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

http://www.examinations.ieExamination 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 & ZincAnnealing 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 cool in air or water.Basic Oxygen Furnace Mild 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 suchas 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 be used 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 Furnace Pig 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 a screw used.In blow moulding a heated thermoplastic tube called a parison isextruded between the two halves of a split mould. The mouldcloses around the parison and air is blown into it forcing the

parison out against the wall of the mould. The component isallowed 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 ZincBrittleness: 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.Bronze Copper 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.

CAM Computer Aided ManufactureCAD Computer Aided Drawing / DesignCAD/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 selecting the 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 shapeof the cam controls the motion of the follower. The follower is kept in contact with the camby 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. Chuck Four 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 is required.

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 the lathe chuck before operating.Chuck guard Due to the dangers of high speed moving parts and / or metal cuttings a chuck guard is put in place before machining to protect the operator from serious injuriesThe 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 ControlCompression 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 oneend 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 bechanged 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 Furnace Cast 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 powerand the air supply is connected to the lower one. Air passes up through the porous material andcauses 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 ina 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. Electric Arc welding. In Electric Arc welding the heat source is produced by an electrical discharge between the electrode (filler rod) and the work piece. The electric arc has a temperature of about 4000°C. and is suitable for welding heavy gauge material. Materials are melted and allowed to solidify as one – arc welding is a fusion process. Application: Table / chair frames made from steel box section.Electric Arc Furnace High Carbon Steel is produced in the Electric Arc Furnace. Cold scrap iron or steel make up the majority of the charge together with small amounts of lime and carbon. Heat for this furnace is by an electric arc created between carbon electrodes and the charge. The lime combines with impurities producing slag. When the correct composition of steel is achieved the slag is removed and the steel tapped from the furnace.

Engraving: In engraving, designs are cut into metal surfaces with sharp tools. Power tools are often used for engraving letters and numbers on ornamental objects.An external hard drive is a portable magnetic disk which can be connected externally to a PC or Laptop by way of a USB socket. The term ‘hard’ is used to distinguish it from a soft, or floppy disk. Hard disks hold more data, are faster than floppy disks and allow large amounts of information to be transferred between computers. Many users now use external hard drives to backup important data.

Faceplate The faceplate is a large circular plate containing a number of machined slots. The faceplate is fitted to the nose of a lathe spindle and is used to hold work whose shapes do not permit gripping in a chuck. The work piece is bolted to the faceplate or to a fixture on the faceplate. It is important to counter-balance the work piece to prevent vibration during the machining operationFeed refers to the distance the cutting tool moves during each revolution of the workpiece. It is expressed in millimeters per revolution. The smaller the feed rate, the smoother the surface finish.Feeler gauge: Feeler gauges are used for checking the gap between two surfaces i.e. spark plug gap or car tappets. Feeler gauges are used to estimate, by sense of touch, the clearance between two separate components by inserting different blades or combination of blades until the thickness is found that will just go between the surfaces. Used to estimate, by sense of touch, the clearance between two separate components by inserting different blades or combination of blades until the thickness is found that will just go between the surfaces i.e. spark plugs, car tappets. Ferrous metals contain iron while non-ferrous metals contain no iron. A Filler rod provides additional filler metal when welding. In the form of a rod or wire, the end of the filler rod is held very close to the weld pool. The intense heat melts the rod causing a globule to drop into the weld pool, thus providing extra metal to the welded joint. Firewall: A firewall is a hardware and/or software barrier between two or more networks. The firewallcontrols who and how, information can be accessed behind the firewall.Fixed Steady The fixed steady is clamped to the bed of the lathe and has three fingers which can be adjusted to accommodate different shaft diameters. A fixed steady is used for supporting long shafts which need to be machined on their end. Always ensure the supporting fingers and work is lubricated and adjusted correctly to reduce overheating.The purpose of a flashback arrestor is to prevent the return of the flame through the hose into the regulator or gas cylinder. Flashback arrestors are positioned on both the acetylene and the oxygen supply between the hose and the regulator.A Flux is used to help a weld joint to form by first producing a gas shield to protect the weld pool from the oxidizing effects of the atmosphere. The slag-forming agents then unite with impurities in the weld pool which float to the top, cool and form a coating, protecting the freshly formed weld from oxidation. This slag coating also helps to slow down the rate at which the weld cools, preventing weld brittleness. A Flux is used to remove oxides from the surface of the parts being soldered facilitating capillary action, allowing “wetting” of the joining surfaces. A Flux also helps to prevent further oxidation when the parts are heated. A passive flux is non-corrosive, resin based which prevents oxidation during soldering. Suitable for electrical work and other applications where it is not possible to wash the joint afterwards. An active flux is corrosive and will remove oxides from the surfaces and prevent further oxidation during soldering. Zinc chloride or ‘killed spirits’ is an active flux and when used the joint must be thoroughly washed afterwards.Former When a thermoplastic sheet is heated, it becomes soft and flexible. Formers are used to retain the shape of the soft plastic sheet until it cools and is capable of maintaining the required shape.A fuse generally consists of a thin wire inside a glass or ceramic tube and is commonly found inside electrical plugs. The fuse prevents too much electricity flowing into the appliance if a fault occurs. It’s purpose is to protect the low voltage electronics found inside all electrical appliances. The fuse acts as a deliberate weak link in a circuit. When the fuse ‘blows’ the thin wire melts and the electricity supply to the appliance is cut off. Galvanising: Steel coated in layers of melted zinc a chemical reaction permanently bonds the zinc to the steel through galvanizing, protecting the steel from corrosion. Galvanised steel is used for outdoor, marine or industrial applications. A Gap gauge is used to determine if a shaft is within its specified limits. If the shaft fits into the ‘GO’ opening and will not fit into the ‘NO GO’ opening then it is within its specified limits. Plug gauge – for checking the limits of holesGap / Snap gauge – for checking the limits of shafts

