Polycarbonate (PC) alloy is one of the most commonly used materials for medical equipment casings. Widely used in surgical equipment, medical imaging equipment, clinical equipment, and in vitro diagnostic equipment. With the emergence of the epidemic, the disinfection methods of hospitals and third-party testing institutions have become more diverse, and the frequency of disinfection has also become more frequent. Disinfectants are one of the main reasons for surface cracking of equipment shells. The disinfectant solvent enters the polymer chain, causing swelling and ultimately causing cracks in the weak parts of the shell structure, which may occur 1-2 years later and cause losses to medical customers.

In the material design of solid source new materials, the addition of material components that can prevent the entry of disinfectant solvents increases the ratio of tightly arranged crystalline materials, increases the strength of the materials, and greatly improves the product's ability to resist stress cracking. In the stress testing model of the spline and sample strip, the new material can extend the cracking time by more than 30% in mainstream disinfectant immersion testing.

Solution to cracking problem

The solution to the cracking problem of PC material products is a complex and comprehensive problem. Based on practical work experience, the author concludes that it is necessary to control and improve product quality from the following aspects in order to effectively prevent the occurrence of batch cracking problems in products.

Design Improvement of Injection Mold

When designing the mold, the position and quantity of the gate should be designed to ensure that the melt evenly and quickly fills the mold cavity. Appropriately increase the flow channel, eliminate unnecessary horizontal reinforcing ribs, increase longitudinal reinforcing ribs, and increase the demolding angle. The ejection device is designed to eject in a large area and use less metal embedded parts. Avoid rectangular connections of plastic parts, increase chamfers, and arc transitions.