The curing temperature and time for liquid silicone rubber (LSR) products produced using liquid injection molding (LIM) machines depend on the specific material formulation and part thickness. However, typical ranges are as follows:
Typical Curing Temperature
150°C to 200°C (302°F to 392°F)
Standard Range: Most LSRs cure efficiently between 170°C to 190°C (338°F to 374°F).
Lower temperatures (e.g., 120°C to 150°C) may be used for slower curing or delicate applications, though this increases cycle time.
Curing Time
5 to 60 seconds per mm of wall thickness
Thin Parts (e.g., 1–2 mm): 5–20 seconds.
Thicker Parts (e.g., 5+ mm): 30–60 seconds or more, depending on heat transfer within the mold.
Cycle Optimization: The curing time can be reduced by maintaining uniform heat distribution and ensuring proper mold design.
Factors Affecting Curing Temperature and Time
Material Grade:
Fast-curing LSR grades require less time at higher temperatures.
Specialty LSRs (e.g., medical or food-grade) might have specific curing recommendations from the manufacturer.
Mold Design:
Efficient heat transfer through the mold ensures faster and more uniform curing.
Thin-walled parts cure faster than thick sections.
Injection Parameters:
Proper injection pressure and flow ensure the material fills the mold quickly, minimizing curing delays.
Post-Curing (Optional):
For some applications (e.g., medical or food-grade), additional post-curing at 200°C to 250°C (392°F to 482°F) for 2–4 hours may be required to improve mechanical properties, remove volatiles, or meet regulatory standards.
Example Curing Schedule
Temperature: 170°C (338°F)
Part Thickness: 2 mm
Curing Time: ~20 seconds
For exact parameters, refer to the LSR manufacturer's technical datasheet, as formulations vary slightly in curing behavior.