What is the appropriate temperature for medical silicone injection molding?

Medical silicone injection molding technology plays a crucial role in the manufacturing of medical devices, and the choice of molding temperature not only affects the quality and performance of the product, but also directly relates to production efficiency and cost control.

Basic temperature range for medical silicone injection molding

The selection of injection molding temperature for medical silicone is not fixed, but needs to be comprehensively considered based on multiple factors such as the type of silicone (liquid or solid), mixing ratio, mold design, and injection molding machine parameters. Generally speaking, the molding temperature for medical silicone injection molding is commonly between 160-200 degrees Celsius. Among them, the molding temperature of liquid silicone injection molding is usually set between 165-185 degrees Celsius, while that of solid silicone injection molding is between 175-195 degrees Celsius. The selection of this temperature range aims to ensure that the silicone can fully melt and evenly fill the mold, while avoiding excessive temperature that may cause oxidation and decomposition of the silicone material, affecting product quality.

Selection of Temperature for Liquid Silicone Injection Molding

Liquid silicone has been widely used in medical device manufacturing due to its good fluidity and high molding accuracy. The key to selecting the temperature for liquid silicone injection molding is to balance its fluidity and curing speed. Generally speaking, higher molding temperatures can improve the fluidity of silicone, which is beneficial for rapid filling of molds and reducing the generation of bubbles. However, excessively high temperatures may also cause the silicone gel to solidify too quickly, resulting in stress concentration inside the mold and affecting the dimensional stability and mechanical properties of the product. Therefore, the selection of injection molding temperature for liquid silicone requires controlling the curing speed as much as possible while ensuring fluidity, in order to achieve the best molding effect.

Selection of Temperature for Solid Silicone Injection Molding

Solid silicone has higher strength and hardness compared to liquid silicone, making it suitable for manufacturing medical devices that require higher mechanical properties. The selection of solid silicone injection molding temperature mainly focuses on its melting state and filling capacity. Due to the poor fluidity of solid silicone, higher molding temperatures are required to ensure that the silicone can fully melt and evenly fill the mold. However, excessively high temperatures may also cause the oxidation and decomposition of silicone materials, resulting in adverse odors and harmful substances that affect the safety and reliability of the product. Therefore, the selection of solid silicone injection molding temperature needs to minimize the molding temperature while ensuring the filling capacity, in order to reduce the risk of oxidation and decomposition.

The influence of mold design and injection molding machine parameters on molding temperature

Mold design and injection molding machine parameters are two other important factors that affect the temperature of medical silicone injection molding. The design of the mold determines the flow path and filling speed of silicone inside the mold, thereby affecting the choice of molding temperature. Reasonable mold design can optimize the flow state of silicone, reduce the generation of bubbles and defects, and improve the quality of product molding. Injection molding machine parameters such as injection pressure, injection speed, and holding time can also affect the melting state and filling capacity of silicone gel. Therefore, when selecting the molding temperature, it is necessary to fully consider the influence of mold design and injection molding machine parameters, and conduct repeated testing and adjustment to obtain the best molding effect.

The influence of silicone preheating and cooling on molding temperature

Silicone preheating is an important step in the injection molding process of medical silicone. Preheating can improve the fluidity of silicone, which is beneficial for rapid filling of molds and reducing the generation of bubbles. At the same time, preheating can also reduce the temperature gradient of silicone in the mold, reducing the generation of internal stress in the mold. Generally speaking, the preheating temperature needs to be 20-30 degrees Celsius higher than the molding temperature to ensure that the silicone has reached the ideal flow state before injection. The cooling process is equally important as it can prevent excessive solidification of silicone in the mold, leading to product deformation or cracking. A reasonable cooling time can ensure that the silicone is fully cured in the mold, while avoiding the adverse effects caused by excessive curing.

Principles for selecting the temperature of medical silicone injection molding

When selecting the injection molding temperature for medical silicone, the following principles should be followed:

1. Ensure that the silicone is fully melted: The molding temperature should be high enough to ensure that the silicone can fully melt and evenly fill the mold.
2. Avoid oxidation and decomposition: The molding temperature should not be too high to prevent the oxidation and decomposition of silicone materials, which can produce adverse odors and harmful substances.
3. Optimize mold design and injection molding machine parameters: Through reasonable mold design and injection molding machine parameter settings, optimize the flow state and filling capacity of silicone.
4. Pay attention to preheating and cooling: A reasonable preheating and cooling process can ensure that the silicone gel reaches the ideal flow and curing state inside the mold.
5. Conduct repeated testing and adjustment: In practical operation, it is necessary to conduct repeated testing and adjustment to obtain the best molding effect.

Practical application cases

Taking the manufacturing of medical silicone catheters as an example, the selection of injection molding temperature requires comprehensive consideration of multiple factors such as the type of silicone, mixing ratio, mold design, and injection molding machine parameters. In practical operation, the optimal molding temperature can be determined by the following steps:

1. Determine the type and mixing ratio of silicone gel: Select the appropriate type and mixing ratio of silicone gel according to the requirements of medical silicone catheters.
2. Design a reasonable mold: Based on the fluidity and filling ability of silicone, design a reasonable mold structure and channel layout.
3. Set injection molding machine parameters: Based on mold design and silicone flowability, set reasonable injection pressure, injection speed, and holding time parameters.
4. Preheating and cooling: Determine a reasonable preheating temperature and cooling time based on the melting state and solidification rate of the silicone gel.
5. Conduct repeated testing and adjustment: In practical operation, determine the optimal molding temperature through continuous testing and adjustment.
Through the above steps, it can be ensured that the medical silicone catheter achieves the best molding effect during the injection molding process, meeting the requirements of medical device manufacturing.

conclusion

The selection of injection molding temperature for medical silicone is a complex and important process that requires comprehensive consideration of multiple factors such as the type of silicone, mixing ratio, mold design, and injection molding machine parameters. By selecting and controlling the molding temperature reasonably, it is possible to ensure that medical silicone products achieve the best molding effect during injection molding, meeting the requirements of medical device manufacturing.