Weld Lines in Polymer Processing

Malguarnera, S. C.

doi:10.1080/03602558208067709

Cited by 42 publications

(22 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Different thermal history and molecular orientation in the weldline area lead to morphological heterogeneities which may cause loss of strength. The subject of weldlines in unfilled plastics has been reviewed by Moslk, et al (1) and by Malguarnera (2). In brittle thermoplastics such as polystyrene or styreneacrylonitrile copolymer, the weldline produces a rather severe reduction in tensile strength (50 percent for a double-gated standard tensile bar mold).…”

Section: Introductionmentioning

confidence: 99%

Weldline integrity of reinforced plastics: Effect of filler shape

Fisa

Dufour²,

Vu‐Khanh³

1987

Polymer Composites

View full text Add to dashboard Cite

The paper is a preliminary report on glass fiber and glass flake orientation in the weldline zone of injection molded reinforced polypropylene. Two types of weldlines were studied using simple shape molds: one where two melt streams meet head‐on and become immobilized, the other where the weldline formation is followed by additional flow. In the weldlines of the first type, which are characteristic of current standard molds used to test weldline strength, the anisometric particles are almost perfectly oriented perpendicular to flow. As a result, the weldlines of this type tend to be weak and brittle. In the second case when the weldline is formed by merging of melt streams separated by an insert, particle orientation in the weldline area remains different from other areas of the sample for long distances from the insert. It is shown that in molds where the weldline formation is followed by laterally expanding flow the change of particle orientation is faster than for unidirectional flow.

show abstract

Section: Introductionmentioning

confidence: 99%

Weldline integrity of reinforced plastics: Effect of filler shape

Fisa

Dufour²,

Vu‐Khanh³

1987

Polymer Composites

View full text Add to dashboard Cite

show abstract

“…There are various investigations of the weld-line in injection molding. Many researchers studied the relationship between mechanical properties of the weld-line and the processing condition [2], [3] . Dairanieh et al [4] numerically predicted the effects of material properties and the processing conditions …”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Viscoelastic Welding Flow

Masanori

Keiichi

Kazuo

et al. 2001

Journal of Textile Engineering

View full text Add to dashboard Cite

In the polymer processing, weld-lines often occur and cause the degradation of the mechanical and optical properties of products. These properties are degraded when the polymer molecules near the weld-line highly orient owing to the elongational flow and the orientation is fixed by solidification of the polymer melts before it returns to a random condition. In the present paper, the viscoelastic welding flow was numerically calculated for analyzing the molecular orientation in the weld-line region. The numerical simulation of the flow around a spider supporting a mandrel was carried out using the single-mode Giesekus model as a constitutive equation. The effects of the spider shape and viscoelastic properties of polymer melts on the anisotropy of the molecular orientation at the weld-line were analyzed. The calculation was carried out for three spider shapes, i.e. the spider-rear-end-angle 9=300, 45°, and 60°. The numerical results showed a simple modification of 9 suppressed the elongational rate, the stress, and the maximum value of the degree of the molecular orientation near the spider rear end, where the weld-line occurred. When the Weissenberg number is large and the influence of shear-thinning is great, the maximum value of the elongational rate was sensitive to 9. Especially at large Weissenberg number (=2.4), the elongational stress was reduced more effectively using the spider of the case that O600.

show abstract

“…Durchbrüche und der verarbeitungstechnische Zwang zu mehreren Anschnitten bewirken dabei häufig unvermeidlich, daß der Schmelzestrom während des Formfüllvorgangs geteilt wird und die Teilströme weiter hinten im späteren Formteil wieder aufeinandertreffen 1,2) . Solche Bindenähte können oft mechanische Schwachstellen des Formteils sein 3) .…”

Section: Introductionunclassified

Untersuchung zur Vorhersage der Bindenahtfestigkeit in spritzgegossenen Formteilen

Haufe

Mennig²

1999

Angew. Makromol. Chem.

View full text Add to dashboard Cite

Bindenähte in spritzgegossenen Kunststoff‐Formteilen sind oft mechanische Schwachstellen des Formteils, die günstigerweise bereits bei der Auslegung besonders berücksichtigt werden sollten. Untersucht wurden die Auswirkungen von Material, Düsen‐ und Werkzeugtemperatur sowie Einspritzgeschwindigkeit auf die Bindenahtfestigkeit. Durch Berechnung der wahren Massetemperatur an der Bindenaht konnten die wechselwirkenden Einflüsse der Verarbeitungsbedingungen mit einer gemeinsamen Gesetzmäßigkeit erfaßt werden. Eine Analyse der physikalischen Zusammenhänge ergibt, daß im Prinzip die molekulare Beweglichkeit an der Bindenaht während des Herstellprozesses maßgeblich ist. Diese Beweglichkeit kann über die Massetemperatur abgeschätzt werden. Dadurch ergibt sich eine experimentell abgestützte Methode, mit der die Bindenahtfestigkeit verschiedener Materialien in Abhängigkeit von den Verarbeitungsbedingungen vorausberechnet werden kann.

show abstract

Weld Lines in Polymer Processing

Cited by 42 publications

References 13 publications

Weldline integrity of reinforced plastics: Effect of filler shape

Weldline integrity of reinforced plastics: Effect of filler shape

Numerical Analysis of Viscoelastic Welding Flow

Untersuchung zur Vorhersage der Bindenahtfestigkeit in spritzgegossenen Formteilen

Contact Info

Product

Resources

About