Glossary
| Term | Definition |
|---|---|
| A | |
| Abrasive belt grinder | A grinding tool that polishes a material using an abrasive belt turned by a motor, commonly referred to as a sanding machine or belt grinder. Abrasive belt grinders are used to remove the corners of materials (chamfering) to grind or polish surfaces, or to remove burrs by bringing the materials into contact with the belt (stationary type) or bringing the grinder into contact with the material (handheld type). As shavings are ejected during machining, many grinders are equipped with a dust collector. |
| Amount of wear |
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| Austenite structure | An austenite structure is a solid solution of gamma-phase iron (γ-Fe) containing one or more elements. This structure is formed when steel is heated to high temperatures (typically around 900°C). The face-centred cubic crystal structure makes the steel soft and tough, resistant to corrosion, and non-magnetic. |
| B | |
| BGA | A BGA (ball grid array) is a type of semiconductor package on which solder balls arrayed in a grid pattern function as external connection terminals. BGAs are ordinarily manufactured by the buildup method in which a core board, consisting of a PCB, is laminated with epoxy resin films. Because of their compact size and ability to support multiple external connections, BGAs are commonly used as packages for PC CPUs, GPUs, and similar units. |
| Backlash | Backlash, also known as lash, is clearance or play that is intentionally left in the movement direction of a pair of gears that engage with each other in order to ensure smooth rotation without excessive load. Insufficient backlash can decrease the service life of a gear as a result of increased wear of the gear surfaces caused by insufficient lubrication. However, excessively large backlash can decrease the life of the machine because the poor engagement of gears produces noise and vibration. |
| Base metal | When welding using a filler metal, base metal refers to the materials which are to be joined together. When welding without a filler metal, the base metal is also called the welding material. |
| Bearing |
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| Bend radius | |
| Beryllium copper | Beryllium copper usually refers to a beryllium-copper alloy produced by adding beryllium to copper, until the composition contains several percentage points of beryllium. While maintaining the properties of copper such as high workability, high electrical and thermal conductivities, and corrosion resistance, beryllium copper exhibits high strength and high elasticity that is comparable to special steel.
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| Bolster | A bolster is a thick top plate installed on the press bed, which is used to mount the lower die in a press machine. A bolster includes grooves or tapped holes that are used to fasten the lower die. Some bolsters have grooves that allow them to be removed from the press together with the lower die. These are called moving bolsters.
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| Burr | |
| C | |
| Cantilever | A cantilever is a beam which is fixed at only one end. In architecture, cantilevers are used at locations such as building eaves, entrances, and the pent-roofs over balconies. Because cantilevers do not require pillars, open space can be created under them. Cantilevers are more likely to bend compared to ordinary beams of the same length. All locations on the top edge of a cantilever are subjected to tensile force, while all locations on the lower edge are subjected to compressive force. As a result, consideration is required in cantilever design and calculations. |
| Carbon fibre reinforced plastic (CFRP) | Carbon fibre reinforced plastic (CFRP) is plastic reinforced with carbon fibres, giving it higher strength and rigidity than plastic alone. CFRP primarily uses thermosetting polymers such as epoxy resin, unsaturated polyester resin, vinyl ester resin, or polyimide. CFRP also uses thermoplastic resins such as polyamide, polycarbonate, polyphenylene sulphide, or polyether ether ketone (PEEK). CFRP can be created to produce compositions with a wide-range of characteristics according to the particular combination of carbon fibres and resin materials.
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| Cavity | The space between the male mould and female mould where the product is formed. A cavity may also refer to the concave shape of a mould, or to the female mould itself (the fixed side in the case of injection moulding).
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| Chamfered surface |
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| Chamfering | Chamfering removes sharp edges from a material such as metal, plastic, or wood. Chamfering is one type of edge cutting process. In addition to chamfering that cuts off the corner at an angle, there are other edge cutting processes such as rounding, which gives an edge a round shape, and light-chamfering, which finely machines an edge within an approximate range of 0.1 mm to 0.3 mm (in the case of metal edges). The tools used for edge cutting differ according to the material and the shape to be cut. When machining metal edges, tools optimised for edge cutting are used, such as chamfering cutters and angled end mills. When machining manually, tools such as files and abrasive belt grinders are used. |
| Charpy impact test piece |
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| Charpy test | |
| Chipping | Chipping is a phenomenon in which small chips occur at the tip of a cutting tool or blade during cutting, pressing, or other machining. This phenomenon can also occur due to an instantaneous impact received during machining, or to vibration from the die or machine that is transmitted directly to the blade tip.
