Rango del momento de magnitud (Mw)

1 PSME CODE 2008, CHAPTER 14

1. Definition

Hobbing – a method of making molds for the plastics and die casting industries.

Infiltration – the process of filling the pores of a sintered product with molten metal in order to decrease porosity or to improve physical properties.

Interferometry – the science of measuring with light waves, measuring to the millionth part of an inch (approx. 25 mm). The small instrument is known as optical flats.

Intraforming – a process in which metal is squeezed at a pressure of about 300 tons or less into a die or mandrel to produce an internal configuration.

Ironing – a name given to an operation for sizing and thinning the walls of drawn cups.

Metal spinning – the operation of shaping thin metal by pressing it against a form while rotating.

Piercing – the method of cold working by compression.

Powder metallurgy – the art of producing commercial products from metallic powders by pressure.

Spinning – the operation of shaping thin metal by pressing it against a form while it is rotating.

Swaging – a force in impact which causes the metal to flow in some predetermined shape according to the design of the dies.

Toughening – a form of tempering used to enhance the toughness of a hardened steel where high hardness is not particularly needed in service.

Ultrasonic Impact Grinding – a means of cutting shapes of all kinds by the rapid motion of abrasive particles.

2. Classification of Manufacturing Processes.

2.1 Processes used to change the shape of materials.

2.2 Processes used for machining parts to a fixed dimension.

2.3 Process for obtaining a surface finish.

2.4 Process used for joining parts of materials.

2.5 Processes used to change the physical properties.

3. Processes

3.1 Brazing – a group of welding operation in which a non-ferrous filler metal melts at a temperature below that of the metal joined but is heated above 425 C.

3.2 Blow Molding – is used primarily to produce thin-walled hollow containers from thermoplastic resin.

3.3 Cold drawing – is a common method for reducing the size of wire, bar, tubing, and other shapes and is a different operation than the drawing (or deep drawing) of sheet metal.

3.4 Electro-forming – is one of the special processes for forming metals. Parts are produced by electrolytic deposition of metal upon conductive removable mold or matrix.

3.5 Explosive-forming – an excellent method of utilizing energy at a high rate, since the gas pressure and rate of detonation can be carefully controlled.

3.6 Electroplating – is done on all the common metals and even on many metal after their surfaces have been prepared.

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3.7 Extrusion – is done intermittently by a plunger in a cylinder, but the common continuous method are the material drop from a hopper into a heated cylinder in which it is pushed along and out through the opening in the die by screw.

3.8 Forging

3.8.1 Hammer forging – a hot work piece is placed on an anvil and struck repeatedly by a hammer.

3.8.2 Drop forging – the operation of forming parts hot on drop hammer with impression or cavity dies.

3.8.3 Press forging – is done in presses rather than with hammer.

3.8.4 Upset forging – also called hot reading and machine forging, consist of applying lengthwise pressure to a hot bar held between grooved dies to enlarge some section or sections, usually the end.

3.8.5 Roll forging – where two rolls are arranged on parallel shafts for roll forging. These roll segments have one or more sets of grooves. A piece of stock is placed between the rolls, which in turn squeeze the stock in one set of grooves.

3.9 Galvanizing – a process by which zinc coating is applied to a wide variety of steel product to provide protection against protection.

3.9.1 Hot dip galvanizing – dipping or passing the steel product through a bath of molten zinc.

3.9.2 Cold electro galvanizing – process of providing any metal with zinc coating by means of an electric current.

3.10 Grinding, Polishing – a process of finishing various materials for either safety, operational, or aesthetic appearances.

3.11 Metallizing – where the equipment for metal spraying consist of a pistol-shaped spray gun through which the metal, in the form of wire is fed to a blowpipe flame which melt it, the molten metal thus produced being sprayed by a steam of compressed air surrounding the flame.

3.12 Magnetic Forming – is another example of the direct conversion of electrical energy into useful work. The process involved charging the voltage is supplied by a high voltage source into a bank of capacitors connected in parallel.

3.13 Plastic processes – the processes employed in plastic technology are compression moulding, transfer moulding, injection moulding, extrusion, calendaring, blow moulding, film forming, thermal forming, vacuum forming, laminating and resin technology processes.

3.14 Plasma-Arc – a gas is heated by a tungsten arc to such a high temperature that it becomes ionized and acts as a conductor of electricity.

3.15 Riveting – mechanical means of permanently fastening parts together to rivet two parts.

3.16 Sintering – application of heat, which must be kept at a temperature below the melting point of the metal powder, in the production of commercial products from metallic powders by pressure or atomic forces, and resulting in the bonding of fine particles together, thus improving the strength and other properties of the finished product.

