How does injection molding create minimally invasive scalpel injection molded shells and injection molded parts that meet strict standards? ​

1. Injection molding process principle: the transformation from plastic particles to medical parts ​
The basic principle of injection molding is to transform solid plastic particles into a molten state by heating, and use the pressure generated by the injection device to inject the molten plastic with good fluidity into a mold cavity of a specific shape. The mold is like a magic box, which determines the shape and structure of the final product. When the high-temperature molten plastic fills the cavity, the plastic gradually solidifies after the cooling system, and fits tightly with the inner wall of the mold cavity. After it is completely cooled and shaped, the mold is opened to obtain a plastic product with the desired shape and size. ​
For Minimally Invasive Scalpel Injection Molded Shell And Injection Molded Parts, this transformation process is of great significance. The injection molded shell of the scalpel handle needs to fit the ergonomic design so that the doctor can hold it for a long time without fatigue; and the injection molded parts of the scalpel head may need to have a special shape to meet the operation requirements of different surgical sites. Through injection molding, these complex designs can be turned from drawings into reality. For example, in order to adapt to the narrow surgical space, the surgical blade injection molded parts need to be designed into a slender shape with a certain bending angle. The injection molding process can accurately fill the molten plastic according to the precise shape of the mold to shape the parts that meet the requirements, providing convenience for surgical operations. ​
2. Key process parameters: the core elements that determine product quality ​
When injection molding the injection molded shell and injection molded parts of minimally invasive surgical blades, the precise control of process parameters such as temperature, pressure and injection speed is the key to ensuring that product quality meets medical standards. ​
Temperature control runs through the entire process of injection molding, involving barrel temperature, mold temperature and other aspects. The barrel temperature affects the plasticization degree of the plastic. If the temperature is too low, the plastic cannot be fully melted, resulting in poor fluidity, and it is difficult to reach the tiny corners when filling the mold cavity, resulting in material shortage; if the temperature is too high, the plastic may decompose, discolor and other problems, affecting product performance. The mold temperature has an important influence on the cooling rate of the plastic and the final molding quality. Lower mold temperature will cause the plastic to cool quickly. Although it can improve production efficiency, it may cause increased internal stress in the product, resulting in defects such as deformation and cracking. Higher mold temperature helps the plastic molecules to fully crystallize, improves the surface quality and mechanical properties of the product, but will prolong the cooling time and reduce production efficiency. Taking the injection molded shell of the surgical knife handle as an example, in order to ensure that its surface is smooth, the texture is uniform, and it has sufficient strength and toughness, it is necessary to accurately set the temperature of the barrel and the mold according to the characteristics of the plastic material used, so that the plastic can be plasticized and formed in the best state. ​
Pressure plays a role in promoting the flow of plastic and compacting plastic in injection molding. Injection pressure is used to overcome the flow resistance of plastic in the runner and mold cavity, ensuring that the plastic can quickly and evenly fill the entire cavity. Holding pressure is to continuously apply pressure after the plastic is filled to compensate for the shrinkage of the plastic during the cooling process and prevent defects such as shrinkage marks and voids in the product. The injection molded shells and injection molded parts of minimally invasive surgical knives with different structures and sizes have different pressure requirements. For injection molded parts with complex structures and thin walls, higher injection pressure and holding pressure are required to ensure that the plastic can be smoothly filled into every detail and maintain a good shape during the cooling process; for parts with thick walls, too high pressure may cause greater internal stress inside the product, so it is necessary to adjust the pressure parameters reasonably. ​
Injection speed also has an important impact on product quality. A faster injection speed can make the plastic flow quickly in the mold cavity, reduce the temperature drop of the plastic during the flow process, and avoid insufficient filling due to premature solidification of the plastic. At the same time, fast injection can also reduce the generation of weld marks and improve the appearance quality of the product. However, too fast injection speed may cause turbulence in the plastic in the mold, entrain air to form bubbles, or produce jet marks on the surface of the product. On the contrary, although a slower injection speed helps to reduce the appearance of bubbles and jet marks, it may cause the plastic temperature to drop too much during the filling process, the fluidity to deteriorate, and it cannot fill the mold cavity. When producing the injection molded shell of the surgical knife handle, in order to obtain a smooth and defect-free product, it is necessary to accurately adjust the injection speed according to the characteristics of the plastic material and the mold structure to find an optimal balance point.​
