Ahmet Can OLDAÇ-030060098- week6 pt.2

Shearforming:(old)


A modern variation of the spinning spinning process is known as shearforming (also called flow forming or floturning). This is a sophisticated version of the ancient art of metal spinning. It has the added ability of coping with appreciable variations in wall thickness; and close tolerances are easily obtainable by the operator through the machine controller.
In metal spinning, a flat or almost flat blank of sheet metal is forced by an operator, learning on a long-handled forming tool, to conform to a convex mandrel. In the process, the wall thickness of the spun part is reasonably constant, except for some streching which occurs where the blank is bent. This thickness change is not sought after -in fact, it is normally undesired- but it is accepted as an inconvenience of the process.
Shearforming, on the other hand, allows the creation of thickness which vary from point to point by as much as 100%. Another constraint of spinning involves blank thickness and radii. In spinning, blank thickness is generally less than 1/8'', and most workpiece radii are more than 5 times blank thickness. Normally, shearforming machines can handle blanks much thicker, and can bend any radius the material itself can endure. Of course, this depends somewhat on machine size. However, both processes can, under the proper circumstances, form steel plate 1'' thick.


(Brown J. A., Modern manufacturing processes, 1991, p. 117,118)



Shearforming (new) [manufacturing method]


In this process, a flat sheet is formed over a mandrel by means of a shear forming roll that is reducing its thickness but keeping its diameter constant. This process should not be mixed with sheet forming process spinning in which the sheet thickness is more or less constant but the diameter of initial workpiece is reduced.
If the final thickness is selscted correctly the plastic deformation is confined only at the roll region, so that the rest of the workpiece remains stress-free.

(Springer Handbook of Mechanical Engineering, Author: Karl-Heinrich Grote,Erik K. Antonsson p.585)
-new definition is more clear
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Electroforming: (10.50 - 24.03.2011)(old)

A variation of electroplating, electroforming actually is a metal-fabricating process. Metal is electrodeposited on a mandrel (also called a mold or a matrix), which is then removed; thus, the coating itself becomes the product. Both simple and cmplex shapes can be produced by electroforming, with wall thicknesses as small as 0.0025 mm. Parts may weigh from a few grams to as much as 270 kg. Production rates can be increased through the use of multiple mandrels.

Mandrels are made from a variety of materials: metallic (zinc or aluminum) or nonmetallic (which can be made electrically conductive with the proper coatings). Mandrels should be able to be removed physically without damaging the electroformed part. They also may be made of low-melting alloys, wax, or plastics, all of which can be melted away or dissolved with suitable chemicals.

The electroforming process is particularly suitable for low production quantities or intricate parts (such as molds, dies, waveguides, nozzles and bellows) made of nickel, copper, gold, and silver. The process is also suitable for aerospace, electronics, and electro-optics applications.

(Kalpakjian S. Schmid S.R.,Manufacturing Engineering and Technology Sixth Edition in SI Units, p. 986)

Electroforming(new) [manufacturing]

Electroforming is the process of synthesizing a metal object by controlling the ectrodeposition of metal via an electrolytic solution. A metal layer is built up on a metal surface or on any surface that has been rendered electroconductive through the application of a paint containing metal particles. The master pattern is placed in electrical contact with the cathode, and the target material for fabrication is placed in contact with the anode. he material at the anode is oxidized and dissolved. the cations are reduced at the cathode and the metal is deposited on the master. The thickness of the electro-formed nickel layer can be controlled by the current density and the deposition time. 

(Micro / Nano Replication: Processes and Applications Author: Shinill Kang p.50)

-new definition is better and more understandable

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Magneforming (24 Mart 2011 12:45)(old)

Magneforming is also called electromagnetic forming(EMF) is an assembly technique that is widely used to both join and shape metals and other materials with precision and rapidity, and without the heat effects and tool marks associated with other techniques. Also known as magnetic pulse forming, the EMF process uses the direct application of a pressure created in an intense, transient magnetic field. Without mechanical contact, a metal workpiece is formed by the passage of a pulse of electric current through a forming coil.
The parameters that determine the applicability of the EMF process are:
· Forming can be accomplished through a nonmetallic coating or container because the magnetic field passes through electrical nonconductors
· Most of the forming takes place after the pressure impulse has ended, in contrast to most metal-forming processes. The metal is rapidly accelerated, gaining a large amount of kinetic energy by moving only a short distance during the impulse. This kinetic energy subsequently does the actual work of forming
· The metals that are most efficiently formed by EMF are those with relatively high electrical conductivity, such as copper, aluminum, low-carbon steel, brass, and molybdenum. Metals with lower conductivity, such as stainless steel, can be formed by using either very high energy or an intermediate, highly conductive "driver" · The ratio of the masses of pieces used in assembly operations may be much more significant than their relative mechanical strength or elastic properties. Because EMF does not use static forces, relatively light structures can be used to support the dies
· No torque is applied to the workpiece in swaging and expanding operations, in contrast to spinning and rolling. Because the magnetic field behaves much like a compressed gas, it exerts a uniform pressure that is relatively independent of variations in spacing between the workpiece and the forming coil
· No lubricant is required because the contact between the magnetic field and the workpiece is frictionless
· The peak pressure is limited (by the strength of the forming-coil material) to much lower values than are commonly encountered in shearing, punching, and upsetting operations. However, the pressure that can be applied by the magnetic pulse can be very high compared to the average pressure in mechanical forming
· The process, being purely electromagnetic, is not limited to repetition rate by the mechanical inertia of moving parts. The timing of the magnetic impulse can be synchronized with microsecond precision, and machines can be made to function at repetition rates of hundreds of operations per minute. The strength of the magnetic impulse can be controlled electrically with high precision The major application of EMF is the single-step assembly of metal parts to each other or to other components, although it is also used to shape metal parts. Within the transportation industry, for example, one automotive producer assembles aluminum driveshafts without welding to save a significant amount of weight in light trucks and vans to meet requirements for reduced energy consumption. Using the EMF process allows the joining of an impact-extruded aluminum yoke to a seamless tube without creating the heat-affected zone associated with welding.

