When in the medical injection mold design process need to consider several key points
1. If the manifold is set too large, it is easy to accumulate too much gas, increase the cold material, increase the production cycle and reduce the processing efficiency. For different plastic materials, the manifold will be very different, but there will be a general principle: make sure the surface area of the manifold and its volume ratio.
2. The main flow channel should be designed to be shorter, so that it can effectively reduce the recovery of cold material, reduce pressure and heat loss. The main flow channel should avoid the block structure as much as possible, so that the plastic will not enter the joints and cause the problem of demolding. To avoid the repeated touching and collision between the main flow path and the high heat plastic and injection nozzle, in order to prevent the damage. For the gate sleeve, high quality steel processing is generally selected and heat treatment is done.
3. The poor exhaust of the injection mold may bring a series of harm to the effectiveness of subsequent medical mold injection and many other aspects. Specific performance has the following points.
①In the injection link, the melt will replace the gaseous material in the cavity, if it is not discharged in time, it may cause the melt filling problem, triggering the injection volume is not enough and no way to fill the cavity.
②If the gas is not removed smoothly, high pressure will be generated in the cavity and will penetrate into the internal structure of the plastic at a certain level of shrinkage, causing quality defects such as porosity, loose tissue, cavities, and silver lines.
③ Considering that the gas is highly scaled down, it leads to a significant increase of heat in the cavity, which then triggers the decomposition of the surrounding melt, scorching, and makes the plastic part partially carbonized and scorched. It basically occurs at the location of the merging of two melt streams, dead ends and gate protrusions.
④ Considering the obstruction of the cavity gas, it will reduce the filling rate of the mold, which in turn will make the molding cycle time longer and reduce the efficiency of medical mold injection molding.