Anıl Uzal, 030070012, 9th week

Peripheral Milling: (07.04.2011 ; 01:00)

Peripheral milling is a milling method which functions with horizontal tool axis. The cutting edges of the plain milling cutter are located at the tool’s periphery. Peripheral milling is subdividen into up- and down milling.

Up milling:

During up milling (Figure 11.1), the milling cutter rotates in a direction opposite to the feed direction of the workpiece. The feed motion direction (Figure 11.2) is characterised by the feed motion angle φ. If, over the course of a single tooth’s contact with the material (from the moment the tooth comes into contact with the material – tool entry - up to tool exit), φ remains less than 90^o, then it is an up milling procedure. During up milling, workpiece material is removed by the resultant force. There is the risk that the workpiece may be pulled out of the mounting or that the milling table will buckle. Specially designed clamping jigs and undercuts in the table guide-ways avoid damage to the workpiece or tool.

Down milling:

During down milling (Figure 11.3), the direction of milling cutter rotation is the same as the workpiece’s feed direction. The milling cutter approaches from the thickest part position of the chip. In down milling, the feed motion angle φ (Figure 11.4) ranges from 90^o to 180^o. The resultant force presses the workpiece against the base. In cases where the cutter arbour is insufficiently stiff, the milling cutter “climbs” onto the workpiece, and cutting edges break off.

During down milling the resultant force direction coincides with the feed motion direction. Thus, if the feed screw experiences backlash, the resultant force makes the lead-bearing flank at the feed screw changes at each start of the cut. Milling machines for down milling should have a feed drive with no backlash, cutter arbours and frame components of high stiffness.

(Heinz Tschätsch, “Applied Machining Technology”, page 173-174)

Torch Brazing: (07.04.2011 ; 01:55)

In torch brazing, flux is applied to the part surfaces and a torch is used to direct a flame against the work in the vicinity of the joint. A reducing flame is typically used to inhibit oxidation. After the work part joint areas have been heated to a suitable temperature, filler wire is added to the joint, usually in wire or rod form. Fuels used in torch brazing include acetylene, propane, and other gases, with air or oxygen. The selection of the mixture depends on heating requirements of the job. Torch brazing is often performed manually, and skilled workers must be employed to control the flame, manipulate the hand-held torches, and properly judge the temperatures; repair work is a common application. The method can also be used in mechanized production operations, in which parts and brazing metal are loaded onto a conveyor or indexing table and passed under one or more torches.

(Groover M.P., “Fundamentals of Modern Manufacturing: Materials, Processes, and Systems 3^rd Edition”, page 749)

Pulsed Arc Welding (07.04.2011 , 02:24)

Pulsed-arc welding is a controlled method of spray transfer welding requiring a more sophisticated power source, whereas the three types of transfer described previously can be obtained with standard power sources and wire feed units. In spray transfer, droplets of metal are projected from the wire tip across the arc gap to the molten pool at a constant current. In dip transfer, metal is transferred to the molten pool somewhat irregularly during the periods of short circuiting. Pulsed-arc welding enables droplets to be projected across the arc gap at a regular frequency, using pulses of current in the spray transfer range supplied from a special power source. Transfer of metal from the wire tip to the molten pool occurs only at the period of pulse, or peak current (see Fig. 5.6). During the intervals between pulses, a low “background” current maintains the arc to keeğ the wire tip molten, but no metal is transferred. Pulsed transfer means that the weld metal is projected across the gap at high current, but the mean welding current remains relatively low. The operator can vary the pulse height and the background current to obtain full control of both the heat input and the amount of metal deposited; however, in many modern power sources the pulse procedure is preset by the manufacturer to simplify use. Pulsed-arc transfer can be used on mild and low-alloy steels, stainless steel and is particularly useful with aluminum and its alloys on light to medium plate sections as dip transfer cannot be used on these alloys.

(P.T. Houldcroft, R. John, “Welding and Cutting: A Guide to Fusion Welding and Associated Cutting Processes”, page 80)

Piezoelectric Transducer (07.04.2011 ; 14:40)

If the dimensions of asymmetrical crystalline materials, such as quartz, rochelle salt and barium titanite, are changed by the application of a mechanical force, the crystal produces an emf. This property is used in piezoelectric transducers.

The basic circuit of a piezoelectric transducer is shown in Fig 21.13. Here, a crystal is placed between a solid base and the force-summing member. An externally applied force gives pressure to the top of the crystal. Hence, it produces an emf across the cyrstal which is proportional to the magnitude of the applied pressure.

As this transducer has a very good high frequency response, it is used in high frequency accelerometers. As it needs no external power source, it is called as self-generating transducer. The main drawbacks are that it cannot measuure static conditions and the output voltage is affected by temperature variations of the crystal.

(S. Salivahanan, N. S. Kumar, A. Vallavaraj, “Electronic Devices and Circuits 2^nd Edition”, page 770)

Aycan PARLAK -- 030060129 - 9th Week

Abrasive Jet Machining (07.4.2011; 01:34)

A high-speed stream of abrasive particles carried by a high pressure gas or air is impinged on the surface of workpiece. The metal is removed due to erosion caused by the impact of high-speed abrasive particles as a jet. The gas stream flow through a nozzle at pressures up to 0.7 MPa and a velocity of 300 m/s. The chipping action produced is very effective on hard and brittle materials.