(Forming and Forging,ASM Handbook Volume 14, Joseph R. Davis; Page:1420,1421)

Magneforming(new) [manufacturing]


Magneforming is when an electric current generates a pulsed magnetic field close to a metal conductuor so that a controllable force is created which can be used to shape metal without actual contact.
The basic components of magneform machine are; energy store capacitors, a work coil and switching devices. High voltage  capacitors are charged, then discharged through a coil, inducing an intense magnetic field. This field, in turn, induces current in the conducting workpiece setting up an opposing magnetic field; the net magnetic force does the forming.

During forming, pressures as high as 50000psi move the workpiece as great as 900feet/second. The strenght of this force can be closely controlled, which is important for versatility. Magneform is a proven, weidely accepted method of forming metal parts.

(Modern manufacturing processes Author: James A. Brown  p.87-88)
-new definition is more summarized and understandable

Erdem Tubun - 503101306 - 6th Week Words (31.03.2012)

1. Trepanning

2. Shearforming

3. Poly-ond

4. Magnaplate

5. Magneforming

6. Electroforming

7. Electrochemical deburring

8. Thermal energy deburring

9. Valisys Program

10.Chemical Engraving

Elif Temiz, 030070195, 6th Week Definitions-part 2

4-Resistance Seam Welding (Previous)

Seam welding is used in the same way as spot welding, and operates on essentially the same principle. The difference is that two wheel-shaped electrodes are used, rolling along (and usually feeding) the workpiece.

The two wheels should be of the same size, in order to prevent the part from being deflected towards one of them. The actual contact profile can be designed in a number of ways, in order to suit the shape of the part to be welded. The current may flow continuously while welding is being carried out, or intermittently to produce a series of spots, so closely positioned as to produce a single, continuous weld. An unavoidable problem of seam welding is that some of the current 'leaks' through the completed weld.

As the electrode rollers rotate, they do not need to be lifted between each spot, as with spot welding. If the weld does not have to be continuous, seam welding can be used therefore to position spots some regular distance from each other, which can be carried out quicker than ordinary spot welding.

(Weman K., Welding processes handbook, p. 83)

Resistance Seam Welding(New)(Better) (Manufacturing Method)

Its features are:

• It is a process in which heat caused by resistance to the flow of electric current in the work metal is combined with pressure to produce a welded seam consisting of a series of overlapping spot welds (see Fig. 9.22).
 

• The disc electrodes are continuously rotated, so that the workpiece gets advanced underneath them while at the same time the pressure on the joint is maintained. The electrodes need not be separated at any time.

• The current is applied through the heavy copper electrodes in a series of pulses at proper intervals.
• The timing is adjusted so that the pulses overlap each other and thus form a continuous scam joint as shown.

• As the welding proceeds, the applied current will try to pass through the already welded portion, thus reducing the heating in the portion to be welded. One way of overcoming this difficulty is to increase the current as the welding progresses. Sometimes, external heating such as high frequency heat to offset the effect of reduced current due to shunting can be adopted.

• The applied pressure in seam welding may range from 3 MN to 8.5 MPA, depending on the thickness of the workpiece.

• The current density may be as high as 775 A-mm2.

• Seam welding can be carried out on steels, aluminium, magnesium and nickel alloys. Seam welding of copper and its alloys is not recommended. 

(Mukherjee, Metal Fabricecation Techonology, pp.310-311)

5-Adhesive Bonding(Previous)

Adhesive bonding is a joining process in which a filler material is used to hold two (or more) closely spaced parts together by surface attachment. The filler material that binds the parts together is the adhesive. It is a nonmetallic substance—usually a polymer. The parts being joined are called adherends. Adhesives of greatest interest in engineering are structural adhesives, which are capable of forming strong, permanent joints between strong, rigid adherends, A large number of commercially available adhesives are cured by various mechanisms and suited to the bonding of various materials. Curing refers to the process by which the adhesive's physical properties are changed from a liquid to a solid, usually by chemical reaction, to accomplish the surface attachment of the parts. The chemical reaction may involve polymerization, condensation, or vulcanization. Curing is often motivated by heat and/or a catalyst, and pressure is sometimes applied between the two parts to activate the bonding process. If heat is required, the curing temperatures are relatively low, and so the materials being joined are usually unaffected—an advantage for adhesive bonding. The curing or hardening of the adhesive takes time, called curing time or setting time. In some cases this time is significant—generally a disadvantage in manufacturing.

