Understanding the melt temperatures of plastics is crucial for successful injection molding. For example, acrylic has a melt temperature range of 220-250°C (428-482°F), while HDPE ranges from 210-270°C (410-518°F). Mold temperatures, such as 122-176°C (252-349°F) for acrylic and 68-140°C (154-284°F) for HDPE, ensure proper cooling and solidification of the plastic within the mold. These temperatures play a critical role in achieving consistent, high-quality molded products by influencing flow, cooling rates, and material properties.