Abstract: For the cracking problem of chair parts, it was found that the injection molded parts had the downward deflection warpage under the original conditions by the simulation analysis of Moldflow. The largest warpage reached 1.6 mm. A quantitative calculation showed that the frictional force between the injection molded parts was greater than 14 kN. It was deduced that the process conditions and mould structure factor were the reason of cracks on the injection molded parts. Finally, by optimizing process parameters and changing the original mould structure, the problem was solved.

Key words: injection molded chair part, crack, Moldflow, mould structure