A low-cost, low-fiber-breakage, injection molding process for long sisal fiber reinforced polypropylene

2004 ◽  
Vol 44 (9) ◽  
pp. 1766-1772 ◽  
Author(s):  
L. M. Arzondo ◽  
A. Vazquez ◽  
J. M. Carella ◽  
J. M. Pastor
2019 ◽  
Vol 39 (4) ◽  
pp. 388-396 ◽  
Author(s):  
Peng Zhao ◽  
Yao Zhao ◽  
Jianfeng Zhang ◽  
Junye Huang ◽  
Neng Xia ◽  
...  

AbstractAn online and feasible clamping force measurement method is important in the injection molding process and equipment. Based on the sono-elasticity theory, anin situclamping force measurement method using ultrasonic technology is proposed in this paper. A mathematical model is established to describe the relationship between the ultrasonic propagation time, mold thickness, and clamping force. A series of experiments are performed to verify the proposed method. Experimental findings show that the measurement results of the proposed method agree well with those of the magnetic enclosed-type clamping force tester method, with difference squares less than 2 (MPa)2and errors bars less than 0.7 MPa. The ultrasonic method can be applied in molds of different thickness, injection molding machines of different clamping scales, and large-scale injection cycles. The proposed method offers advantages of being highly accurate, highly stable, simple, feasible, non-destructive, and low-cost, providing significant application prospects in the injection molding industry.


2018 ◽  
Vol 37 (15) ◽  
pp. 1020-1034 ◽  
Author(s):  
Christoph Lohr ◽  
Björn Beck ◽  
Frank Henning ◽  
Kay André Weidenmann ◽  
Peter Elsner

The MuCell process is a special injection molding process which utilizes supercritical gas (nitrogen) to create integral foam sandwiches. The advantages are lower weight, higher specific properties and shorter cycle times. In this study, a series of glass fiber-reinforced polyphenylene sulfide foam blanks are manufactured using the MuCell injection molding process. The different variations of the process (low-pressure also known as structural foam injection molding) and high-pressure foam injection molding (also known as “core back expansion,” “breathing mold,” “precision opening,” decompression molding) are used. The sandwich structure and mechanical properties (tensile strength, bending strength, and impact behavior) of the microcellular and glass fiber-reinforced polyphenylene sulfide foams are systematically investigated and compared to compact material. The results showed that the injection parameters (injection speed, foaming mechanism) played an important role in the relative density of microcellular polyphenylene sulfide foams and the mechanical properties. It could be shown that the specific tensile strength decreased while increasing the degree of foaming which can be explained by the increased number of cells and the resulting cell size. This leads to stress peaks which lower the mechanical properties. The Charpy impact strength shows a significant dependence on the fiber orientation. The specific bending modulus of the high-pressure foaming process, however, surpasses the values of the other two processes showing the potential of this manufacturing variation especially with regard to bending loads. Furthermore, a high dependence of the mechanical properties on the fiber orientation of the tested specimens can be found.


2020 ◽  
Vol 4 (4) ◽  
pp. 161
Author(s):  
Jochen Wellekötter ◽  
Julia Resch ◽  
Stephan Baz ◽  
Götz Theo Gresser ◽  
Christian Bonten

Although fiber-reinforced plastics combine high strength and stiffness with being lightweight, major difficulties arise with high volume production and the return of manufactured parts back into the cycle of materials at the end of their lifecycles. In a novel approach, structural parts were produced from recycled material while utilizing the so-called injection molding compounding process. Recycled fibers and recycled polyamide matrix material were used by blending carbon and matrix fibers into a sliver before processing. Injection molding was then used to produce long fiber-reinforced parts through a direct fiber feed system. Recycled matrix granules were incorporated into the injection molding process by means of an injection molding compounder to investigate their influences on the mechanical properties of the parts. The findings show that the recycled fibers and matrix perform well in standardized tests, although fiber length and fiber content vary significantly and remain below expectations.


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