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| Coefficient of thermal expansion | The coefficient of thermal expansion refers to the ratio of thermal expansion of an object resulting from a change in temperature at constant pressure. The amount of expansion per unit of volume when the temperature of an object rises 1°C is called the volumetric expansion coefficient. The amount of increase in the length of a solid object per unit of length when the temperature rises 1°C is called the linear expansion coefficient. |
| Compressive stress | Compressive stress is a force generated inside a material when a compressive force (force in the direction that crushes an object, opposite to tensile force) is applied. |
| Coplanarity | |
| Core | A die core refers to a male die which has a convex part. In most cases, it has the shape which forms the inside of the formed product. When used in injection moulding, the core is the moving side.
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| Cross hatch | A cross hatch is a pattern that consists of two sets of intersecting parallel lines created by grinding marks. For example, a cross hatch pattern can be created by moving the grindstone perpendicular to the rotation of a rotating target instead of parallel to the rotating direction.
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| D | |
| Deformation | |
| Die | In pressing, the die, also known as the lower die, female die, or drawing die (in drawing applications), is the part on the opposite side from the punch. In some pressing workplaces, “die” may refer to a plate or block that is a part of the die. In most cases, a piece that forms sheet metal or other solid material into a particular shape is called a die, while a piece that forms molten material into a particular shape in injection moulding or casting is called a mould.
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| Draft angle | Draft angle refers to a predetermined angle on the product and mould shapes that facilitates the removal of moulded plastic products from the moulds. Ordinarily it is said that the necessary angle is around 1°. However, a draft angle of 2° or more may be required when surface texturing is performed in order to ensure mould release performance. Selecting a draft angle that is as large as possible within the range that does not interfere with product functions or appearance can prevent trouble when removing the product from the mould. |
| Droop |
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| E | |
| Erosion | Erosion refers to material damage that occurs as a result of mechanical action caused by liquid droplets, vapor bubbles, or solid particles. Types of damage include plastic deformation caused by compression, gouging, cracking, shaving, and peeling. This term was originally used in geology to refer to the natural phenomenon of erosion, but is now also used as a term that refers to similar phenomena occurring in industry. Similar terms referring to specific types of erosion include cavitation damage, erosion-corrosion, and impinging corrosion.
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| Exponential taper |
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| F | |
| Fatigue failure | Fatigue fracture occurs in an object when cracking gradually progresses as a result of external force generating repeated stress that is smaller than the stress which would cause fracture (static fracture stress), eventually resulting in loss of load capacity and fracture.
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| Fillet | |
| Fitting tolerance | Fitting tolerance is the degree (allowable range) of fitting for a shaft and hole. The specified fitting tolerance varies according to the conditions and purpose. For example, a shaft may be completely fixed in the hole, or it may continually rotate. |
| Flaking |
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| Flash land | In die forging, a flash land is a pathway that allows excess material to escape from the die to a gutter. A flash land also functions to improve filling of the die with material while controlling the outflow of material to the gutter, while the gutter prevents an increase in load caused by the formation of wide burrs. |
| Flatness | |
| Flux | Flux is an agent applied to solder bonding locations prior to heating. Flux functions to clean the PCB and allow solder to more easily spread on the surface. Flux cleans oxides and dirt from the solder bonding surface, preventing oxidation during heating. It also increases the wettability of molten solder on the bonding surface by decreasing the solder surface tension. Flux is broadly categorised into organic flux and inorganic flux. Inorganic flux mainly uses hydrochloric acid, zinc chloride, and ammonium chloride. |
| Functionality evaluation | Functionality evaluation is a quality engineering method that measures the degree of variation in basic characteristics of a product or part in various environments in order to rapidly conduct a practical evaluation of the technical level. Ordinarily, when judging the actual capabilities of a product or part, a large number of items including reliability are evaluated. However, even when a product passes this evaluation, defects may still occur in the market after shipping. The precise methods used for functionality evaluations differ according to the target and its service environment. Utilising functionality evaluations appropriately makes it possible to more accurately evaluate the practical performance of products and parts. |
| G | |
| Galling |
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| H | |
| Heat treatment | |
| Holding pressure | In injection moulding, holding pressure is applied to prevent the molten plastic that was injected into the mould cavity from flowing back before the gate seals (solidifies). Insufficient holding pressure allows plastic to flow back from the gate, creating sink marks in the moulded product. This can also increase plastic shrinkage, resulting in a product that is smaller than the design dimensions. However when holding pressure is too high, it can increase the size of the moulded product, produce burrs, or cause mould release failure.
