What processes should we pay attention to in the manufacture of POM materials ligature clips?

POM (polyoxymethylene), as a high-performance engineering plastic, is widely used in the manufacture of single-use polymer tissue closure clips (hereinafter referred to as tissue closure clips) due to its high strength, rigidity, abrasion resistance, chemical resistance and self-lubricating properties. As a key consumable in laparoscopic surgery, the quality and performance of tissue closure clips are directly related to the safety and effectiveness of surgery. Therefore, in the injection molding process of POM materials, various parameters must be strictly controlled to ensure the quality and reliability of the final product. The following is a detailed discussion of the main considerations of the injection molding process of POM material in the manufacture of tissue closure clips.

I. Drying treatment of POM material

POM material, although the water absorption is small, generally 0.2% -0.5%, but in the injection molding before the drying process is still required to remove the water in the material to prevent it from bubbles, hydrolysis and other problems in the injection molding process. Drying temperature is usually set at 80 ℃ or above, the time is not less than 2 hours, the specific drying conditions should be adjusted according to the information provided by the supplier. For wet POM raw materials, drying treatment is particularly important to ensure that the material in the injection molding process to maintain stable performance.

Ⅱ, The choice of injection molding machine

Nylon PA screws for injection molding, because the design of these screws can better adapt to the crystalline properties of POM materials, improve injection efficiency and product quality. However, due to the wide range of POM processing, the use of general injection molding machine can also complete the injection process, but need to pay attention to adjust the parameters of the injection molding machine to adapt to the characteristics of the POM material.

Ⅲ, Mold and gate design

Mold temperature has an important impact on the injection molding of POM materials. Common mold temperature control range of 80-90 ℃, to ensure that the POM material in the mold can be fully crystallized to improve the strength and rigidity of the product. At the same time, the mold runner diameter and gate design also needs to be adjusted according to the characteristics of the POM material.

 Ⅳ, The melt temperature and injection speed

Melt temperature is one of the key parameters in the POM injection molding process. The choice of melt temperature needs to be adjusted according to the type of POM material and performance requirements to ensure that the material can be fully melted and crystallized in the injection molding process. The choice of injection speed also needs to be determined according to the characteristics of the POM material. Generally speaking, the injection speed is medium-fast, too slow and easy to produce ripples, too fast and easy to produce shot lines and shear overheating. Therefore, in the injection molding process according to the product shape, size and performance requirements to adjust the injection speed.

V. Back pressure and retention time

Back pressure is an important parameter in the injection molding process, which affects the density and uniformity of the melt. For POM material, the lower the back pressure the better, generally not more than 200 bar. too high back pressure will lead to overheating and degradation of the melt, affecting the quality and performance of the product. At the same time, the retention time of the melt in the barrel should be strictly controlled. If the equipment does not have a melt retention point, 20 minutes of retention will not result in serious decomposition. At the injection temperature, the melt should not be retained in the barrel for more than 20 minutes, otherwise it will lead to material degradation and performance loss.

Conclusion

POM material has significant advantages in the manufacture of tissue closure clips, but its injection molding process also requires strict control of various parameters to ensure the quality and performance of the final product. Donho can significantly improve the quality of POM material through reasonable drying treatment, the use of reused and recycled materials, the selection of injection molding machines, mold and gate design, melt temperature and injection speed control, back pressure and retention time adjustment, downtime cleaning and maintenance, and post-processing measures. These measures can significantly improve the application of POM materials in the manufacture of tissue closure clips, providing safer, more reliable and more efficient consumables for laparoscopic surgery.