The air or gas is compressed and mixed with abrasive powder in the mixing chamber of nozzle. The jet diameter is 0.12 mm to 1.25 mm. The delivery nozzle is made of sapphire or tungsten carbide. The useful life of nozzle is about 30 hours. The abrasive powder is made of aluminium oxide, silicon carbide and sodium bi-carbonate mixture. The particle sizes vary from 10 to 50 micrometer.

(R.K. Singal, Mridul Signal, Rishi Signal, Fundamentals of Machining and Machine Tools,I.K. International Pub., 2008, p.210-211 )

Electron Beam Welding (07.4.2011; 02:05)

Electron beam welding is a process in which the heat required to produce fusion is obtained from the impact of a high velocity high density stream of electrons on the work piece. Upon impact the kinetic energy of the electrons is converted the thermal energy causing both vapourisation and melting. The vapourisation of the material beneath the beam enables the beam to penetrate into the material to be welded, with the beam and the vapour forming a hole. As the beam moves along the joint, the molten metal flows round the hole leaving the welded joint in the wake of the beam.

The EB welding have depth to width ratio of more than 10:1 due to the extremely high heat concentration. The beam is very narrow, less than 0.25 in. diameter and the welding speed is high. The net heat input is very low.

(V.M.Radhakrishnan, Welding Technology and Design, New Age International Pub., 2005, 2nd Edition, p.30-31 )

Liquid Thermal Polymerization (LTP) (07.4.2011; 12:49)

LTP process is quite similar stereolithograpy in a way that the part is built by solidification of successive layers of liquid polymer. However, polymers used in LTD process are thermosetting polymers instead of photopolymers and hence the solidification is induced by thermal energy rather than light energy. The thermal nature of the process is expected to make the control of the size of the voxels difficult due to dissipation of heat.

(Narendra B. Dahotre, Sandrip P. Harimkar, Laser Fabrication and Machining of Materials, Spr,nger Pub., 2008, p.356)

Beam Interference Solidification (BIS) (07.4.2011; 13:02)

This process is based on the point-by-point solidification of photosensitive polymers (contained in transparent vat) at the intersection of two laser beams having different wavelengths. The first laser excites the liquid polymer to the reversible metastable state which is subsequently polymerized by the radiations from the second laser. The process is associated with various technical limitations such as insufficient absorption of laser intensity at higher depths, shadowing effect of already solidified material, and diffraction of laser lights leading to difficulties in obtaining the precise intersection of the beam.

(Narendra B. Dahotre, Sandrip P. Harimkar, Laser Fabrication and Machining of Materials,Spr,nger Pub., 2008, p.356)

Selçuk TEVRÜZ, 030070128, 9th week

Chip Breakers (April 7, 2011 - 00:40)

Chip breakers are important element of tool design. Ductile materials such as low carbon steel, copper, aluminium, zinc, brass, etc. when, produce long continuous ships which are difficult to handle and dispose of as they occupy large volumes. The chip breaking and chip curl have assumed great importance.

Chip breakers are obstacles provided in the cutting tools which reduce the swarf into small pieces as they are formed. The metal plastically deformed during cutting resulting in work hardening. The chip breaker performs effectively with work hardened material. There are basically two types of chip breakers.

(i) Groove type

(ii) Obstruction type

(Singal R.K., Singal M., Singal R., Fundamentals of Machining and Machine Tools, 2008, pg.101)

Electrochemical Machining (ECM) (April 7, 2011 - 00:49)

Application of the electrochemical processes for machining has become one of the most prospective fields for manufacturing. These processes use the principle of metal removel by the electrochemical means and are an enhancement of the chemical machining process. In the electrochemical processes, an electrolytic cell is formed by using workpiece as anode and a cathode of suitable material having the shape of tool in the midst of an electrolyte solution. The well-known Faraday's laws of electrolysis govern the metal removal. The metal is removed in the form of sludge formed by the electrochemical and chemical reactions occuring in the electrolytic cell, which precipitates at the bottom. Hence, these processes are known as electrochemical machining processes.

(Parashar B.S.N., Mittal R.K., Elements of Manufacturing Processes, 2006, pg.335)

Electrochemical Grinding (ECG) (April 7, 2011 - 00:57)

The basic apparatus used in the aspect of ECG is shown in Fig. 4.18. The main feature is the use of a grinding wheel in which an insulating abrasive, such as diamond particles, is the set in a conducting bonding material. This wheel becomes the cathode-tool. The non-conducting particles act as a spacer between the wheel and workpiece, providing a constant inter-electro gap, through which electrolyte is flushed.

