Assessment of Porosity Defects in Sand Metal Casting Process A Case Study at Tanzania Automotive Technology Centre.

Porosity defects reduce mechanical performance and cause much reject in TATC.The purpose of this paper was to identify the porosity causes at the TATC and examine effects of pouring temperature, permeability of sand and rate of solidification through sequential mixed-methods and ANSYS numerical simulation approach.Porosity was reduced from 6.8% at 1200 °C to a minimum of 3.4% at 1440 °C before increasing back to 5.2% at 1600 °C.A range of sand permeability from 80 to 140 lowered porosity from 5.1% to 2.2%.Increasing the solidification rate from 0.8 °C /sec to 2.0 °C /sec resulted in a reduction from 5.5% to 1.9% porosity.The study selects at approx.1440 °C as the best pouring temperature.To reduce defect, the suggestions are controlling temperature, making higher sand permeability, strengthening solidification, and using more simulation, and it needs further experiment to verify these ideas.