Pinhole Reduction of Glove and Motion Design for Uniform Coating of Glove

Chin, Louis Chun Kai (2022) Pinhole Reduction of Glove and Motion Design for Uniform Coating of Glove. Masters thesis, Tunku Abdul Rahman University of Management and Technology.

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Abstract

The conventional and standard glove production line is a continuous chain dipping system where most stations and parameters are interdependent. Therefore, it is not flexible, giving rise to difficulties in studies involving changes to the line design, parameters, and etc. To tackle this problem, a Malaysia glove company, Top Glove Sdn. Bhd., is developing a flexible robotic-arm-based discrete pick and place dipping system for research & development purpose, the system is known as Research & Development Robotic Simulator (RRS). However, due to differences in mechanism between the conventional production line and RRS, gloves produced by RRS have several defects. This project aims to tackle 2 of the defects found on RRS gloves, which are pinhole and uneven glove thickness. The approaches taken is system design-based and manufacturing process-based rather than chemical-based as the chemical used is sourced directly from the production line. Literature review have been done on pinhole and bubble formation, bubble reduction methods, uniform film coating methods, pinhole detection methods, and thickness uniformity measurement method. A new coagulant tank design with different heating system and circulation system is proposed and fabricated to reduce bubble in the coagulant, and therefore reducing pinhole on gloves. Solidworks Flow Simulation is used to conduct Computational Fluid Dynamic (CFD) analysis on the tank heating design. The new coagulant tank is able to reduce the number of gloves with pinhole from 8 out of 40 gloves (20%) to 0 out of 40 gloves (0%). Effect of increasing dipping/withdrawal speed of latex dipping on thickness uniformity is studied. The standard deviation of thickness is used as a measurement of thickness uniformity, the lower the standard deviation of thickness, the more uniform it is. Result shows increasing dipping/withdrawal speed of former from 18.5mm/s to 200mm/s can reduce the standard deviation of glove thickness by 22.1% to 48% depending on region, improving the glove thickness uniformity. A former motion is added post latex dipping to improve latex film coating uniformity on the former. By increasing the duration of this motion from 0 second to 45 seconds, the standard deviation of glove thickness is reduced by 18.3% to 38.6% depending on region. Principal Component Analysis (PCA) is used to determine the extent of improvement of each method on the thickness uniformity on different region of the glove. At the end of this project, all 4 research objectives are achieved. Future works include studying angle of the rotating motion and its effect on glove thickness uniformity, sequence of rotating motion and its effect on glove thickness uniformity, and etc.