Feed channel depth

Table 5.3 Approximate Feed Channel Depths and Barrel Groove Dimensions as a Function of Barrel Diameters [49]...

Barrel Diameter, mm Feed Channel Depth, mm Grove Width, mm Maximum Number of Grooves... 

Grooved bore extruders are common on European extruders up to barrel diameters of about 120 mm and on some applications up to 150 mm diameter [44]. For a 60 mm diameter machine, the maximum feed channel depth for a PP resin application is about 5 mm and 6 mm for HDPE resin applications channel depths are not much larger than this for larger diameter machines. Ingen Housz and Meijer [44]... 

Mixer type Interdigital horizontally multi-lamina-ting micro mixer (I) Feed channel depth, width 70 pm, 100 pm... 

Feed channel depth, width, length 100 pm, 100 pm, 20 mm Width of mixer chamber 11.2 mm... 

Feed Channel Depth Metering Channel Depth... 

The amount of screw compression is quantified by the compression ratio compression ratio = feed channel depth s- metering channel depth... 

Metal/siHcon mixer 40 tm 300 pm feed channel width depth Slit depth in steel 60 pm housing... 

Why does the channel depth of the screw generally decrease as you move from the feed zone to the metering zone of an extruder ... 

In the simplest and most often used form, the screw has a free channel cross-section that diminishes at a steady rate from the feed to the delivery end. The ratio of the channel depths from feed to die region along the screw is usually referred to as the compression ratio, since it gives a crude indication of the relative conveying capacities at feed and discharge. 

Apart from improving the mixing effect in the deeper part of the screw the restriction that occurs towards the delivery end also helps to make sure that the screw runs full. If a screw does not have a diminishing channel depth along its length then it is difficult to feed rubber at a rate that will keep up with its unrestricted conveying capacity. The screw then runs partially filled after the feed opening and only becomes completely filled at a point that allows sufficient pressure to be developed to overcome the restriction at the die. 

Figure 6.6 Melting profiles for a 63.5 mm diameter extruder running an ABS resin at 60 rpm for screws with a 8.89 mm deep feed channel, 6 diameters of feed section, and a metering channel depth of 3.18 mm (C = 2.8) (a) 8 diameters of transition section for R = 0.00342, and (b) 4 diameters of transition section for R = 0.00684 [13, 14]. The pushing flights are on the right side of the section photographs...

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