Quality Control of Medical plastic Injection Molding
Plastic Injection Molding
Details
Details:
Model
Material
Brand
Origin
Application
Booling-Injection-1
P20, 718, S136, 2738 etc
Booling
China
Automotive parts, industrial parts, medical parts, household
The medical products produced by plastic injection molding technology have good quality and can effectively protect food from contamination. They can also be used to manufacture water pipes and water storage tanks, with good corrosion resistance and durability.
Advantages of Plastic Injection Molding：
- High Precision and Repeatability
- Low Cost per Part
- Fast Production Rate
- Wide Material Choice
- Little Waste
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Medical products manufactured by medical plastic injection molding have excellent quality and precision, comply with ergonomic and medical hygiene standards, and ensure the health and safety of patients. This process can effectively manufacture medical devices by injecting heated plastic into molds, hardening, and demolding to form injection molding parts. PVC injection molding and HDPE injection molding account for the largest proportion, reaching 28% and 24% respectively.
The Advantages of Injection Molding in Medical Device Manufacturing
Medical injection molding has gradually become a key process for manufacturing high-quality medical devices, and its significant characteristics have brought many advantages to the medical industry, including high-precision manufacturing level.
- Injection molding technology can manufacture high-precision medical molds. Manufacturers can accurately replicate mold design details by controlling parameters such as temperature, pressure, and flow rate during the injection molding process, ensuring the accuracy and quality of the final product. This is very suitable for scenarios in the medical industry that require high product accuracy, such as the manufacturing of medical supplies and equipment.
- Medical molds with complex shapes and structures can also be manufactured through injection molding. Due to the different requirements of patients and the variability of clinical medicine, medical devices, and devices often require complex structures and intricate designs. Injection molding technology has strong flexibility and plasticity, which can easily meet different medical design requirements and produce molds with complex structures, thereby ensuring the performance and functionality of medical products.
- Injection molding technology can achieve large-scale production and significantly improve the economic benefits of production. Due to the high degree of automation in injection molding technology, it is possible to produce a large number of products with consistent specifications in a short period. This not only reduces production costs and customer budgets but also improves production efficiency, allowing medical molds to be put into the market more quickly to meet the needs of the medical industry.
- The plastic materials used in injection molding have good biocompatibility and most of them are environmentally friendly and non-toxic. The medical field has extremely high requirements for the biocompatibility of materials, ensuring that the products produced are harmless to the human body. Many plastic materials used for injection molding meet the biocompatibility standards of the medical industry and can be used to manufacture medical devices and equipment that come into direct contact with the human body.
Basic Settings for medical Plastic Injection Molding
-Manufacturing Environment
The medical injection molding industry has very strict control over the manufacturing environment. Its workshops are usually required to be fully enclosed and clean, and manufacturers are required to install high-power air conditioners with ventilation functions to timely eliminate harmful substances in the workshop and prevent product contamination by impurities. Injection molding manufacturers also need to pay attention that in the production process of products, to prevent secondary pollution, employees are strictly prohibited from using release agents rust removers, and other additives.
-Production Equipment
- In terms of equipment, all production facilities need to comply with GMP production standards to ensure cleanliness and sterility.
- A small number of medical injection molding manufacturers have currently developed specialized injection equipment for medical purposes, which can effectively reduce contamination of medical products while ensuring their precision.
- Medical injection molding manufacturers have two main forms of layout for injection molding machines and cleanrooms. One is to place the injection molding machine as a whole in the cleanroom, which has a larger cleanroom space and higher cleaning costs; The second is to only place the locking mechanism of the mold in the clean room, purify the space inside the mold, and transport the product through the assembly line to the clean room assembly line for subsequent processing.
-Plastic Materials
In terms of materials, manufacturers have studied the market share of plastics in recent years. The most commonly used materials for medical injection molding, polyvinyl chloride (PVC) and polyethylene (PE), account for 28% and 24% of the market share of plastics, respectively. Polystyrene (PS) ranks third at 18%, polypropylene (PP) at 16%, and engineering plastics (commonly PET, SAN, PC, PMMA, PA, POM, etc.) account for 14%. The high frequency of use of these materials is due to their common characteristics of medical polymer materials:
- It can withstand the process of high-temperature sterilization without changing its biological and mechanical properties at high temperatures.
