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Assignment DG206 Manufacturing Technology

Rachel van Berlo B1.1

S118985 13-12-2011

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Table of Contents

Table of contents 2 1.Studying the book: ‘Fundaments of Modern Manufacturing’ Materials, Processes, and Systems by Mikkel P. Groover 3 2. Visiting the TNO-building 4 3. Analysis of the Nokia N70 6 4. Reflection assignment DG206 13 5. Enclosure 1: Summary of the studied topics chapter 27, 28 and 29 14 6. Enclosure 2: Different engineering materials schematized 24 7. Enclosure 3: Different manufacturing processes schematized 25

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1. Studying the book ‘Fundaments of Modern Manufacturing’ Materials, Processes, and Systems by Mikkel P. Groover

Our group chose the following topics: Particulate processing for Metals and Ceramics + Surface Processing Operations + Electronics Manufacturing Group 2 consists of: Jonathan Ota, Hú Jiéníng (Jenny), Rachel van Berlo We each took one topic, I studied the topic ‘surface processing operations’ When studying I made a summary of the chapters: 27. Heat treatment of metals

- Annealing - Martensite formation in steel - Precipitation hardening - Surface hardening - Heat treatment methods and facilities

28. Cleaning and surface treatments - Chemical cleaning - Mechanical cleaning and surface preparation - Diffusion and ion implantation

29. Coating and surface treatments - Plating and related processes - Conversion coating - Physical vapor deposition - Chemical vapor deposition - Organic coatings - Porcelain enameling and other ceramic coatings - Thermal and mechanical coating processes -

The complete summary can be found in enclosure 1.

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2. Visiting GTD; different manufacturing techniques

During week 47 and 48 we visited the GTD, to experience and actually see different manufacturing techniques ourselves. eek 48: Glas and metal , welding, bending (metal, plastic)

Glass Glass is a ceramic compound, which is an amorphous structure. The component is silica, coming from natural quartz in sand. Variations in properties and colors are obtained by adding oxides. of for instance aluminum. Laboratory glassware are products that are containers for chemicals. Glass that is high in silica called ‘vicor’ is used because the glass needs to withstand chemical attacks and thermal shock. These products need to be calibrated and therefor are not handmade. Glass is melted generally at temperatures around 1500°C and 1600°C. Hollow pieces and laboratory glassware are made by machine. A lot of other applications are made by hand.

Making our own stirrer: At the atelier, we were able to experiment with crafting glass ourselves. This appeared to be harder then expected. Expertise is needed to get a good result. While rotating we were able to bend, thicken, shape both regular and hollow glass sticks.

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Metal Making a metal box: To understand and experience the metal manufacturing techniques we made a little metal box. First of all, it is important to make a good drawing of the design. A drawing with measurements and useable for the manufacturers. Many metal materials are very expensive, Within a designers choice of material, especially as a student, this can be of effect as well. The box will be made out of sheet metal. This can be cut very precisely before further techniques are used. The metal then is bended, this can be done fully automatically, or by hand. Two holes are punched in to be able to open the box. Metal of course can be welded, there are different welding machines and techniques, depending on accuracy and cost, you can chose the machine and technique. Expertise is required to make a nice weld. Bending of metal can be done fully automatically and different types of bends can be made. Manually is less precise, easier and cheaper. Experience and expertise are required to handle the machines at GTD. Also because of the many details that must be taken into perspective when manufacturing. Plastics We can bend plastics, primarily thermoplastics are bendable. This can be done by adding more plastic or by heating and bending.

