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Optimizing Mechanical Performance of Injection Molded Multiple Gated Rotating Thermoplastic Components: Part 2 - Knit Line
1
/Weld Inter-Phase Integrity
Technical Paper
2001-01-0439
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Event:
SAE 2001 World Congress
Language:
English
Abstract
Due to the wide and ever increasing application of thermoplastics for the transportation and automotive industries, the performance of the under-the-hood plastic parts depend upon optimized design and processing technology and properties of polymer based materials. Nylon (polyamide) based plastics are used widely for automotive cooling fans and various under-the-hood injection molded components.
For injection molding of multi-blade cooling fans and various rotating plastic parts the complex of multiple gating injection molding tools were used. Both the design of the various rotating parts (including industrial and automotive cooling fan, and the molding tool design are very important to get optimum flow patterns and to predict the locations and interaction of stress-bearing areas and knit lines (planes or inter-phases)1. The mechanical performance of the injection-molded thermoplastic components depends on the peculiarity of the part and the molding tool design.
In Part 1 of this paper2, we are presenting results of structural design analysis (comprehensive analytical and linear FEA) and design optimization of a multiple gated rotating components with a ring under the influence of the design parameters. In Part 2 of this paper, we are discussing the mechanical properties of fiber-glass reinforced thermoplastic in local (weld plane) and bulk (molded part) areas with the influence of molding and end-use conditions.
The analysis of this study shows, that for non-reinforced or non-filled nylon, the mechanical performance in the knit-line (weld plane) areas are approximately equal to the mechanical performance of used resin (polyamide).
For fiber-glass reinforced and fiber-glass/mineral nylons, the mechanical properties of plastic in the knit (weld) line (plane) are different from the basic mechanical properties of reinforced plastic due to flow patterns and local fiber-glass re-orientation in the weld plane areas. Due to the above changes, the knit (weld) lines become likely areas of crack initiation and propagation and possible molded part failure or damage.
The results from this complex study should help plastic part designers to accurately interpret the results of the structural analysis and complex tensile properties such as strength, deformation and fatigue of nylon based plastics and to utilize these important material parameters at end-use conditions for a plastic part life assessment.
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Authors
Citation
Kagan, V., Mazza, J., and Roth, C., "Optimizing Mechanical Performance of Injection Molded Multiple Gated Rotating Thermoplastic Components: Part 2 - Knit LineAlso In
References
- Rosato, Donald and Rosato Dominick “Injection Molding Handbook” Second Eddition Charman & Hall New York 1145 pages, 1995
- “Engineering Plastics” Engineered Materials Handbook Vol. 2 ASM International Metals Park OH 882 pages, 1988
- Trantina, G. Nimmer, R. “Structural Analysis of Thermoplastic Components” McGraw-Hill, Inc. New York 366 pages, 1994
- Maxwell, J. “Plastics in the Automotive Industry” Woodhead Publishing Limited Cambridge, England 189 pages, 1994
- Kohan, M. “Nylon Plastic Handbook” Hanser/Gardner Publications, Inc. New York 598 pages, 1997
- “Automotive Specification Guide” Honeywell International, Engineered Applications & Solutions Morristown, New Jersey 17 pages, 1998
- Carlson, E. Nelson, K. “Nylon Under-the-Hood. A History of Innovation” SAE, Automotive Engineering pp. 84 89 December 1996
- MacDermott, C. Shenoy, A. “Selecting Thermoplastics for Engineering Applications” Marcel Dekker, Inc. New York 305 pages, 1994
- Cloud, P. McDowell, F. and Gekaris, S. “Reinforced Thermoplastics: Understanding Weld-Line Integrity” Plastic Technology August 1976
- “Fans: Fan and System Characteristics For Turbulent Airflow” Honeywell International, Engineered Applications & Solutions Morristown, New Jersey 34 pages, 2000
- “Capron® Nylon Typical Properties Charts” Honeywell International, Engineered Applications & Solutions Morristown, New Jersey 14 pages, 1998
- “Injection Molding Processing Guide for Capron® Nylon” Honeywell International, Engineered Applications & Solutions Morristown, New Jersey 58 pages, 1998
- “Carrier a ‘Fan’ of Plastic” ASSEMBLY pp. 74 76 Cashier Publishing Inc. February 1999
- Jia, N. and Kagan, V. A. “Effects of Time-Temperature Conditions on the Tensile-Tensile Fatigue Behavior of Short Fiber Reinforced Polyamides” SPE Conference Proceedings Vol. 2 pp. 1844 1848 ANTEC'97
- Turning, L. S. Chiang, H. H. Stevenson, J. F. “Optimizing Molding at Low Injection Pressures” Plastic Engineering, SPE October pp. 33 36 1995