(McGeough J.A, Advanced Methods of Machining, 1988, pg.82)

Optical Encoder (April 7, 2011 - 07:50)

Very often, it is required to detect the position, velocity, acceleration and direction of movement of rotors, shafts, pistons, of the actuating devices such as rotary machines and translational systems. This is achieved by the use of optical encoders. The optical encoder is a device, which provides encoded pulsed signals in response to the movement. Continuous optical signals are modulated (coded) by the use of a specially designed rotating disk containing code patterns called 'track'. The pattern or track on the disk consists of alternate appearance of opaque and transparent segment and the pattern is circular. Basically, two types of encoders, such as incremental encoder and absolute encoder exist.

(Mahalik N.P., Mechatronics, 2nd reprint, 2006, pg.170)

Osman Süzen 030060804 9th week

Broaching Machine : A broaching machine typically consist of a workholding device, a drive mechanism, and a supporting frame. Shown is a vertical push down machine. The broaching tool is pushed through or across the workpiece, which is held stationary. Other types of broaching machines include pull broach, surface broach, and continuous broach. These broaching machines are either horizontal or vertical. Most machines are hydraulically powered, but some are driven electromechanically. ( Manufacturing process reference guide - Robert H. Todd, Dell K. Allen, Leon Alting - page 16 )

Overcut ( in EDM ) : Overcut in Edm is due to side sparks and is dependent on the gap length and crater dimensions. Lazerenko has shown experimentally that overcut O can be expressed by the relationship O= A(C) ^ (1/3 ) + B where A and B are constants, the values of which depend upon the tool work pair. Dependence of the overcut on the capacitance C is shown in Fig. 4-30 ( Modern machining process - P.C. Pandey, H.S. Shan - page 110 )

Laser Welding: The main advantages of laser welding are that it is a process having a very low hydrogen potential(which in other processes may cause hyrogen embrittlement), it gives less tendency to liquation cracking owing to the reduced time for segregation and it causes less distortion owing to the smaller pool size. Table 4.7 provides a summary of some of the laser welding characteristics for the main alloy systems. ( Laser material processing - William M. Steen, Jyotiromoy Mazumder - page 232 )

Submerged Arc Welding: Submerged arc welding (SAW) is a process that melts and joins metal by heating them with an arc established between a consumable wire electrode and the metals, with the arc being shielded by a molten slag and granular flux. In this process dffers from the arc welding processes discussed so far in that the arc is submerged and thus invisible. The flux is supplied from a hopper, which travelswith the torch. No shielding gas is needed because the molten metal is seperated from the air by the molten slag and granular flux. Direct -current electrode positive is most often used. However, at very high welding currents AC is preferred in order to minimize arc blow. Arc blow is caused by the electro magnetic force as a result of the interaction between the electric current itself and the magnetic field it induces. ( Welding metallurgy - Sindo Kou - page 23 )

Onur OZAYDIN___9th Week

1 . Abrasive Jet Machining (AJM)

2. Electrochemical Machining (ECM)

3. Electrochemical Grinding (ECG)

4. Peripheral Milling

5. Overcut (in EDM)

6. Broaching Machine

7. Broaches (Cutting Tools)

8. Chip Breakers (Tools)

9. Circular Sawing

10. High Speed Machining (HSM)

503101307 Onur OZAYDIN

Gökhan Güngör (8th week)

1- Dinking
2- Fullering
3- Heading
4- 2d laser processing systems
5- 3d laser processing systems
6- Cupola
7- Governor
8- Pickling
9- Seaming
10- Thermit

Burak Çınar 030060132 8th Week

Hook's Coupling (Universal Joint)

This joint is used to connect two non-parallel interesting shafts. It is also used for shafts with angular misalignment where flexible coupling does not serve the purpose. Thus, Hooke's joint is means of connecting two rotating shafts whose axes lie in one plane, their directions making a small angle with each other.

(The theory of machines and mechanisms, Emilio Bautista, p. 68)

Evrim Berk 030060161 8th Week

Rolling Through Time

In requirements planning environments, as a result of the limited visibility into the future, the manufacturers often plan their replenishment schedules on a rolling horizon basis. Using the currently available data, they determine their best replenishment quantities over a specified planning horizon and implement a subset of the earlier replenishment decisions. After rolling through time, the schedules are updated utilizing recently collected data.

Application of rolling schedules is common in industry; however, appropriate use of rolling schedules requires careful consideration as it poses many challenges for channel integration. First of all, one needs to be aware of the limitations of rolling schedules. Even if the best possible replenishment schedule is determined in each planning cycle, the long-term replenishment schedule may not necessarily represent the best possible schedule. This is usually the result of the length of each planning cycle. If each cycle is not long enough, it is not possible to determine the best replenishment schedule that would be found knowing demand beyond the end of the planning cycle.

(Supply Chain Coordination Through Schedule Integration, Sahin F., 2008, Page #1)

First Day Load

When resources have excessive loads the workload will be pushed backward until the load on the first day is greater than the available capacity. Such a condition is referred to as a first-day-load peak and reveals the presence of a constraint resource.