3.17 Soldering – uniting of two pieces of metal by means of a different metal which is applied between the two in a molten state.

3.18 Thermo-forming – consist of heating a thermo-plastic sheet until it softens and then forcing it to conform to some mold either by differential air pressure or mechanical means,

3.19 Ultrasonic machining – a mechanical process was designed to effectively machine hard brittle materials.

3.20 Wire drawing – where wire is made by cold drawing hot rolled wire rod through one or more dies to decrease it size and increase the physical properties.

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3 4. Welding and Metal Cutting

4.1 Gas Welding – the process in which gases are used in combination to obtain a hot flame.

4.2 Electric-Arc Welding – a process wherein the metal is heated to its liquid state and allowed to solidify thereby making the joint.

4.3 Atomic Hydrogen Welding – an arc struck between two tungsten electrodes into which a jet of hydrogen is directed.

4.4 Electro-beam Welding – a work pierce contained in an executed chamber is bombarded by a beam of electrons from an electron gun at voltages between 0.5 kV and 100 kV. The energy of the electrons is transformed into heat on striking the work piece.

4.5 Electro-slug Welding – the work piece are usually set vertically, with a gap between them and copper plates or shoes are placed one or both sides of the joint to form a bath at the bottom of which an arc is established under a flux between one or more continuously fed electrode wires and a metal plate.

4.6 Flash Welding (Butt Welding) – the two metal parts to be welded are connected to a low voltage high current source.

4.7 Friction Welding (Cold Welding) – a purely mechanical welding technique in which one component remains stationary while the other is rotated against it under pressure.

4.8 Laser Welding and Drilling – laser beams are used for these purposes in industrial application requiring exceptionally high precision.

4.9 Metal Spraying – wire or powder from the nozzle of a spraying gun is fused by a gas flame, arc or plasma-jet, and the molten particles are projected in the form of a spray by means of compressed air or gas.

4.10 Plasma-Arc Welding – the heat source is an arc formed at a relatively small orifice through which stream of air, argon, helium, nitrogen or mixture if these gases flow.

4.11 Resistance Welding – a high current at low voltage flows through two components from electrodes.

4.12 Spark Erosion Machining – the metal is removed from the piece to be machined by the action of electric discharges between the piece and an electrode immersed in electrolyte.

4.13 Stud Welding – an arc is struck between the components to be joined and raised the temperature of the ends of the components to melting point.

4.14 Thermit Welding – a mixture of aluminum powder and a metal oxide powder is ignited by a special powder in a crucible.

5. Common Weld Defects

5.1 Lack of Penetration – caused by the base metals did not reach fusion temperature, fast welding rate or too large an electrode used.

5.2 Weld Cracks – occur at the weld heat affected zone due to brittle weldment associated with stresses.

5.3 Pinholes – are small holes through the weldment normally caused by gas bubbles escaping through the molten weld metal while cooling.

5.4 Porosity – are gas bubbles or minute impurities trapped in the weldment normally due to dirty or moist electrode or contaminated base metals.

5.5 Inclusion – a common weld defect. Slags or foreign materials are trapped inside the weld metal.

5.6 Weld Undercuts – are cuts between the weld metal and the base metal normally due to excessive welding current.

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4 6. Destructive Testing

Destructive testing - a process where materials can be randomly tested by actual destruction of a work piece for examination.

6.1 Tensile test – a test specimen is cut-out from the work piece and stretched to failure.

6.2 Bending test – a test specimen is cut-out from the work piece and bended 90 deg to 180 deg.

6.3 Sectioning – the weld joint is cut by hacksaw along the centerline of the weld to allow visual examination of the weld.

7. Non-Destructive Testing

Non-Destructive Testing – a process wherein weld examination is done without destroying the material.

7.1 Dye Penetrant Examination – this determine surface cracks and porosities which may not be readily seen.

7.2 Hardness Testing – a method of determining the hardness of the weld more particularly the heat affected zone.

7.3 Magnetic Particle Testing – uses electrical current to create a magnetic field in a specimen with the magnetic particles (iron powders) indicating where the field is broken by discontinuities such as cracks in the material.

7.4 Radiographic Examination – employs radioactive isotopes such as Cobalt-60, Iridium-192, Thulium-170, or Cesium-137 and radiographic films.

7.5 X-ray Examination – essentially the same with radiographic examination except only on the source of radiation. This utilized electricity powered X-ray machine that generate ionizing radiation.

