Analysis of shrinkage by dual kriging for filled and unfilled polypropylene molded parts

Abstract

This paper examines, through holding pressure, packing time, melt temperature, mold temperature and distance from the gate, the effect of molding conditins on the shrinkage of polypropylene and 40% calcium carbonate (CaCO3) filled polypropylene. The shrinkage longitudinal and transvrse to the flow direction were determined using a 127 × 76 × 4 mm thick plaque with a film gate. Marks were made ont he mold cavity to measure shrinkage at various distances from the gate. The results show that holding pressure and packing time are the most significant parameters. Cooling runners, however, could significantly influence local shrinkage values. Calcium carbonate reduces the shrinkage anisotropy as well as the cycle time of the molded parts. Shrinkage models have been developed using dual kriging statistical interpolation techniques and show an excellent fit with experimetnal data.

Effect of Melt and Mold Temperatures on the Solidification Behavior of HDPE during Gas‐Assisted Injection Molding: An Enthalpy Transformation Approach

“…As a consequence, the time for the melt to stay above and within the phasechange temperature range is sufficient, and more time is given for the growth of spherulites from the melt. [45] Thus, both crystallinity and shrinkage (due to crystallization) are high, and the latter in turn results in the TCR, which should be responsible for the deviation between simulations and measurements. Table 3 shows the comparison of the experimental cooling rates (estimated according to ref [46] .)…”

Investigation of the microstructures, properties, and toughening mechanism of polypropylene/calcium carbonate toughening masterbatch composites

“…They were stored at 23 °C for a week before the measurements. The formula of the shrinkage in percentage is given as follows: where L 0 is the length measured in the mold cavity and L is the length of the specimen.…”

“…They were stored at 23 8C for a week before the measurements. The formula of the shrinkage in percentage is given as follows 25 :…”

Injection molding shrinkage of PP: Experimental progress

“…Local and anisotropic shrinkage have been measured at the surface of injection molded parts mostly by optical methods. Jansen et al [1] and Schift et al [3] used microscopes, Régnier and Trotignon [2] employed a camera, Liao et al [4] a scanner and finally, Mamat et al [5] employed a profile projector for this purpose. Shrinkage in the thickness direction has also been measured using mechanical means such as micrometers [6] and coordinate measuring machines [7,8], which are more appropriate for this type of measurements.…”