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| I | |
| Insert | An insert is a separate moulding part that is used to replace or adjust part of the metal mould. By using an insert for sections that require accuracy control such as cavities, cores, punches, and dies, it is generally possible to improve the efficiency of quality maintenance and management, and to reduce costs. |
| Izod impact strength test | |
| L | |
| Land | A land is a conductive pattern formed on a PCB for the purpose of mounting and connecting devices. Lands include pads for surface mount devices (SMDs), holes for mounting lead parts, and conductive patterns around vias. |
| Lattice constant |
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| Lead lifting | |
| Lead-free solder | Lead-free solder refers to solder that contains no lead (Pb). Lead-free solder contains primarily tin (Sn), as well as silver and copper. Lead-containing eutectic solders were the main type of solder used until the 1990s. However, groundwater pollution caused by acid rain dissolving the lead contained in discarded electronic components and PCBs became a problem, and lead-free solders have been used since around 2000. The European Union (EU) established the RoHS Directive on July 1, 2006 to in principle ban the use of lead and other hazardous substances in electrical and electronic equipment. Lead-free solders have less environmental impact compared to conventional eutectic solders. At the same time, lead-free solders have low wettability and many of them have high melting points around 217°C. This means that attention must be given to the temperature profile in reflow processing in order to protect PCBs and electronic components from deformation and damage. |
| Linear taper |
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| M | |
| Martensitic structure | A martensitic structure is formed when austenite is heated for quenching. It is a metastable solid solution having a body-centred tetragonal crystal system or a body-centred cubic crystal system, and has the same chemical composition as the original austenite. When austenite is rapidly cooled, a needle-like structure is produced by diffusionless transformation at temperatures at and below the MS (martensitic transformation start) point. This structure gives the material hard, brittle properties. Quenched martensite has a non-equilibrium and unstable structure. Martensite is ordinarily tempered to give it suitable mechanical properties. |
| Micro cracks | Micro cracks refer to fine cracks that are generated by corrosion or chemical change. Micro cracks caused by corrosion can gradually progress inward due to the effects of stress, eventually resulting in a major fracture. This process is called stress corrosion cracking (SCC). |
| O | |
| Optical flat | An optical flat is a transparent glass plate, one side of which is polished flat to high accuracy. It is used for measurement of flatness using light interference. The surface accuracy is evaluated based on the Newton's rings that appear between the flat and a standard surface. A transparent glass plate with both sides flat and parallel is called an optical parallel, and is used for measurement of flatness and parallelism using optical interference.
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| P | |
| PGA | A PGA (pin grid array) is a type of semiconductor package in which external connection terminals (pins) are arranged in a rectangular pattern. A PGA made of plastic is a PPGA and one made of ceramic is a CPGA. Using special sockets makes it easy to remove and replace them. |
| Parallelism |
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| Peeling |
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| Pitting | Pitting is a form of localised or spotty erosion or corrosion. Pitting usually occurs on gear surfaces due to fatigue, but it can also occur on gears during the initial stages of use. Load is concentrated in locations of maximum surface irregularities on gear surfaces, and the contact stress generates maximum shearing stress at a certain depth below the surface. This stress creates fine cracks that can progress and cause pieces of the gear surface to fall off. Pitting that occurs during the initial stages in some cases may not progress further. |
| Plastic flow | Plastic flow is irreversible deformation that occurs in a material subjected to stress that exceeds a certain limit. An object subjected to an external force exceeding a certain level will deform in a fluid manner. Plastic flow refers to deformation that remains even after this external force is removed. |
| Pocket machining | Pocket machining removes the material from the inside of a circular, square, or other closed line by milling to a specified depth. There are various types of pocket machining, including stepped machining and island milling, which leaves part of the original shape inside the pocket. The tools used differ depending on the material and machining details. They may include end mills, radius end mills, chamfer cutters, ball end mills, and a combination of an end mill and ball end mill. |
| Projected area | In injection moulding, the projected area can be described as the area of the shadow produced when a formed product is illuminated by even lighting. The mould tightening force required for injection moulding (F: tf) can be calculated based on the total projected area (A: cm2) and on the pressure in the mould cavity (p: kgf/cm2). The formula is as shown below. F = p x A / 1000 * Internal pressure (p) may be expressed in units of MPa or kgf/cm2. These units can be converted using the following formula. 100 kgf/cm2 = 9.8 MPa |
| Punch | A punch is a die that presses on a material to perform plastic forming in the press forming process. A punch is also known as a male die. A punch is generally mounted opposite a corresponding die, and transfers its shape to the material by pressing the material between the punch and die. There are various types of punches including blanking punches, bending punches, and drawing punches that are selected according to the forming purpose.
