Instron's HDT and Vicat systems provide reliable, standardized methods for evaluating how plastic materials behave when exposed to elevated temperatures. These instruments measure two key thermal properties essential for material selection and quality control: Heat Deflection Temperature (HDT), which indicates the temperature at which a material deforms under load, and Vicat Softening Temperature, which identifies the point at which a polymer begins to soften. Together, these tests help manufacturers and researchers understand a material's thermal limits, ensure compliance with international standards, and predict performance in real-world applications where heat resistance is critical.