Multiparametric study of Leidenfrost point and wettability of lubricants on high-pressure die-casting dies

This work is aimed at improving the lubricant film formation on the die surfaces in high-pressure die-casting (HPDC) pursuing enhancing cooling, temperature homogenization and casting release. An original test procedure was employed to study the Leidenfrost point (LFP) and the contact angle (CA) of various lubricants on die steel grades in the temperature range from 20 to 320 °C. The effects of various parameters such as steel grade, surface roughness, ageing, temperature, droplet size, water hardness and lubricant concentration on LFP and CA were isolated and analysed. It was found that the LFP remarkably increased for aged die surface with fine grains and relatively high roughness. The CA was affected mainly by the type of the lubricant. These findings lay the ground for optimal selection of the HPDC lubrication depending on the specific operating conditions.