Strength improvement of leather bracelet by utilizing experimental design

Abstract

This research aims to improve tensile strength of leather bracelet chain with a target of the tensile strength is greater than or equal to 78 newtons. This research started with brainstorming and analysis by jewelry experts. Next, the Cause and effect diagram was used, then all the factors were analyzed with Cause and Effect Matrix, as well as an analysis of the defects and effects by Failure Mode and Effects Analysis. According to the Risk Priority Number, the number was classified and showed on a Pareto Diagram. Consequently, the factors that account for 80 percent are a ratio of glue mixing Resin to Hardener, the amount of glue and the size of crimp tool. It seems that there is a significant influence on the tensile strength; therefore, the researchers brought these factors to design an experiment. In addition, the 3k factorial experimental design was used as a method in this research. The experiments were tested 3 factors, each factor at 3 levels. Also, the experiments were replicated and a total number of the experiments was 54 experiments. Each experiment was tested with 10 pieces. After data collection and analysis, the result showed that an appropriate factors level with highest tensile strength used in standard-setting was a ratio of glue mixing Resin to Hardener as 1 : 0.6, the amount of glue as 12 grams and the size of crimp tool as 2.7 millimeter. Moreover, the result from this experiment was used in assembly process for a leather bracelet chain and it was found that the average of tensile strength was 111.40 newtons. It can be concluded, an increasing on tensile strength causes a reduction of assembly failure 58.46 percent.