Investigation of Thermoforming Tool Design and Pocket Quality

Thermoforming is widely used in manufacturing industries to produce a range of polymer products. The Reflex tape thermoforming system is designed to form flat tape film into pockets. These formed pockets, also called carrier tape, are used in numerous applications to package a large variety of electronic or small mechanical parts. Thermoformed pocket walls are generally not uniform in thickness and often break during the forming process. Uniform wall thickness distribution, especially for deep pockets, plays significant role on pocket quality improvement and scrap reduction. This paper investigates the influence of the tool design, tool material, and some thermoforming process parameters on wall thickness distribution in formed pockets using polymer flat films. Conventional tool and a hybrid tool with 3d printed inserts were used in the experiments. The process parameters, plastic film and tool set temperatures were controlled by the Reflex machine and also measured using infrared thermometer and thermocouple. Film temperature ranges from 150 to 200 °C and a range of tool set temperatures (40 to 85°C) were used in the thermoforming. It has been found that the temperature difference between the plastic film and the forming tool was important for uniform wall thickness distribution. The results from this experimental study concluded that the most influential factors for good pocket quality are the tool design, tool material, and heat transfer dynamics in the plastic film - tool set system. Another aim of the study was to investigate the viability of the 3D printing process to manufacture rapidly tool inserts compared to conventional CNC machining.