Cycle time is one of the most critical parameters determining production efficiency in plastic injection applications. The cooling phase, which constitutes 50–70% of the total cycle time, directly affects production capacity, and problems arising during this phase threaten the efficiency of the entire line. Using a dehumidifier permanently solves one of the most common problems in plastic injection facilities, mold sweating.
Why Does Mold Sweating Occur?
During cooling, cold water passing through the injection mold brings the mold surface temperature below the ambient dew point. When the mold surface stays below the dew point, water vapor in the air condenses on the surface and becomes liquid, a phenomenon known as "mold sweating." When cooling water temperature is raised to prevent condensation, the cooling time increases and the cycle time grows longer.
Negative Effects of Mold Sweating
- Loss of Production Efficiency: Raising cooling water temperature extends the cycle time and reduces the number of parts produced per shift.
- Mold Damage: Continuous moisture contact from condensation causes rust and corrosion on mold surfaces, shortening mold life and increasing maintenance costs.
- Product Quality Issues: Moisture on the mold surface, when in contact with injected plastic, can cause surface defects, color deviations, and structural weaknesses.
- Occupational Safety Risk: Water accumulating in the mold area can cause floor slipping and damage electrical equipment.
Solution with a Dehumidifier
By using industrial dehumidifiers, the mold area is continuously supplied with air at a low dew point. As long as the ambient dew point is kept below the cooling water temperature, condensation on the mold surface becomes physically impossible. This allows cooling water to be used at optimal low temperatures, shortening the cooling time and reducing cycle time.
Benefits Achieved
- Shorter Cycle Time: Since cooling water can be used at optimal temperature, cycle time shortens and production capacity increases.
- Extended Mold Life: With rusting and corrosion eliminated, mold maintenance intervals are extended and the total mold investment gains value.
- Improved Product Quality: Moisture-related surface defects are eliminated, reducing scrap and rework rates.
- Labor and Maintenance Savings: The need for labor to continuously dry and clean molds is eliminated.
For more information about dehumidifier systems for your plastic injection facility, please fill out the contact form below to get in touch with NKT – Humidity Control Technologies and receive support from our specialist humidity control engineers.
