Before the extrusion molding machine is used for product molding, the raw materials need to be heated first. This process is to ensure that the raw material has the appropriate processability, so that it can be successfully extruded and formed in the subsequent molding process. This article will describe in detail how extrusion hollow molding machines heat raw materials in order to help you better understand the importance of this critical step.
1. Basic working principle of extrusion hollow forming machine
Before in-depth understanding of the heating process of the extrusion hollow forming machine, it is first necessary to briefly understand its basic working principle. The extrusion hollow molding machine heats and melts the plastic raw materials through the screw, and then extrudes the melted plastic through the mold to form the required hollow plastic products. Throughout the process, the heating state of the raw material directly affects the molding effect, and the appropriate melting temperature must be reached to ensure that the raw material has good fluidity and is easy to smooth extrusion.
2. Why is heating the raw material important
Heating the raw material is a key step in the extrusion hollow molding machine, which is not only to heat the plastic raw material to a molten state, but also to ensure uniform and precise temperature control. The main purpose of heating is to transform the raw material from a solid to a plastic fluid, so that it can be smoothly formed through the mold. However, different types of plastic materials require different temperatures and heating times, so control of the heating process is crucial. Under normal circumstances, the raw materials suitable for the production process of the hollow molding machine are HDPE. The nature of HDPE is stable, easy to form and process, and the quality of the products produced can also meet the corresponding quality standards. Other raw material options for hollow blow molding are also available.
The heating process has a direct effect on the quality of extrusion. If the heating of the raw material is insufficient and the melting is incomplete, it will lead to problems such as rough surface, unstable size and poor strength of the product; Excessive heating may lead to degradation of raw materials or loss of performance, affecting the durability and appearance of the product. Through proper heating treatment, the molecular chain of the plastic material can obtain enough fluidity to achieve the best molding effect.
3. Heating system design of extrusion hollow forming machine
The heating system design of extrusion hollow molding machine is usually very precise, mainly including heating elements, temperature control system and heat transfer medium. The task of the heating system is to provide heat through the heating element to bring the raw material to the desired temperature. The efficiency, accuracy and stability of the heating system are directly related to the smooth progress of the molding process.
3.1 Electric heating element
Electric heating element is the heating method used in most extrusion hollow forming machines at present. The electric energy is converted into heat energy and transferred to the heating area through the equipment such as electric heating wire, electric tropical wire or electric heat pipe. Electric heating elements are usually distributed in the heating area of the screw, the die area and around the barrel to ensure uniform heating. The power and efficiency of these heating elements directly affect the heating speed and accuracy of raw materials.
3.2 Hot oil heating system
Some high performance extrusion hollow molding machines use hot oil heating systems. The advantage of hot oil heating is that it has uniform heating and stable temperature, which can effectively avoid local overheating or uneven heating. This heating method is suitable for demanding precision machining, and can precisely control temperature fluctuations to ensure the heating effect of raw materials.
3.3 Temperature control system
Modern extrusion hollow molding machines are equipped with a highly automated temperature control system that can monitor and adjust the temperature in the heating zone in real time. The system collects data through the temperature sensor and adjusts the power output of the heating element according to the set value. The precise temperature control system ensures that the temperature in each heating zone is kept within the ideal range, avoiding molding problems caused by too high or too low temperature.
4. Control of heating temperature
Controlling the heating temperature is the core factor to ensure the quality of extrusion molding. Different plastic materials have different melting points and processing temperatures, so the extrusion hollow molding machine needs to set the appropriate heating temperature according to different raw materials. In general, plastic raw materials need to be heated above their melting temperature to ensure that the material has sufficient fluidity and formability.
4.1 Reasonable heating temperature range
Generally, the heating temperature range of plastics is divided into three main stages:
Preheating stage: In this stage, the heating element will gradually increase the temperature of the raw material, so that it enters a preliminary softening state. The temperature at this time is usually low, in order to avoid excessive heating and degradation of plastic materials.
Melting stage: In this stage, the raw material needs to reach its melting point and enter a state of full flow before it can be molded by the extruder’s screw and die. Different kinds of plastics have different melting points.
Stability stage: Once the raw material reaches the ideal melting state, the temperature control system will keep the temperature stable, ensuring the uniformity and consistency of heating throughout the production process.
4.2 Influence of temperature control on product quality
The precise control of heating temperature is directly related to the quality of extruded products. If the heating temperature is too low, the raw material can not be completely melted, resulting in poor plastic fluidity, may appear uneven molding, bubbles and other defects. If the heating temperature is too high, the material may degrade, affecting its strength and appearance. Therefore, the precise control of temperature is a key factor in ensuring product quality and production efficiency.
5. The effect of heating on molding quality
The heating process has a profound influence on the molding quality of the extrusion hollow molding machine. Proper heating can ensure the uniformity and fluidity of plastic raw materials, so as to achieve the ideal molding effect. Specifically, good heating can improve the product’s:
Dimensional accuracy: Uniform heating can ensure the uniform flow of plastic in the mold, thereby reducing the size of the product error.
Surface smoothness: Proper heating can prevent rough or bubbles on the plastic surface and improve the appearance quality of the product.
Mechanical properties: Heating can help the plastic raw materials to fully integrate, ensuring that the molded product has sufficient strength and durability.
6. Continuous improvement of heating technology
With the progress of science and technology, the heating technology of extrusion hollow molding machine is also constantly improving. For example, in recent years, advanced digital control technology has been adopted to make the heating process more accurate and efficient through real-time monitoring and self-regulation. In addition, the application of new heating elements and heat transfer technology also makes the heating efficiency greatly improved. The process of heating raw materials of extrusion hollow molding machine is the key link in the whole production process. By precisely controlling the heating temperature and the stability of the heating system, the uniform melting of plastic materials can be ensured, and the quality and production efficiency of products can be improved. Reasonable heating can not only reduce the defects in production, but also optimize the production cycle, reduce energy consumption, and bring higher production benefits to enterprises. We can also take their own product production needs, to consult the relevant hollow blow molding machine equipment manufacturers, such as Shandong Great Machinery Co., LTD., according to the actual production needs, not only will give the appropriate extrusion hollow molding machine equipment production program, but also will give the corresponding raw material selection program and product production formula.