A study of warpage and weld line defects on a plastic composite’s manhole cover

Abstract

Manhole covers are generally made out of cast iron in order to bear the large loads [1]. This study is about choosing and identifying the most suitable plastic composites material which can best replaced cast iron The plastics composites must be high durability and low cost. Besides that, the effects of parameter which causes warpage and weld line also must be done to identify the most suitable plastic composite material. Therefore, the goal of this project is to achieve the parameter’s combinations which are able to minimize causes of warpage and weld line on plastic part. This project is begin with the design concept of the manhole cover which is suitable with the new material of plastic composite material condition and identifying all factors which may effects warpage and weld line defects responses. Then, the experiment is held by using Moldflow Plastics Insight (MPI) software. Eight parameters have been chosen included the filling time, mold surface temperature, melt temperature, cooling time, packing time, packing pressure, injection time, and injection pressure. This project begins with the Design of Experiments (DOE) by applying Taguchi Method with Orthogonal Array 1 7 L18 2 3 . The results from eighteen trial experiments are analyzed to get the optimum condition and estimate values of warpage and weld line values. The last steps in this project is the confirmation test to see the difference or how far the actual value error percentage from the predicted value. All the results have been discussed in Chapter 4.