Deniz Alsan 030080093 7th week

1 - Stiffness (design)

previous description

Stiffness is a measure of a systems's resistance to deformation. A rubber band is easily deformed by hand but a steel wire or rod of the same cross-sectional area is not. The stiffness of steel is greater than that of rubber.
(Frederick A. Leckie,Dominic J. Dal Bello, The strength and the stiffness of The Engineering Systems, P.48)

new description (better)

Stiffness is a measure of how strongly an object resists being deformed. If is normally measured as the deforming force (in newtons) divided by the deformation it causes (in milimeters) so a convenient unit of stiffness is the newton/milimeter (N/mm).

(Michael A. Adams,Kim Burton,Nikolai Bogduk,Patricia Dolan, The Biomechanics of Back Pain, p7)

2 - Guillotine shear (manufacture)

previous description

Guillotine shears are used to cut sheet materials such as metal, plastic, paper, card and composite material and may be treadle operated or power driven. Before using any machine, the operator should be fully conversant with the controls, ensure that all the guards are in position and know the the emergency stop procedure. On some power driven machines a photo-electric cell is positioned in front of the blade to prevent operation if any object breaks the beam. For efficient use, the blades should be kept sharp and the clearence between the blades should be adjusted to suit the type and thickness of the material being cut.
(Basic Manufacturing, Roger Timings, P.157)

new description (better)

A type of carrier-mounted, single-action, anvil shear used in mechanized cutting, where the blade is pushed through a stem and away from the carrier, instead of being pulled, as in the draw shear.
(Julian Andrew Dunster,Katherine Dunster,Katherine Jane Dunster, Dictionary of natural resource management, p155)

3 - Carousel Storage Systems ( storage , manufacture )

previous description (better)

A carousel storage system is a series of bins or baskets fastened to carries that are connected together and revolve around a long, oval track system. The track system is similar to a trolley conveyor system. Its purpose is to position bins at a load/unload station at the end of the oval. The operation is similar to the powered overhead rack system used by dry cleaners to deliver finished garments to the front of the store. The typical operation of the storage carousel is mechanized rather than automated. The load/unload station is manned by a human worker who activates the powered carousel to deliver a desired bin to the station. One or more parts are removed from the bin, and the cycle is repeated. Carousel come in a variety of sizes, ranging between 10 and 100 ft in length of the oval. As the length of the carousel is increased, the storage density increases, but hte avarage transaction time (Storage or retrieval) decreases. Accordingly, the typical carousel size ranges perhaps between 30 and 50 ft to achieve a proper balance between these opposing factors.
(S. A. Kumar, Production And Operations Management, p. 186)

new description

Carousel-type storage systems are very suitable for storing small parts and hence are very common among electronic and light assembly industries. Carousels may be floor mounted or may be hung from overhead rails. Rotation of the carousel may be controlled by using a hand lever, a foot pedal or a keyboard. A carousel consists of carries that are spaced apart by a certain distance. Each carrier will have a certain number of bins. The location of a part in the storage system is identified by the carrier and bin number. Retrieval of the part to the load or unload point is done simply by entering the part number in the computer. The computer looks for its location and rotates the carousel to bring thecarrier or bin to the load or unload point.
(Raja G. Kasilingam, Logistics and Transportation, p148)

4 - Pulse Generator ( manufacture )

previous description (better)

A pulse generator is a device that produces a series of electrical pulses whose total number and frequency are specified by the control computer.The total number of pulses might be used to drive the axis of a positioning system.The frequency of the pulse train , or pulse rate, could be used to control the rotational speed of a stepper motor.A pulse generator operates by repeatedly closing and opening an electrical contact ,thus producing a sequence of discrete electrical pulses.The amplitude (voltage level) and frequency are designed to be compatible with the device being controlled.
(Automation, production systems, and computer integrated manufacturing,3rd edition, Mikell P. Groover,p.135)

new description

The pulse generator is a versatile instrument with multiple uses in high-speed work. As one specific example, the bandwidth of a scope-probe combination can be rapidly evaluated with such a generator by observing the displayed rise and fall times. Aberrations introduced by defective or improperly calibrated instruments and cables are also readily observed. Given that the typical alternative is to measure frequency response by sweeping a sine-wave generator over a gighertz range, the pulse generator is clearly an extremely inexpensive option.
(Thomas H. Lee, Planar Microwave Engineering, p273)

5 - Kudinov's Expression ( manufacture )

previous description

It is a well-known fact that, in general, the cutting force consists of forces acting on the tool face and on the tool flank. Kudinov derives his dynamic cutting force expressions for two cases:
1- The cutting force is determined only by forces acting on the tool face; this occurs, for instance, during machining of nonhardened steels with a sharp cutting tool
2- The cutting force is determmined by forces acting on the tool face as well as the tool flank.This obviously is a more general case which one may often come across while machining with a worn tool.
(Mehta, Machine Tool Design and Numerical Control, p.30)
new description (better)

Figure 6.9 shows the polar curves for combined (tool face and flank) force, for 3 different values of flank wear. At zero frequency (w), the polar curves intercept the real axis Re at x=Ks, the static characteristic. It has been observed that the flank wear land dampens the vibrations. Also, as the flank wear increases, there is a reduction in the frequency range, in which the dynamic cutting force lags behind the displacement. For flank wear land of 1 mm, frequency w=1,000. For all vibrations with frequency w>150Hz, the cutting process provides a damping effect. There are more vibrations during the idle run of the machine than during actual metal cutting.(P H Joshi, Machine Tools Handbook: Design and Operation, pp512,513)