Designing Ergonomic Standing Chair for Computer Numerical Control Machine Operators using TRIZ

Abstract

In this research, the working hours and posture of CNC (Computer Numerical Control) machine
operators were investigated to determine the physical workload that they experienced during their
daily work. Based on our observations, the operator works 8-hour regular shifts or 12-hour long
shifts for 5 – 6 days a week. During these shifts, the operators work in front of the CNC machine
while standing upright without any tools to rest. Preliminary research was conducted to evaluate
these conditions the results show 13 out of 20 CNC machine operators complained about physical
fatigue while working the CNC machines. It can also be concluded that the operators are
experiencing excessive workload based on a workload assessment using the Quick Exposure Check
(QEC) method. To solve this problem, a standing chair is designed with ergonomics in mind. The
dimensions of the standing chair are based on the anthropometry of the CNC machine operators,
which was never used before. The design process is conducted using the Theory of Inventive
Problem Solving (TRIZ) methodology. Need statements from the CNC machine operators and
design requirements from the stakeholders are converted into design specifications using TRIZ
methodology. Parameters are determined to increase the capability of the existing design based on
the design specifications. The result of this research is a standing chair that is suitable for the
operator’s needs. Based on the analysis of the design result and the stress analysis simulation, it can
be concluded a functional standing chair can be ergonomically designed with the TRIZ
methodology.