Tube extrusion

Greater care should be taken and proper procedures followed by the condenser manufacturer when rolling the tube ends to avoid excessive wall reduction and tube extrusion. To prevent crevice corrosion in the tube-to-tubesheet joint, the tube end should be rolled for the full thickness of the tube sheet.12... 

The parison head, sometimes called the die head or simply the die, is a specialized form of tube extrusion die (Chapter 17). Its function is to deliver a straight parison in the correct diameter, length, wall thickness, and at the correct temperature for BM. Prior to being clamped in the mold, the parison is suspended unsupported in free air. To avoid undue deformation, it is necessary to extrude the parison vertically downwards. 

Two-stage EBM treats the parison as a true preform by separating the functions of parison preparation and BM. Parisons are produced by conventional tube extrusion methods (Chapter 5). The tube is cooled and cut into parison lengths that are stored before being reheated and BM in the normal way. 

Fluoroplastics Tubing Extrusion Formulation- specific PTFE unstable, to FEB stable at 25 kGy and higher... 

Figure 6.16 Typical spider-type tube die for pipe and tube extrusion.

Tube extrusion is quite similar to the wire insulation process. Processing details depend on the size and type of the tube. Tube can be manufactured by both in-line and crosshead dies. FEP tubing can be produced with outside diameters as low as 1 mm to over 20 mm. This range is broken into three processing zones based on the size of the outside diameter small, medium, and large. The sizing die determines the outside diameter of the extrusion output and the line speed determines the inside diameter. Take-up speed and the die gap, and the difference between the inside diameter of the die and the outside diameter of the tip, set the wall thickness. 

Figure 19.4 SIPOC for PVC tubing extrusion by ACME Tubes, Inc.

Fig. 3-30. Examples of calibration systems for pipe/tube extrusion lines.

Calibrator with ultrasonic gauging for pipe and tubing extrusion A=rubber seals B = stainless steel guides C brushes (to remove bubbles) D ultrasonic probes E water drain and water inlet. 

Figure 1. Pipe or tubing extrusion die conf uration.

Tubetrol, Total control of tubing extrusion, Harrel Inc. 

Pipe and Tubing. Extrusion of pipe and tubing accoimts for a very small fraction of LLDPE consumption. LLDPE offers higher burst strength, environmental stress crack resistance, and higher heat-distortion temperature than LDPE. Plastomer grades have been used to replace plasticized polyvinyl chloride in medical tubing applications (129). 

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