- When implanting materials into the body, there should be sufficient chemical stability, physiological inertness, and stability, and the physical and mechanical properties should not undergo significant changes except for biodegradable materials.
- Good physical performance, able to meet the requirements of human physiological functions and usage environment, and in line with ergonomics;
- It has good plasticity, high flexibility, and is easy to process into various shapes of products.
- The materials used for medical injection molding should have good anticoagulant properties when in contact with blood, which can achieve no damage to the tangible components of blood, no reduction in blood cells after hemolysis, and no protein denaturation in the blood.
- Plastic raw materials should be non-toxic to the body, do not produce heat source reactions, have no carcinogenic, teratogenic, or genetic mutagenic effects, do not damage adjacent tissues and immune mechanisms of the human body, and do not produce calcification on the surface of the material.
- Medical molding materials require very low levels of heavy metal content, soluble substances, and soluble substances, making them medical-grade plastics.
-Injection Mold
- The selection of mold material, the mold material should be rust-proof and anti-corrosion materials, such as S316 stainless steel;
- In mold design, full consideration should be given to the position of the gate and the arrangement of some easily stress-induced cores, pins, etc;
- The design of the molded waterway, as medical products have extremely strict requirements for size and post-deformation, the layout of the waterway should fully consider the uniformity of product cooling to prevent post-deformation caused by uneven cooling.
-Processing Technology
In the process of medical injection molding, there are also special points to pay attention to. The most common problems mainly include product size, appearance of burrs, warping deformation, and internal stress of the product.
Stress problem is an urgent issue in the medical product injection molding industry, as stress can cause deformation or cracking of products, resulting in changes in mechanical properties and airtightness.Therefore, manufacturers should consider the following points during the process of process debugging:
- Increase the cooling time of medical injection molding products, adjust the cooling water volume inside the mold, and maintain a balanced cooling of the entire mold’s moving and fixed parts;
- If necessary, the pressure and time for injection molding and insulation can be reduced, and multi-stage injection molding technology can also be used. During the pressure holding stage, manufacturers can also adopt segmented pressure holding to minimize internal stress as much as possible.
- When designing molds, manufacturers need to consider the position and size of the gate, and the ejected area should be as large as possible under reasonable circumstances, but balance should be maintained. Minimize the difference in wall thickness of the product as much as possible to prevent melt retention, resulting in defects such as water ripples, and reduce the accuracy of the product.
- After the production of the product is completed, annealing treatment is required.
In addition to addressing stress issues, stable and unified dimensions are also crucial for medical injection molded products. To achieve dimensional stability, manufacturers need to do the following:
- It is necessary to ensure the stability of the feeding system of the forming equipment and regularly inspect the check valve for wear.
- Set the material temperature, mold temperature, and room temperature parameters of the dust-free workshop. Under normal conditions, these parameters will remain unchanged in the future.
- Ensure that the moisture content of the material meets the requirements for molding, and re-dry the materials for secondary use, which is beneficial for the stability of product dimensions.
- Manufacturers can increase buffer bands and establish appropriate holding and cooling times.
Quality Control of Medical Plastic Injection Molding
Attention should be paid to the quality control of medical products. The testing of medical injection molded products will change with the change in usage methods. Common testing methods include weather resistance testing, impact resistance testing, fatigue resistance testing, and tensile strength testing of products. For some special high-demand products, such as oxygen masks, atomization bottles, etc., airtightness testing and gas flow rate testing per second are required.
China’s medical injection molding technology has made significant development and progress in the past few years, but it still lags. However, the country’s emphasis on the medical industry has provided significant development space for medical injection molding technology. Manufacturers are constantly researching molds, equipment, products, and materials related to the medical industry, constantly improving their technology and experience to meet the needs of the times.
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