Feeler gauges – for checking the gap between two surfaces

Gas welding In Oxy-Acetylene welding the heat source is a flame of acetylene burning in an atmosphere of pure oxygen. This produces a flame whose temperature can reach 3250 degs. C.Suitable for welding light gauge material with the filler rod fed in by hand.G Codes: Determine the tool path. The cutting tool will move in a particular way depending on the number following the letter G. G01, for example, will cause the tool to travel in a straight line.Gearbox: A structure containing a combination of gears in mesh. The particular gear arrangement can change the ratio of input to output speed, the direction of drive rotation and the relative position of the input to the output shaft. A reduction in output to input speed increases turning power or torque, while an increase in output to input speed reduces turning power or torque of the output shaft. The purpose of a generator is to produce electricity for DC welding. Powered by an electric motor, petrol or diesel engine the generator provides sufficient current for the arc. Leather gloves must be worn to protect the user from hot metal particles, UV light and or high temperatures.Computer Hardware All the physical parts of a computer system are classified as hardware.Keyboard, mouse, VDU and printers are examples of computer hardware. Hardware can be further subdivided into either input or output devices. A keyboard is an example of a computer input device and a VDU / monitor is an example of a computer output device. Many hardware devices are connected to PCs via USB ports.Hard disk: A fixed magnetic disk generally fitted internally in a PC, on which you can store computer data. The term ‘hard’ is used to distinguish it from a soft, or floppy disk. Hard disks hold more data and are faster than floppy disks. Hardening produces a brittle metal which resists wear, indentation and scratching.Height gauge – for accurate marking out of componentsInjection Moulding Thermoplastic is softened by heating it inside an injection nozzle. The softened plastic is forced by a plunger into a cold mould where it hardens rapidly and is then ejected. Injection moulding is used for the rapid moulding of components such as buckets or the casings for a wide range of computer hardware devices.

Electrical insulator: An electrical insulator is a material which offers very high resistance to current

flow. Plastic is an example of an electrical insulator as it will not allow electricity pass through.Interference fit In this assembly there is no space between the parts. The shaft is always made larger than the hole it is intended to fit into. Force is usually required to assemble the parts. An interference fit results where the lower limit on the shaft is always greater than the upper limit on the holeLaminating High strength plastics can be produced by impregnating sheets of paper or cloth with a resin. Layers of this material are bonded by allowing the resin to set into a solid structure. Heat and pressure are often used in this process.Light Dependent Resistor (LDR): An electrical component, whose resistance changes with light levels. Suitable for use in light controlled circuits.