(Manufacturing planning and control for supply chain management, Vollman T.E., Page #558)

Dyad by Dyad Approach

A dyad by dyad approach means that pairs of organizations jointly develop the new processes and MPC systems that allow them to ever more effectively integrate their detailed operations. It is dyad by dyad because the joint working and definitions of improvement projects will tend to be unique to the dyad. This said, best practice will be able to learn as mush as possible from each dyad improvement effort, and then imbed the MPC thinking, processes, and systems int modular approaches to whatever extent possible. That is, one should work hardest with smart partners where new chain benefits are achived, but then try to leverage the learning in other dyads."

(Manufacturing Planning and Control For Supply Chain Management, T. E. Vollmann, page# 665)

Flexible Systems

Leading-edge firms are coming to understand requirements for volume and product flexibility. Some have had experience in repetitive manufacturing applications of JIT and are moving into nonrepetitive applications. An example is a telecommunications equipment manufacturer, which began JIT in its high volume telephone handset operations. The firm had a limited number of high-selling models; in two years its inventory turns were tripled, work in process was reduced by 75 percent, failure rates in manufacturing were cut in half, and setup times fell 50 percent. Thereafter, the firm turned to its low-volume telecom systems plant, where more than 150 basic circuit boards were manufactured, and every end item was somewhat of a custom order. The company learned it needed to go back to the basics of JIT - product engineering, process engineering, and the whole person concept - to successfully implement JIT for its nonrepetitive products.

The firm developed cellular designs, began cellular manufacturing with freat flexibility, and cross trained people with an emphasis on being able to handle volume surges in the telecom systems plant. MRP was still used for overall planning, but far fewer transactions were processed by the hidden factory of indirect labor. In the first six months, first pass yields improved 27 percent, work in process fell 31 percent, and manufacturing cells under JIT hit 100 percent of schedule. The people then helped out other parts of the company that were behinde schedule.

(Manufacturing Planning and Control For Supply Chain Management, T. E. Vollmann, pages321-322)

Osman Pehlivanoğlu 030040089 8th Week

Emulsifier
Two types of emulsifiers, hydrophilic and lipophilic are available. Hydrophilic emulsifiers are composed of materials similar to common detergents, which react with the oil based penetrant in a way that removes the penetrant from the surface. Diffusion plays a minor role in the action of the hydrophilic emulsifiers. Lipophilic emulsifiers, on the other hand, are oil soluble and they diffuse into penetrant, breaking down the structure so that the penetrant may be rinsed away with water. There are a number of methods used in the cleaning process such as wiping with a cloth, dipping in a tank, rinsing with a hıse, or some combination of these. (Practical non-destructive testing, 2nd Edition, Raj, p.11)
Bandwidth Concept
Depending on the area of networking, bandwidth can take on a couple of different meanings. The concept of bandwidth originated in wireless applications, such television broadcast, microwave, and radio. It was often used to convey a spectrum of frequencies, often expressed in units of hertz, available for use by a transmitter or receiver. This spectrum is often referred to as a channel. This concept was later extended to the voice and data networking worlds as well. In these worlds, bandwidth is often used to convey data speed. This is actually not exactly accurate. Because it indicates how much data, in bits or bytes, flows between two points in a given time, it is actually a transfer rate. (Mission-critical network planning, Liotine, p.53)
Order Point Methods
Once the components of statistical replenishment have been determined for each product, inventory planners have the option of selecting from four basic order point techniques. These methods can be divided into two types based on the point when items are reviewed for possible replenishment. Two of the techniques (order point and min/max) are dependent on a continuous rewiev cycle, whereas the remaining two (period order quantity and line point) are considered as periodic review ordering systems. (Distribution: planning and control, 2nd Edition, Ross, p.322)

Selim Tevfik İLKER, 030060028, 8th week

Deoxidizing: Deoxidizing is the process of removing metal oxides,particullarly on aluminium components. A caustic soda (%5) solution in water is quite effective in removing ozide on aluminium parts. The deoxidized parts are later immersed in a bath having 20 to 50 % nitric acid solution in water to clean up the surface completely.

(Manufacturing Processes Second Edition, J.P. Kaushish, pg. 891)

Fatih GÜNDÜZ 030060144 (8th week)

Lanxide process:

The lanxide process involves the formation of a ceramic matrix by the reaction between a molten metal and a gas, e.g., molten aluminium reacting with oxygen to form aluminia. Growth of the ceramic occurs outwards from the original metal surface and through a perform as shown in Figure 4.11. In fact a preform is not a prerequisite and particulate reinforced composites may also be produced by simply placing the particles above the liquid metal. In both cases the only requirtements are that the fibers/particles do not react with the gas and are wetted by the ceramic.

(Composite materials: engineering and science, F.L. Matthews, p.131)

FAS (Final Assembly Schedule):

This refers to a schedule of finished goods in a make-to-order or assemble-to-order environment, It is sometimes referred to as finishing achedule. The FAS is prepared to suit customer orders as costrained by the availability of material and capacity. FAS schedules the operations required to complete the product from subassemblies and components that are stocked to the end-item level. FAS may be stated in terms of customer orders or end product items.

