Visualization of Injection Molding

Abstract

Even though it is considered a mature technology, the commercial importance of injection molding continues to drive research on how processing parameters impact final part characteristics. In particular, the influence of flow phenomena, which largely control molecular orientation within the mold cavity, is not fully understood. Results are presented from a study of polymer flow during injection molding using a clear mold that allows optical access from three sides, in a standard commercial machine, under standard molding conditions for polystyrene. Comparisons are drawn between the experimental results and the predictions of a commercial code for global mold filling properties.

Simulations and measurements of in‐mold melt flow during the injection molding of polystyrene

“…Polystyrene was chosen for this study because it was transparent, easy to mold, and commonly used in industry. The mold also allowed visualization of the flow through the 109.5 mm × 66.7 mm face of the cavity [16]. A CCD camera with a resolution of 600 × 480 pixels and a frame rate of 30 Hz was used to make digital movies of the mold filling process.…”

“…Recently, real time velocity vector field data for polystyrene flowing into a corner‐gated rectangular mold have been reported [15], and the present study follows from this prior effort. An optical access mold was constructed that allowed passage of a laser sheet through the midplane of the mold [16]. STYRON 615APR was seeded with 0.02% by weight aluminum flakes and digital particle velocimetry (DPIV) [17] was used to extract the time‐varying velocity field at the midplane of the mold.…”

Particle image velocimetry in molten plastic

“…The heart of the molten‐plastic flow‐field measurement scheme was an optical access mold, specially designed for this experiment and described previously [14]. Themold was constructed from a mild tool steel mold base.…”

Capacitive transducer for in‐mold monitoring of injection molding

“…Yokoi et al (3Ϫ6) were perhaps the first to succeed in observing the melt flow in a mold by flow visualization through glass inserts fitted on the mold wall. This technique was modified by Bress and Dowling (7) for observing the surfaces of large parts. This kind of visual technique, using glass inserts, allows direct observations of the melt flow status, typically using a high-speed camera.…”