(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.756)

Adhesive Bonding(New) (Better) (Jointing Method)

Adhesive bonding is a method of joining structure together that eliminates some, or all, of the cost and weight of mechanical fasteners. In adhesive bonding, cured composites or metals are adhesively bonded to other cured composites, honeycomb core, foam core, or metallic pieces. Cocuring is a process in which uncured composite plies are cured and bonded simultaneously during the same cure cycle to either core materials or other composite parts. The ability to make large bonded and cocured unitized structure can eliminate a significant portion of the assembly costs.

 Adhesive bonding is a widely used industrial joining process in which a polymeric material (the adhesive) is used to join two separate pieces (the adherends or substrates). There are many types of adhesives; sonic are strong and rigid while others are weak and flexible. Adhesives used for structural bonding are always cured at either room or elevated temperatures and must possess adequate strength to transfer the loads through the joint. There are many types of structural adhesives; howeve,. Epoxies, nitrile phenolics, and bismaleimides are the most prevalent. In addition to fabricating large bonded components, adhesive bonding is frequently used for repairing damaged structural parts.

Bonded joints may be preferred it thin composite sections are to he joined where bearing stresses in bolted joints would be unacceptably high, or when the weight penalty for mechanical fasteners is too high. In general, thin structures with well-defined load paths are good candidates for adhesive bonding, while thicker structures with complex load paths are better candidates for mechanical fastening.

Advantages of Adhesive Bonding

 The advantages of adhesive bonding include:

 • Bonding provides a more uniform stress distribution than mechanical fasteners by eliminating the individual stress concentration peaks caused by mechanical fasteners. As shown in Fig. 8.1, the stress distribution across the joint is much more uniform for the adhesive bonded joint than for the mechanical .joint. leading to better fatigue life than that for mechanically fastened joint. Bonded joints also provide superior vibration and damping capability.

 • Due to the elimination of mechanical fasteners, bonded joints are usually lighter than mechanically fastened joints and are less expensive in some applications.

 • Bonded joints enable the design of smooth external surfaces and integrally sealed joints with minimum sensitivity to fatigue crack propagation. Dis-similar materials can be assembled with adhesive bonding and the joints are electrically insulating, preventing galvanic corrosion of metal adherends.

 • Bonded joints provide a stiffening effect compared to riveted or spot welded constructions. While rivets or spot welds provide local point stiffening. bonded joints provide stiffening over the entire bonded area. The significance of this effect is shown in Fig. 8.1, where bonded joints may increase the buckling strength of the structure by as much as 30-100%. 

Disadvantages of Adhesive Bonding

 Adhesive bonding also has some disadvantages, including:

• Bonded joints should be considered permanent joints. Disassembly is not easy and often results in damage to the adherends and surrounding structure.

 • Adhesive honding is much more sensitive to surface preparation than mechanical fastening. Proper surface preparation is absolutely essential to producing a strong, durable bond. For field repair applications, it can be extremely difficult to execute proper surface preparation. For original manufacturing, adhesive bonding requires clean rooms with temperature and humidity control.

• Adhesively bonded joints can be non-destructively tested for the presence of voids and tin bonds: however, at this time there is no reliable non-destructive test method for determining the strength of a bonded joint. Therefore, traveler or process control test specimens must be fabricated and destructively tested using the same surface preparation, adhesive, and bond cycle as the actual structure.

 • Adhesive materials are perishable. They must be stored according to the manufacturer's recommended procedures (often refrigerated). Once mixed or removed from the freezer. they must be assembled and cured within a specified time.

• Adhesives are susceptible to environmental degradation. Most will absorb moisture and exhibit reduced strength and durability at elevated temperature. Some are degraded by chemicals such as paint strippers or other solvents.

(Flake C. Campbell, Manufacturing Technology for Aerospace Structural Materials,pp.370,372)

