In the field of magnetic data storage devices, especially hard disk drives, thin-film magnetic heads have played an important role in the increase of the magnetic recording density. The thin-film magnetic head has the advantage of its possibility to precisely fabricate narrower head gaps and tracks, which enables higher and higher areal recording density. In this field, an electrochemical method is one of the important technologies for fabricating thin-film inductive heads using magnetic alloy such as an electrodeposited permalloy. In 1990, IBM Corporation first announced shipment of a merged MR (magnetoresistive) head for higher recording density. The increase of the areal density has since accelerated faster and has become 100 times per decade. In a merged MR head, the reading and writing elements are separated from each other. The writing clement is still usthg almost the same configuration as a thin-film inductive head. The reading element consists of the multi-thin films prepared by sputtering, which exhibits a change in resistance in the presence of a magnetic field. GMR (giant magnetoresistive) head technology has allowed areal densities to increase at a rate of over 100% per year.
(Krongelb S. Magnetic Materials Process, and Devices VI: Applications to storage and Microelectromechanical Systems, page:167)
There is no previous definition.
Mixed friction (Friction type is seen generally on bearing)
Whenever lubricated surfaces slide together at low sliding speeds or with a high applied normal load, the lubricant may not separate the two solid surfaces completely. However, the lubricant can still significantly reduce the friction coefficient by reducing the shear strength of adhesive junctions between the two surfaces. In this so-called boundary lubrication regime, the effectiveness of the lubricant can be improved if the lubricant molecules adhere well to the solid surfaces. This is best accomplished by introducing a lubricant or additive that forms a surface film through adsorption, chemisorption, or chemical reaction with the surface. The ensuing reduced shear strength of the surface film can lower the friction coefficient by as much as an order of magnitude from the dry friction value.
When a good supply of a viscous lubricant is available, the separation between the surfaces will increase as the sliding speed increases or the normal load decreases. As the separation increases, the amount of solid/solid contact between the surfaces will decrease, as will the friction coefficient and wear rate. In this Òmixed frictionÓ regime, friction is determined by the amount of plowing deformation on the softer surface by the harder surface asperities and by adhesion within the solid/solid contacts. When the surfaces become completely separated by a self-acting or externally pressurized lubricant film, the lubricating regime is hydrodynamic, wear is reduced to nearly zero, and friction reaches a low value governed by viscous shear of the lubricant. Friction coefficients in such cases can be 0.001 or lower, depending on the surface velocities and the lubricant viscosity. This is the case for most journal or thrust bearings (see subsection on fuid film bearings).
(Mechanical Engineering Handbook, Ed. Frank Kreith, p3-133)
Mixed friction (new and better)
This occurs when boundary friction combines with fluid friction. From a lubricants technology standpoint, this form of friction requires sufficient loud bearing boundary layers to form. Machine elements which are normally hydrodynamically lubricated experience mixed friction when starting and stopping.
For roller bearings, one of the most important machine elements, it has been shown that the reference viscosity either of lubricating oils or of the base oils of greases is not sufficient to ensure the formation of protecting lubricant layers and the required minimum lifetime. Under mixed friction conditions it is important to choose the appropriate lubricant, i.e. that which enables the formation of tribolayers by anti-wear and extreme pressure additives.9
In 2004, Schwarze and Wiersch described a means of calculating mixed lubrica-tion contacts over a wide range of operating conditions and applications. The performance of the mixed friction model was demonstrated using the example of a cam tappet contact [2.8,2.9]
Figure:2.8
Figure:2.9
(Editor: Mang T. Dresel W. ,Lubricants and Lubrication. page:13)
Deformation processes (Manufacturing Technique)
In deformation processes, the workpiece material is plastically deformed and takes on the geometric shape of the die. Deformation of the workpiece occurs at a temperature below its melting point, and the workpiece is never in a molten state. The basic process energy that causes the workpiece deformation is mecanical, and the deformation is caused by mechanical forces developed between the workpiece and the die. The desire shaped is created through relative motions between the dieand workpiece material. No material is removed. The ability of the workpiece material to deform plastically without fracture is an important process parameter. The flow or deformation of the material depends on the material properties, the state of stress in the material, the temperature, and the strain rate of the workpiece material ( velocity of deformation) during the process.
