Journal of the Chinese Society of Mechanical Engineers

CSME 2024/06
Volume 45 No.3 : 219-228

A Method of Reducing Tolerance Stack-Up For Parts Assembling of Molds

Yuo -Tern Tsai^a and Chun-Sheng Chen^b
^aDepartment of Mechanical Engineering, Hungkuo Delin University of Technology, 236, Taiwan, R.O.C.
^bYCI Industrial Co., Ltd.

Abstract: Allocating appropriate tolerance to the components to meet the functional requirements of products is an important task in the design phase. This article introduces the methods of tolerance analysis including tolerance marking for improving the assembly precision for injection molds. The influences of modification symbols of geometric tolerance are reported to support tolerance designing. The dimensional chains of the mold are constructed for performing tolerance analysis and design improvements. The statistical methods of tolerance analysis are used to evaluate the unqualified rates of the mold under different tolerance designs. The unqualified rates are estimated based on the precision requirements and the natural tolerances of the manufacturing capability. A method of assembly positioning is proposed for the mold to reduce the stacked tolerances as well as improving its assembly precisions. The studied results show that the total tolerances of the mold can be reduced by the modified designs. The unqualified rates of the mold can be improved from 5.76% to 3.38% for the sane precision requirements and the tolerance designs. The study offers a systematic method of tolerance designing and analysis to ensure the designed tolerances satisfying the functional requirements.

Keywords: tolerance, positioning, mold.

*Corresponding author; e-mail: yttsai@mail.hdut.edu.tw

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