060070103-Rifat Yılmaz-11 th Week Bonus Definitions-Part 2

Fineblanking (PREVİOUS) -Group: Sheet metal forming process


Fineblanking a high tech forming process that more closely resembles cold extrusion than stamping gives manufacturers new options for improved part quality,greater detail and the elimination of many secondary operations.It can form accurate parts that require only a minor secondary operation such as deburring in one press stoke.This eliminates most conventional operations such as casting,drilling,milling,broaching thereby reducing production time. Fineblanking produces high quality parts faster and can reduce production cost.


(Exploring advanced manufacturing technologies,Stephen F. Krar,Arthur Gill)

Fineblanking (New)(Better) 

Fineblanking is a method for producing smooth edges and other improved features on stamped metal parts. It involves both blanking and forming. The method requires closer control and several features in presses and tooling compared to those in conventional stamping. These features include a more precisely controlled press stroke, a closer fit between punches and dies, the use of a shaped pressure plate with a v-shaped impingement ring surrounding the die to hold the work material and provide compressive stress in the part, a floating ejector pin to provide pressure on the material and against the punch force, and somewhat slower press speeds. Another difference is that the closefitting punch does not enter the die. A typical fineblanking operation is shown in Fig. 2C9- 1. The operation requires a press with the following characteristics: separate actions for the punch, v-ring pressure, and counterpressure; capability for a fast approach stroke, a slow shearing speed, and a fast ram retraction rate; control of the shut-height setting within 0.0004 in (0.01 mm) to insure that the punch stops at precisely the correct point; and sufficiently accurate guideways that the punch-die clearance can be maintained within half percent 2% of the stock thickness. Fig. 2C9-2 illustrates the difference between the edges of conventionally blanked and fineblanked parts. Fineblanking is utilized in the manufacture of precision parts that otherwise may require machining or other secondary operations after blanking, and for making parts that may not be feasible by conventional stamping methods. Stacked gears, cams, sewing machine and business machine parts are examples. The method is not limited to blanking: forming, piercing, coining, embossing, etc. may also be performed on the workpiece with a separate operation or with compound and progressive dies, when required.

(James G. Bralla, Handbook of Manufacturing Process, pages  46-47-48)

Abrasive Waterjet Cutting (AWC)-GROUP: Cutting Method


There is no previous definition.

Abrasive Water Jet Machining is a process that uses a very high speed (supersonic about 2.5 Mach number) water jet mixed with abrasives to cut any type of material without in any way affecting the work material or the environment. If the process is used without any abrasives, it is called as water jet machining. The inlet water is typically pressurized between 1300 to 4000 bar which is forced through a liny hole in the jewel, which has a typical 0.18-0.4-mm diameter, creating a very high velocity beam of water. The process is generally used for cutting operation, but can also be used for selective removal of the material.

Water jet cutting started in late 1960's for cutting space age alloys as the conventional processes were adding the thermal stresses due to the heat produced. High pressure water jets that were used for cleaning in the mining industry were used to cut composites and other space age materials. The commercial machines were available since 1971. In the early I98()*s, abrasives were introduced into the water jet and thereby the A WJM process was born. Originally garnet abrasive was introduced into the jet stream to cut harder materials such as steel, glass and concrete.

The AWJM machines aim a highly focused, supersonic stream of water at the material such that it can cut composites smoothly by eroding them without generating any heat. Thus the AWJM process eliminates all the thermal and mechanical distortion caused by conventional cutting methods. Also, the water jet nozzle can be directed in any angle to the material thereby allowing for angled cuts. For cutting soft materials such as textiles and food stuffs, pure water without any abrasives is used.

Equipment

A typical AWC system consists of the following major sub-systems:
-An intensifier pump to provide high-pressure water.
-The abrasive delivery system and a cutting head for producing the abrasive water jet.
-Computer-controlled manipulator to provide the desired motion of the cutting head.
-A catcher that dissipates the remaining jet energy after cutting.
Typical system is shown in Fig. 11.38.

( Rao, Manufacturing Technology Vol-Ii 2E, 2. Cilt, pages 334,335)

Transmission Electron Microscope (TEM) - GROUP: Micro structure characterization device/technique

There is no old definition.

Transmission electron microscopy (TEM) is a technique whereby a beam of electrons is transmitted through an ultra-thin specimen (0.1-1 µm). This beam interacts with the specimen as it passes through. An image is formed from the interaction of the electrons through the specimen; the image is magnified and focused onto an imaging device, such as a fluorescent screen, or is detected by a sensor such as a CCD camera.

The principle of a modern TEM is schematically shown in Fig. 1.14. From the top down, the TEM apparatus consists of an emission source (gun), which may be a tungsten filament or a LaB6 source. By connecting this gun to a high voltage source (typically ~ 100-300 kV) the source will begin to emit electrons either by thermionic or field electron emission. The upper lenses of the TEM allow for the formation of the electron beam to the desired size and location for later interaction with the specimen. The example of an image showing dislocations is given in Figure 1.15.

(Dominique François, André Pineau, André Zaoui,Mechanical Behaviour of Materials, there is no page number)