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3. Analysis of a product: The Nokia N70 (casing)

Jonathan Ota and Rachel van Berlo The Nokia N70 The Nokia N70 is a multimedia 3G smartphone made by Nokia and launched in Q3 2005. This phone is one of the first phones released for Nokia's line of Multimedia computers, the Nokia Nseries. The Nokia N70 (Model N70-1) is one of the handsets in Nokia's Nseries lineup of smart phones. It is equipped with a 2 megapixel camera with built-in flash, a front VGA camera to allow video calling, FM radio, Bluetooth, digital music player functionality, and support for 3D Symbian, Java games and other S60 2nd Edition software. The production quantity range is high: 10.000-million units/year are made. Disassembling the Phone When disassembling the phone we see different layers with different functions. We gave the disassembled parts letters in the picture. We were particularly interested in the casing, the electronic circuit board is a good example of capital good. hich leads us to another field of manufacturing.

In short:

- Parts A, B(which are the three components), C, F and J primarily are the casing. - Part D(which are the six components) from top to bottom:

The antenna, the camera casing, speaker, camera, vibrator, memory card. - Part E is the printed circuit board and the control center of the phone. - Part G is a thin piece of metal that is a conductor - Part H is another small circuit board with buttons - Part I the actual buttons for the user.

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Dividing the tasks: Jonathan did part B, I and J. I will first discuss the casing, and then specify on each part. Part A, C, F (B and J are analyzed by Jonathan); the casing These parts have the same type of casing, thus I will analyze them together and then individually. What is the initial engineering material of these pieces? The scheme in enclosure 2 shows the different engineering materials. The material at first sight appears to be a plastic, thus a polymer. There are three types of polymers: Thermoplastic: A solid material at room temperature, but become viscous liquids when heated to temperatures of only a few hundred degrees. They are easily and economically shaped into products. They can be subjected to this heating and cooling cycle repeatedly, without significant degradation of the polymer. Thermosetting: Cannot tolerate repeated heating cycles as thermoplastics can The elevated temperatures also produce a chemical reaction that hardens the material into an infusible solid. If reheated thermosetting polymers degrade and char rather than soften. Elastomer: These are the rubbers. Elastomers are polymers that exhibit extreme elastic extensibility when subjected to relatively low mechanical stress. Some can be stretched by a factor of 10 and yet completely recover to their original shape. When evaluating and comparing the three types, We can say this material is a thermoplastic:

- It is not a elastomer because we cannot bend it extremely. - It is not a thermosetting, because we are still able to bend the material to some extent. It is not

a hardened material, If I drop the phone to the floor, the material does not shatter. - Thus it is a thermoplastic.

There are different types of thermoplastic. Which thermoplastic is used? All of the parts also have a SPI resin identification code: The SPI resin identification coding system is a set of symbols placed on plastics to identify the polymer type. It was developed by the SPI in 1988, and is used internationally. The primary purpose of the codes is to allow efficient separation of different polymer types for recycling. The symbols used in the code consist of arrows that cycle clockwise to form a rounded triangle and enclosing a number, often with an acronym representing the plastic below the triangle. When the number is omitted, the symbol is known as the universal recycling symbol, indicating generic recyclable materials. In this case, other text and labels are used to indicate the material(s) used. Previously recycled resins are coded with an "R" prefix (for example, a PETE bottle made of recycled resin could be marked as RPETE using same numbering). Contrary to misconceptions, the number does not indicate how hard the item is to recycle, nor how often the plastic was recycled. It is an arbitrarily-assigned number that has no other meaning aside from identifying the specific plastic. The code found on the casings are corresponding. The code says ABS+PC ABS: Acrylonitrile-Butadiene-Styrene. This is an engineering plastic due to its excellent combination of mechanical properties. Typical applications include components for automotive, appliances, business machines; and pipes and fittings.

