Prediction of Wall Thickness Distribution in Simple Thermoforming Moulds

Abstract

Thermoforming is widely used in manufacturing industries to produce large and labour-intensive products. Compared to other manufacturing techniques, thermoforming is an extremely efficient process that is suitable for high-efficiency mass production. In this paper, experimental thermoforming operations were carried out using a lab-scale, sheet-fed thermoformer. Carbon fibre-reinforced PP and unreinforced PS thermoplastic sheets were used in experimental thermoforming operations. The processing parameters were determined for each thermoformed material. Furthermore, a simulation of the thermoforming process was performed using LS-Dyna TM software. The thickness distributions obtained from the experiments were compared with the simulation results. The results show that the parameter that most affects the wall thickness distribution is the geometry of the clamping ring. To produce thermoformed products that have a more uniform thickness distribution, the clamping tool geometry must be selected according to the geometry of the product being thermoformed.

Evaluation of the Thickness and Oxygen Transmission Rate before and after Thermoforming Mono- and Multi-layer Sheets into Trays with Variable Depth

“…[2,[7][8][9]12,14,21]. To obtain commercially acceptable trays, processing parameters for each material were optimized based on stability and visual criteria of the formed trays.…”

“…However, various studies have shown that the OTR of the sheet material cannot easily be extrapolated to thermoformed packaging [4][5][6]. One of the reasons might be a poor control of the material thickness distribution in the walls, the corners, and/or the bottom, which is a major drawback of thermoforming [7][8][9]. On the other hand, the effect of physical thinning on the OTR can be partially neutralized by reorientation, closer chain packaging, and restriction of chain mobility of polymer chains in the amorphous zones during deep drawing and stretching of the material [10].…”

Dimensional and Geometrical Errors in Vacuum Thermoforming Products: An Approach to Modeling and Optimization by Multiple Response Optimization

“…• The parameters of heating influence all types of geometrical and dimensional errors in a more significant way, considering all their different levels. • In addition to mold characteristics [15], [36] the parameters of mold can influence geometric errors; • The interaction of two factors can influence the deviations of the product by reducing the value of dimensional errors, but a significant increase of geometric errors can occur; • The manufacturing parameters interact simultaneously with the errors in a non-linear and non-proportional model;…”

Experimental determination of the viscoelastic parameters of K-BKZ model and the influence of temperature field on the thickness distribution of ABS thermoforming

“…It was found that the friction coefficient of the sheet varying with temperature greatly influences the thickness distribution. Erdogan and Eksi [8] investigated the effect of circular and rectangular clamping tools to the thickness distribution. The side areas and bottom areas of the thermoformed products are significantly affected by the geometry of the clamping tool.…”