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

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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.

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Abbreviations

a :

Amplitude

ABS:

Acrylonitrile butadiene styrene

a xx, a yy, a zz :

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

L 0 :

Melt-layer thickness after heating

P:

Unit vector

PA:

Polyamide

PP:

Polypropylene

p W :

Welding pressure

p x, p y, p z :

Component of the unit vector P

ROI:

Region of interest

s J :

Joining displacement

T HP :

Hot-plate temperature

v J :

Joining velocity

Vib:

Vibration welding

σW :

Weld strength

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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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Authors and Affiliations

  1. Kunststofftechnik Paderborn, Paderborn University, Paderborn, Germany

    Isabel Fiebig & Volker Schoeppner

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  1. Isabel Fiebig
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  2. Volker Schoeppner
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Correspondence to Isabel Fiebig.

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Recommended for publication by Commission XVI - Polymer Joining and Adhesive Technology

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Fiebig, I., Schoeppner, V. Influence of fiber orientation and weld position in welding injection-molded fiber-reinforced thermoplastics. Weld World 62, 1301–1309 (2018). https://doi.org/10.1007/s40194-018-0649-8

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  • DOI: https://doi.org/10.1007/s40194-018-0649-8

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