Long, A., Thornhill, D., Armstrong, C., and Watson, D., "The Impact of Die Start-Up Procedure for High Pressure Die Casting," SAE Int. J. Mater. Manf. 6(3):416-426, 2013, doi:10.4271/2013-01-0829.
Die pre-heating has a beneficial effect on die life, by reducing thermal shock and stress fluctuations on the die surface. The findings from this paper indicate that the die surface stress decreased by 44% when the die is pre-heated to 150°C, and decreases by 57% when the die is pre-heated to 200°C, in comparison to when the die is started "cold" with an initial temperature of 20°C.Changes to the die start-up procedure, by switching off the die internal water cooling for the first four casting cycles, results in the die heating to operating temperature in fewer casting cycles, resulting in fewer castings being scrapped before the die achieves steady state operating temperature. From this, a saving of four castings per start-up can be made, reducing scrap by 4.5%, leading to lower manufacturing costs, reduced energy usage and increased useful die life. The modified die start-up procedure had a negligible effect on the die surface stress fluctuation, with a beneficial reduction in scrap.The process improvements which were run to improve die life, show that by modifying the die start-up procedure, the scrap rate can be reduced making the process more profitable.