(Encyclopedia of production and manufacturing management, P.M. Swamidass, p.205)

Evaluating Effectiveness:

The effectiveness of any training program should be evaluated periodically. During this evaluation, the progress made by individual toward skill development should be observed. Periodic reviews of the skills, training system, training process, and the curriculum are essential ingredients for continious improvement. For this purpose, a worker-skill inventory form can be used. This form provides the information regarding additional skills needed by each worker and also the total additional skills for all the workers with respect to maintaining a particular equipment. The data obtained before the onset of a training program may be compared with the data collected after completion of the program.

(Planning and control of maintenance systems: modeling and analysis, s. Duffuaa, A. Raouf, p.290 )

Chemical Synthesis:

Chemical synthesis is uniquelly positioned at the heart of chemistry, the central science, and its impact on our lives and society is all pervasive. For instance, many of todays medicines are synthetic and many of tomorrows will be conceived and produced by synthetic chemist. To the field of synthetic chemistry belongs an array of responsibilities which are crucial for the future of mankind, not only with regard to the health, material and economic needs of our society, but also for the attainment of understanding of matter, chemical change and life at the highest level of which the human minds is capable.

(Chemistry 1981-1990, B.G. Malmström, p.686)

Çağatay Kadir Aktaş, 030060176, 8th week

Fracture Mechanics: (13:24 5.4.2011)
Fracture mechanics is the study of mechanical behavior of cracked materials subjected to an applied load. In fact, Irwin developed the field of fracture mechanics using the early work of Inglis, Griggith and Wester gaard. Essentally, fracture mechanincs deals with the irreversible process of rupture due to nucleation and growth of cracks. The information of cracks may be a complex fracture process, which strongly depends on the microstructure of a partcular crystalline or amorphous solid, applied loading and enviorement. The microstructure plays a very important role in a fracture process due to dislocation motion, precipitates, inclusions,grain size and type of phases making up the microstructure. All these microstructural feature are imperfections and can act as fracture nuclei under unfavorable conditions.
(Nestor Perez, Fraction Mechanics, pg: 25)

Pressure Casting: (13:40 5.4.2011)
Molten metal is injected under pressure into a hardened steel die, usually watercooled. Metal cores are used to produce cavities and undercuts. AFter solidification, one half of the die is moved and the casting is pushed out by ejector pins. This process is suitable for non-ferrous castings of small to medium size, varying complexity and thin walls.
(B. Ravi, Metal Casting: Computer-Aided Design and Analysis, pg:8)

Squeeze Casting: (13:46 5.4.2011)
In these processes, solid metal is forced nder pressure in to a metal mould, giving a fine microstructure free from dendrites(tree like structures) otherwise obtained in conventional casting processes. The mechanical properties of the castings approach those of forging. These are useful for non-ferrous metals and composites and are applied for aerospace and automotive parts.
(B. Ravi, Metal Casting: Computer-Aided Design and Analysis, pg:8)

Ion Plating: (13:51 5.4.2011)
Ion plating is another surface treatment process that has recently attracted a great deal of attention. Ion plating also possesses many advantages as compared to conventional coating techniques. Therefore, although the present study has concentrated on ion implantation, it is appropriate to compare this proces with ion plating There are also striking diferences. Thusi each method is likely to find its own regime of application.

Ion plating is carried out in a gaseous electrical discharge in which the substrate to be plated is the cathode. The discharge is created by an applied ptential of 500 to 5000 volts. The prmary component of the gaseous enviroment is usually an inert gas, most often argon. Atoms of material to be plated are introduced into the gas by evaporation are ionized before striking the substrate. The small protion og evaporant are drawn to cathode by the electric field and scattering effects. Deposition rates can approach 25micrometer/min, but are acoomonly about a tenth of this amount.
(National Research Council (U.S.), Committee on Ion Implantation and Competing New Surface Treatmen Technologies Robert Wiliam Keyes, Ion Implatation as a New Surface Treatment Technolohy: Report, pg:19)

Armin Bijanzad 8.WEEK

1.Slip casting
2.Filament winding
3.Slurry infiltration
4.Chemical synthesiz
5.Melt infiltration
6.Fracture mechanics
7.Pressure casting
8.Squeeze casting
9.Lanxide process
10.Ion plating

Armin Bijanzad 7th week unanswered

Precursor station

To achieve longer production runs,precursor packages will get larger and once a 'one man lift' operation is exceeded, suitable lifting gear must be provided.Creels and improved box handling facilities designed to suit the larger packages, probably with the introduction of robotics for continuous splicing, hence reducing downtime, is required. The golden rule with precursor handling is to have the least number of contact points in order to minimize filament damage.
It is possible that in the future , precursor fiber will be produced on textile beams, but these would be heavy and difficult to manipulate and would necessitate the return of the empty beams to the precursor supplier.( Carbon fibers and their composites PETER MORGAN P.194)


Precursor creel

The batch numbers of all precursor spools used on the line should be recorded and a list made of any defects found.The correct degree of braking should be applied to all spools so that they rotate freely and give a uniform band of precursor entering the oxidation oven. ( Carbon fibers and their composites PETER MORGAN P.438)

