Mehmet Can ÇAPAR 7th week definitions

1-Wiper Bending (Manufacturing method)

(old answer)

Bending is the operation of deforming a flat

sheet around a straight axis where the neutral plane lies. it is a very common forming process for changing sheet and plate in to channel, drums, tanks, etc. Wiper bending is used for 90 degree bends only. Here the work is held firmly to the die, and the punch bends the extended portion of the blank. ( Manufacturing Processes - R.K. Rajput - page 178 )

(new answer) (better)

Roll bending is achieved by moving the workpiece through the gap created by 
moving adjustable rolls. In roll forming the sheet is formed into a section between
rolls with the form of the section. Folding is bending with aa folding wing that folds
the workpiece around the bending edge, whereas wiper bending or wiping bending creating
a full plastic section between a roller and a tool. The section is forced to conform to
roller as the tool is dragged around the roller. In roll straightening the roll axes can
be normal or inclined to the bending plane. The workpiece is roll bent by corrugated
rolls in the corrugating process.

(Karl-Heinrich Grote,Erik K. Antonsson, Springer Handbook of Mechanical Engineering, Volume:10, pg:591)

2-Planer (machining) (Manufacturing equipment)


(old answer)
Planer and shaper are popular single point precision machining methods. A shaper operates by moving a cutting tool backwards and forwards across the workpiece. The workpiece mounts on a rigid square table that can traverse sideways underneath the reciprocating tool, which is mounted on a ram. The table motion is controlled by a precise feed mechanism. The ram slides back and forth about the workpiece and the tool can be positioned to cut the flat surface on the top of the workpiece. A Planer is a type of machining tool analogous to a shaper, but larger and with the entire workpiece moving beneath the cutter instead of the cutter moving above a stationary workpiece. Planers and shapers are generally used for two types of work: generating large accurate flat surfaces and cutting straight microgrooves. Modern planers are used for producing precision stamping dies and plastic injection molds for light-guiding plates of liquid crystal displays, large scale linear fresnel lenses.


( J. Paulo Davim, Mark J. Jackson, Nano and micromachining, page 178)

(new answer) (better)
 Planers are usd to machine plane surfaces that may be horizontal, vertical, or at an angle. Profilled
surface can be planed to a layout line or to a template if the planer is equipped with tracing attachment.
Also, a planer having a tracing attachment can duplicate certain three-dimensional contours from a master. However, most of the work done on a planer involves the machining of plane surface on workpieces that range are relatively inexpensive in terms of their initial cost and are easy to resharpen
   Altough some of the work formerly done on planers is now done on  planer-type milling machines using large-face milling cutters, there are still many jobs that can be carried out better and more economically on the planner. For example, angular surface are often easier to machine on a planer. Planing is also the most effective method of machining some parts because of their shape and for machining long and narrow surfaces. Flat-bearing and reference surface that are to be hand-scraped after machining are preferably machined by planing. Here the reason for the desirability of planers is that surfaces produced by a face milling cutter tend to be glazed or work hardened because of the pressure of the face milling cutter on the work. This glazed or work-hardened surface is difficult to hand scrape. Planed surfaces, on the other hand, are easily scraped since work-hardening is kept to a minimum on the surfaces produced by a single-point cutting tool. Because many plane surfaces on machine tools require hand scraping, planers find wide application in machine tool plants.

(Karl Hans Moltrecht, Machine Shop Practice, 2. cilt, pg:40)

3-Porosity Sealing (Kind of Sealing)

(old answer)
Most castings and powdered metal parts have porosity, inherent in the powder metal compacting and sintering process and caused by volatilization of organic impurities in castings. With castings such as iron or aluminum, this porosity allows fluid leakage and with powdered metal parts, can cause severe plating problems. Pores can be quite large, designated as macroporosity, or very small, called microporosity. Sealing of the pores is a routine necessity and is carried out by impregnation with a liquid sealant followed by a curing step. The modern way of sealing this porosity is to use anaerobic impregnants. They are low viscosity impregnants and have revolutionized porosity sealing because of their ability to penetrate microporosity and cure very quickly at room temperature.