III. Mold design and manufacturing: an important carrier for process realization​
As a key tool for injection molding, the design and manufacturing quality of the mold directly determines the precision and quality of the injection molded shell and injection molded parts of the minimally invasive scalpel. Since medical products have extremely high requirements for dimensional accuracy and surface quality, the mold of the minimally invasive scalpel must meet the micron-level precision standard. ​
During the mold design stage, engineers use advanced computer-aided design (CAD) technology to optimize the overall structure, flow channel system, cooling system, etc. of the mold in an all-round way. The overall structural design of the mold needs to consider factors such as the demoulding method and the position of the parting surface of the product to ensure that the product can be smoothly removed after molding, while avoiding leaving obvious parting line marks on the surface of the product. The design of the flow channel system is related to the flow path and flow resistance of the plastic in the mold. Reasonable design of the shape, size and layout of the flow channel can make the plastic fill the mold cavity evenly and quickly, reducing pressure loss and filling time. For example, the use of a balanced flow channel design can ensure that the plastic filling speed and pressure of each cavity are consistent, avoiding the situation where some cavities are underfilled or overfilled. The design of the cooling system is also crucial, as it directly affects the cooling speed of the plastic and the molding cycle of the product. By designing a reasonable cooling water channel in the mold and controlling the flow and temperature of the cooling water, the plastic can be evenly cooled in the mold, shortening the cooling time, improving production efficiency, and reducing the deformation and internal stress of the product caused by uneven cooling. ​
During the mold manufacturing process, high-precision processing equipment, such as five-axis linkage machining centers and EDM machines, are required to perform precision processing on the mold. The five-axis linkage machining center can achieve high-precision processing of complex curved surfaces of the mold and ensure the shape accuracy of the mold cavity; the EDM machine can process small and complex structures that are difficult to achieve with traditional mechanical processing, such as tiny holes and fine patterns on the mold. After the processing is completed, the mold needs to be finely polished to achieve a mirror effect on the mold surface, thereby producing a smooth surface and extremely high-precision minimally invasive scalpel injection molded shell and injection molded parts to meet the strict requirements of medical products for appearance and performance.​
Fourth, quality control: a necessary link to ensure medical safety​
In order to ensure that the injection molded shell and injection molded parts of minimally invasive scalpels meet medical standards, ensure the safety of patients and the smooth progress of surgery, a strict quality control system is indispensable. During the injection molding process, it is necessary to conduct comprehensive inspections of raw materials, production processes and finished products. ​
For raw materials, their quality must be strictly controlled, and various performance indicators of plastic particles, such as melt index, density, mechanical properties, etc., must be tested to ensure that they meet the requirements of medical-grade materials. During the production process, process parameters such as temperature, pressure, and injection speed are monitored in real time through online monitoring equipment. Once the parameters deviate from the set range, they are adjusted immediately to prevent product quality problems caused by parameter fluctuations. At the same time, the mold is regularly inspected and maintained to ensure that the accuracy and surface quality of the mold are not affected. For the finished products produced, comprehensive quality inspections must be carried out, including dimensional measurement, appearance inspection, mechanical property testing, etc. Dimension measurement uses high-precision measuring instruments, such as three-coordinate measuring machines, to accurately measure the key dimensions of the product to ensure that it meets the design requirements; appearance inspection uses visual inspection or optical inspection equipment to check whether there are defects on the product surface, such as bubbles, cracks, deformation, etc.; mechanical property testing tests the strength and toughness of the product to ensure that the product can withstand normal operating forces without damage during surgery. Only products that pass all inspection links can enter the medical market and provide reliable protection for surgery.