Reason and Regularity of Injection Mold Wear for Glass⁃fiber⁃reinforced Part

doi:10.19491/j.issn.1001-9278.2020.08.007

Abstract

Abstract:

In the injection molding process of the thin-walled part based on glass-fiber-reinforced polyetherimide, the core of the mold is easily worn, which seriously affects the quality of the part. Taking the thin-walled part of certain mobile phone as an example, and the micro wear characteristics of the core surface were analyzed in view of the practical production, and the melt flow behavior near the wall of the cavity and the erosion failure form and wear law of the surface material of the core were studied by a numerical method. The results indicated that during the injection process, the surface material of the core was eroded to form a crescent shaped groove, and the melt velocity near the wall of the cavity determined the shape and size of the crescent shaped groove. The incidence angle and dip angle of the glass fiber particles determined the erosion failure form of the material on the surface of the core. The wear amount increased with an increase of the roll angle of glass fiber particles, and the increment was exponential with an increase of the incidence speed.

Key words: glass-fiber-reinforced polyetherimide, thin-walled part, injection molding process, mold core, erosion wear

CLC Number:

TQ320.66⁺2

Yiren GAO, Minjie WANG, Hongxia LI. Reason and Regularity of Injection Mold Wear for Glass⁃fiber⁃reinforced Part[J]. China Plastics, 2020, 34(8): 44-49.

Figures/Tables 13

Fig.1. Erosion area and surface micro wear morphology of the mould core

Fig.2. Deformed lip formed on the surface of the mould core

Fig.3. Defect of the thin?walled part caused by core wear

Fig.4. Grid generation of the mould gating system

Fig.5. Local graph near the mould gate

Fig.6. Flow condition of melt near the mould gate

Fig.7. Multi field cloud pattern in the cavity near the wall and orientation of glass fiber particles

Fig.8. Vector graph of melt velocity near the mould gate

Fig.9. Melt velocity distribution near the wall 1 of the cavity

Fig.10. Erosion diagram of glass fiber particle on the mould surface

Fig.11. Grid generation of physical model in erosion process

Fig.12. Erosion of mould target material at different incident angles (H13 mould steel)

Fig.13. Influence of different incident conditions on erosion amount of the mould target material

References 10

1	陶国源. 聚醚酰亚胺(PEI)的性能、加工及应用[J]. 塑料制造, 2006(7):38⁃45.
	TAO G Y. Properties, Processing and Application of Polyetherimide[J]. Plastics Manufacture, 2006(7):38⁃45.
2	KIM S H, YOUM J S, LEE M S, et al. Effect of Poly (ether imide) Blends on the Physical Properties of Thermoplastic Glass Mat Composites [J]. Advanced Composite Materials, 2018, 27(6):637⁃652.
3	BREZINOVA J, GUZANOVA A. Friction Conditions During the Wear of Injection Mold Functional Parts in Contact with Polymer Composites [J]. Journal of Reinforced Plastics and Composites, 2010, 29(11):1 712⁃1 726.
4	BLUTMAGER A, VARGA M, SCHMIDT T, et al. Abrasive/Erosive Wear on MMCs in Plastic Molds as a Function of Volumetric Flow Rates and Glass Fiber Distribution [J]. Polymer Engineering and Science, 2019, 59(1):302⁃311.
5	GIUSTI R, VEZZU S, LUCCCHETTA G. Wear⁃resistant Cobalt⁃based Coatings for Injection Moulds by Cold Spray [J]. Surface Engineering, 2016, 32(9):677⁃685.
6	NUNTHAVARAWONG P. Slurry Erosion Model for Wear Performance Prediction of Tool Steel [J]. Advanced Materials Research, 2013, 717(2):194⁃195.
7	MARTINEZ⁃MATEO I, CARRION⁃VILCHES F J, SANES J, et al. Surface Damage of Mold Steel and Its Influence on Surface Roughness of Injection Molded Plastic Parts [J]. Wear, 2011, 271(9/10):2 512⁃2 516.
8	蒋奔, 翟明, 任建行,等. 纤维增强塑料注射充模过程中纤维对模具的冲蚀磨损模拟[J]. 化工学报, 2018, 69(7):3 174⁃3 180.
	JIANG B, ZHAI M, REN J X, et al. Simulation of Fiber Erosion on Mold During Filling Process of Fiber Reinforced Plastic Injection Molding [J]. CIESC Journal, 2018, 69(7):3 174⁃3 180.
9	WANG Y, YANG Z. Finite Element Model of Erosive Wear on Ductile and Brittle Materials[J]. Wear, 2008, 265(5/6):871⁃878.
10	林福严, 曲敬信, 陈华辉. 磨损理论与抗磨技术[M]. 北京: 科学出版社, 1993:64⁃69.

[1]	MA Xiuqing, SUN Kaixin, LI Rui, ZHANG Yajun, FAN Yiqiang. Experimental Study on Optimal Injection⁃molding Process of PMMA Microfluidic Chip [J]. China Plastics, 2021, 35(4): 47-52.
[2]	Ligang DING, Guofei CHENG, Wenqiang WEI, Siqiao HU, Kaixiang GUO. Design of Front Mold Core Pulling Injection Mold with S⁃type Valve Chamber [J]. China Plastics, 2020, 34(8): 95-100.
[3]	. Injection Mold Design of Motor Canteen Rear Covers with Threads [J]. China Plastics, 2016, 30(03): 109-112 .
[4]	. Effects of Injection Molding Process on Angular Deviation of Curved Transparent Polycarbonate Parts [J]. China Plastics, 2015, 29(11): 87-91 .
[5]	. Shrinkage Prediction of Cylindrical Thin-walled Parts in Plastic Injection Molding Base on Design of Experiments [J]. China Plastics, 2014, 28(06): 82-87 .