Erdem Özdemir - 030070307 - 6th Week Definitions

Cladding

Manufacturing

New - Better Definition

The term weld cladding usually denotes the application of a relatively thick layer t£3 mm. or % in.) of weld metal for the purpose of providing a corrosion-resistant surface. Hard facing pro¬ducer a thinner surface coaling than a weld clad¬ding and is normally applied for dimensional restoration or wear resistance, Typical base metal components that are weld -cladded include the in¬ternal surfaces of carbon and low-alloy steel pres¬sure vessels, paper digesters, urea reactors, tubesheets, nuclear reactor containment vessels, and hydrocrackers The cladding material is usu¬ally an austenitic stainless steel or a nickel-base alloy. Weld cladding is usually performed using submerged arc welding. However, flux-cored arc welding (either self-shielded or gas-shielded), plasma arc welding, and electrolsag welding can also produce weld claddings. Figure 6 compares' deposition rates obtainable with different welding processes. Filler metals arc available as covered electrodes, coiled electrode wire, and strip elec¬trodes. For very large areas, strip welding with cither submerged arc or electros lag techniques is the most economical. Table 4 lists some of the filler metals for stainless steel weld claddings.
Application Considerations. Weld cladding is on excellent way to impart properties to the surface of a substrate that are not available from that of a base metal, or to conserve expensive or difficult to-obtain materials by using only a relatively thin surface layer on a less expensive or abundant base material. Several inherent limitations or possible problems must be considered when planning lor weld cladding. The thickness of the required surface must he less than the maximum thickness of the overlay that can be obtained with the particular process and filler metal selected.
Welding position also must be considered when selecting an overlay material and process. Certain processes are limited in their available welding positions (e.g.. submerged arc welding can be used only in the flat position). In addition, when using a high-deposition-rate process that exhibits a large liquid pool. weIding vertically or overhead may be difficult or impossible. Some alloys exhibit eutectic solidification, which leads to large molten pools that solidify instantly, with no "mushy" (liquid plus solid) transition. Such materials arc also difficult to weld except in the flat position

(Stainless steels, 1993, Joseph R. Davis, ASM International. Handbook Committee, P 110)

Previous:

Cladding

Explosive welding or cladding, as it is often called, brings together two metal surfaces with sufficient impact and pressure to bond. Pressure is developed by a high-explosive shot placed in contact with or in close proximity to the metals. In some instances a protective material such as rubber is placed over the upper panel to prevent damage to the surface. The entire assembly is placed upon a buffer plate or anvil to absorb energy generated during yje jıining operation. Of the two arrangements showing cladding or laminating of metals, the left one is preferred.

To obtain a metallurgical bond, atoms from boh surfaces must come into intimate contact. The oxides and films always present on the surface of metals are broken or dispersed by high

pressure or dissolved in the molten region. The explosive force brings the clean surfaces together and produces a sound bond.

(Amstead, B. H., Ostwald,P. F., Begeman, M. L., MAnufacturing Processes,8th Edition, pg. 189)

Pickling

Surface Cleaning
New – Better Definition

Pickling is a treatment that uses an acid or a mixture of acids to remove scale. Scale is produced in high-temperature operations like welding, heat treatment or hot working. It is important to remove the scale because scale works against the natural corrosion resistant properties in stainless steel. The acids you use and the pickling procedure you follow depend on the grade of stainless steel being treated.
It can be dangerous to handle acids as they can burn your skin and other materials. You should know how to use them and how to dispose of them.
Sulphuric acid, nitric acid and hydrofluoric acid are some of the kinds of acids that you use in the pickling process.
Pickling is usually done by using baths or pickling paste. In a pickling bath, the weld is submerged in acid and the acid then eats away the scale.This is not useful if you have welds on large workpieces or in difficult to reach spaces. For these areas, it is much easier and safer to use pickling paste, which is a specially prepared, stiff paste made of strong acids. In this form, it can be applied to vertical or overhanging surfaces and localised areas. We often use pickling paste to remove post-weld discolouration.
The pickling process also removes rust caused by the corrosion of stainless steel or contaminant materials, like iron and steel particles.

(FCS Engineering Fabrication & Sheet Metalwork L4, 2009, Brink, McNamara, Rademeyer and Kiddelin, P36-37)

Previous:

Another chemical cleaning process is pickling, which is an acid-cleaning treatment that removes oxide scale and flux residues. Pickling involves cleaning of metal parts in dilute acids by spraying or immersion. Common acids used in pickling are 10% H2SO4 at 150-185°F or HCl acid in room temperature. The part is first cleaned with an alkali to allow acid to reach all surfaces. Pickling solution does not attack certain types of oils and grease, and alternative cleaning treatments may be needed.

(Asthana R. et al., Materials Processing an Manufacturing Science, p.316)

Alkaline Surface Cleaning

Surface Cleaning

New – Better Definition

Among chemical cleaners, the alkaline base cleaners have been and continue to be the most widely used type of formulated cleaners. When formulated with synthetic agents they create an effective detergent cleaning action.
Alkaline cleaners can remove a wide range of soils including heat-treating salts; inorganic soldering, brazing and welding fluxes; lubricants and coolants; and polishing and buffing compounds. They can be applied by just about any method of application known-by soak or tank cleaning, by spray, in electro-cleaning or barrel tumbling.
The most commonly used alkali bases are carbonates (such as sodium carbonate or soda ash), phosphates (such as trisodium phosphate or TSP), silicates (such as sodium orthosilicate or metasilicate), and hydroxides (such as sodium hydroxide). Another common alkali base is the borates.

Applications of Alkali Bases
Each alkali base serves a specific purpose. The carbonates, for example, serve as buffers, as low-cost alkalinity sources, and as water softeners.
The phosphates serve primarily as water softeners. In hard water areas, that is, where there are relatively large proportions of calcium and magnesium ions in the water, these ions will combine with ingredients in the cleaning solution to form insoluble materials. This formation of insoluble materials can be combatted by a sequestering agent in the formulated cleaner which, in effect, ties up the calcium and magnesium ions. And the phosphates are effective sequestering agents. They also impart alkalinity, rinsability, some buffer action, and are fair emulsifiers.
The silicates are excellent emulsifiers, good buffers (where pH is over 9). will hold soils in suspension, and provide active alkalinity. Hydroxides supply the necessary alkalinity, increase electrical conductivity of the solutions, and improve saponification.

