Trim flash open mold injection molding products processing, and most of the products need to finalize the design tools to finalize the design, and complete a products processing.
With relative molecular mass of about 2. 89 million raw material processing of relative molecular mass of the ultra-high molecular weight polyethylene products for 2. 59 million.
Because of ultra-high molecular weight polyethylene degradation is inevitably produced in the process of machining, so the result is ideal, that of all the parameters on the forming process and the process is more reasonable.
In spite of ultra-high molecular weight polyethylene products produced a part of the degradation, the lower the relative molecular mass, but not degradation is not much effect on its performance.
directly processed into finished products, press 1.
5% computation, when processed into blank, because must leave machining allowance, therefore the shrinkage rate be larger, general according to 6 -
8% consider it.
It is difficult to accurately determine the size of the shrinkage and affected by many factors: associated with the variety and proportion of packing, packing, even if the same proportion of different varieties shrinkage rate is not the same.
With the size of the coupling agent type, the molding pressure and the mold temperature and so on.
heating time t in the molding method refers to the sum of heating and heat preservation time, i. e. t2, this is due to ultra-high molecular weight polyethylene powder thermal conductivity is very low, even if the oven to reach the set temperature, the mould of ultra-high molecular weight polyethylene powder also amounted to less than the temperature, especially in the central part of the raw material, so usually considering put the two together.
Take out the mould on the machine, the side pressure 8 -
12 mpa, cooling, cooling to 65 -
two kinds of packing with the increase of adding ratio, shrinkage rate decreased, under the same proportion, explored the shrinkage rate is larger than glass beads, this is because the talcum powder density is larger than glass beads, that is to say, the volume accounted for the talcum powder is smaller than glass beads, so the shrinkage rate.
Mold design must be considered when the size of the bin, bin size slightly more than products the actual volume, this is because the density of the ultra-high molecular weight polyethylene powder is about 0.
said take good ultra-high molecular weight polyethylene powder, into the coated with release agent in a mould, about 5 mpa pressure, because not for molding, just to rule out the air in the material, increase the raw material is close-grained, thermal conductivity and reduce the sintering time, so don't too much pressure.
The mould in the heating furnace for heating, heating temperature of 195 ℃ or so.
If the sintering time is insufficient, can make the products are not familiar with core to burn.
Products performance fell sharply, causing the products for the defective goods.
sintering suppression method is suitable for mass production of small and medium-sized ultra-high molecular weight polyethylene plastic injection products processing.
The molding process while the production efficiency is low, but the method is simple, low cost, less number of mold, and do not need to heating furnace with inert gas protection, so also can yet be regarded as a kind of good processing method.
Sintering suppression method you just need to a mold, mold design should first consider shrinkage rate, shrinkage rate depends on the size of the.
if the sintering time is too long, the degradation of ultra-high molecular weight polyethylene will produce too much, because the degradation of ultra-high molecular weight polyethylene is related to time, temperature and environmental conditions, in addition has also extended the individual products of the production cycle, waste precious production time and unnecessary energy consumption.
The thickness of the sintering time and the products is not a linear relationship, this is because the smaller thermal conductivity of ultra-high molecular weight polyethylene, product thickness, doubled the sintering time is not doubled, but some more than doubled.
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