Ozan Kovancı - 8th Week

1. Emulsifier
2. Rolling through time
3. Evaluating Effectiveness
4. FAS (Final Assembly Schedule)
5. Order Point methods
6. Flexible systems
7. FDL (First Day Load)
8. Dyad by dyad approach
9. Implosion
10. Bandwidth concept

think in industrial way guys :)

İbrahim İLGÜZ 030040113 (8th week)

Slip Casting (12:33 5.4.2011)
The slip casting method is commonly used in designs calling for bodies of intricate shape. In slip casting the material is placed into suspension to form a slurry or slip which is introduced into a mold of a liquid absorbing material. Common liquid and mold materials are water and plaster of paris. The slurry is allowed to remain in the mold until removal of liquid through the walls causes the desired amount of solids to be deposited on the mold form. The time of deposition is controlled so as to permit formation of either a thin wall or a solid piece remains in the mold will vary with its size and the absorbtion rate of the mold. This may vary from several minutes to days. When the piece becomes free of the mold it is removed for further drying prior to sintering.
(Vivian A. Johnson,Solid State Physics,pg:138)

Filament winding:(12:44 5.4.2011)
Filament winding is a relatively simple process in which a band of continuous reinforcements (fibres) or mono-filaments is wrapped around a rotating mandrel and cured to produce closed-form hollow parts. The winding operation is achieved by the use of specially designed machines. These machines, which can have up to 6 - axes (even 7-axes with robotic enhancements), allow the operator to control various parameters, includig the winding speed, winding angles, fibre placement, resin temperature and fibre tension. THe filaments (or reinforcement bands) are wrapped around the mandrel as adjacent bands of repeating patterns. These cover the mandrel surface to produce one complete layer. The winding is continued with successive layers, which can be in different winding angles until the number of layers required by the designer is reached. The winding angle may vary with respect to mandrel axis. Winding angles are very close to 90 degree are termed hoop winding, whereas winding using other angles is termed helical winding.
(Guneri Akovali, Handbook of Composite Fabrication, pg:103)

Slurry infiltration: (12:55 5.4.2011)
Continous-fiber composites are made b allowing fibers from a spool to pass through a glass powder slurry(containing water and a water-soluble acrylic binder), winding the slurry-impregnated fibers onto the sides of a hexagonal prism(mandrel or take-up drum), cutting up the flat unidirectional tapes from the mandrel, stacking up the pieces (plies) in the correct orientation, burning out the stack to remove the binder and hot pressing the stack at a temperature above the working temperature of the glass. This process is known as slurry infiltration.
(Deborah D. L. Chung, Compostie MAterails: Functional Materials for Modern Technologies, pg:47)

Melt Infiltration:(13:07 5.4.2011)
The melt infiltration method involves holding a porous body of the reinforcing phase in a mold and infiltrating it with the molten metallic material, which flows through the interstices to fill the pores, thus producing a composite material. This method can be divided into two categories:

-pressure-assisted infiltration
-pressure-less infiltrration

For pressure-assisted infiltration, either an inert gas or a mechanical device is used as the pressurizing medium. The composite produced using this method generally features a near pore-free matrix. There are also some drawbacks associated with this method:

-Reinforcement preform damage or breakage during infiltration
-Microstructural heterogenecity

In view of these disadvantages, other types of forces such as ultrasonic vibration, electromagnetic force and centrifugal force are used to more effectively force the molen metal into nonwetting reinforcement preforms.

In pressure-less infiltration, the liquid metal infiltrates a porous reinforcement preform without an external pressure or vacuum. This process is also known as spontaneous infiltration. In comparison with the pressure-assisted infiltration method, the composites formed exhibit a higher level of porosity.
(Manoj Gupta, Nai Mui Ling Sharon, Magnesium, Magnesium Alloys and Magnesium Composites, pg:20-21 )

A. Selim PARLAKYİĞİT - 7th Week Missed Term

Magnaplate:

Magnaplate coatings are a series of multistep, proprietary processes that become an integral part of the top layer of the base metal. Each coating series serves a particular purpose by protecting a specific metal or group of metals. Most coating series can be further adapted to solve specific problems.

The process begins with a through cleaning of the parts, followed by a deposition of an intermediate high-density film or by thermal spraying, depending on the coating. The process continues with a controlled infusion of selected polymers or other dry lubricating particles. These particles are then mechanically cross-linked and locked in by a proprietary process to become a permanent, integral part of the newly enhanced surface layer.

Magnaplate series of coatings: Tufram, Nedox, Plasmadize, Hi-T-Lube, Lectrofluor, Canadize, Magnaplate HMF, Magnaplate HCR, Magnadize, Magnagold, Magnaplate TCHC, Magnaplate SNS

(James Brown, Advanced Machining Technology Handbook, Page 427-431)

Utku Genç 8th Week 030060070

Disk Clutches

The clutch is a component that connects a driving and driven part in a mechanism. When the clutch is engaged, the power produced by the engine is transmitted through the clutch to the transmission. When the clutch is disengaged, the power flow stops at the flywheel. The clutch is generally made up of the clutch housing, the flywheel, the clutch disc (or discs), the pressure plate, the release assembly, and the controls. The clutch forces plate surfaces together under pressure. The disk clutch is a clutch which consists of a series of flat friction plates or discs (which enable power transmission) held together by a spring.

