Complete Guide to Injection Molding Temperature and Mold Temperature Settings for TPE and TPV

Thermoplastic elastomers including TPE and TPV are widely used in automotive parts, electronics, daily necessities, sealing components, and handfeel soft-touch products due to their excellent elasticity, processability, and environmental performance. However, the two materials differ significantly in molecular structure, rheological behavior, and thermal stability, so their injection molding temperature and mold temperature settings must be precisely controlled to ensure stable production, qualified appearance, and reliable mechanical properties. Improper temperature settings can easily lead to defects such as poor flow, burning marks, bubbles, weld lines, sticky mold, deformation, and performance degradation, which seriously affect production efficiency and product yield.

For barrel temperature settings, a gradient pattern from rear to front is recommended. The rear zone is set at 150–170℃ to avoid premature melting and bridging, ensuring smooth feeding. The middle zone is set at 170–190℃ to complete melting and mixing, allowing additives and color masterbatch to disperse evenly. The front zone is set at 180–200℃ to improve melt flowability for better cavity filling. The nozzle temperature is controlled at 170–190℃, slightly lower than the front zone to prevent drooling and stringing. Soft TPE with hardness below 50A should use lower temperatures, while hard TPE above 50A can adopt higher temperatures. Transparent TPE requires strict temperature control between 180–190℃ to avoid yellowing.

Actual melt temperature should be stabilized at 160–210℃. Low temperature results in high viscosity, insufficient filling, rough surface, and obvious weld lines. Excessively high temperature above 210℃ causes molecular degradation, volatilization of plasticizers, yellowing, odor, reduced elasticity, bubbles, and black spots. Real-time monitoring with an infrared thermometer is essential to avoid deviations between displayed and actual temperatures.

Mold temperature for TPE is generally 20–40℃ to achieve rapid cooling, short cycle time, and easy demolding. Excessively low mold temperature causes poor surface quality and insufficient filling. Excessively high mold temperature above 50℃ extends cooling time, increases production cost, and causes sticky mold and deformation. For high-gloss, transparent, or overmolded parts, mold temperature can be increased to 40–50℃ to improve surface finish and bonding strength, but the cooling system must be optimized accordingly.

Barrel temperature is set in a stable gradient: rear zone 170–180℃, middle zone 180–190℃, front zone 190–210℃, and nozzle 185–195℃. The temperature must not exceed 230℃, as the crosslinked rubber phase will degrade rapidly, leading to brittle fracture, poor elasticity, and severe oil resistance reduction.

Melt temperature should be maintained at 180–220℃. Below 180℃, melt viscosity is too high for proper filling. Above 220℃, thermal decomposition occurs with strong odor, gas generation, and internal bubbles. High-hardness TPV can approach the upper limit, while low-hardness grades should use lower temperatures.

Mold temperature is typically 30–50℃, higher than TPE to balance flow and demolding. Too low mold temperature causes poor surface finish and weak weld lines. Too high mold temperature leads to excessive shrinkage, dimensional instability, and deformation. For thick-walled industrial parts, mold temperature can be increased to 40–60℃ for better filling performance.

3. Core Differences and Practical Tuning PrinciplesTPE features a wide temperature window and low sensitivity, while TPV is narrow and sensitive. TPE favors low-to-moderate mold temperature, and TPV requires slightly higher mold temperature. Both materials benefit from gradient barrel temperatures, stable mold temperature control, and temperature adjustment based on product thickness and hardness. The fundamental principle is to start from lower temperatures during trial production and gradually optimize to avoid overheating and material degradation.

In actual production, temperature parameters must cooperate with injection speed, holding pressure, and cooling time to achieve stable molding. Only by comprehensively controlling temperature conditions can manufacturers reduce defects, improve consistency, and achieve efficient mass production of TPE and TPV products.