Single-screw extruders are the most common machines in plastics processing. Though basically simple in function, they are subject to many destabilizing factors that can result in out-of-spec product or a shutdown. When trouble strikes, you will need a strategy for identifying the causes quickly. An essential element of that..
Causes: Flow line defects are caused by the varying speed at which the molten plastic flows as it changes direction through the contours and bends inside the mold tool. They also occur when the plastic flows through sections with varying wall thickness, or when the injection speed is too low causing the plastic to solidify at..
NPTEL - Mechanical Engineering - Forming. Joint Initiative of IITs and IISc Funded by MHRD. Page 1 of 9. Further analysis and extrusion defects. R. Chandramouli. Associate Dean-Research. SASTRA University, Thanjavur-613 401..
In particular, we investigate how die defects, material properties and operating conditions affect die lines. The results are compared with the ex- perimental observations. Die Lines in Plastics Extrusion: Film Blowing. Experiments and Numerical Simulation. FAN DING and A. JEFFREY GIACOMIN*. Department of Mechanical..
Jun 30, 2010 . Category. Travel & Events. License. Standard YouTube License. Music. "One Step Beyond" by Karsh Kale Listen ad-free with YouTube Red. Show more. Show less. Comment 1. Default profile photo. Add a public comment. Top comments. Top comments; Newest first. Syakuro Abdan7 months ago
Aug 25, 2017 . I, pimple. 1, the phenomenon that produces pimple. (1) Resin in the process of plastic formation of lumps, on the plastic layer surface has a small crystal dots and small particles, distributed in the plastic layer surface four weeks. (2) Coke burning of the knot, on the surface of the plastic layer has charred,..
Jan 21, 2013 . To ensure successful extrusion manufacturing, every parameter must be identified, controlled, and monitored. Some of the variables are based on equipment, others on operating conditions. The variables range from the quality of the die and materials to temperatures and pressures
Jun 15, 2010 . A. Polymeric Gels are a common occurrence in the extrusion process and are primarily visual defects. Gels can originate either during the resin polymerization or the film extrusion process and can be caused by a number of factors
Figure 1.3 General extrusion results of sharkskin instabilities for linear polymer. 9. Figure. 104 Polymer extrusion under different shear rate, during higher shear rates (or above some critical values), melt fracture start to appear on polymer products. 11. Figure 2.1 Components of a single screw extruder of plastics. 15
The. Dynisco. Extrusion. Processors. Handbook. 2nd edition. Written by: John Goff and Tony Whelan. Edited by: Don DeLaney ... by far the largest group of plastic materials extruded; approximately 65% of all plastics pass through an .. for subsequent examination to reveal defects such as sharkskin and melt frac-. 64..
Apr 8, 2017 . The defects in Extruded Products can be classified into the following categories, Center burst, Piping and Surface cracking
3.Thermoforming. 4. Injection molding. 5.Compression and transfer molding. 6. Rotational molding. 7. Blow molding. 8. Plastic foam molding. Processes. Page 5. 1.Extrusion. -the forcing of a plastic or molten material through a shaped die by means of pressure. .. defects, by thermally relaxing the stresses and lowering..
Jun 2, 2017 . Some plastics, such as PET, the nylons, and polycarbonate, can degrade and weaken if even a tiny amount of moisture is present When the polymer pellets are heated, the absorbed moisture is also heated and turned into steam. It passes through the extruder and boils when the pressure is relieved at..
Comprehensive polyethylene pipe extrusion troubleshooting guide and tips available for all applications. Find solutions to your technical challenges
process which lead to defects in the product. The purpose of this review paper is to focus on the various defects in the extrusion process, to identify its impact on the product quality and to suggest the remedies for the improvement of extrusion process. Keywords: Extrusion process, Defects in plastic pipe, Impact of defect,..
Film defect that occurs when corona treatment intended for one side of the film appears on both sides, resulting in blocking and picking in the material. Barefoot An additive-free .. Additives designed to enhance the extrusion ability of plastics, reduce surface defects and improve color consistency. Proposition 65 (The Safe..
Abstract. The objective of this paper is to study the defects in the plastic pipe, to optimize the plastic pipe manufacturing process. It is very essential to learn the process parameter and the defect in the plastic pipe manufacturing process to optimize it. For the optimization Taguchi techniques is used in this paper. For the..
Sep 1, 2010 . So many things can go wrong during sheet extrusion that it's almost a miracle processors are able to produce as much good product as they do. Chatter marks can be a common problem when processing sheet, but with this checklist you'll be able to locate and fix a weak spot quickly. (Editor's note: The K..
Dec 21, 2017 . Full-text (PDF) | Melt flow instabilities associated with surface defects for polymer extrudates and commonly referred to as the Sharkskin Effect, are . The "Sharkskin Effect" in polymer extrusion . The occurrence of these instabilities for plastics is known at least since 1945 (Rudolf and Molenaar, 1998)
This paper deals with defects in multilayer plastic films in the extrusion process. A methodology to link process parameters and fluid rheology to onset of certain types of defects is developed. The defects considered include zigzag features that can form on the surface or interfaces in the extruded multilayer films, and..
Abstract: This study present a systematic approach to find the root causes for the occurrence of defects and wastes in plastic extrusion process in the case company. Particularly defects such as surface roughness and scratch, bulging, sink marks, uneven wall thickness, dimensional variation, centering problem, tears and..