LINE SPEED

Other important operating parameters include plasticizer changes, gas type and pressure, gap length between spinneret and quench bath, line speed, and rope tension. All variables must be carefully controlled to obtain a hoUow fiber of desired characteristics. 

Typical substrates for siUcone release coatings are supercalendered kraft paper, glassines, and thermally sensitive films such as polyethylene and polypropylene. Ideal curing conditions are 150°C or lower, and line speeds are as fast as 460 m /min. Key properties for release coatings are cure speed, integrity of cure, and stable release values. 

Wire and Gable. PVC has been used in wire and cable appHcations since World War II, when the U.S. Navy demanded lower combustibiUty materials in constmction. These products are manufactured by cross-head extmsion, usually from pellet compounds on single-screw extmders. Some line speeds are 1524 m (5000 ft) per minute (60 mph). The compounds are optimized for the requirements, including low temperature flexibiUty, high use temperature, especially low combustibiUty, weatherabiUty, and high resistance to cutthrough. 

When 150 SSU at 100°F (38°C) oil is necessary, inlet temperatures should be limited to 110-120°F (43 9° C) to maintain an acceptable viscosity. Oil should be supplied in the temperature and pressure range specified by the manufacturer. Up to a pitch-line speed of approximately 15,000 feet per minute (4572 mpm) the oil should be sprayed into the out-mesh. Spraying allows maximum cooling time for the gear blanks and applies the oil at the highest temperature area of the gears. Also, a negative... 

In the erecting and lowering operation, the slowest practical line speed should be used. 

Optimum depth of immersion depends on pitch-line speed. Deep immersion is permissible at low speeds because power losses from churning are low, but at moderate speeds the immersion depth should not be more than three times the tooth height. At the highest speeds, only the addenda of the teeth need be submerged (Figure 52.8). 

The purpose of this section is to explain in a qualitative way how the product quality is related to the calendering parameters. Therefore a simplified calender model is presented. The model describes the pressure buildup in the calender nip region as a function of compound viscosity, clearance, calender line speed, rolling bank height, as well as geometrical data. The general layout of a typical steel and fabric cord calender is explained by means of the result of the presented calender model. 

Pressure between two calender rolls Calender line speed... 

From the diagrams in Figures 35.34 through 35.40 it might become clear that all parameters will have a tremendous influence on the calendering process and therefore on the calendered product. The calender line speed seems to have the least influence on the calendering performance. 

Major changes in calender line speed to be avoided... 

After paint application, all coils are cured in an oven. Curing temperatures depend upon basis material, conversion coating, paint formulation, and line speed. Typical temperatures range from 93°C to a maximum of 454°C. Upon leaving the oven, the coils are quenched with water to induce rapid cooling prior to rewinding. 

Figure 6. UV absorption spectra before and after 20 msec exposure of a thin film of an equimolar TTDBM/SEGDVE mixture to a Fusion D bulb (I = 1.4 W cm"2 line speed = 45 m min"1 total exposure 28 mJ cm"2).

While the Dove composition described in Table 9.4-2 was processable at reasonable line speeds on a conventional soap processing line (roll mills, extruders, stampers), some equipment modifications were necessary. For example, whereas soap is normally mixed in large agitated tanks, the Dove mixture had a much greater viscosity and therefore required use of a steam-jacketed kneader mixer such as those used to make bread dough, pastes or mastics. 

There are three basic principles to understand and apply in value analysis and cost reduction when selecting the proper equipment. The first is that equipment costs are typically amortized over 10 years, and it is usually a small fraction of the finished product cost. The costs are typically less than 5% of the total cost per unit mass for a product. Secondly, decreasing the amount of resin in the finished product without sacrificing product quality is a major cost reduction. And finally, increasing production efficiency by increasing line speeds and decreasing downtime will decrease the cost of production. 

Pultrusion is a steady-state process in which the fiber-resin mass changes its properties as it moves from the entrance to the exit of the die. In order to track the temperature, polymer conversion, and other properties of the fiber-resin mass as it moves along the die, it is useful to define a representative volume element (RVE) that rides along the fiber at the line speed of the pultrusion process. An RVE is defined such that it will contain both the solid phase (i.e., fibers and resin), irrespective of its location in the composite. In real-life pultrusion, a thermocouple wire that passes through the pultrusion die tracks the temperature of an RVE in the composite. 

Relative line speed Normal Slower Very slow... 

Process parameters involve line speed if dose rate and line speed are combined, the dose delivered to the product to be cured can be calculated. A processor specific yield factor depends on the relationship between the beam current... 

Line speed Speed of the material being irradiated, usually expressed in m/min or ft/min. It determines the exposure time of the material. 

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