Industry News

In the plastic processing industry, the drying process machine plays a crucial role in controlling the moisture content of raw materials and ensuring the quality of the final product. Proper operation procedures not only extend the lifespan of equipment but also help reduce energy consumption and minimize raw material waste. This article outlines the key steps for standardizing the operation of plastic dehumidifiers and dryers, focusing on three core areas.

1. Pre-Startup Preparation: Ensuring Safety and Effectiveness

Before starting the equipment, proper preparation is essential to achieve effective drying results. The first step is to check the moisture content of the raw materials. It’s recommended to use a halogen moisture analyzer with an accuracy of ±0.1%. If the initial moisture content exceeds 0.3%, it’s necessary to extend the pre-drying time.

Next, the hopper must be cleaned following a "two-channel" process: first, use compressed air at 0.6MPa to blow away any dust, and then clean the hard-to-reach corners with a non-woven fabric to avoid cross-contamination.

A critical step involves verifying the activation of the molecular sieve. If the equipment has been idle for more than 48 hours, place the molecular sieve in a 180°C constant temperature oven for 3 hours and check if the dew point stays below -40°C (installing a dew point meter for real-time monitoring is recommended). Some businesses have suffered significant losses due to neglecting this step, leading to bubbles in recycled PET materials even after drying.

2. Operational Control: Managing Temperature, Dew Point, and Airflow

Drying parameters should be adjusted based on the characteristics of different materials. For example, ABS materials are effectively dried at 80°C for 4 hours, while PC materials require a higher temperature of 120°C and an extended drying time of 6 hours for optimal moisture removal.

The operation interface should be equipped with a two-level alarm system. A warning is triggered when the dew point exceeds -30°C, and immediate shutdown for maintenance is required if the dew point exceeds -25°C to prevent moisture reabsorption.

Airflow control directly impacts energy efficiency. A closed-loop control system is recommended, linking the main fan’s frequency with the pressure difference in the drying tower. If the pressure difference exceeds 1.2kPa, the system will automatically increase airflow to ensure uniform heat penetration across the material. A large injection molding factory successfully reduced drying energy consumption by 18% through optimized airflow control strategies, saving over 500,000 RMB annually.

3. Shutdown and Maintenance: Scientific Cooling to Extend Equipment Life

During shutdown, follow a gradual cooling principle, ensuring the cooling rate does not exceed 15°C per minute (this can be controlled through PLC programming). This prevents deformation of metal parts caused by rapid cooling.

Maintenance focuses on managing filters and molecular sieves. When the pressure differential reaches 50mbar, the filter must be replaced. If the moisture absorption capacity of the molecular sieve decreases by 15% (this can be detected by weight measurement), regeneration or replacement is required.

It’s recommended to establish a digital maintenance record, documenting dew point curves, energy consumption data, and fault codes for each operation. One company in Zhejiang successfully predicted the failure of molecular sieves three months in advance by analyzing data, preventing material waste due to sieve issues.

While plastic drying may seem straightforward, it involves complex technical processes. From precise dew point control to managing molecular sieves, every step requires strict adherence to scientific operational standards. By turning these procedures into measurable action plans, businesses can achieve cost reduction and efficiency improvements. For customized parameter charts or maintenance plans, feel free to reach out to our Wensui technical team.