Real-time diagnosis of co-injection molding using ultrasound

• Published in: Polymer engineering and science Vol. 47; no. 9; pp. 1491 - 1500
• Main Authors: Cheng, Chin-Chi, Ono, Yuu, Jen, Cheng-Kuei
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-09-2007; Wiley Subscription Services; Society of Plastics Engineers, Inc; Blackwell Publishing Ltd
• Subjects: Applied sciences; Evaluation; Exact sciences and technology; Injection molding; Injection moulding; Machinery and processing; Molds & molding; Moulding; Plastics; Polymer industry, paints, wood; Polymers; Real-time control; Real-time systems; Technology of polymers; Thickness measurement; Ultrasonic imaging; Ultrasonic waves; Viscosity; United States; Process control; Pressure control; Experimental study; Real time; Optimization; Thickness measurement; Non destructive method; ABS; Quality assurance; Sandwich molding; Flow control; Injection molding; Polycarbonate; Ultrasonic method
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.20852

Co‐injection molding, also known as sandwich molding, is a process in which two or more polymers are laminated together in a mold cavity. Integrated ultrasonic sensors embedded into a mold insert of a co‐injection‐molding machine have been used for real‐time, nonintrusive, and nondestructive diagnosis of co‐injection‐molding processes. Diagnosis of core arrival, core flow speed, part solidification, part detachment from the mold, thickness of skin and core, and core length at the mold was demonstrated. It is found that core flow speed and peak cavity pressure monotonically increased and decreased with the core volume percentage, respectively. Thicknesses of the skin and core of the molded part were estimated using the presented ultrasonic technique during molding with an accuracy better than ±17%. In addition, the core length had correlation with core thickness, core flow speed, and peak cavity pressure. Among them, the core thickness measured by the ultrasonic technique had the better correlation. This technique enables process optimization, the maximum process efficiency, and in‐process quality assurance of the molded parts. POLYM. ENG. SCI., 47:1491–1500, 2007. © 2007 Society of Plastics Engineers