Using Design of Experiments to Reduce Defects of Painting Process of Grille
|摘要:||本次實驗對象為汽車水箱護罩。為迎合消費者喜好，汽車零件製造商會將塑膠塗料塗裝在汽車水箱護罩上，以提升光澤、遮蓋射出成形時的瑕疵並增加金屬質感，進而影響消費者的購買意願並提升商品的價值。但台灣汽車零件製造業已進入微利時代，塗裝品質不良會增加水箱護罩不良品，輕微之塗裝不良狀況經過整修後可再點交予汽車製造廠客戶端進行組裝，不良狀況較嚴重之水箱護罩則必須直接報廢，對於一家汽車零件製造廠而言，這是相當龐大也無謂的成本浪費。在塗裝製程中，烘烤時間、烘烤溫度、噴槍壓力及各種參數及環境設定都會影響塗裝品質。為協助A公司降低塗裝不良缺點並提升塗裝良率，本研究透過實驗設計方法(Design Of Experiments ,DOE)，找出塗裝製程中影響品質之顯著因子，透過變異數分析(Analysis of variance ,ANOVA)，發現適當的烘烤溫度及增加噴漆房的清潔次數有助於降低塗裝品質之不良缺點數，並提升良率。
The purpose of this study is to test the effect of painting on the grille. In order to meet consumers’ preference, auto parts manufacturers paint the plastic-coating on the grille to improve gloss, cover injection defects and increase the metal texture. The improvement of the grille may affect consumers' willingness to buy and increase the value of the goods. The auto parts industry in Taiwan has entered the era of little profit. The poor quality painting on the grille will increase defective products. For example, if the grille painted has slight defect, these parts will be delivered to automobile assembly factory to refurbish; the other serious situations of painting on the grille will be scrapped. The defect for painting may increase tremendous cost for an auto parts manufacturer. The time of baking, temperature of baking, pressure of nozzle, and any other setting in the painting process will affect the painting quality. In this study, we use design of experiment (DOE) to find distinct factors which affect quality more of the process to help this company to reduce defect amounts of their products. Analysis of variance(ANOVA) was applied to find that the number of defects will be decreased if the parts baked moderately and cleaning frequency of Spray booth increased. The goal of this study is to help the company to find the optimum parameter improved painting yield quickly and reduce the cost of produce and rework. This study may also provide as a reference to improve painting quality and process improvement of cost reduction for auto parts manufacturers.