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PC: Polycarbonate is noted for its generally excellent mechanical properties like high toughness and good creep resistance. This is one of the best thermoplastics for heat resistance, it is transparent and fire resistant. What manufacturing processes can be described? The second scheme, enclosure 3, shows different manufacturing processes. The pieces each have very specific shapes. The pieces have details both on the in and outside. This suggests a manufacturing method that can deliver 3D-features. Shaping a thermoplastic can be done using different methods: Conventional machining: Operations such as turning, drilling and milling. Injection molding: A polymer is heated to a highly plastic state and forced to flow under high pressure into a mold cavity, where it solidifies. The process produces discrete components that are almost always net shape. Complex and intricate shapes are possible with injection molding. Injection molding is economical only for large production quantities. A mold can be expensive because of it complexity or and size. Blow molding: Method used to make hollow, seamless parts. Blow molding is more suited to the mass production of small disposable containers. Air pressure is used to inflate soft plastic into a mold cavity. The technique is borrowed from the glass industry. There are many specific blow molding techniques. Rotational molding: Method used to make hollow, seamless parts. Rotational is more suited to mold large, hollow shapes. Uses gravity inside a rotating mold to achieve a hollow form. There are many specific rotational molding techniques. Compression molding: compression molding, loading a precise amount of molding compound into the bottom of a heated mold. Bringing the mold halves together to compress the charge, heat the charge by means of the hot mold to polymerize and cure the material into a solidified part. Thermo-forming: A flat thermoplastic sheet is heated and deformed into the desired shape. This is widely used in packaging of consumer products and to fabricate large items such as bathtubs. The two steps are heating and forming. There are specific thermo-folding techniques. Polymer casting: This involves pouring of a liquid resin into a mold, using gravity to ill the cavity, and allowing the polymer to harden. Advantages of casting over alternative processes such as injection molding include:

- The mold is simpler and less costly - The cast item is relatively free of residual stresses ad viscoelastic memory - The process is suited to low production quantities.

Resin transfer molding: Transfer molding :A charge of thermosetting resin is placed in a pot or chamber, heated, and squeezed by ram action into one or more mold cavities. Resin transfer molding is a closed mold process in which a preform mat is placed in the lower mold section, the mold is closed, and a thermosetting resin, is transferred into the cavity under moderate pressure to impregnate the preform. RTM is used to manufacture such products as bathtubs and swimming pool shelves.

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When evaluating and comparing the shaping techniques and considering that the pieces are very detailed and have tiny 3D-features: injection molding

- Conventional manufacturing do not address to the casing - Injection molding can produce complex shapes and is used for mass production - Blow molding and rotational molding are methods used to make hollow seamless parts, the

parts are not hollow. - Compression molding is only 2-D and thus not suitable - The shapes are to complex to have been formed thermally. - Polymer casting produces simple molds. - Resin transfer molding cannot produce products this complex.

specifications Part A The part is a ABS+PC thermoplastic. There appears to be a coating on the outer side of the casing. We can scratch it away, and the edges show that a coating was added. There are three coating processes for polymers. Planar coating: Coating fabrics, paper, carboard etc. Wire and cable coating Contour coating: coating a three-dimensional object. Part A is subjected to contour coating. Dipping involves submersion of the object into a suitable bath of polymer melt or solution followed by cooling and drying. Spraying is an alternative method for applying a polymer coating to a solid object. Since the coating is not on the entire part, the part has been sprayed.

Part B Jonathan

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Part C Part C can be seen as the skeleton of the phone. All of the parts are directly or indirectly attached to this part. The black casing is a ABS+PC thermoplastic The metal is a very thin detailed, easily bendable metal which holds the battery and the sim. The casing has little pins on which the metal is placed after which the plastic pins where molted/pressed. The metal could have been worked cold and warm. Cold working: Metal forming at room temperature

- Better accuracy, - Better surface finish - Strain hardening increases strength and hardness - No heating of the work is required which saves furnace and fuel costs and permits higher

production rates. Warm Working: Metal forming at temperatures above room temp. But below the recrystallization temp.

- Lower forces and power are needed - More intricate work geometries possible - Need for annealing may be reduced.

The metal is worked cold. The surface must be smooth for users, accuracy is required, the costs are lower. This product has a high production quantity range, thus cold working was the technique. Part C also shows gold pieces (1), these are conductors from and to the printed circuit board. These are folded in or with use of springs.

