Extrusion dies

The extrusion die shapes the polymer melt into its Anal profile. It is located at the end of the extruder and used to extrude 

As shown in Fig. 3.13, depending on the functional needs of the product, several rules of thumb can be followed when designing an extruded plastic profile. These are  

Sheeting dies. One of the most widely used extrusion dies is the coat-hanger sheeting die. A sheeting die, such as the one depicted in Fig. 3.14, is formed by the following elements  

To overcome weld line problems, the cross-head tubing die is often used. Here, the die design is similar to that of the coat-hanger die, but wrapped around a cylinder. This die is depicted in Fig. 3.17. Since the polymer melt must flow around the mandrel, the extruded 

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Finite element modelling of flow distribution in an extrusion die... 

We consider a co-extrusion die consisting of an outer circular distribution channel of rectangular cross-section, connected to an extrusion slot, which is a slowly tapering narrow passage between two flat, non-parallel plates. The polymer melt is fed through an inlet into the distribution channel and flows into... 

Figure 5.20 (a) The predicted non-uniform exit flow distribution in a co-extrusion die. 

Nassehi, V. and Pittman,. 1. F. T., 1989. Finite element modelling of flow distribution in an extrusion die. In Bush, A. W., Lewis, B.A. and Warren, M.D. (eds), Flow Modelling in Industrial Processes, Chapter 8, Ellis Horwood, Chichester. 

W. Michaeh, Extrusion Dies for Plastics and Rubbers, Hanser Pubhshers, Munich, Germany, 1992. 

Design considerations for air knives are discussed by Senecal (ibid.). Design procedures for extrusion dies when the flow is laminar. 

Thus it is found that extrusion die swell, when compared at equivalent shear rates, tends to go down with an increase in temperature and go up with molecular weight. As shear rates are increased, polymer uncoiling is increased and die swell increases Figure 8.9). A point is reached, however, where the die swell no longer increases and in fact it can be argued that it goes down. At this point it is... 

The strong dependence of apparent viscosity on shear rate. This necessitates particular care in the design of complex extrusion dies. 

Opening from an extrusion die used for excess material to overflow. 

Piece of an extrusion die that serves to hold die block. 

Part of extrusion die that holds the core and forming bushing. 

Part of an extrusion die used to separate and form material. 

Figure 3-35 provides design features in extrusion dies that influence product performance. The guiding principle should be to keep it simple whenever possible, (a) The method of balancing flow to produce this shape requires having a short land where the thin leg is extruded. This design provides the same rate of flow for the thin section as for the heavy one. (b) This die for making square... 

Wear parts Bearings Jet-nozzle coatings Slurry valves Extrusion dies Abrasive pump seals Computer disk coatings Engine parts Medical implants Ball bearings Drawing dies Textile machinery... 

Molding tools and dies for glass-filled plastics (Ti(C,N)) Extrusion dies for ceramic molding (TiC)... 

The principles of the extrusion-die pressing production of pipes and rods from powders are well known. The flow diagram of the production of parts is as follows ... 

Michaeli, W, Extrusion Dies. Design and Engineering Computations Hanser Publishers, New York 1984... 

The wastewater characterization data for the extrusion die cleaning rinse are summarized by classical and toxic pollutants in Table 5.6. 

Figure 14.1 illustrates the general principles of extrusion blow molding. A molten tube of polymer, known as a parison, is extruded vertically downwards from an extrusion die, as shown in Fig. 14.1 a). The two halves of the blow mold surround and then close on the... 

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