Malleability is the property of a material which allows it to be extended in all directions by rolling or hammering without rupture. The malleability of most metals is increased by heating.Manual metal arc welding: Metals are melted and fused using high temperatures. The joint produced is very strong. Special equipment and a high skill level is required to weld. Only similar metals can be joined using this process.Memory stick : Memory sticks are solid state storage devices which operate from a computer’s USB port. They can be fitted and removed with ease. Based on flash memory technique memory sticks can be used to store large files for transfer between computers. They are physically very small, very light and provide faster access than other portable memory device.A Morse taper sleeve can be used to hold tools such as taper shank drills and reamers in drilling machines and in lathe tailstocks. The morse taper sleeve is used when the taper shank of a tool is too small for the machine socket in which it is to be used. The shank of the tool is inserted into the sleeve, which is then inserted into the tapered socket of the machine. The morse taper sleeve maintains the frictional drive between the machine spindle and the cutting tool being used.

Network: A computer network consists of a collection of computers, printers and other equipment that is connected together so that the equipment can share information, share resources and communicate with other equipment on the network.Neutral Flame – Equal amounts of Oxygen & Acetylene

A non-ferrous metal does not contain any Iron.Output device: Any device that takes information from the computer and makes it available to the user in a human understandable form such as a: Visual Display Unit, Printer, Plotter, CNC machine/Lathe or Robot.

Oxides are formed when the oxygen in the air reacts with the surface of metals producing a thin skin on the surface of the metal. Iron oxide or rust is an example of an oxide. When metals react with oxygen, oxides are formed on their surface. This oxide layer interferes with the thermal joining process and must be removed by fluxes or by keeping the oxygen away from the joint area.An Oxidizing flame: Additional oxygen is supplied to the neutral flame.

In Oxy-Acetylene welding the heat source is a flame of acetylene burning in an atmosphere of pure oxygen. This produces a flame whose temperature can reach 3250°C. Suitable for welding light gauge material with the filler rod fed in by hand. Materials are melted and allowed to solidify as one – gas welding is a fusion process. A pplication : Joining of light gauge steel pipesA pilot hole must be drilled before using a large drill. This keeps the large drill central, and it also means that the chisel edge of the drill does not have to do any cutting.A plastic dip coating tank consists of a fluidizing unit and an air supply unit. A means of regulating the air flow must also be provided. The fluidizing unit has two compartments which are separated from each other by a porous material. The upper compartment contains the plastics power and the air supply is connected to the lower one. Air passes up through the porous material and causes the plastics power to act like a fluid. This allows the heated article to sink into the powder and receive an even coating all over. Application: Articles made from steel, such as shopping baskets, kitchen utensils and dish washer holding trays are all plastic dip coated for protection.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 etc. The article is heated to 180 degs. C in an oven and dipped into the tank where fluidized power particles of polyethylene melts and adheres to its surface. When removed, the particles fuse together and cool, providing an attractive and protective coating. Plug gauge: A plug gauge is a used to compare the size of holes against a set of pre-determined limitsidentified by the GO and NO GO parts of the gauge. It is used to determine if a hole is within its specified limits. If the ‘GO’ end of the gauge passes through the hole and the ‘NO GO’ end does not then the hole is within its specified limits. A pop rivet is used for joining light gauge material. A special tool is used to draw a pin through the rivet enlarging one end of the rivet until the pin breaks leaving it’s head behind. A pop rivet has an advantage in that it can be used to join hollow sheet metal articles where only one side of the joint is accessible. A pressure gauge indicates the pressure in the oxygen or acetylene cylinders as used in gas welding. Often referred to as ‘gas pressure regulators’ pressure gauges can also indicate the pressure in the supply pipe to the torch.Printed Circuit Board (PCB): A PCB is usually a plastic board about 1.6mm thick with a thin layer of copper on one side. Unwanted portions of the copper are routed or etched away to leave pads and strips which form electrical connections between the components. The components are soldered to the pads, allowing the strips to connect the components together.Pulley drive: A pulley drive is used to transmit motion and force from one shaft to another by way of pulleys and belts. Household machines such as sewing machines, spin driers and washing machines are often driven by round grooved pulleys and round rubber belts. Machine tools such as drilling machines and lathes use vee pulleys and vee belts.PVC The term PVC refers to the plastic Polyvinylchloride.Oil is less drastic than water in quenching and presents less risk of distortion and cracking. Oil gives better control of hardening with slightly less brittleness. Care needs to be taken in its use as fumes are given off by the oil.A Rack and pinion is used to convert between rotary (circular) and linear (straight line) motion. The rack is the flat, toothed part, the pinion is the gear. A rack and pinion can convert from rotary to linear

or from linear to rotary. Rack and pinions are commonly used on drilling machines to bring down the drill into the work. The feed lever rotates the pinion and moves the rack, causing the drill spindle to move down in a straight line. A rack and pinion can be used in the steering mechanism of a car or on a pillar drilling machine to raise or lower the table.