Parts C & D

Part D (2,3,4,5 and 6 in picture) 2: this is a speaker . 3: the back of a powerled (flash of the camera) 4: vibrator 5: The antenna 6: the casing of the camera

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‘D’ is a collection of extra features to the phone. We will only notify these parts, because they are products on their own. Part E Part E is the printed circuit board and the control center of the phone. A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. I t is also referred to as printed wiring board (PWB) or etched wiring board. A PCB populated with electronic components is a printed circuit assembly (PCA), also known as a printed circuit board assembly (PCBA). Printed circuit boards are used in virtually all but the simplest commercially produced electronic devices. Conducting layers are typically made of thin copper foil. Insulating layers dielectric are typically laminated together with epoxy resi prepreg. The board is typically coated with a solder mask that is green in color. Other colors that are normally available are blue, black, white and red. There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of the circuit The vast majority of printed circuit boards are made by bonding a layer of copper over the entire substrate, sometimes on both sides, (creating a "blank PCB") then removing unwanted copper after applying a temporary mask (e.g. by etching), leaving only the desired copper traces. A few PCBs are made by adding traces to the bare substrate (or a substrate with a very thin layer of copper) usually by a complex process of multiple electroplating steps. The PCB manufacturing method primarily depends on whether it is for production volume or sample/prototype quantities. Double-sided boards or multi-layer boards use plated-through holes, called vias, to connect traces on either side of the substrate. Part F Primarily is a ABS+PC thermoplastic. A speaker is in the casing. Furthermore little metalparts are used to click in the printed circuit board. Part G Part G is a thin piece of metal that conducts electricity from the keyboard to the printed circuit board. This has also been cold worked. Some gold parts are attached to improve the conductibility. These gold parts are the actual conductors. Part H Part H is another small printed circuit board with buttons.

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Part I Jonathan the actual buttons for the user. Part J Jonathan The final piece of exterior. The front of the phone.

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4. Reflection I chose the assignment manufacturing technology because I wanted to develop the competency integrating technology. I was aware of the fact that implementing electronics was a part of this competency. Now I have learned that the complete manufacturing of the product is another part of the competency integrating technology. While studying the book, I understood the quantity of manufacturing techniques. A door has been opened for me. I do value the importance of this part of the entire design process, however, when these techniques are not related to my product or prototype, I am not interested. The GTD visits showed me that there is a lot more to it then the book implies. Experiencing something simple as crafting a glass stirrer made me realize that it takes expertise, knowledge and experience to get a good result. This goes for experts from other fields as well. It can be very convenient to have some knowledge to communicate with experst from different fields. Knowing that the manufacturing drawing needs to be well considered, is just an example of the importance of communication. I will now be able to communicate my idea to the manufacturers much better. With the little knowledge I know have of some techniques, from actually seeing the manufacturing and seeing the people that are working, and the analyses of the product, I can relate to this field of the design process much better. I think, as being a student at Industrial Design, I will not manufacture things myself, but I can approach the techniques. One technique that might be the best suitable is polymer casing. I do not think that in the near future, as a student here, I will encounter manufacturing techniques very often. But in the long term, manufacturing will be a great part of the process and being aware of this I think, is important.

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5. Enclosure 1: summary of chapter 27, 28 and 29. Chapter 27: Heat treatment of metals 27.1 Annealing Annealing: Heating a metal to a temp. hold it at the temp. for a certain time (=soaking), cooling it down slowly Reasons:

- Reduce hardness and brittleness - Alter microstructure - Soften metals (increases formability) - Recrystallize cold-worked (strain hardened) metals - Relive residual stresses from prior shaping processes

