Wire speed

Note that the flow rate increases with the pressure drop and decreases with increasing wire speed at constant die geometry. 

Note that the thickness of the coating layer is proportional to the pressure drop and inversely proportional to wire speed. 

The bare wire is unwound, sometimes by a controlled tension device, and is preheated to a temperature above the Tg or Tm of the polymer to be extruded this is done so that the layer next to the bare wire adheres to it, and to drive moisture or oils off the conductor surface. The wire is fed in the back of the cross-heat die and into a guider tube. Upon exiting the guider, it meets the molten plastic, which covers it circumferentially. Since the wire speed, which is controlled by a capstan at the end of the line, is usually higher than the average melt velocity, a certain amount of drawdown is imposed on the melt anywhere from a value slightly greater than unity to 4. 

Figure 3. Effect of wire speed on relative response (Pye Unicam detector). Sample, vacuum gas oil solvent, n-heptane (1 mL/min) concentration, neat sample volume, 10 fiL column, l ft fi-Porasil mode, backflush operation for...

Evaporator temp., 200 C, oxidizer temp., 800°C, and wire speed X6. Area response per mg of sample shown in parenthesis. 

Table rolls contribute a gentle suction in the downstream expansion zone between wire and roll, while some of the water pulled through clings as a film on the underside of the fabric to be pushed up through the wire on the upstream side of the next roll this vertical pressure pulse helps consolidate the web. Where wire speeds exceed about 25 m s the suction increases excessively and rolls are no longer used. 

Table III. Defect Count as a Function of Wire Speed...

A residence time in the reactor of 12-15 seconds sufficiently hardens the resin to allow rerouting die coated wire inside the reactor for longer, total exposure. The dependence of defect count on wire speed and total exposure is shown in Table III. 

When quarrying granite, a relatively low wire speed is typically used, 20-30 ms and, for a medium grade of material, a block measuring 30 m long x 10 m wide X 5m deep can be separated from the surrounding material in less than 12h. 

Finally, entering angle and back relief angle apparently do not affect the process, but they control the wire vibration between a capstan and another. In fact, in practice a sequence of dies are used to reduce diameter (tandem drawing) and the wire speed increases up to 50 m/s or more. 

The sensitivity of the instrument for diazepam was found to be about 4 x 10 g/ml. The wire samples the eluent at 10 jil/min at the maximum wire speed and thus as the scan speed of the mass spectrometer was 1 scan/sec this sensitivity corresponded to ca. 7 X 10 10 g of diazepam per spectrum. The pressure in the source could be maintained at 1 x 10 mmHg. The use of helium as a purge gas in the interface reduces the noise level of the mass spectrometer by a factor of three with a commensurate increase in sensitivity. 

Table 11.6. Effect of Wire Speed on the FEP Foam Cell Size i...

Wire Speed, m/min Average Cell Size, pm Number of Cells per cm ... 

Figure 4.35 Pressure drop versus wire speed results (symbols) when a full nonisothermal for flow of an LDPE melt in an industrial wire- analysis is used with appropriate thermal coating die. The results from the simulations boundary conditions at the wall and the...

Fig. 18.1 Schematic diagram depicting the principie of the muitiwire sawing technique. The c stai is pushed against the wire web with a constant feeding rate, which is equai to the materiai-removai rate. The force on the wire determines the wire bow. The wire speed is maintained constant.

Material is continuously removed through the interaction of the SiC particles below the moving wire and the silicon surface. The abrasive action of the SiC depends on many factors such as the wire speed, the force between the wire and the crystal, the solid fraction of SiC in the suspension, the viscosity of the suspension, the size distribution and the shape of the SiC particles. The viscosity of the slurry depends on the temperature and the solid fraction of particles and changes because of the continuous abrasion of silicon and iron from the wire. This gradually deteriorates the abrasive action and the slurry finally has to be replaced. The kerf loss... 

The Fourdrinier former is likely the most widely used forming method employed in modem papermaking. It has proven uniquely versatile in the variety of paper grades it can produce. Wire speeds up to 5000 feet per minute are possible with some lightweight grades. The following description follows the pulp flow fi-om the headbox to the couch roll just prior to the press section. A Fourdrinier wet end is shown in Figure 3. 

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