Deficiencies
However, pure raw alkalies have serious deficiencies as far as cleaners are concerned -for example, they can form insoluble residues with hard water salts, and will not rinse freely; they can corrode or pit metal; they can be dangerous to personnel—and these deficiencies must be overcome. To this end, the alkali bases are mixed with surface active agents, which, in essence, utilize the desirable features of the alkalies even as they tone down the undesirable features. At the same time, the surface active agents or surfactants add certain benefits of their own.

(Cleaning Stainless Steel, 1973, ASTM International, P17)

Previous:

Alkaline Surface Cleaning:
The most used industrial cleaning method is alkaline surface cleaning, the action which is basically physical as well as chemical, aided by combination of surfactants, emulsifiers, separating agents, saponifiers, and wetting agents all attacking the part to be cleaned.The solution may be heated or agitated in motion by stirring.
Dissovable particles of dirt are washed away. Solid particles are seperated from the part and allowed to either settle in the form of sludge to the bottom or be floated away and removed from the solution by means of filtering similar devices.

(Ivana Suchy, Handbook of Die Design 2nd Edition, p668)

Fillet Welding

Manufacturing

New - Better Definition

A (did weld is the type of weld nude on the lap joint and lee joint It should be build up equal to the thickness of tin-plate, figure 1 13-30. On thick plates the fillet must be nude up of several passes as with a groove weld. The difference with a fillet weld is that a smooth transition from the plate surface to the weld is required If this transition is abrupt, it can cause stresses lh.it will weaken the joint
I he lap joint is made by overlapping the edges of the plates They should be held together tightly before tack welding them together A small tack weld may be added in the center to prevent distortion during welding, Figure I VII. ( hip the lacks he lore you start to weld
The lee joint is made In tack welding one piece of metal on another piece o( metal at a right angle. Figure I 3-32. After the joint is tack welded together, the slag is chipped from the tack welds If the slag is not removed, it will cause a slag inclusion in the ltn.it weld.
Holding thick plates tightly together on tee joints may cause underbad cracking or lamellar tearing. Figure 13-33. on thick plates the weld shrinkage can be great enough to pull the metal apart well below the head or its heat-affected zone In production welds cracking can be controlled by not assembling the plates tightly together The space between the two plates can be set by placing a small wire spacer between them. Figure 13-34
A fillet welded lap or tee joint can be strong if it is welded on both sides, even without having deep penetration Figure 1V-3-35. Some tee joints may be prepared for welding by cutting cither a bevel or a j-groove in the vertical plate This cut LS not required for strength but may he necessary because of design limitations unless otherwise instructed, most fillet welds will he equal in size to the plates welded A fillet weld will be as strong as the base plate if the sue of the two welds equals the total thickness of the base plate The weld bead should have a flat or slightly concave appearance to ensure the greatest strength and efficiency. Figure 13-36.
The root of fillet welds must be melted to ensure a completely fused joint A notch along the root of the weld pool is an indication that the root is not being fused together. Figure 13-37. To achieve complete root fusion, move the arc lo a point as close as possible to the leading edge of the weld pool. Figure I3-38. If the arc strikes the unmelted plate ahead of the molten weld pool, it may become erratic, which will increase weld spatter

(Welding: principles and applications, 2002, Larry F. Jeffus, P308-309)

Previous:

A fillet weld is used to fill in the edges of plates created by corner, lap and tee joints.Filler metal is used to provide a cross section approximately the shape of a right traingle.It is the most common weld type in arc and oxyfuel welding because it requires minimum edge preparation- the basic square edges of the parts are used.Fillet welds can be single or double (i.e., welded on one side or both) and can be continuous or intermittent. (i.e., welded along the entire length of the joint or with unwelded spaces along the length.)

(Fundamentals of modern manufacturing,materials,processes and systems,3rd edition Mikell P.Groover, p.694)