Full annealing: Is associated with ferrous metals (iron containing) low and medium carbon steels. Steel will be heated to austenite region (crystal structure) and cooled down. It will produce coarse pearlite (a microstructure of layered structure) Normalizing: The cooling rates are faster than in normal annealing, result: fine pearlite, higher strength and hardness, lower ductility (buigzaamheid) Process anneal: When annealing is performed to allow further cold working of the part. An anneal: When performed on the complete part without subsequent deformations being accomplished. Recrystallization: Full recovery of the cold-worked metal to its original grain structure. It can have a new geometry by the forming, but its grain structure and properties are essentially the same. Recovery anneal: Within the process the grain structure is only partially returned to original state, strain hardening obtained but the toughness is improved. Stress-relief annealing: Just to relief stresses in the work piece, no other functions. Reduce distortion and dimensional variations. 27.2 Martensite formation in steel When cooling iron-carbon from high temp. slow enough, austenite will decompose into a mixture of ferrite and cementite at room temperature. Under conditions of rapid cooling, the equilibrium reaction is prevented, austenite transforms into a non-equilibrium phase called martensite. It is a hard, brittle phase that gives steal its unique ability to be strengthened to very high values.

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27.2.1 The time-temperature-transformation curve Nature of the martensite transformation can be understood using the TTT curve for eutectoid steel. (eutectoid two components have a lower melting temp. then the two components: L = a + b) The curve shows how cooling rate affects transformation of austenite into various possible phases.

- Alternative forms of ferrite and cementite such as pearlite and bainite (bainite has a needle or feather-like structure consisting of fine carbide regions)

- Martensite (the cubic structure of austenite is transformed into the body centered tetragonal structure (BCT), a lattice strain created by carbon atoms trapped in the BCT provide the extreme hardness.

The TTT curve shows the transformation of austenite into other phases as a function of time and temperature for a composition of about 0.80% C steel. 27.2.2 The heat treatment process Creating martensite consists of two steps: Austenitizing: Heating the steel to a temp. which will make the steel convert entirely or partially to austenite. This involves a phase change, so time and heat are neaded to form new phase and the required homogeneity. Quenching: Cooling the austenite rapidly enough for it to become martensite. Different quenching media are used, but the quenching should not go to fast, to avoid stresses, distortions and cracks In the product. Media that are used:

- Brine-salt water, usually agitated; - Fresh water, not agitated - Still oil - air

the rate of heat transfer depends on mass , geometry and the coefficient of thermal conductivity k (which is a variation for different grades of steel)

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Tempering : A heat treatment applied to hardened steel to:

- reduce brittleness - increase ductility and toughness - relieve stresses in the martensite structure.

It will change the structure from BCT to BCC which is called tempered martensite. These three steps to form tempered martensite consist of two heating and cooling cycles. The fits to produce martensite and the second to temper the martensite.

27.2.3 Hardenability

- This refers to the relative capacity of a steel to be hardened by transformation to martensite. Steels with good hardenability can be hardened more deeply and do not require high cooling rates.

- Hardenability is increased through alloying. The elements added extend the time before the start of the austenite-to-pearlite transformation. The TTTcurve is moved to the right, thus permitting slower quenching rates. And the cooling can be slower.

- The Jominy end-quench test is a method to measure hardenability. 27.3 Precipitation hardening Precipitation hardening: This involves the formation of fine particles (precipitation) that act to block the movement of dislocations and thus strengthens and hardens metal. This is used for alloys of aluminum, copper, magnesium and other nonferrous metals. This can also be used when the steal alloys cannot form martensite by the usual method. To determine if an alloy can be strengthened by precipitation hardening: It contains two phases at room temp., but which can be heated to a temp. that dissolves the second phase. This heat treatment process consist of three steps:

1. Solution treatment, in which the alloy is heated to a temp. above the solvus line. 2. Quenching (to room temperature)

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3. Precipitation treatment to cause precipitation of the fine particles of the beta phase. This is called aging.

It can be called age hardening/precipitation hardening Performed at room temp. it is called natural aging, at an elevated temp. it is called artificial aging. Continuation of the aging process results in to reduction of hardness and strength and is called overaging which is same as annealing. 27.4 Surface hardening The composition of the part surface is altered by several thermochemical treatments by addition of carbon, nitrogen, or other elements. Carburizing: Heating a part of a low carbon steel in a carbon–rich environment so C is diffused into the surface.

