Use and maintenance of high temperature melt pressure sensors

High-temperature melt pressure sensors are essential components in extrusion lines, playing a crucial role in enhancing melt quality, ensuring production safety, and protecting equipment. These sensors are highly sensitive, and their performance depends on proper installation and maintenance. For more information, contact Xiaogan High Temperature Melt Pressure Sensor Co., Ltd. at 15172194641.

In the extrusion process, achieving precise product quality—such as dimensional accuracy or surface flatness of mineral filler parts—requires optimal control of extrusion pressure. This is made possible through high-temperature melt pressure sensors, which are critical for maintaining consistent output and reducing material waste. By integrating a melt pressure sensor and a pressure control device at the mold inlet, operators can stabilize yield and improve overall efficiency. These sensors not only enhance melt quality but also increase safety and extend the lifespan of production equipment.

Measuring pressure through filters and melt pumps is also vital for ensuring safe operations and optimizing equipment performance. If the melt becomes blocked while flowing into the mold, the sensor located under the filter will alert the operator. A pressure alarm from the filter screen indicates that the internal pressure of the extruder is too high, potentially leading to excessive screw wear. For melt pump manufacturers, monitoring both inlet and outlet pressures ensures smooth flow into the mold, preventing damage caused by blockages.

The high-temperature melt pressure sensors installed in the extrusion line can be single-point sensors or part of a network measuring across the entire production line. Connected to data loggers and audible alarms, these sensors allow real-time adjustments to extruder parameters via the control system. However, due to their sensitivity, improper installation or maintenance can easily lead to damage. Following some simple guidelines can help prolong the life of the sensors and ensure accurate measurements.

● Proper Installation

Improper installation is a common cause of sensor failure. If a sensor is forced into a small or irregularly shaped hole, its diaphragm may be damaged. Using the right tools to machine the mounting holes helps maintain precision. Applying the correct torque ensures a good seal, but over-tightening can cause the sensor to slip. To prevent this, an anti-seize compound is often applied to the threaded portion before installation, making it harder to move even with high torque.

● Check Mounting Hole Size

If the mounting hole is not properly sized, the sensor's threads may wear during installation, affecting both sealing and performance. It can also create safety risks. Ensuring the mounting hole meets the standard (1/2-20 UNF 2B) is essential. A mounting hole gauge can be used to verify the size and make necessary adjustments.

● Keep Mounting Holes Clean

Maintaining clean mounting holes is key to reliable operation. Before cleaning the extruder, all sensors should be removed to prevent damage. If molten material enters the hole and hardens, it can damage the sensor when reinstalled. Cleaning kits help remove residues, but repeated cleaning can worsen wear. In such cases, raising the sensor’s position within the hole may be necessary.

● Choose the Right Location

Installing the sensor too close to the upstream area may expose it to unmelted material, causing wear. Placing it too far downstream might result in a stagnant zone between the screw and sensor, where melt degrades and pressure readings become distorted. Installing the sensor too deep in the barrel could lead to contact with the rotating screw, causing damage. Typically, sensors are placed in front of the screen, before or after the melt pump, or in the mold.

● Careful Cleaning

Before cleaning the extruder with a wire brush or special compound, all sensors should be removed. These methods can damage the sensor’s diaphragm. When the barrel is heated, the sensor should also be wiped with a soft cloth. The sensor’s hole must be cleaned using a clean drill and guide sleeve to avoid contamination.

● Keep Dry

Although high-temperature melt pressure sensors are designed to withstand harsh environments, they are not fully waterproof. Moisture can interfere with their operation. Ensure that cooling water systems do not leak into the sensor area. If exposure to moisture is unavoidable, choose a water-resistant model specifically designed for such conditions.

● Avoid Low-Temperature Interference

During extrusion, plastic materials need sufficient time to transition from solid to molten. If the extruder hasn’t reached operating temperature before starting, the sensor and equipment may be damaged. Also, removing the sensor from a cold extruder can cause material to stick to the sensor’s top, damaging the diaphragm. Always ensure the barrel is sufficiently heated and the material inside is softened before removal.

● Prevent Pressure Overload

Even if the sensor is designed to handle up to 50% overload, it's best to avoid exceeding the safe operating range. Selecting a sensor with a range twice the expected pressure ensures protection against extreme conditions. This prevents damage in case the extruder operates at unexpectedly high pressures.

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Cement Superplasitcizer

Manufacturing method
Using methyl naphthalene and sulfur trioxide as raw materials, the product was synthesized by sulfonation, condensation, neutralization and drying.
The degree of polymerization of water reducing agent is generally about 6-12, that is: n= 6-12, if the degree of polymerization is 1-3, it is used as a dispersant.
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