Friction spinning

Friction spurning is a variation of the open-end spinning system and often referred to as the DREF system. In this system, one or more slivers are fed onto a rapidly rotating card drum which opens the si iver to form single fibers. The separated single fibers are blown from the card dram by a stream of air onto the junction of two parallel perforated drams turning in the same direction. The rotating perforated drams under suction cause the fibers to be compressed and twist around aie another to form a uniform yam which is continuously removed onto a spool. The resultant yarns are bulky and have properties similar to woolen yarns. 

---

An example of welding is frictional spinning that can be applied to two plastic prod-... 

Fehrer E. Engineered yams with DREF friction spinning technology. Can Textil J 1987 104(8) 14-5. 

To improve the mechanical properties of activated carbon fiber, a dual viscose and PAN based carbon filament has been developed [14], with the core made of PAN based fiber and an external layer of viscose based fiber, which can readily be activated with CO2. The central core comprises of about 50 discontinuous PAN filaments held together by a continuous filament of PVOH and concentrically wrapped by discontinuous viscose filaments using a friction spinning process. The dual filament is carbonized in an inert atmosphere at 900°C and activated by CO2 at 900°C. Another way of achieving a coating of cellulose would be to apply a solution of cellulose in a mix of water and 4-methylmorpholine-A-oxide. 

In spin or vibrational welding, heating is achieved by rubbing the two surfaces together at a sufficiently high speed to melt the polymer by friction. Spin welding is suitable for circular objects, whereas vibrational welding can be achieved by either circular or linear motion. Total cycle times are of the order... 

The introduction of nonconventional spinning technologies in the 1970s, such as open-end rotor and friction spinning and air-jet spinning in recent years, led to a 10- to 15-fold increase in yarn production speed over the last four decades. 

Figure Bl.19.30. Height and friction images of a spin-cast polystyrene-poly(methyl methacrylate) blend obtained with (a) gold and (b) silica probes under perfluorodecalin. Note the reversal of frictional contrast and the high spatial resolution. (Taken from [142], figure 7.)...

Spin Welding. Spin welding is an efficient technique for joining circular surfaces of similar materials. The matching surfaces are rotated at high speed relative to each other and then brought into contact. Frictional heat melts the interface and, when motion is stopped, the weld is allowed to soHdify under pressure. 

Game-Related Properties. Eot some activities, such as miming and wrestdng, the only consideration is the direct impact by the player. Eot others, eg, tennis, baseball, or soccer, the system must also provide acceptable bad-to-surface contact properties. Important bad-response properties on the artificial surface ate coefficients of restitution and friction, because these direedy determine the angle, speed, and spin of the bad. 

First, for Figure 14-22, enter at the top at rpm and move to the first estimating turbine wheel diameter then read down to the TSR (calculated or from tables) at Ib/kw-hr read across to base steam rate in Ib/hp-hr. Note that the base steam rate is per hp-hr, and the TSR is per kwh (or kw-hr). Now correct the base steam rate for the horsepower loss (i.e., the portion of blades of turbine spinning outside the nozzle arc, creating friction and windage). From Figure 14-23, at the top read rpm at the exhaust pressure on curved lines noted cond, read down to the estimated wheel diameter, and read the horsepower loss on the left vertical axis. 

The spinning operation consists of highspeed rotating and suitably shaped tool that creates frictional heat that will permit the stud to conform to the configuration in the tool. Pressure exerted on the tool and... 

TPEs can be bonded to other materials by adhesive, heat bonding, electromagnetic filling, radio frequency, heat-sealing lamination, friction and spin welding, and ultrasonic welding. For TPUs, the most widely used techniques are radio frequencies, and ultrasonic and hot stamping. A few typical applications include football bladders, valves, and conveyer belts. 

Under the influence of a gravitational (centrifugal) field, a solute particle of mass m — M/Ni immersed in a solvent of density p at a distance r from the rotor axis experiences three forces. Within the frame of reference of the rotor, spinning with angular velocity co, these are the centrifugal force Fc, the buoyant force Fb, and the frictional force Ff. 

Van Ekeren, P.J., Jacobs, M.H.G., Offringa, J.C.A., De Kruif, C.G. (1983) Vapour-pressure measurements on rnms-diphenylethenc and naphthalene using a spinning-rotor friction gauge. J. Chem. Thermodyn. 15, 409—417. 

---