Organic Solvent Cleaning

Surface Cleaning

New – Better Definition

Organic solvent cleaners use organic solvents, solvent blends, or their vapors to rénove water-Insoluble soils such as grease, oils, waxes, carbon deposits, fluxes and tars from metal, plastic, fiberglass, printed circuit boards, and other surfaces.   Organic solvent cleaning is performed prior to processes such as painting, plating, inspection, repair, assembly, heat treatment, and machining.   The same type of machine that 1s used in cleaning applications can also be used for drying wet parts (by displacing surface moisture with solvent and evaporating the solvent) and for conditioning the surface of plastic parts.   Both nonhalogenated and halogenated solvents may be used 1n solvent cleaning.   Examples of the nonhalogenated solvents typically used are mineral spirits, Stoddard solvents, and alcohols.   The five commonly used halogenated solvents used are methylene chloride (MC), perch!oroethylene (PCE), trichloroethylene (TCE), 1,1,1-trlchloroethane (TCA), and trichlorotrlfluoroethane (CFC-113).   These five solvents can be used alone or in blends which contain two or more halogenated solvents and sometimes alcohols.
Organic solvent cleaning does not constitute a distinct industrial category but rather is an Integral part of many major industries.   The five 2-digit Standard Industrial Classification (SIC) codes that use the largest quantities of halogenated solvents for cleaning are: SIC 25 (furniture and fixtures), SIC 34 (fabricated metal products), SIC 36 (electric and electronic equipment), SIC 37 (transportation equipment) and SIC 39 (miscellaneous manufacturing Industries).   Additional industries that use halogenated solvents in cleaning include SIC 20 (food and kindred products), SIC 33 (primary metals), SIC 35 (nonelectric machinery), and SIC 38 (instruments and clocks).   Nonmanufacturing industries such as railroad, bus, aircraft, and truck maintenance facilities; automotive and electric tool repair shops; automobile dealers; and service stations (SIC 40, 41, 42, 45, 49, 55, and 75, respectively) also use organic solvent cleaners.

(Halogenated solvent cleaners: emission control technologies and cost analyses, 1990, Radian Corporation, P12)

Previous:

Organic solvent cleaning consists of an application of solvents to the organic contaminants such as oils or grease, in an attempt to remove them from the surface of parts. Sometimes this cleaning method has to be followed by an alkaline wash, in order to remove the solvent itself from the part surface. This type of cleaning may also be used for removal of water from electroplated parts.
Solvents may be either petroleum-based or chlorinated hydrocarbons or alcohols. Other solvents include but are not restricted to benzol, acetone, and toluene.
The mechanism of cleaning is applicable mainly to contaminants of organic origin, such as grease or oils. These impurities may be easily solubilized and removed, or washed off the part's surface
(Ivana Suchy, Handbook of Die Design 2nd Edition, p669)

Ahmet Can OLDAÇ-030060098-week6

Tool life (old) -none


Tool life (new) [material property]
Tool life is the time a tool can be reliably used for cutting before it must be discarded or repaired. In other words, tool life is the lenght of time in minutes between two neighbouring changes of the cutting tools. Tool life is important in machining since considerable time is lost whenever a tool is replaced and reset.


Tool life depends on a number of factors that include machine tool, tool material and geometry, work material, cooland and lubricant conditions and other cutting conditions. Recently numerous new tool materials have been especially developed to machine numerous new workpiece materials, and thus the situation of tool wear and tool life becomes further complex


(Machining dynamics: fundamentals, applications and practices Author: Kai Cheng p.142)


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Ultrasonic Staking:(27 March 2011, 03:43 am)(old)

In ultrasonic staking, a thermoplastic stud is melted and reformed to mechanically lock another dissimilar material (usually metal) in place. Staking provides an alternative to welding when the two parts are to be joined are made of dissimilar materials that cannot be welded or when simple mechanical retention of one part to another is adequate. Advantages of staking include short cycle times, tight assemblies with virtually no tendency for recovery, repeatability, design simplicity, and the elimination of consumables such as screws, rivets, adhesives and fasteners.

(Plastics Design Library, Handbook of Plastics Joining: A Practical Guide, p.61-62)



Ultrasonic Staking (new) [manufacturing method]


Ultrasonic staking is another common process that uses ultrasonic energy to join components. It is usually used to mechanically join dissismilar materials. This is accomplished by molding bosses n the thermoplastic part, which are inserted in holes in the second part. Ultrasonic heating and shaping is used to form headslike screw heads) from these bosses. as shown in figure, there is a wide range of possible cross-sectional profiles for staking.

(Plastics and composites welding handbook Author: Avraham Benatar  p.167)
-new definition is more understandable and better
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Gökhan GÜNGÖR 5140101006 (6th Week Terms)

1. Cladding

2. Metallizing

3. Pickling

4. Alkaline Surface Cleaning

5. Organic Solvent Cleaning

6. Adhesive Bonding

7. Plastic Welding

8. Tee Joint (welding)

9. Fillet weld

10. Bead Weld

MÜGE BAŞARAN 030090704 6TH WEEK

CATALYTIC CONVERTER group: Fuel economy, Enviromental protection

Old definition:

The Catalytic Converter is one of the most effective emission control devices available. The Catalytic Converter processes exhaust to remove pollutants, achieving considerably lower emissions than is possible with in-cylinder techniques. Vehicles with catalytic converters require unleaded fuel, since lead forms deposits that poison the catalytic converter by blocking the access of exhaust gases to the catalyst. The catalytic converter comprises a ceramic support, a washcoat (usually aluminum oxide) to provide a very large surface area and a surface layer of precious metals (platinum, rhodium and palladium are most commonly used) to perform catalyst function.

(A.Faiz, C.Weaver, M. Walsh, Air pollution from motor vehicles: standards and Technologies for Controlling Emissions, p.67)

New definition:

A catalyst is a substance that causes a chemical reaction to occur without undergoing any change to itself. The chemical reaction is one that normally would not occur at all, or one that occurs at a much faster rate than normal because of the catalyst. Catalytic converters have been installed on most cars since 1975, the same time unleaded fuel came into use. The catalytic converter is often called a cat. It is located in front of the muffler in the exhaust system and looks like a heavy muffler.

