Stationary Mandrels

Filament winding A process to produce a composite part from a continuous fiber impregnated by a matrix resin by winding it onto a rotating or stationary mandrel. 

Dwell In filament winding, the time that the transverse mechanism is stationary while the mandrel continues to rotate to the appropriate point for the traverse to begin a new pass. 

Some special dies are shown in Fig. 3-20 they produce interesting flow patterns and products such as tubular to flat netting dies. For a circular output, a counter-rotating mandrel and orifice have semicircular-shaped slits through which the melt flow emerges. If one part is held stationary, then a rhomboid or elongated pattern is formed if both parts rotate, then a true rhombic mesh is formed. When the slits overlap, a crossing point is formed... 

Another method of improving circumferential orientation in tubing and pipe dies is by inducing relative motion between the tip and the die. This can be done by rotating the tip relative to a stationary die or by rotating the die relative to a stationary tip. It is even possible to rotate both the tip and the die separately and in different directions. With rotation of the tip and/or die there is a greater degree of control over the orientation of the extruded tube than with a spiral mandrel section. Obviously, this is at the expense of increased mechanical complexity. 

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