- Gas carburizing, with gas, will give a think 0.13-0.75mm layer. - Pack carburizing with carbonaceous materials such as charcoal, gives a thick 0.6-4mm layer - Liquid carburizing thickness between gas and pack carburizing - HRC up to 60

Nitriding: Nitrogen is diffused into the surface to produce a thin hard casing without quenching. Effectiveness increases when ingredients such as aluminum and chromium are in the alloying because these elements form nitride compounds.

- Gas nitriding, will give a 0.025mm to 0.5mm layer. - Liquid nitriding difference in thickness of the layer. - HRC up to 70

Carbonitriding: Both carbon and nitrogen are absorbed usually by heating in a furnace containing carbon and ammonia. Thickness ranges from 0.07mm to 0,5mm . Different thickness, different process Chromizing and boronizing: Additional surface-hardening treatments: the diffusion of chromium and boron

- only 0.025-0.05mm thick Chromizing: requires higher temp. and longer treatment:

- hard, wear, heat and corrosion resistant. Boronizing: Performed on tool, steels, nickel- and cobalt-based alloys and cast irons.

- Thin casing ,high abrasion resistance and low coefficient of friction, - HRC up to 70

27.5 Heat treatment methods and facilities There are two categories of methods and facilities for heta treatment:

- Furnaces - selective surface-hardening methods

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27.5.1 Furnaces for heat treatment Furnaces vary in heating technology, size, capacity, construction and atmosphere control. Fuel-fired furnaces: These are direct-fired. The work is exposed directly to the combustion products. Fuels include gases and oils that can be atomized. Electric furnaces: Use electric resistance for heating, cleaner, quieter and provide more uniform heating, more expensive. Batch furnaces: Simply a heating system in an insulated chamber with a door for loading and unloading. For instance box furnaces, car-bottom furnaces and bell-type furncaces. Continuous furnaces: Have higher production rates, product is movable in the chamber. Vacuum furnaces: Here Oxidation is prevented, an attractive alternative to atmosphere control. It does take a lot of time to get it vacuum. Salt bath furnaces: Vessels containing molten salts, parts are immersed into the molten media. Fluidized bed furnaces: Container with small inert particles in high0veolcity hot gas. It will become fluid-oike and heat up. 27.5.2 Selective surface-hardening methods Heats only the surface or local areas, so no chemical changes occur. The treatments are only thermal. Flame hardening: Heating by means of more torches followed by rapid quenching. This is a precise process. It is fast and versatile, and has a high production and big components that do not fit In a furnace can be treated. Induction heating: Using electromagnetically induced energy to create heat. When used for hardening steel, quenching follows heating. This is a fast and efficient method of heating any electrically conductive material. Time is short, production high. High-frequency (HF) resistance heating: Used to harden specific areas, localized resistance and heating at high frequency. Electron Beam (EB) heating: EB processing is the concentration of high energy densities in a small region of a part. It is precise. Austenitizing temp. can be achieved in less than a second. The area is immediately hardened and quenched. A disadvantage, it has to be done in a vacuum Laser Beam (LB) heating: Same as EB, but with light and no need of vacuum to achieve best results. Energy density levels in EB and LB heating are lower than in cutting or welding. Chapter 28 Cleaning and surface treatments Work parts must be cleaned. Chemical processes to remove substances, or to enhance its properties. 28.1 Chemical cleaning

- to prepare the surface for subsequent industrial processes (coating etc.) - to improve hygiene conditions for workers and customers

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- to remove contaminants that can chemically react with surface - enhance appearance and performance

28.1.1 General considerations in cleaning important when cleaning:

- what is the contaminant? - Degree of cleanliness required - Substrate material to be cleaned - Purpose - Environmental and safety factors - Size and geometry of the part - Production and cost