Rake angle: The purpose of the rake angle on a lathe cutting tool is to make an easy escape for the chip/swarf being cut. The size of the rake angle contributes to the size of the tool angle, determined by the type of material being cut. Ratchet and pawl mechanism: Ratchet and pawl mechanisms are used in ratchet spanners, fishing reels, ratchet screwdrivers, micrometers and winding machines etc. A ratchet and pawl mechanism is used to allow a shaft, axle or pin to rotate in one direction only. The teeth on the ratchet wheel are so shaped that the pawl slides over them in one direction and engages with them so as to restrict movement in the other direction.

Reamer: A reamer is used to enlarge an existing hole making it round, smooth and accurate in size. For the most part reamers are parallel with a slight taper at the leading end, have many more flutes than drill bits and are available as hand reamers or machine reamers.Safety switch: Located on CNC lathes to check if the safety guard is in the correct position before manufacturing. The CNC lathe will not start if the guard is opened. Scanner: A hardware device connected to a computer. Scanners can be used to copy / scan text and or graphics to software packages. Scanners can also be used as a fax machine.Self-locking nut: A special nut used to prevent loosening by movement or vibration. On assembly, the screw thread cuts through a nylon or fiber insert within the nut, holding it in position. CNC lathe. Simulation: This is a means of checking out the CNC program. The machining of the component can be simulated on the computer screen. It can detect errors thus avoiding lathe damage and waste of material. Simulation: The production of a part is simulated by computer graphics and shown on the monitor. This is to check for correct programming and off set any dangers that may occur during machining.Software The programs which direct the operation of a computer i.e. Microsoft Word,Solid Works, Games etc.Electric soldering iron An electric soldering iron is used to apply solder. It can be used whensoldering electrical wires or components together. A fine tip electric soldering iron is used when soldering electronic components to circuit boards such as printed circuit boards (PCB). When the

electric iron is plugged in, its tip heats up and can reach temperatures of over 200ºC. The tip heats the metal and melts the solder so that it flows round the lead of the component and the track on the board.Heat is produced when electricity flows through a heating element inside the soldering iron. The element is made of a material which electricity finds difficult to pass through. The resistance of the material to the flow of electricity causes the element to heat up, heating the tip.Stepper motor: A stepper motor is an electric motor designed to rotate incrementally in steps subject to signals received from a computer. Used to move the cutting tool on CNC lathes.A strip heater is used to form straight or small curvature bends in thermoplastic sheet material. An electric element or hot wire is enclosed in a channel which has an opening at the top. Thermoplastic sheet is placed across supports above the opening. By adjusting the height of the supports the width of strip to be heated can be altered. The supports are set to a low height for tight bends. If a more gradual bend is required the heated area is widened by setting the supports higher. Different thicknesses of sheet may be formed by thermostatically controlling the heating temperature.A surface plate is used for marking out small pieces of work and can be used as a datum surface for this purpose. The surface plate has an accurately machined flat surface with it’s four edges finished square with the top surface and one another. The plate is made from cast iron with the underside ribbed to prevent distortion while supported on three feet to give rigidity. Swarf is the waste material produced when the chip is cut from the workpiece.A tailstock is part of a centre lathe. The tailstock sits on the lathe bed at the opposite end to the lathe headstock. It can be clamped to the bed at any point. The tailstock contains a barrel which slides in the body when you turn the hand wheel. The barrel can be locked in any position. The barrel can accommodate different tools for drilling, reaming, or for supporting long shafts when machining. The tailstock can be moved from side to side on it’s base, this feature is used for taper turning.A tapping size hole is smaller than the required thread size. This is to allow the tap to cut the thread into the wall of the drilled hole. A temporary joint describes a joint which can be dismantled.Tempering To temper point A, first polish with emery cloth so that the tempering colours can appear. Heat slowly behind the hardened portion and allow the heat to travel gradually to the point. The tempering colours will appear as the temperature rises. When the correct colour reaches the point, cool it in oil or water.Tensile force A tensile force is when a bar is subjected to a pull. If the pull on one end results in an equal and opposite pull on the other end then the bar is said to be in tension.Tensile strength: The ability of a metal to withstand a pulling force is know as it’s tensile strength.A tensile force occurs when a bar is subjected to a pull. If the pull on one end results in an equal and opposite pull on the other end then the bar is said to be in tension. 12/11 Thermoplastics are linear chain type polymers and are relatively soft and flexible, they melt easily and can be repeatedly softened and remoulded.Thermosetting plastics are three dimensional in structure with strong cross-links between molecules. They are therefore rigid and hard, they cannot be reset once they have hardened in the mould. A thermostat is a device used to control the temperature of a system, e.g. a central heating system, a cooling system in a motor car, etc. The thermostat operates by switching on / off or otherwise regulating the supply of heat from the source so as to maintain the temperature of the system within a predetermined level. Tinning refers to coating each of the materials to be joined with a thin layer of solder before joining. Tinning supports the production of a successful joint by allowing the solder on both parts to unite when melted.The tolerance is the amount by which a dimension is allowed to deviate from the nominal size. Tolerance can be obtained by subtracting the lower limit from the upper limit.Toughness: ability of a material to withstand an impact Transition fit: This fit can either be a clearance or interference fit.

