中華商用車貨床之側板及底板於1998年採用塑化纖維材質，然而生產中易發生尺寸控制不易及外觀瑕疵等問題，不良率往往高達5成以上，造成相當沈重的品質及成本負擔。
本文係針對不良率問題逐一介紹，並導入電腦輔助工程分析，採用Moldex模流分析軟體，經由分析結果，探討問題造成之主因，並提供改善對策，進而與現場驗証；同時，利用電腦輔助工程分析結合田口式品質工程分析，建議最佳成型參數組合。
另外，利用毛細管流變儀、PVT-100量測儀，量測黏度(Viscosity)及PVT，了解人造代木材加入二次料其材料物性變化，最後，探討國內外針對PS回收之方法，以達充分回收之目的。
研究結果顯示，經由Moldex分析結果與現場驗証，可獲得下列三點結論：
1.體積收縮率之改善比率可有效評估產品瑕疪。
2.適度改變材料性質，如黏度及PVT等，發現有大幅降低體積收縮率不均問題。
3.經由田口式分析最佳組合之加工參數，採用較低螺桿轉速、低料溫及高模口溫度，可獲得最佳均勻體積收縮率。

Continuous Glass Fiber Reinforced Extruded Polystyrene Foam Composites have been applied to the side plate and base plate of the loading bed of CMC Trucks in 1998. However, the defect rate, which was higher than 50 percent, often caused heavy burden on quality and cost. Defects included size control and appearance flaw.
These problems caused to production low yield were detailed disclosed in this paper. In order to understand the root causes to these defects, CAE methodology and Moldex mold flow analysis software were applied adopted. By analyzing simulation result, root caused have been found out. In order to solve these problems, some improving methods have been provided, and spot inspection have been executed for verification. In this paper, the optimal forming parametric matrix is also provided using the combination of CAE analysis and Taguchi Methods.
Furthermore, Capillary Viscometer and PVT-100 meter were used for measuring Viscosity and PVT to develop further understanding of the physical change after recycled material was added to the artificial alternate wood. Finally, international and domestic PS recycling methods were explored for meeting the aim of full recycling.
By means of Moldex analysis and spot inspection, the findings are concluded as followings:
1.The improvement of the volume shrinkage rate could effectively evaluate the product defects.
2.Proper change of the material property, for instance, PVT, could effectively reduce the problem of disproportionate volume shrinkage.
3.Analyzing the best process parameter by means of Taguchi Methods with lower screw rotation rate, low material temperature, and high mold temperature could attain the optimal proportionate volume shrinkage rate.

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