Surface contaminants found in the factory can be divided in - Oil and grease - Solid particles, metal chips etc. - Buffing and polishing compounds - Oxide films, rust and scale

28.1.2 Chemical cleaning processes Alkaline cleaning: Is most commonly used, to remove oil grease and solid particles. The metal surfaces cleaned are typically electroplated or conversion coated. Electrolytic cleaning: While adding alkaline electricity is run through which generates gas bubbles, causing a scrubbing action. Emulsion Cleaning: Uses organic solvents in aqueous solution. This is a two-phase cleaning fluid. Emulsion cleaning must be followed by alkaline cleaning to eliminate all residues. Solvent Cleaning: Dissolves the soils such as oil and grease with chemicals. Vapor degreasing uses hot vapors of solvents to dissolve rand remove oil and grease. Acid cleaning and pickling: Removes oils and light oxides from metal surfaces by soaking, spraying, manual brushing or wiping. Ultrasonic Cleaning: Chemical cleaning and mechanical agitation of the cleaning fluid to clean. Mechanical agitation by high-frequency vibrations. 28.2 Mechanical cleaning and surface preparation Involves the physical removal of siols, scales, or films from the work surface. Processes often serve other functions such as deburring and improving surface finish. 28.2.1 Blast finishing and shot peening Blast finishing: Uses a high-velocity impact of particulate media to clean and finish surface, such as sand blasting. Shot peening: High velocity stream of small cast steel pellets (called shot) is directed at a metallic surface. Primarily to improve fatigue strength of metal, by-product of the operation is cleaning the surface.

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28.2.2 Tumbling and other mass finishing Mass finishing: Finishing processes that involve in bulk by a mixin action inside a container, usually in the presence of an abrasive media. The mixing causes the media and the parts to rub together. Tumbling(/barrel finishing/tumbling barrel finishing): Horizontally oriented barrel of hexagonal or octagonal cross-section in which parts are mixed while rotating. This is a fairly slow process, uses large floor space and includes high noise levels. Vibration finishing: The vibrating vessel subjects all parts to agitation with the abrasive media. Processing times are reduced, inspection during processing is possible and the noise is reduced. Used media: Most of the used media are abrasive. Natural media: corundum, granite, limestone, hardwood (softer, thus wear more rapidly, are nonuniform in size and sometimes clog) Synthetic media: Al2O3 and SiC, made with greater consistency both in size and hardness. Shapes include regular geometric forms. The mass finising compound is a combination of chemicals for specific functions.

28.3. Diffusion and ion implantation Impregnating a surface with foreign atoms to alter its properties. 28.3.1 diffusion Diffusion: Altering the surface of a material by diffusing atoms of a different material into the surface. Metallurgical applications of diffusion: Surface hardening by diffusion, like carburizing, nitriding, carbonitriding etc. (27.4). Aluminizing or calorizing: Diffusion of aluminum into carbon steel, alloy steels, and alloys of nickel. Accomplished by pack diffusion: Workparts are packed wit hAl powders and baked at high temp. to create the diffusion layer. Or slurry method: Workparts are dipped or sprayed with Al powders and binders and then dried and baked. Semiconductor Applications: Diffusion of an implurity element into the surface of a silicon chp to change the electrical properties at the surface. (also see 35) 28.3.2 Ion implantation Is an alternative to diffusion when the latter method needs to have a high temp. A big amount of atoms of element(s) is embedded into a surface. Penetration of atoms, thinner altered layer, then using diffusion.

