Molding is a complex process so one must consider the number of settings on plastic injection machines. The complexity of the different controllers, the number of variables in. The process and the significant fact that identical settings do not produce identical results. One of the most important objectives of. The injector is that the filling of the mold cavities is carrie out at a spee that is as uniform as possible. This is due to the non-Newtonian behavior of plastics. Which modify their viscosity or fluidity depending on. The applie stress or shear. Since the viscosity of plastics decreases when we apply “shear rate” during. The injection process, it is important that. The plastic circulates inside the cavity at a constant spee, that is, with a constant viscosity.
Controlling the plastic during injection
In order to control the homogeneity of the advance of the material inside. The cavity, the injector only one control element. Though it is quite sophisticate in some injection machine controls . The forward spee of the spindle or injection spee. If the plastic accelerates or decelerates significantly. The viscosity will decrease or increase depending on that forward spee so we will be filling . The mold in a non-homogeneous way . If the plastic advances constantly. The viscosity will be constant and the properties, contractions, etc. will be constant. They will also be constant throughout the piece. When we observe that. The flow front during filling accelerates is when Industry Email List we have to decide if it is necessary to profile during this stage. of filling the.
The injection machines
Currently, injection machines are designed and intended to quickly reach. The programmed injection speed and maintain it cycle by cycle. The performance of a good injection machine can be measured by. The repeatability of the injection time, that is. Tthe repeatability of compliance with the injection speed programmed. The machine setting. We can also apply speed profiles when some type of de as bursts of shear degradation in narrow areas, air trapping, shine, etc. Two aspects must be taken into account when programming filling profiles . One is that, even if we spend time desspeed profile based on the reate a profile with a geometry somewhat different from the one programmed due CU Leads to the action of valves, electronics, inertia. The second One efine is the flat profile, that is, without a profile.
