Modeling of Flexible Polyurethane Foam Shrinkage for Bra Cup Moulding Process Control

Abstract

Nowadays, moulding technology has become a remarkable manufacturing process in the intimate apparel industry. Polyurethane (PU) foam sheets are used to mould three-dimensional (3D) seamless bra cups of various softness and shapes, which eliminate bulky seams and reduce production costs. However, it has been challenging to accurately and effectively control the moulding process and bra cup thickness. In this study, the theoretical mechanism of heat transfer and the thermal conductivity of PU foams are first examined. Experimental studies are carried out to investigate the changes in foam materials at various moulding conditions (viz., temperatures, and lengths of dwell time) in terms of surface morphology and thickness by using electron and optical microscopy. Based on the theoretical and experimental investigations of the thermal conductivity of the foam materials, empirical equations of shrinkage ratio and thermal conduction of foam materials were established. A regression model to predict flexible PU foam shrinkage during the bra cup moulding process was formulated by using the Levenberg-Marquardt method of nonlinear least squares algorithm and verified for accuracy. This study therefore provides an effective approach that optimizes control of the bra cup moulding process and assures the ultimate quality and thickness of moulded foam cups.

Compressive Behavior of Aluminum Microfibers Reinforced Semi-Rigid Polyurethane Foams

“…In recent years, different techniques have been developed for manufacturing flexible [22,23] and rigid [24,25,26] PMs with closed, open, or mixed (partly open and partly closed) cells. Also, the effect of different reinforcements (particles, fibers, etc.)…”

Study on realizing the personalized customization of bra cup by solving the inverse problem of bra cup design

“…14 Therefore, the design of a suitable cup is vital to accomplish the personalized customization of the molded cup bra. 15,16 The conditions for the cup pressing process have been extensively studied. 17 In a related study, Yip and Ng 18 identified the optimal molding conditions for each spacer fabric by thermomechanical analysis (TMA).…”

“…Wu et al. 19 optimized the bra cup molding process by employing the Levenberg–Marquardt non-linear least-squares algorithm. These studies provide the scientific explanation and theoretical foundation for the molding of the cups.…”