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6 issues that should be paid attention to in the manufacture of Medical Injection Mold and injection molding production


The development of modern medical technology has made plastics widely used in the medical field. From general medicine and pharmaceutical packaging, disposable medical equipment, to multiple precision and high-tech medical measuring instruments, surgical instruments, etc., medical plastics have played an important role in improving the level of medical technology. Since medical devices have special requirements for hygiene, safety, smooth surface, and corrosion resistance, molds for medical plastic products play a pivotal role in the production process of their products. Mold is an important symbol to measure the manufacturing level of a country's medical plastic products, and it determines the quality, efficiency and new product development ability of products to a large extent. With the gradual improvement of my country's medical care system, the demand for disposable medical devices has grown rapidly. Higher requirements are put forward for medical devices, especially for Precision Medical Injection Mold manufacturing, product production equipment and processes.

(1) Strict requirements for mold material selection

Precision Medical Injection Mold mostly uses medical grade polyvinyl chloride (PVC) and polycarbonate (PC). Because PVC has better corrosion resistance than steel, PC has higher hardness, so there are strict requirements for the selection of mold materials.

(2) heat treatment process control hardness

Due to the good fluidity of medical-grade PVC materials, the parting surface is deformed due to the soft mold material during the use of the mold, which in turn leads to flashes and burrs during the injection molding process. Therefore, there are high requirements for the hardness of this type of mold material. The heat treatment process adopted in the mold manufacturing process is to carry out quenching and tempering treatment after rough machining of the template, and the hardness is controlled at HRC32-36; after the mold test sample is qualified, vacuum quenching and hardness control of the empty mold, moving mold and core At HRC58-620.

(3) Reasonable and accurate structural design

For transparent products, choose hot runners as much as possible to reduce the traces of feeding; when using cold runners, the size of soft PVC should be shortened as much as possible; due to the small size and large batches of disposable medical devices, automatic unloading and shear pouring should be used. In order to ensure production efficiency and quality; there are many transparent tubular parts in disposable medical devices, and attention should be paid to the feeding position of the gate and the Z fixing method of the moving model during design, so as to avoid improper selection of the gate position and the core fixing method , resulting in uneven material flow during injection molding, causing elastic deformation of the core, uneven product or inability to fill the phenomenon. For products in the shape of extended tubes, attention should be paid to adopting an appropriate exhaust method. Out of the overflow well, to avoid product molding difficulties caused by air closure; the mold cooling system should adopt multiple groups of separate cooling water channels, and reasonably control the temperature of the dynamic and fixed mold to control the deformation of the product.

(4) High precision requirements for mold manufacturing

During the manufacturing process of Medical Injection Mold, the parting surface is required to be tight, and the precision of the mold should be ensured by equipment processing as much as possible. The gap between the parting surface should be less than 0.01mm, and the matching gap between the push rod and the push tube of the ejection system should be less than 0.01mm. The push plate ejection structure is adopted, and the push plate should have a certain hardness. The fixed mold and moving mold core of transparent products should be finely polished to ensure that the Ra value is above 0.20. If necessary, liquid polishing can be used.

(5) The selection of injection molding machines and parts is particular

The injection molding machine should use a small screw to ensure the accuracy of the injection molding, and an automatic unloading device, and the gas-assisted unloading can be used when the mold is ejected; the machine tool is equipped with a manipulator to realize the fully automatic process from product molding to packaging, and minimize pollution; The feeding mechanism of the injection molding machine should adopt closed vacuum feeding, adopt a closed storage tank, arrange the feeding pipe to each injection molding machine, and install an automatic metering vacuum feeding device at the inlet of the injection molding machine to ensure that the raw materials are not entering the injection molding machine. uncontaminated before.

(6) The injection molding workshop should be clean and up to standard

The production workshop should be fully enclosed, with high-power air-conditioning and ventilators installed to remove harmful gases in time to ensure constant temperature and clean air in the workshop; during the production process, it is strictly forbidden to use mold release agents and rust removers to ensure that the products are not polluted PVC products During the production process of the injection molding machine, the melting temperature should be strictly controlled to avoid harmful gases caused by the decomposition of the raw materials caused by the high temperature of the sub-materials and the long-term stay in the barrel. When the machine is shut down, the screw and barrel should be cleaned immediately to avoid damage to the screw of the injection molding machine caused by residual raw materials; Implement the GMP standard and strictly follow the IS0 9000 quality management system to ensure that there are no problems at all points in the production process.

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