(Mike Byrnes, Bumper to bumper: the complete guide to tractor-trailer operations, p.92)

Cone Clutches

The clutch is a component that connects a driving and driven part in a mechanism. When the clutch is engaged, the power produced by the engine is transmitted through the clutch to the transmission. When the clutch is disengaged, the power flow stops at the flywheel. The clutch is generally made up of the clutch housing, the flywheel, the clutch disc (or discs), the pressure plate, the release assembly, and the controls. The clutch forces plate surfaces together under pressure. A cone clutch consists of inner and outer conical surfaces. The outer cone is keyed to the driving shaft, while the inner cone is free to slide axially on the driven shaft due to splines. The axial force required to engage the clutch is provided by means of helical compression spring. In engaged position, power is transmitted from the driving shaft to the outer cone by means of the key. Power is then transmitted from the outer cone to the inner cone by means of friction. Finally, power is transmitted from the inner cone to the driven shaft by means of splines. In order to disengage the clutch, a fork is inserted in the shifting collar to shift it axiallt towards right side. This releases pressure between inner and outer cones and no torque can be transmitted.

(V.B. Bhandiri, Design of Machine Elements, p.461)

Electrochemical Corrosion

Electrochemical Corrosion is understood to include all corrosion processes that can be influenced electrically. Corrosion in general is the chemical reaction between the metal and the surrounding environment. Electrochemical corrosion occurs in corrosive environments depending on the galvanic series. There are several types of electrochemical corrosion such as uniform corrosion, galvanic corrosion, hydrogen induced cracking etc. these can be present either one at a time or both in one case.

(Baeckmann, W, Handbook of cathodic corrosion protection, p.29)

Film Deposition

Thin-film deposition is about phase transition from the vapor phase to solid phase. Atoms condense on a substrate. These adsorbed atoms are subject to desorption and surface diffusion. Some adsorbed atoms bond to each other, reducing the desorption probability. More atoms aggregate and some of the bigger clusters avoid desorption.

(Franssila, S., Introduction to Microfabrication, p. 78)

Kayra Ermutlu-030060081 (8th Week)

Uni-Directional Roller Clutches

Roller Clutches are less noisy than toothed clutches. There is lesser engaging shock during engagement. Roller clutches can be operated at much higher speeds (up to 4 m/sec) than toothed cluthes (0.7 m/s). Their simple design and ease in manufacture make them convenient for use in uni-directional operation, despite a bigger size and rapid wear. The wear is minimized by using hardened inserts at the contact faces.

(Joshi P.H., Machine Tools Handbook: Design and Operation, pg.332, Kayra Ermutlu)

Mechanical Alloying

Mechanical alloying is a high energy dry ball milling process used to make composite metallic powders with a controlled fine microstructure. Powders of the desired composition are blended and then placed in a high energy ball mill. The intensive milling process repeatedly fractures and then rewelds the powder particles. During each collision with the grinding balls, the particles are plastically deformed to the extent that the surface oxides are broken, exposing clean metal surfaces.

On subsequent impacts, the clean surfaces are welded together. This cold welding process increases the size of the particles, while at the same time additional impacts are fracturing particles and reducing their size. As the process continues, the microstructure of the particles is continually being refined. Milling is continued until every powder particle contains the same composition as the starting mix.

(Campbell F.C., Manufacturing Technology for Aerospace Structural Materials, pg.232, Kayra Ermutlu)

Tape Forming

Tape formingis used to make thin ceramic parts like alumina substrates for integrated circuit chips and special capacitor. A thin layer of slip is laid on a flat carrier which can be a paper sheet or polymer film. A doctor blade controls the slip thickness, resulting in a tape that can be stamped into small shapes. These can be stacked or coiled for subsequent sintering.

(Ohring M., Engineering Materials Science, Part I, pg.420, Kayra Ermutlu)

Mechanical Overload

As the name implies, This type of fracture results when load applied exceeds the available strength of a component. This seems straight forward enough, but there are some subtleties. For example, "What is the available strength of a component?". Actually, it is a function of two things. It is derived from both the inherent strength of the material and how much of that material is available to carry the load. If the material strength is compromised (through alteration of its heat treatment, for example) then the strength of that component is not as intended. Similarly, if the amount of load bearing material is deminished (through corrosion or cracking) then the component is similarly weakened.

