Meaning
Steel tooling used in high-temperature molding processes is subjected to cyclic heating and cooling that induces repetitive thermal stress. This cyclical stress eventually leads to cracks or degradation, a duration measured by the thermal fatigue life of the mold. It determines the number of injection cycles a tool can undergo before heat checking or surface failure requires the tool to be refurbished or replaced.
Material Choice
Toughness and thermal conductivity of the tool steel play a critical role in resisting cyclic thermal stress. High thermal fatigue life is achieved by using premium hot-work tool steels that resist tempering at elevated temperatures, which keeps the mold surface intact for millions of cycles. In contrast, lower-grade steels crack quickly under the same thermal loads.
Cooling Channel
Drastic temperature differences between the cooling water lines and the hot cavity surface accelerate the accumulation of thermal stress. Optimizing the cooling channel design to reduce these temperature gradients extends the thermal fatigue life of the tool, minimizing unplanned production stops.
Cost Prevention
Tooling failures disrupt production and increase the cost of mold maintenance. Specifying high-quality tool steels and controlled heating schedules protects the mold from premature cracking, securing the long-term profitability of the molding project.