A catalytic converter must be hot before it can begin to operate. Therefore, it is mounted closer to the engine than the muffler so it can be quickly heated by exhaust. The point where the converter begins to work is called its light oft temperature, which is about 500°F. Prior to the invention of the catalytic converter, exhaust emissions were controlled by engine systems that included leaner air-fuel mixtures, which resulted in lower performance and fuel economy. The catalytic converter allowed automotive manufacturers to improve engine performance and fuel economy and let the convener take care of the emissions.

The catalyst is either monolithic or it has pellets. A monolithic catalyst is like a big honeycomb (Figure 43.21). It has a thin coating of platinum and palladium applied to either a ceramic or in monolith coated with alumina. Alumina is an oxide of aluminum that is very porous. The catalyst's metals (platinum and palladium) fill the holes in the alumina. Newer catalysts also include the rare silvery white metal rhodium.

There are three types of catalytic converters:

· The earliest catalytic converter, called a two-way converter, was designed to oxidize HC and CO, converting them into H₂O and CO₂.

· The three-way single bed converter oxidizes HC and CO and also reduces harmful NO_x into harmless nitrogen and O₂. The NO_x portion of the converter is called a reduction catalyst. The O₂ produced in the NO_x portion of the converter aids in oxidizing HC and CO.

· The three-way dual bed converter has two chambers. A tube between the two chambers provides O₂ to the rear oxidation chamber, supplied from the air pump (Figure 43.23).

(Tim Gilles, Automotive Service: Inspection, Maintenance, Repair, pg. 736,737)

My definition is more detailed and makes it easy to understand why and how this device used by given figures.

ELECTROCHEMICAL DEBURRING group: Manufacturing/electrochemical mach.

Old definition:

Electrochemical deburring (ECD) is a special version of ECM (Fig. 39). ECD was developed to remove burrs and fins or to round sharp corners. Anodic dissolution occurs on the workpiece burrs in the presence of a closely placed cathodic tool whose configuration matches the burred edge. Normally, only a small portion of the cathode is electrically exposed, so a maximum concentration of the electrolytic action is attained. The electrolyte flow usually is arranged to carry away any burrs that may break loose from the workpiece during the cycle.

Voltages are low, current densities are high, electrolyte flow rate is modest, and electrolyte types are similar to those used for ECM. The electrode (tool) is stationary, so equipment is simpler than that used for ECM. Cycle time is short for deburring. Longer cycle time produces a natural radiusing action.

(Kutz M., Mechanical engineers’ handbook 3rd edition: Manufacturing and management, p. 228)

New definition:

Electrochemical deburring (ECD) is a deburring process which uses electrical energy to remove burrs in a very localized area, as opposed to thermal energy machining which provides general deburring. The part to be deburred is placed in a non-metallic fixture which positions an electrode in close proximity to the burrs. The workpiece is charged positively (anode). the electrode is charged negatively (cathode), and an electrolytic so-lution is directed under pressure to the gap between the electrode and the burr. This flow of electrolyte precedes the applica-tion of the current in order to flush out any loose chips which probably would cause a short in the system that could damage the part. the tooling, or the equipment As the burr dissolves, a very controlled radius is formed. The process is consistent from part to part.

The process always requires fixturing to establish the anode—cathode relationship. A typical fixture consists of a plastic locator which holds the part and insulates (masks) areas of the part which do not require ECD. The fixture also positions a highly conductive electrode, designed with a contour that con-forms to the desired dimensions of the area to be deburred. The locator and electrode direct the flow of electrolyte. The vari-ables of voltage, current, electrolyte flow, and cycle time provide precise control of the ECD process. The process depicted in figure  21.1.

Fig. 21.1. How electrochemical debumng works. A. DEBURRING of a workpiece by electrolytic means relies upon ndeplating" the anodically connected workpiece, using a cathodically connected tool, both immersed in electrolyte such as salt water. B. WORKPIECE with a burr. C. WORKPIECE mounted on anode connection in a tank of electrolyte. D. CYLINDRICAL brass tool has slots to cause turbulence, and is connected to negative lead.

(James A. Brown, Modern manufacturing processes,pg. 160)

My definition became more rich with the visual explanations about the process

PIEZO VELOCITY SENSOR group: Control

old definition is not exist

New definition:

Typically piezoelectric sensors accomplish a velocity output measurement by applying a filter to an accelerometer that acts as an integrator circuit. Fig. 4 shows the estimated sensor dynamics of a PCB sensor that was used successfully in a control circuit. The vertical line at 2.5 Hz indicates the lower bandwidth of the sensor. The straight line in each graph represents the relationship of velocity to acceleration if an infinite sensor bandwidth was possible. It should be noted that the magnitude is reasonably predicted at frequencies above the lower bandwidth line. This might imply that a good measure of velocity can be achieved for frequencies above the lower bandwidth. When used in a control configuration, the phase is more important than the amplitude. If this sensor were to be used to measure resonant frequencies near the lower limit of the bandwidth, the phase would be about 66 degrees instead of 90 degrees. At 66 degrees, the projection on to the imaginary axis (sin(33)=0.55) would be only 55% of the actual velocity, whereas, at 2x the lower bandwidth, the projection on to the imaginary axis would be about (sin(66) = 0.91) 91% of the actual velocity. This has proven to be an acceptable distortion of the actual velocity. It is therefore recommended that piezoelectric velocity sensors only be used to control floors with fundamental natural frequencies at least 2x the lower limit of the sensor bandwidth.

