How to reduce the contraction of plastic processing
HC plastic net News: shrink plastic processors are facing the enemy, especially for large-scale high surface quality requirements Plastic Products , Contraction is a chronic illness. Therefore, various techniques have been developed to minimize shrinkage and improve product quality.
Thick plastic parts in injection location, such as reinforcement ribs or protrusions formed at positions near the shrinkage is more serious than it is due to thicker regions of the cooling rate is much slower than the surrounding region. Different cooling rates lead to depression formed on the interface connection, that is, the contraction of the familiar marks. This deficiency severely limits the design and molding plastic products, especially the large thick-walled products such as TV cabinet and monitor housing so inclined. In fact, this type of household electrical products demanding contraction marks must be eliminated, but the toys do not ask some of the surface quality of the product allow the presence of scar contraction.
The formation of scar contraction may be due to one or more, including processing methods, part geometry, material selection and Mold Designs. Geometry and material selection which is usually decided by the suppliers of raw materials, and not easy to change. But there is still a lot of mold makers mold design on factors that may affect the contraction. Cooling channel design, gate type, gate size may produce a variety of effects. For example, the small gate such as gate tube cooling than the cone of the gate much faster. Early cooling will reduce the gate to the cavity filling time, thereby increasing the probability of resulting scar contraction. For forming the workers, to adjust processing conditions is one way to resolve contract issues. Filling pressures and time significantly affected shrinkage. Parts filled, the excess material to fill to compensate the material shrinkage cavity. Filling stage is too short will result in increased contraction will eventually produce more or larger contraction marks. This approach in itself may not be able to shrink down to a satisfactory level of marks, but the molding conditions of workers can be adjusted to improve the filling contraction marks.
Another way is to modify the mold, there is a simple solution is to modify the conventional core hole, but can not count on this method applies to all of the resin. In addition, gas-assisted method is also worth a try.
Column, gas and foam
GE Polymer Processing Research Centre ( PP DC) conducted a 12-month study to evaluate eight kinds of different ways to reduce the contraction of scar. These technologies reduce the contraction marks represent some of the latest thinking. These methods can be divided into two types: one method can be called a place of material, and the other to remove the heat method. Replace the material law is likely to shrink by increasing or reducing the amount of materials to reduce the regional contraction of scar. Method to quickly remove the heat will be possible to remove the heat shrinkage of the area, thereby reducing the thinner and thicker areas of regional and produce the possibility of uneven cooling.
I am an expert from Mp3 Player Manufacturers, usually analyzes all kind of industries situation, such as plastic toothbrush holder , the swatter.
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