Melting flow chart

The temperature of the screw was measured by several investigators [29-32]. The measurements were performed by mounting thermocouples in an axial hole bored in the center of the screw or by protruding the thermocouples into the melt flow. The sensor signals were then transmitted to a chart recorder using an electrical rotary union. The technology available at the time of these measurements limited the number of sensors in the screw and the quality of the data. 

After interesterification has proceeded to the desired point, the catalyst is destroyed by adding water and carbon dioxide. Carbon dioxide buffers the caustic to a lower pH and minimizes saponification of the lard. The neutralized lard is heated to melt the trisaturated glyceride crystals. Soaps are removed by conventional water washing and centrifuging, and the lard is dried in a continuous-vacuum drier. A basic flow chart for the process is shown in Fig. 12-8. 

Fig. 2.2. Simplified flow chart of the Phillips process (solution phase polymerisation) (Elias 1992). The solvent (for example isobutane), ethylene, co-monomers and the catalyst are fed into the reactor. The polymer solution is de sed (flashed) from the reactor through a gas separator after a certain reaction time. In a cleaning nnit (centrifuge, washing device, drier) the polymer is separated out and ethylene and solvent residues are processed. The polymer emerges in the drier in the form of snow white flakes. Flakes, carbon black, stabiliser and further additives, for example Ca-stearate, are mixed in a mixer and this mix is fed into an ex-tmder at an adequate mix raho with the polymer flakes. Here the mix is melted, homogenised and finally granulated. The black pellets are then transported to the storage facihties...

Figure 16-3 Quality Control Run Chart (Melt Flow Rate)...

Relocate gate so that the melt impinges off wall as it enters cavity. Flow chart 5.2.6 illustrates a schematic approach to the problem of jetting. 

In some cases, relocation of gate makes the flow pattern of the melt alter. Modify the vent location also in the cavity at the area of weld line and provide overflow well. Machine size has also to be considered to resolve the problem. Flow chart 5.2.11 illustrates the ways to solve the problem of poor weld line. 

Check and/or change machine settings, change mould or moulding compound, start new cycle and go through Flow Chart 9.2 reducing melt temperature. 

Thickness variations can be categorized as either time-dependent or position-dependent. For the case of time-dependency, thickness varies in the machine direction (MD) of the film, which may be caused by extruder surging (as described above). Also, temperature drifts on the extruder can lead to longer-term changes in the flow rate of polymer, hence thickness variations. It may be beneficial to document melt temperature on a chart recorder over several hours if this cause is suspected. 

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