Spider dies

Processing can use spider dies, spiral mandrel dies, or basket-type dies that support the inner mandrel with a perforated sleeve through which the melt flows. Figure 17.12 provides examples of different die designs. 

Both pipe and tubing are made in dies with an annular die exit. A pipe product is defined as being greater than 1 in. in outer diameter and a tube less than 1 in. Dies for these products are made in two styles 1) in-line dies (also called spider dies) shown in Fig. 4A and... 

Figure 15.6 A hollow die, or a spider die with a fixed mandrel as an integrate part of the die to make the tongue-and-groove profile (see Fig. 15.2).

Most dies produced today are spiral channel dies, though some antique side entry and spider dies are still in use. In spiral channel dies, the polymer melt is introduced through several ports into spiral channels, as shown in Fig. 7.9. It then flows partially up the channel and between the channel and the die wall. This type of smearing flow reduces any existing temperature differences in the melt. As the flow moves up the die channel, the spiral disappears and the melt flows into a relaxation chamber designed to allow the melt to lose the memory of its previous... 

High-purity A1 was obtained in the form of 60.3-mm-diameter bar stock. The bar stock was then extruded into a tube 24.4-mm OD and 19.8-mm ID. The extrusion was carried out at room temperature with a spider die arrangement. With a standard four-point probe method, the resistivity ratio, P298k/P4.2k of the extruded high-purity A1 tube was about 1700. 

Extrusion was conducted by using a ram extrusion machine with a spider die of 31 mm in diameter. Figure 4.50 shows a schematic of the extruder and spider extrusion die. Before extmsion was started, the extmsion die was preheated to 140 °C. The granulated thermoplastic-ceramic mixture was then added into the die. The bottom of the die was blocked, while the ram was pressed to a pressure of 2.3 MPa. The die was cooled to 50 °C, while the stop was removed from the end of the die. A smaller heati ng mantle was then used to heat the spider region of the die. As the spider was heated to 120-130 °C, mbes with length of up to 0.7 m could be extmded out at a rate of about 2 mm min, at die pressures of about 1 MPa. 

Figure 4.1 Cross section of simple spider die (Courtesy of Battenfeld)...

Pipe die n. An extrusion die whose lands form a circular annulus used in extrusion of plastic pipe or tubing. The outer shell of the die is usually called the die, the core is called the mandrel. Pipe dies may be side-fed or end-fed, and the mandrel may be supported by a trio of legs called a spider, or it may be supported from the rear of a side-fed die. It is easier to achieve circumferential uniformity of wall thickness with a spider die, but the splitting of the melt stream at the legs has sometimes caused weak welds because of insufficient knitting time before the pipe emerges and is chilled. 

The blown films were prepared from both the fresh materials (not sheared) and the materials extruded for the fifth time. The preparation of all the blown films were carried out with a 65-mm extruder having a polyethylene-type screw of L/D ratio 26 and a screen combination of 80,100,and 80 mesh and a spider die under the following extrusion... 

Rathoie O, Sogah DY. Self-assembly of j8-sheets into nanostructmes by poly(alanine) segments incorporated in multiblock copolymers inspired by spider silk. J Am Chem Soc 2001 123 5231-5239. 

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