7.6 Ultrasonic Examination – utilizes ultrasounds that penetrate most common materials. The time of rebound of ultrasounds from the probe which is pressed on one side of the material to the other side or any discontinuity is converted to unit of linear measure.

8. Air Pollution Control Equipment for collecting particulate matter (smoke, dust, fumes, mists, etc.) 8.1 Inertial separators – used for collecting medium and coarse size particulates.

8.2 Centrifugal separators – where the tangential inflow tube or cyclone separators are normally suitable for medium size (15 to 40 microns) and coarse size particulates while the axial flow inversion type or multiple cyclone separators are effective in collecting particulates in the 5 to 15 microns range.

8.3 Rinsing or wet collection device – these devices include spray-type, cyclone type, orifice-type, mechanical venture-type, jet-type, and packed tower scrubbers.

8.4 Filtration devices – have a high collection efficiency for sub-micron size particulates.

8.5 Electrostatic precipitators – suitable for the collection of a wide variety of dust and fumes.

8.6 Gravitational precipitators – used as pre-cleaners to remove coarse and abrasive particulates to protect and augment the main dust collectors.

9. Air Pollution Control Equipment for the collection of a wide gaseous and vapor emission.

9.1 Adsorption equipment – the absorbent selectively capture or remove gases or liquids from dirty gas streams even at very small concentrations.

9.2 Absorption equipment – by using selective liquids solvents, one or more constituents of a gas stream can be removed or covered.

9.3 Afterburners – combustion converts the combustible constituents of a gas stream into carbon and water.

9.4 Vapor condensers – by extracting heat or increasing pressure, vapor condensation is achieved.

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5 10. Water Pollution

10.1 Pollution – is the downgrading of water quality by sewage or other wastes to the point where it unreasonably affects water use for domestic, industrial, agricultural, navigational or other beneficial uses.

10.2 Clarifying waste water – is the process of removing turbidity, sediment and floating materials.

10.3 Coagulation – is the gathering together of finely divided or colloidal suspended matter into the particles.

10.4 Flocculation – is the agglomeration of finely divided suspended matter and floc caused by gently stirring or agitating the waste water.

10.5 Floatation – is basically sedimentation in reverse to remove floatable materials and solids with a specific gravity so close to water that they settle very slowly or not at all.

10.6 Gravity separation – is used to remove liquid pollutants that are insoluble in water such as petroleum oils and the cutting and coolant coils used in metal-finishing operations.

10.7 Granular activated carbon - has long been used in filtering equipment to remove color and turbidity and improve the taste of water by removing residual chlorine.

10.8 Biological filters (Trickling filters) – are basically a pile of rocks over which a sewage or industrial waste slowly trickles.

10.9 Activated sludge – is the process by which masses on settle able solid formed by simply aerating waste water containing biologically degradable compounds in the presence of microbes.

10.10 Anaerobic digestion – is widely used to stabilize concentrated organic solids removed from settling tanks, biological filters and activated sludge plants.

11. Chemical Processes

11.1 Adsorption – using granulated activated carbon is a reliable and effective way of removing organic impurities found in most water supplies.

11.2 Coagulation – is the process of adding chemicals to waste water to produce a flocculent precipitate that will remove fine suspended matter and colloidal substances by adsorption or mechanical entrainment.

11.3 Dialysis – a practical toll for recovering chemical from process waste.

11.4 Electro dialysis – reduces the dissolved solids content of water.

11.5 Ion exchange – is a versatile process that keeps extending its range of service. In waste water treatment it is used to remove or recover anions and cations depending on whether or not they are valuable, undesirable or both.

11.6 Neutralization – is frequently needed to keep pH in the range of 6 to 8 required by most water quality criteria.

11.7 Oxidation reduction and precipitation system – are widely applied for the treatment of plating wastes.

11.8 Sludge handling and disposal – is a final step from waste water treatment plants.

11.9 Sludge concentrators – are mainly used to thicken sludge from secondary clarifiers or mixtures of sludge from both primary and secondary treatment units.

11.10 Digestion under anaerobic conditions – makes sludge solid easier to dewater and convert parts of the inorganic matter to gaseous end products.

11.11 Dewatering – is handled by drying beds, lagoons, filters, and centrifugal.

11.12 Vacuum filtration – is the most widely used method of mechanical sludge dewatering.

11.13 Gravity filters – consists of two cells operating at atmospheric pressure. These cells are formed by a fine-mesh nylon filter cloth continuously travelling over front and rear guide wheel.

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