(Broker J.P., Hill P.F., Bicycle Accidents: Biomechanical, Engineering, and Legal Aspects, pg.242, Kayra Ermutlu)

Didem Tarkun(503101304) - 7th week - missing terms

Product and manufacturing information (PMI) Product and manufacturing information (PMI) is used in 3D CAD and/or collaborative product development systems to convey information about the design of a product’s components for manufacturing. More specifically, PMI conveys information such as geometric dimensioning and tolerancing (GD&T), 3D annotation (text), surface finish and material specifications. Product and manufacturing information Enhances and shortens the design cycle by enabling product teams to incorporate product and process information during the design phase, thereby facilitating beter communications, fewer errors, streamlined design/manufacturing processes and faster change management. PMI accelerates decision making by enabling product teams to remove drawings from the supplier communication chain and replacing that information with persistent, associated 3D product data that can be deployed across multiple lifecycle processes. (Product and Manufacturing Information (PMI) management,NX Siemens,2011)

Sezgin Koçak-030070026-8th Week

Stress Corrosion Cracking:

Stress corrosion is an interaction of sustained tension stress and corrosive attack causing cracking that can result in premature brittle failure of a ductile material. Before stress corrosion can occur, there must be the proper combination of a chemical environment and metallurgical condition of the material. Failures of this type have been identified with certain alloy systems of practically all menas, and in most instances the failures have been shown to be associated with electrochemical activity. In aluminum alloys, stress corrosion can be promoted by a film of moisture on the surface of metal exposed to the atmosphere or by contaminants such as chlorides. Only a prolonged surface tension stress will cause SCC, and sustained compression stresses actually prevent it. The tensile stress required to cause SCC are small, usually below the macroscopic yield stress. These stresses can be externally applied, but rsidual stresses often cause SCC failures. Susceptically to SCC limits the static strength of a material in certain applications just as fatigue cracking does in others. Both types of failure are caused by tension stress, but there the similarity ends. While fatigue failures occur under dynamic loads, stress-corrosion failures occur under dynamic loads, stress-corrosion failures are caused only by sustained static tension loads. An important difference with aluminum alloys is that stress-corrosion cracks are predominantly intergranular, most fatigue cracks are transgranular. It should be noted,however, that transgranular SCC has been observed for a few alloys under highly specific environmental conditions.

(Joseph R. Davis, Corrosion of aluminum and aluminum alloys, p.99)

Chemical Vapor Deposition:

Chemical vapor deposition (CVD) is a widely used materials- processing technology. The majority of its applications involve applying solid thin-film coating to surfaces, but it is also used to produce high-purity bulk materials and powders, as well as fabrikating composite materials via infiltration techniques. It has been used to deposit a very wide range of materials. The majority of the elements in the periodic table have been deposited by CVD techniques, some in the form of the pure elements, but more often combined to form compounds.

(Jong-Hee Park,T. S. Sudarshan, Chemical vapor deposition, p. 1)

Olcay Türkoğlu 8th week

1 Corrosion (as a mechanical failure mode)

2 Mechanical overload (as a mechanical failure mode)

3 H-bridge

4 Disk clutches

5 Cone clutches

6 Uni-directional roller clutches

7 Electro-magnetic clutches

8 Bayonet-type clamping

9 Hydro-dynamic bearings

10 Kudinov’s expression

Didem Tarkun - 8th week

1. Abrasive wear

2. Electrochemical corrosion

3. Addition polymerization

4. Film deposition

5. Mechanical alloying

6. Tape forming

7. Chemical vapor deposition

8. Cold rolling

9. Hot rolling

10.Stress corrosion cracking

Osman Selçuk Şahin 030060090 8th week

Non structural adhesives:are characterized by relatively low strenght and poor creep resistance at slightly elevated temperatures.The most common non structural adhesives are based on elastomers and thermoplastics.Altough these systems have low strenght they usually are easy to use and fast setting.Because of this characteristics most non structural adhesives are used in assembly line fastening operations where the ultimate joint strength is not required and enviromental service conditions are not severe.(Handbook of adhesives and sealants,p:392)

Structural adhesives:are distinguished from other adhesives by being high strenght materials that are designed to support loads, often substantial loads.These adhesives are also often subjected to cycling high and low temperatures and aggressive fluids or the weather.In general they are used for the bonding of rigid structures although some degree of flexibility and toughness is often desirable in adhesives to counter the effects of movement impact or vibration.(Engineering and structural adhesives,D.J.Dunn,p:3)

Reinforced Plastics:An important class of composites are reinforced plastics that consist of fibers are dispersed in a discontinious manner within a continious matrix of polymer.Reinforced plastics with more than one type of fiber are said to be hybrid.The commonly used fiber materials include glass,graphite,boron nylon,silicon nitride,silicon carbide etc.(Rapid prototyping : laser based and other technologies,Patri K. Venivinod,Weiyin Ma,p:52)

H-Bridge: The control of motors using PWM circuits typically performed by using the H-bridge configuration shown in Fig. 10.1. In this figure, the circuit has been implemented using four IGBT devices as the switches and four P-i-N rectifiers as the fly-back diodes. This is the commonly used topology for medium and high power motor drives where the DC bus voltage exceeds 200 V. When the H-bridge topology is used for applications that operate from a low DC bus voltage, it is typically implemented using four power MOSFET devices as the switches and four Schottky recfiers as the fly-back diodes. ( Fundamentals of power semiconductor devices - B. Jayant Baliga - page 1027 )