Die defects are the main root problem of many extrudate material defects in extrusion process. Die defects can cause undesirable scraps on production and decrease efficiency of production type. To decrease production scrap rates we must control the process that effects scrap rate directly. There is various types of die defects that effects scrap rates such as die-swelling phenomena, die-plating effect, dead-zone problems, hungry-horse issues, wave-effect etc. To overcome scrap rate issues on extrusion process we have established a numerical simulation methodology to our extrusion process. This methodology contains non-newtonian material definitions and modellings, obtaining boundary conditions with process conditions, defining initial conditions, measuring outcomes and making cross-checkings to be assure right conditions defined. In a summary to achive extrusion scrap rate reduction we need to gather those values and implement them to our simulation methodology; 1. Rheologically investigated EPDM material definitions to the numerical calculation softwares. Our EPDM compounds producing in-house. To define numerical simulation softwares we need to gather rheology of compounds(viscosity – shear rate curves), thermal conductivity & specific heat of compounds, wall-slip velocity, density of material, best-fit non-newtonian material model. 2. Process conditions as boundary & initial conditions. Process conditions are extruders capacity&outputs, temperature of compound inside of extruder, pressure of compound that pushing towards extruder, die temperature, viscous melt compound temperature and pressure, extrudate material temperature, extrudate material shape factor, heater capacity & power, traction speed of extrudate material. 3. Defining gathered rehological and termophysical properties to numerical simulation softwares with boundary and initial conditions. Numerically investigating experimental test equipments in simulation softwares and making on-site experiments to corralate simulation results between experimental test results. Correlation includes temperature and pressure of viscous melted fluid, extrudate material temperature, die temperature, mass flow output of extudate material.