the tool comes into contact with the work. Without clearance, the tool would just rub against the work without cutting.

Clearance fit In this assembly there is a space between the two parts. The shaft is always smaller than the part it fits into.A clearance fit results in the assembly of a shaft and hole where the upper limit of the shaft is smaller than the lower limit of the hole.

A clearance size hole is slightly larger than the screw that passes through it. The clearance enables machine screws to be inserted quickly. Washers have clearance holes.

Computer Numerical Control is where a machine is controlled by a computer program based on numbers. CNC lathes are examples of such machines.

CNC Computer Numerical Control

Compression Moulding: A raw thermosetting plastic in powder form is placed in a mould and subjected to heat and pressure for a given period of time, during which the material solidifies (cures). After this stage the mould is opened and the component ejected. Using this process thermosetting materials can be moulded into screw top lids, plug tops or light fittings.

Computer Aided Manufacture (CAM) refers to the use of computers for controlling machines in the manufacture of products. The CNC lathe is an example of Computer Aided Manufacturing system.

Computer Control: Computer is used to operate a CNC lathe, Robot or any external device i.e. traffic lights.

A computer network is a collection of computers, printers and other equipment, which are connected together so that they can communicate with each other. The linking of computers by special cables or radio waves known as wireless networks allow data and resources to be shared among users.

A computer simulation provides a computer generated animation of a procedure or process. Utilised in many fields from training of aircraft pilots to safety checks on machining operations, CNC software provides a simulation facility to trial run programs before manufacture.

Compressive force A compressive force is when a bar is subjected to a push. If the push on one

end results in an equal and opposite push on the other end than the bar is said to be in compression.

The Compressive strength strength of a metal is the metal’s ability to support a heavy weight or withstand large equal and opposite push forces. Tubular metal legs of chairs need to have good compressive strength to support the weight of the person sitting down.

Compression Moulding: A raw thermosetting plastic, in powder form, is placed in a mould and subjected to heat and pressure for a given period of time, during which the material solidifies (cures). After this stage the mould is opened and the component ejected. Using this process thermosetting materials can be moulded into screw top lids, plug tops or light fittings.

Conductivity The haphazard movement of free electrons in a piece of metal can easily be

changed to a movement in one direction if the metal is connected to the terminals of a battery. Metals therefore allow electrons / electricity to pass through easily. If the end of a piece of metal is heated, the resulting increase in the movement and vibration of the electrons and ions causes nearby electrons and ions to move and vibrate faster. Heat energy is transferred along the piece of metal in this way. Metals are, therefore, very good conductors of heat.

Coolant: Cools the cutting tool and the work piece. Helps to reduce friction between the cutting tool and work piece reducing wear and improving surface finish.

Counterboring is the increasing of the hole diameter to a certain depth in order to accommodate cheese head or round head screws.

Countersink drill: A special drill made from high-speed steel, used to cut a large chamfer of the correct angle, usually 90 degrees, in the top of a hole. The use of a countersink drill provides seating for countersink – head screws. The seating allows the screw head to sit flush with the material face.

A countersink is the tapered enlargement at the mouth of a hole formed to receive the heads of countersunk-head screws and rivets. The enlargement is formed by a countersink cutter.

CPU A CPU is the central processing unit of a computer where the instructions of a computer program are used to process input data and change them into the required form or information before output.

CPU: Refers to the central processing unit of the computer where the instructions of the computer program are used to process the data and change them into the required form or information.

Cupola FurnaceCast Iron is produced in the Cupola Furnace. Pig iron and scrap steel or cast iron, together with other elements are the raw materials. Similar to the blast furnace, the cupola furnace is coke-fired with limestone acting as a flux to trap the impurities into slag. The molten cast iron is tapped from the bottom of the furnace and cast into moulds of different shapes and sizes as required.

Cutting speed: Refers to the relative speed between the cutting tool and the work. In turning, the cutting speed is the surface speed of the work and is measured in meters/minute.

A depth gauge can be used to measure the dept of holes, recesses and the distances between surfaces. A depth gauge consists of a blade which is adjustable in its stock.

Depth of cut: The amount by which the cutting tool is engaged in the work piece. In turning it is the distance from the diameter being reduced to the new diameter.

The ‘Desktop’ is the homepage of a computer’s operating system. The desktop screen can contain many icons such as ‘My Computer’, ‘Recycle Bin’, ‘My Documents’, shortcuts, files and folders. The desktop can be changed to facilitate user access to required files or programs in a fast and convenient way, providing an alternative to using the Start menu.

Plastic dip coating tank A plastic dip coating tank is used to put a more socially acceptable finish on articles made from steel, such as shopping baskets and kitchen utensils. The plastic dip coating tank consists of a fluidizing unit and a blower unit. The fluidizing unit has two compartments which are separated from each other by a porous material. The upper compartment contains the plastic power

and the air supply is connected to the lower one. Air passes up through the porous material and

causes the plastic power to act like a fluid. The article is heated to 180ºC and dipped into the tank. The plastic close to the article melts and sticks to the component providing an even coating all over. The component is then removed and the molten plastic is allowed to cool and harden covering the article in

a protective coating.

Dip coating is the application of plastic coating by dipping the heated article into a tank of fluidized thermoplastic powder and allowing the powder to fuse and adhere to the surface.

Downloading: Bringing text, pictures or files, etc. to your computer through an on-line connection.

DVD-R Digital Versatile Disc or Digital Video Disk is a type of CD that can have a potential storage capacity of up to 8GB of data, enough for a full-length movie. DVD-R is a DVD recordable format only which means that data, once written to a DVD-R, cannot be changed, whereas a DVD-RW can be rewritten multiple times. A DVD-R provides portable memory in the form of a compact disk, however, a DVD player or drive is required to read its contents.

DVD: Digital Versatile Disc or Digital Video Disk is a type of CD-ROM which holds a minimum of 4.7GB of data., enough for a full length movie. A DVD player or drive is required to read the contents of a DVD.

Ductility is the ability of a metal to be drawn into wire. A material is ductile when it can be permanently stretched by a tensile force without fracture.

The earth clamp is required to complete the circuit for current flow through the metal being welded and back to the welding unit.

Elasticity: Elasticity enables a metal to return to it’s original shape after external forces which cause distortion are removed.

Elastic memory: The ability of a thermoplastic to return to its original shape when heated.