( Fundamental principles of manufacturing processes - Robert H. Todd, Dell K. Allen, Leo Alting - page 79 )
Deformation processes (new)
In deformation process, the starting workpart is shaped by the application of forces that exceed the yield streght of the material. For the material to be formed in tis way. it must be sufficient ductile to avoid fracture during deformation. To increase ductility (and for other reason), the work material is often heated prior to forming to a tempereature below the melting point. Deformation process are associated most closely with metalworking and include operations such as forging and extrsion shown in figure.
(Groover M. P., Fundamentals of Modern Manufacturing, Ed. 3rd, p. 14)
Honestly said that both of them is the same because there is no detail about definition. Because definition is a general name of manufacturing technique.In additionally I support the definition with example to easy understand.
Property-enhancing operations ( General Process Name)
Property-enhancing operations are designed to improve mechanical or physical properties of the work material. The most important property-enhancing operations involve heat treatments, which include various temperature-induced strengthening and/or toughening processes for metals and glasses. Sintering of powdered metals and ceramics is also a heat treatment, which strengthens a pressed powder workpart. Property-enhancing operations do not alter part shape, except unintentionally in some cases, for example, warping of a metal part during heat treatment or shrinkage of a ceramic part during sintering.
(Groover M. P., Automation, production systems, and computer-integrated manufacturing, Ed. 3rd, p. 32)
Property-enhancing operations (new)
Property-Enhancing operations The second major type of part processing is performed to improve mechanical or physical properties of the work material. These processes do not alter the shape of the part, except unintentionally in some cases. The most important property -enhancing processes involve heat treatments, which include various annealing and strengthening processes for metals and glasses. Sintering of powdered metals and ceramics, mentioned above, is also a heat treatment that strengthens a pressed powder metal workpart.
(Groover M. P., Fundamentals of Modern Manufacturing, Ed. 3rd, p. 14)
Definition is same as done in upper. Addinitionally Had to be carefull to recognise quatation.
The books are not same onlu writer is same..Honestly said that both of them is the same because there is no detail about definition. Because definition is a general name of manufacturing technique
Doctor-Blade Process
Doctor-Blade Process (Tape casting) is used to make flat ceramic sheets having a thickness up to about 1 mm. The process was developed during the 1940s for capacitor dielectrics. The production of ceramic capacitors is still one of the most important applications of tape casting.
In tape casting, a slurry (also called a slip) containing a powdered ceramic together with a complex mixture of solvents and binders is spread onto a moving polymer (such as MylarTM) sheet as shown in Figure 27.1. In the early form of tape casting the slurry was actually spread onto moving plaster-of-Paris plates. The use of a polymer sheet was patented in 1961 and since then the process has not significantly changed. The principle of the process is essentially identical to spreading plaster on a wall, icing on a cake, or painting.
(C.C. Barry, M.G. Norton, Ceramic materials : Science and Engineering, pg. 480-481)
Doctor-Blade Process
Doctor-blade Process This process is used for making thin sheets of ceramic. One common application of the sheets is in the electronics industry as a substrate material for integrated circuit& The process is diagrammed in Figure . A ceramic slurry is introduced onto a moving carrier film suclias cellophane Thickness of the ceramic on the carrier is determined by a wiper, called a doctor-blade. As the slurry moves down the line, it is dried into a flexible green ceramic tape At the end of the line a take-up spool reels in the tape for later processing lasts green condidon, the tape can be cut or otherwise shaped before firing.
figure:
(Groover M. P., Fundamentals of Modern Manufacturing, Ed. 3rd, p. 372)
(My definition is better one. Because explain totally and support the definition with examples.)
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