Products color is common defects in injection molding, because the accessories and aberration caused by injection molding machine, does not see small batch scrap. Aberration affected by many factors, involving raw materials for resin, pigment, pigment mixed with raw materials, such as injection molding process, injection molding machine, mold, and because of the impact is widespread, so the aberration control technology is also one of recognized difficult to master the technology of injection molding. The actual production process we generally from the following six aspects: to control the aberration.
1, to eliminate the influence of the injection molding machine and mold factors to choose with considerable injection molding machine, injection molding products for capacity if material corner problems in injection molding machine, best replacement equipment. For mould gating system, such as exhaust slot cause off color, through the corresponding part of the mould maintenance mode to solve. Must first solve the problem of good injection molding machine and mold to organize production, to reduce complexity of the problem.
2, eliminate the influence of raw material resin, color master control of raw materials is the key to thoroughly solve the aberration. Therefore, especially the production of light color products, not ignore the thermal stability of resin raw material the obvious effects of different colour and lustre of products fluctuations. Given that most of the injection molding manufacturers itself does not produce plastic masterbatch or masterbatch, such, can be the focus of attention on the production management and raw material inspection. Namely to strengthen raw material incoming inspection; As much as possible in the production of the same products using the same manufacturer, same brand masterbatch, masterbatch production. For pigment, we will try to check the color before mass production, as well as with the last time to proofread, and in the comparison, if the aberration is not big, qualified, can be thought of as has slight aberration, color master batch can be used after mixing pigment back again, in order to reduce uneven mixing pigment itself the brightness of the photo. With, we still need to focus on inspection raw material resin, pigment, the thermal stability of the poor thermal stability, we suggest that the manufacturer and exchange.
3, eliminate the influence of uneven pigment mixed with masterbatch plastic masterbatch mixed with pigment is bad also can make the product color changes. After mother and masterbatch mechanical mixing, through the absorption into the hopper, due to electrostatic interactions, masterbatch masterbatch with separation, easy adsorption in the hopper walls, and this is bound to cause injection cycle at the mother volume changes, resulting in a aberration. This kind of circumstance can take again after raw material suction hopper to artificial mixing solution. Now there are a lot of companies feed machine is used to add pigment, thereby saving a lot of manpower, and for the aberration control provides a lot of help, but many companies because of improper use, the results are often difficult to satisfactory. Join masterbatch feeding machine under fixed speed depends on plasticizing time, and plasticizing time itself is volatile, sometimes even more volatile, so to ensure the constant feed rate, the feeder must be fixed feeding time, and set a time less than the minimum plasticizing time. In the use of feeding machine need to notice, due to the feeder exports is small, use after a period of time, may be because the accumulated material used in the feeding machine screw powder caused blanking, even cause feeding machine stops, so need to regular cleaning.
4, reduce the influence of cylinder temperature on aberration in a heating coil damage failure of production often encounter or control of heating control part long fire ChengLiao tube rapid changes in temperature to produce off color. This kind of reason of aberration is easy to determine, general damage of heating coil Produce off color, but at the same time will be accompanied by plasticizing uneven phenomenon, and the heating control part is out of control long burning gas spot is often associated with products, severe discoloration even coking phenomenon. So the need to check the heating part of the production, found that the heat damage or change in time maintenance when out of control, in order to reduce this kind of aberration.
5, and reduce the influence of the injection molding process adjustment when the chromatism reason need adjust injection molding process parameters, as far as possible, don't change the molding temperature, the amount of back pressure, the injection molding cycle and masterbatch, adjust at the same time also need to observe the effects of process parameters change on colour and lustre, for example, when found aberration should be and adjustment. As far as possible avoid the use of high speed and high back pressure injection cause strong shearing action of the injection molding process, prevent due to factors such as local overheating or thermal decomposition of the brightness of the photo. Strict control of cylinder each heating section temperature, especially the nozzle and close to the heating part of the nozzle.
6, master cylinder temperature, the influence of the change of product color masterbatch quantity before color adjustments must also know the product color change with temperature, pigment volume trends. Different mother color change with the temperature of the production or the amount of pigment, the product color change law is different. Color can be through the test process to determine its change law. Unless you have know this kind of pigment color change rule, otherwise cannot be quickly adjusted the aberration, especially in the new color masterbatch production.