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Influence of fiber orientation and weld position in welding injection-molded fiber-reinforced thermoplastics

  • Isabel Fiebig
  • Volker Schoeppner
Research Paper
  • 12 Downloads

Abstract

Several publications deal with the influence of the initial fiber orientation in joining parts on the weld strength of fiber-reinforced thermoplastics. The welding partners have been sawn before welding. Preparing the joining parts after injection molding is not suitable since it is an additional manufacturing step. Since injection molding results in a non-uniform fiber orientation, there is a possibility that the position of the weld influences weld characteristics. The influence of the initial fiber orientation was investigated by preparing parts with longitudinal or transverse initial fiber orientation. Short and long glass fiber-reinforced thermoplastics with a glass fiber content of 30% have been welded by hot-plate and vibration welding. The initial fiber orientation in non-welded parts influences the weld strength: longitudinal fibers are more advantageous for the weld strength than transverse fibers. The influence of the position of the weld in injection-molded parts was investigated by welding the plates at the end of the flow path, at the sawn gate, and at the lateral side. The weld strength is similar at the gate or at the end of the flow path. For PA-GF30, the weld strength at the gate is even higher. Positioning the weld at the lateral side in injection-molded parts results in significantly lower weld strengths for short and long glass fiber-reinforced thermoplastics in hot-plate and vibration welding.

Keywords

Polymer joining Fiber reinforced thermoplastics Composites Vibration welding Heated tool welding 

Symbol list

a

Amplitude

ABS

Acrylonitrile butadiene styrene

axx, ayy, azz

Component of orientation tensor

CT

Computed tomography

d

Thickness

DVS

German Welding Association

FRP

Fiber-reinforced plastics

GF

Glass fiber-reinforced

HP

Hot plate (welding)

LGF

Long glass fiber-reinforced

L0

Melt-layer thickness after heating

P

Unit vector

PA

Polyamide

PP

Polypropylene

pW

Welding pressure

px, py, pz

Component of the unit vector P

ROI

Region of interest

sJ

Joining displacement

THP

Hot-plate temperature

vJ

Joining velocity

Vib

Vibration welding

σW

Weld strength

Notes

Acknowledgements

The IGF Project 18702 N of the research association “Forschungsvereinigung Schweißen und verwandte Verfahren e. V. des DVS. Aachener Straße 172. 40223 Düsseldorf” was on the basis of a resolution of the German Bundestag, promoted by the German Ministry of Economic Affairs and Energy via AiF within the framework of the program for the promotion of joint industrial research and development (IGF).

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Copyright information

© International Institute of Welding 2018

Authors and Affiliations

  1. 1.Kunststofftechnik PaderbornPaderborn UniversityPaderbornGermany

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