In tri state plastic molding company the pellets are dosed through a loading system. The pellets deposit in an insulated hopper. It prevents the plastic from contacting the external environment. Hot, dry air enters the drying hopper from the diffuser cone. Air flows evenly through the material, heating it to the temperature described by the material manufacturer.
At the appropriate drying temperature, the molecular attraction between the polymer and the humidity weakens. The released water molecules diffuse and moves towards the surface of the pellet. Here the dry air absorbs them and carries them to the air outlet return at the top of the hopper.
Moisture-laden air passes through a filter to remove fines and other potential contaminants. If necessary, the return air passes through a heat exchanger to reduce its temperature to less than 150 ° F (65 ° C) before it enters the desiccant bed. Relatively cool and relatively humid return air flows through the desiccant, where it gives up its moisture.
A process air blower forces the dry air through a heater and back into the drying hopper. It is to start the cycle again in tri state plastic molding company. Ambient air enters the regeneration circuit through a filter. The air comes by the regeneration blower. The regeneration air heater raises its temperature to 425 ° F (218 ° C) before it enters the desiccant bed offline.
At these temperatures, the moisture holding capacity of the molecular sieve desiccant is very low. The hot regeneration air increases the temperature of the desiccant. It begins to release adsorbed moisture and the moisture laden air vents to the atmosphere through the moisture outlet port.
The moisture expelled from the desiccant during regeneration consumes a considerable amount of the regeneration heat. So the outlet air temperature will be low typically 200 ° F (93 ° C). After the adsorbed moisture has been purged from the desiccant, the outlet air temperature will rise rapidly. It comes to a level approaching the regeneration inlet air temperature according to tri state plastic molding company.
It is a programmable and decisive value to carry out the dosage correctly. For example, it guarantees the heating and homogenization of the melt, especially in semi-crystalline materials.
In injection molding there is a term common as dosing. It corresponds to the action of loading into the injection chamber enough molten plastic to fill the cavities of the mold. The dosage carries out by the accumulation of material in the injection chamber. It is common by the action of the rotation of the screw. The pressure comes in the injection chamber forces the spindle back to a programmed value.
As explained by a tri state plastic molding company, the plastic heats up to a greater extent. It is due to the effects of friction provided by the spindle and the cylinder (approximately 80%). Therefore, at higher dosing speeds, the cutting forces in the plastic increase. It is gaining heat, which could to some extent, favor the process.
Injection molding machines offer different programming options. The vast majority are programmed in RPM. In this option the number of turns that the spindle will make during one minute is programmed. Each machine has a maximum RPM capacity. It comes on the size of the spindle diameter.
Tri state plastic molding company says that for different screw diameters and at the same speed in RPM, the screw will travel at different tangential speeds. At a larger diameter and the same amount of RPM, the spindle travels a greater path. Because the perimeter of that circumference is greater, therefore, the tangential speed is also greater.
There is a rule in molding that indicates that the spindle turning speed must be programmed according to the desired dosing time. It must be less than the closed mold time (at least one to two seconds). If the rule is met, the mold will open seconds after dispensing is complete, reducing spindle idle time.
There is a risk that the mold opens when the dosing stage is comes out in a tri state plastic molding company. It generates a pressure drop in the injection chamber. Although there is the possibility of avoiding the effects through valve molds and sealing nozzles the recommendation. It is to try to finish the dosage before the end of the cooling time.
It is acceptable to apply this rule to most parts. However, it is not important to apply it in processes where cooling times are long and dosing times are short. In this case, the dosing rate can be so low that little shear stress would apply to the material affecting its homogeneity and heating in a tri state plastic molding company.
The recommendation for programming the speed of the spindle rotation comes by the manufacturer of the plastic. However, it is a misleading data since the manufacturers offer speed values in (rpm) revolutions per minute. But do not specify in which diameter of screw. And it is not the same speed to dose 200 rpm in a screw of diameter of 90 mm to one of 40 mm, the tangential speed will be different.
Tri state plastic molding company recommends for programming the spindle turning speed comes on first knowing the maximum tangential speed that the plastic can withstand. For example, Polypropylene (PP), which is a highly crystalline plastic. It supports dosing speeds of up to 1.3 m / s. This is a high speed compared to other materials such as Acetal (POM).
There are a lot of options you can choose for molding. I would suggest you to hire a professional plastic molding company for future project. Moreover, you can negotiate the price of injection molding if you are going for bigger project.