(Manufacturing Engineering Handbook, H. Geng, p. 50.10 - 50.11)

(new answer) (better)

Most casting and powdered metal parts have porosity, inherent in the powder metal compacting
and sintering process and caused by volatilisation of organic impurities in castings. With castings
such as iron or aluminium, this porosity allows fluid leakage and with powdered metal parts, can
cause severe plating problems. Pores can be quite large, designated as macroporosity, or very
small, called microporosity.
   Sealing of the pores is a routine necessity and is carried out by impregnation with a liquid sealant
followed by a curing step.
   The sealants that have been used are:
-Sodium silicates
-Unsaturated polyesters
-Acrylics
    Water solutions of sodium silicate are the oldest types of impregnants and have the benefits of low
cost and very high temperature resistance (over 300 degrees of Celcius). They suffer from long curing times
and high shrinkage and are best suited for sealing macroporosity.
    Unsaturated polyesters are polyesters diluted with styrene monomer and are fairly low cost
impregnants of high viscosity, which must be cured at high teperatures for long times. Their high
viscosities again makes them most suitable for sealing large pores.
    The newest types of impregnants are based on acrylics, usually methacrylate monomers. They are
low viscosity, high cost impregnants and have revolutionised porosity sealing because of their
ability to pnetrate microporosity and cure very quickly. The earliest versions were pioneered by
Loctite Corporatin (USA and Europe) in the 1970s and were based on anaerobic resins. Processing typically involved placing parts in a basket, immersing in the resin and removing air from the system and pores by pulling a vacuum. On release of the vacuum, the impregnant flowed into the pores. The next step in the operation was to raise the basket and spin the basket of parts (called "centrifuging") to remove excess resin and re-use this resin. Because anaerobic resins are very expensive compared to sodium silicates and polyesters, this was a step that was critical to the economic viability of the process. Following the centrifuging parts were rinsed in a chlorinated solvent bath and then placed in an activator bath, again based on chrolinated solvents. This process was carried out entirely at room temperature avoiding the heating of parts which can lead to bleed out of resin from the pores. Developments in the 1980s led to the use aqueous detergent washing and activating solutions. Several process variations are possible with all types of impregnants, sometimes involving dry vacuum, wet vacuum and pressure cycles to seal very dificult parts.

 (David J. Dunn, Adhesives And Sealants: Technology, Applications And Markets, pg:135)

4-Piezoelectric Transducer (A system element)

(old answer)
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^ndEdition”, page 770)

(new answer) (better)

Piezoelectric transducers are key elements of many broadband ultrasonic systems, either pulse-echo or through-transmission, used for imaging and detection purposes. In ultrasonic broadband applications such as medical imaging, or non-destructive testing, piezoelectric transducers should generate/receive ultrasonic signals with good efficiency over a large frequency range. This implies the use of piezoelectric transducers with high sensitivity, broad bandwidth and short-duration impulse responses. High sensitivity provides large signal amplitudes which determine a good dynamic range for the system and the short duration of the received ultrasonic signal provides a good axial resolution.

The most important and common type of piezoelectric transducer elements used in ultrasonic broadband applications is a thin piezoelectric plate, with lateral dimensions much greater than the thickness, driven in a simple thickness extensional mode of vibration [I-21. They usually operate in the frequency range 0.5-15 MHz. Different types of piezoelectric materials are used for the active transducer element. Ferroelectric ceramics, like lead zirconate titanate (PZT), lead metaniobate, etc., have a high piezoelectric coupling coefficient. Piezoelectric polymers like polyvinylidene di-fluoride (PVDF) and copolymers have useful low-acoustic impedances, Piezoelectric composites are mixtures of piezoceramics with nonpiezoelectric polymers.

(Antonio Arnau, Piezoelectric Transducers and Applications, pg:97)

5-Vertical Lift Storage Modules (VLSM) (Storage system)

(old answer) (same but from different source)

These are also called vertical lift automated storage/retrieval system (VL-AS/RS). All of the preceding AS/RS types are designed around a horizontal aisle. The same principle of using a center aisle to access loads is used except that the aisle is vertical. Vertical lift storage modules, some with heights of 10 m (30 ft) or more, are capable of holding large inventories while saving valuable floor space in te factory.

(Groover, M.P. , Automation, Production Systems, and Computer-Integrated Manufacturing, 3^rd Edition, pg. 324)

(new answer) (same but from different source)

Vertical lift storage modules (VLSM). These are also called vertical lift automated storage/retrieval system (VL-AS/RS). All of the preceding AS/RS types are designed around a horizontal aisle. The same principle of using a center aisle to access loads is used except that the aisle is vertical. Vertical lift modules, some with height of 10 m (30 feet) or more, are capable of holding large inventories while saving valuable floor space in the factory.

Riccardo Manzini, Warehousing in the Global Supply Chain: Advanced Models, Tools and ..., pg:164)