Process control and quality improvement of plug-assist thermoforming process : a case study

Abstract EN

Problem recognition was obvious to the management body of the disposable cup factory as looking at the scrap bin and realizing that some specific part of the process is causing substandard and defected products.

Fourteen types of defects were recognized and the problem solving approach combined with quality control charts and tensile testing was used to solve the problem and called Thermo-mechanical approach (TMA).

The results of the TMA showed that an uneven distribution of temperature after preheating is the most effective variable in increasing the number of defects.

Changing the design of the heating system from free convection to forced convection by adding fans helped in overcoming the heat distribution problem.

An optimum temperature of 171 0C of the heating elements was also determined to give the best productivity results.