(Tom Proulx, Dynamics of Civil Structures, Volume 4: Proceedings of the 28th IMac, pg.192,193)

There is no older definition to compare, but I faund my definition is enoug to explain the device.

SHEAR JOINT group: Manufacturing /welding

Old definition:

The shear joint is used in welding semicrystalline materials that have a sharp and narrow melting point. Energy directors are not useful with crystalline materials because material displaced from the energy director either degrades or recrystallizes before it can flow across the joint interface and form a weld. The small, initial contact area of the shear joint is the first to melt during welding; melting then continues along the vertical walls as the parts telescope together in a smearing action that eliminates exposure to air and premature solidification. Strong hermetic seals can be obtained. Rigid side wall support is necessary to prevent deflection during welding, and the walls of the bottom section must be supported by the holding fixture. The top part of the joint should be as shallow as possible, similar to a lid, but of sufficient structural integrity to withstand internal deflection. Shear joints provide part alignment and a uniform contact area.

(Plastics Design Library, Handbook of Plastics Joining: A Practical Guide, p.49)

New definition:

Shear joints are typically used for applications that require a hermetic seal It should be noted that hcmictic scals can also be achieved with energy director joints. hut the shear joint is usually preferred. Figure 8.16 shows a typical cross section of a shear joint along with recommended dimensions. Table 8.6 lists some of the advantages and disadvantages of shear joints.

It should be noted that one major disadvantages of the shear joint is the relatively high dimensional tolerance that is required to obtain a uniform weld. Therefore, when the part size increases, the shear joint is not generally recommended. Another disadvantage of the shear joint is that complex fixture design may be needed when part geometry cannot provide sufficient support for the shear joint. This is due to the fact that without providing support over the entire part. the part can deflect outwards as the upper part shears into the lower part. This will reduce the actual interference and result in poor welds. If the fixture provides uniform support over the entire weld surface, it is usually Important that the fixture incorporates moving parts to allow removal of the assembled parts at the end of the weld cycle. (inc solution to this problem is to use a double shear joint, as seen in Fig. 8.17. which also shows other variations to shear joint design. Table 8.7 provides general guide-lines for the dimensions and tolerances of shear joints for different part sizes.

(Avraham Benatar, Plastics and composites welding handbook, 10. Cilt, pg. 161,162)

My definition fulfills the missing of the older definition by well explanation of process and added figures.

COST TRADE-OFFS group: Project management

Old definition:

The importance of marketing orientation for business success has been well documented. How management allocates scarce resources to the product, price, promotion, and place components of the marketing mix will determine a company's market share and profitability. Management can improve a firm's competitive position by spending more effectively and efficiently to the individual components of marketing mix, and/or efficiency. The cost trade-offs that management must make. The objective is to allocate recources to product, price, promotion, and place in a manner that will lead to the greatest long-run profits.

(J. A. Tompkins, J. D. Smith, Warehouse Management Handbook, p.184)

New definition:

The decision to introduce new technology into a space mission involves intelligent, thorough cost/risk trade-off assessments that must be conducted at the system level. These assessments must include accurate estimates of the nonrecurring costs associated with development and space qualification. An up-front mission philosophy that governs trade-off decisions should be articulated. In all cases, available off-the-shelf technologies must be included in the trade-off considerations.

Cost trade-off studies at the program level could also consider technology and hardware from the growing commercial space infrastructure. For example, infrastructure costs, such as launch, mission ground control, and retrieval and distribution of scientific data—the life-cycle costs—can often be lowered signifi-cantly by using commercially available products and services instead of duplicat-ing them in-house. The recent DOD experience of introducing commercial off-the-shelf elements into military specification systems is also relevant.

Figure 3.4 Visualizing a Time/Cost Trade-Off

The graph shows the range of cost versus-time solutions for a given project scope. For any project, there are three critical data points:

1. The earliest finish date of the last activity

2. The latest allowable finish date of the last activity

3. The least cost to accomplish all the work required

By extension, we can find a point that describes the late finish and last dollar. This point is the sponsor's expectation that she or he will receive the final product or service on or before a given date and at a cost not to exceed some predefined amount. The area between any point on the time/cost trade-off line and the outer limits of the project is a manage-ment reserve or contingency for the project manager.

(Larry Richman, Improving Your Project Management Skills, pg.36,37)

(National Research Council (U.S.). Committee on Technology for Space Science and Applications of the Aeronautics and Space Engineering Board, Reducing the costs of space science research missions, pg.11,43)

In older definition it is not clear what is mentioned about the subject. But my definition explains the word graphically. On the other hand I am not satisfacted about my defibition about its being understandable.