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29 Coating and deposition processes why coating a metal:

- provide corrosion protection - enhance appearance - increase wear resistance - increase electrical conductivity - increase electrical resistance - prepare for subsequent processing

why coating non-metal parts:

- to give them a metal look - anti reflection coatings for glass -

29.1 Plating and related processes Coating a thin metallic layer onto the surface of a substrate material. 29.1.1 Electroplating Electroplating using anode cathode to put on a layer of ions. V=CIt Theoretical amount of Metal deposited on the catode V=ECIt Plate thickness d=V/A Rack plating for parts that are large Strip plating is a high production method using small sheet-metal parts Zinc-plated include fasteners, wire goods and electrics Nickel plating is used for corrosion resistance and decorative purposes Tin plate corrosion protection (tin foodcans) Copper decorative coating, in printed circuit boardsm base for nickel other chrome plate Chromium plate decorative appearance 29.1.2 electroforming Electroforming same process different purpose. Electrolytic depositon of metal onto a pattern until the required thickness is achieved, used on cd’s. 29.1.3 electroless plating Electroless plating totally chemical deposition of metal on a surface. 29.1.4 Hot Dipping Hot dipping 29.2 Physical vapor deposition PVD, when a material is condensed onto a substrate surface. This can be done in a vacuum = vacuum evaporation 29.2.2 sputtering when bombarding a surface with atomic particles, enough energy is to collision them from the surface. This makes them that they are injected in the surface.

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29.3.3 Ion Plating A combination of sputtering and vacuum evaporation to deposit a thin film onto a substrate. Using a cathode and anode, within a vacuum, argon and an electrical feeld, this results in ion bombardment. It will get clean. The fapor molecules pass and coat the substrate. It is an excellent method. 29.4 chemical vapor deposition CVD this involve an interaction between gases and the surface of a heated substrate. CVD is important in integrated circuit fabrication Advantages:

- Capability to deposit refractory materials at temp. below melting temp. - Control of grain size possible - At atmospheric pressure - Good bonding of coating

Disadvantages - Corrosive and toxic nature - Certain ingredients are expensive - Material utilization is low

29.5 organic coatings Organic coatings are polymers and resins. Creates different colour, protection, has low costs. Binders reinsure the solid state properties of the coating, like strength and physical properties. Dyes and pigments colour the coating Solvents, Additives 29.5.1 Application methods are brushing and rolling, spraying, immersion and flow coating, drying and curing 29.5.2 Poweder coating. Above are liquid, these are dry finely pulverized solid particles, that are melted on the surface to form a uniform liquid film, after they dry. Powder coatings are Thermoplastic or thermosetting. 29.6 porcelain enameling and other ceramic coatings Used for the value of beauty, color, smoothness and ease of cleaning Porcelain enameling is the name of the process of coating ceramics:

- Preparation of the coating material - Application onto surface - Drying - Firing

29.7 thermal and mechanical coating processes 29.7.1 thermal surfacing processes Thermal spraying, molten and semi-molten coating materials are sprayed onto the substrate, where they solidify and adhere to the surface. This can also be used to give a metal coating. The leading end of the wire is heated, then atomized by a high-velocity gas and spattered on the surface. Hard facing a surfacing techniquein which alloys are applied as welded deposits to substrate metals. Fusion occurs between coating and the substrate. Flexible overlay process depositing very hard coating material, onto a substrate surface.

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29.7.2 mechanical plating Mechanical energy is used to build a metallic coating on the surface. The surface is placed in a barrel. Through the glass beads pound the metal powders against the part surface, which causes a metallurgical bond. Mechanical galvanizing is used for parts that are zinc coated.

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6. Enclosure 2: Different engineering materials schematized

Glasses Engineering materials

Metals Polymers Ceramicss

Composites

Ferrous metals

Nonferrouss

metals

Steel

Cast iron

Thermoplast

Thermosetting

Elastomerss

Crystalline ceramics

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7. Enclosure 3: Different manufacturing processes schematized

Manufacturing processes

Processing operations

Assembly operations

Shaping Property enhancing

Surface processing

Permanent joining

Mechanical fastening

Casting, molding

Particulate processing

Deformationn processes

Material removal

Heat treatment

Cleaning and surface

treatments

Coating and Deposition processes

Welding g

Brazing and soldering

Adhesive bonding

Threaded fasteners

Permanentt Fastening methods

Material Incress mfg.