A USB (Universal Serial Bus) port provides a quick an easy way of connecting many different external devices to computers. A single USB port can be used to connect up to 127 peripheral devices, such as mice, keyboards, printers, digital cameras and Mp3 players. Vacuum Forming: Vacuum forming is used to make articles from thermoplastic sheet. The sheet is clamped and a heater raises the temperature of the sheet until it becomes soft and flexible. The mould table is raised and air is removed from beneath the sheet allowing atmospheric pressure to push down, forcing the sheet to take up the shape of the mould. When the mould table is lowered the vacuum formed sheet can be removed for finishing. Using this process thermoplastic sheet can be formed into baths, interior panels of lorry cabs or for biscuit tin liners.A variable resistor can facilitate the flow of more or less current in a circuit. Depending on its application the resistance of a variable resistor can be changed in a number of ways. Mechanical adjustment may be achieved by the rotation of a spindle while variable resistors which respond to light or heat levels are also available.Vee blocks and clamp are used for holding round material while being marked or drilled. Vee blocks are usually obtained in pairs, because two blocks are required when supporting long bars. The clamp is held in two groves that are cut in the sides of the vee block and when tightened holds the round bar in position. Vee blocks may also be used to support round material vertically on a surface table for marking out. Vernier calipers. Application: a precision measuring instrument used for external and internal measurements i.e. shafts and holes.

A Vernier height gauge is a precision measuring instrument used for accurately measuring heights and testing for parallel. The gauge consists of a heavy base and a fixed main scale rule with a sliding vernier scale attached. When used on the surface plate, the relationship between the main scale and vernier scale has the potential to provide limits of 0.02 mm. A finger or knife edge made of hardened steel, fixed to the sliding vernier scale, is used to scribe lines when marking out. The use of lock and fine adjustment screws helps the user to achieve accurate settings. A vernier height gauge is a precision marking out instrument which utilises the vernier scale principle. Enabling a greater degree of accuracy, 0.02mm, it is used to measure or mark off vertical distances relative to a datum surface such as a surface plate.

Virus A virus is a program or piece of code that operates by attaching itself to some other program or downloaded file. When the program starts the virus code runs, replicates itself and infects other programs or documents on the computer without the user’s knowledge. Written with the deliberate

intention of corrupting files, a computer virus can seriously damage or completely destroy files of software on a computer.A voltmeter is used to measure voltage. It measures the potential difference between two points in a circuit. A voltmeter can be used to measure the voltage drop across the terminals of a bulb or the voltage rise across a battery.Welding Torch Oxygen and acetylene are delivered to the torch through separate hoses. Each gas can be controlled by a valve on the torch. The welding torch mixes the two gases together and after they are ignited they burn at the nozzle.Work hardening: When a metal is hammered or shaped when cold it becomes hard and brittle at the point where the cold - working occurs. Some metals are prone to work hardening; copper and aluminum are typical examples where hardness values can be increased by cold working. Worm Gear: A worm gear is a single toothed gear. When used with a worm wheel will provide a large speed reduction coupled with increased torque output. A worm and worm wheel arrangement also transmits rotary motion through an angle of 90 degrees. A worm and worm wheel drive will only allow input and out rotation in one direction only i.e. worm to worm wheel.

A worm and wheel drive is a gear system which consists of a worm gear and a wormwheel. The worm gear, which looks like a screw thread, is fixed to a drive shaft or motor axel. It meshes with the wormwheel which is fixed to the driven shaft. The worm gear runs at 90º to the wormwheel. A worm and wheel drive provides large speed reduction while increasing output torque. This gear system only allows drive from worm to wormwheel.