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| R | |
| Rake angle |
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| Residual stress | Stress is generated inside an object by external forces such as pulling, compressing, bending, and heating. Residual stress is stress that remains in the object even after these external forces are removed. Residual stress is also known as internal stress, inherent stress, initial stress, and assembly stress. |
| Resistance (Ω) | Resistance (Ω: ohms) is the degree of resistance that impairs the flow of electricity (electrons). When a metal wire is pulled, its cross-section is reduced and its length increases, resulting in higher resistance. Conversely, when a metal wire is compressed, its resistance decreases. The resistance of metal changes in proportion to the elongation or compression of the metal based on a certain constant. This principle is used by strain gauges, which are attached to a target to measure strain based on the change in resistance. |
| Roll forming | Roll forming is a method that forms sheet metal into a roll shape using rotating tools called rolls. It is a forming method in which a series of multiple forming stands bend and plastically deform a strip of sheet metal in multiple stages in order to continuously manufacture products having the desired cross section. Some roll forming equipment includes various other processes such as automatic welding to continuously produce ducts and other products with complex shapes. |
| Round | |
| S | |
| Shearing force | Shearing acts like scissors cutting an object. When a pair of parallel forces act on an object in directions opposite to each other, the object is subjected to a force which acts to produce sliding and cutting along that plane. The force which produces this action is shear force. The internal force generated at the cross-section of the object as a result of shear force is called shearing stress.
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| Sink mark |
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| Slide | The slide, also known as the ram, is the vertically reciprocating part of a press. Rotation of the motor is transmitted to the crankshaft. This motion is transmitted via the connecting rod and constrained by the slide guide gib, producing reciprocating vertical motion. In other words, the original rotary motion is converted by the slide to the vertical motion which is required for pressing. In an automobile, this relationship is reversed. Movement of the piston caused by pressure in the engine cylinder is transmitted to the crankshaft, and is then converted to the rotary power required for driving.
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| Solder fillet | |
| Spunbond method | The spunbond method is a method used to manufacture non-woven fabrics made of synthetic resin. Resin chip materials are melted and spun to create long fibres. These are opened directly from the spinning nozzles to randomly accumulate on a net in order to form a web. The web is bonded in a sheet shape by thermocompression bonding or other means.
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| Spunlace method | The spunlace method, also known as hydroentangling, is a type of method for manufacturing non-woven fabrics. Cotton or other short fibres are untangled, cleaned, and mixed by carding to form a web. Jets of water are sprayed onto the web, applying water pressure to the fibres. This causes the fibres to entangle with one another and bond in a sheet shape.
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| Strain |
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| Stress concentration | Stress concentration is a phenomenon in which stress is concentrated in a specific part of a plate, rod, or other mechanical or structural component where the cross section suddenly changes due to a hole, notch, foreign matter, or other cause.
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| Surface area | |
| Surface mount device (SMD) | A surface mount device (SMD) is an electronic component that is mounted on the surface of a PCB. Compared to through-hole devices that are mounted by inserting pins into holes in the PCB, a greater number of SMDs can be mounted in the same area on a PCB. This allows PCBs and SMDs to be made smaller, and devices to be mounted more densely. Mounting efficiency is also higher as the series of processes can be easily automated. |
| Surface mount technology (SMT) | Surface mount technology (SMT) is a method in which electronic components are mounted onto the surface of a printed circuit board (PCB). Components in the form of surface mount devices (SMDs) can be directly soldered onto the surface of the PCB. A connector on which an SMD is soldered is called a land. |
| Surface texture | |
| T | |
| Taper |
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| Temperature profile | The temperature profile in reflow processing refers to the soldering temperature and time conditions, and to a graphical representation of these conditions. Temperature profiles of the soldering process can be used for testing and evaluation of temperature resistance of PCBs and electronic components. |
| Tensile stress | Tensile stress is a force generated inside an object when it is subjected to tensile force (force which pulls it toward the outside). |
| Tool bit | A tool bit is a cutting tool used with lathes. The shaft of the tool bit is called the shank and the blade is called the tip. Replaceable tips are called throw-away tips.
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| Tooth thickness | |
| U | |
| Undercut | |
| Underhead |
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| Uneven surface sheet |
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| W | |
| Warpage | |
| Waviness | |
| Wear of metal moulds |
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| Welding bead | |
| Wire bonding | Wire bonding mounts the bare chips or dies of IC and LSI circuits directly onto the PCB and connects them to the pattern on the board using wires. This process is performed in a clean room where the level of dust is low. Wire bonding is one step in the mounting process known as chip on board (COB). Depending on the specifications, chips may be mounted before or after COB mounting. |
