To make good parts, except mould design ,also need to consider plastic material,mould structure and machine parameter. 1）Soft material to use for overmolding ,we call it TPE(thermoplastic elastomer) generally, it includes TPS/TPE,TPR,TPV,TPU,TPO,TPEE,TPAE,SBS,SEBS,but usually just name TPS (a mixed material by SBS and SEBS )as”TPE”in a narrow sense.because it is used most widely. 2）It is critical to consider SP(solubility parameter)of soft and hard plastic.they are more similar more better ,then the two materials can fuse more tighter. 3）To communicate with professional material supplier enough about part function and working enviroment ,decide suitable material because the physical property is much different in differenct material,here list some frequently-used TPE material as below. 4）In addition,it is necessary to control machine parameter, sometime,we often meet soft material lack in the molded part,so we need to enhance mould tempreture and pressure to make soft material fuse enough with hard plastic.If meet soft material overflow ,we need to lower mould tempreture,at the same time enhance mould clamping force.professional experience is important !