How is residence time calculated in injection molding?
How is residence time calculated in injection molding?
As for the residence time: If you calculate the volume of material in the barrel as 10 ounces and your part is 5 ounces your screw contains two shots of material. Multiply the number of shots in the barrel by your cycle time and you will get a residence time for the material.
What is material residence time?
The amount of time it takes for plastic to travel from the feed throat of the molding machine to the mold cavity is known as the residence time. Depending on the molding material, having too large or too small of a total shot capacity compared to the shot size of the mold can cause several molding issues.
What is barrel residence time?
Barrel residence time is the time the resin spends from the first inception into the injection barrel until it leaves through the end of the nozzle. Barrel capacity is generally rated by the amount of polystyrene they can inject in one shot and is usually rated in ounces or grams.
How do you process polycarbonate?
Since polycarbonate is highly viscous, it is usually processed at high temperature to reduce its viscosity. In this process, the hot polymer melt is pressed through into a mold with high pressure. The mold when cools, gives the molten polymer its desired shape and characteristics.
What is plasticizing capacity in injection molding?
The plasticizing capacity is the amount of plastic that can be melted and homogenized with heat in the barrel per unit of time (lb/h or kg/h). If the plasticizing capacity is too low in relation to the shot size required, the chances are that the injected plastic will not be com- pletely melted.
How do you calculate barrel capacity?
How to Find the Volume of a Barrel
- volume = h × π × ((2 × r22) + r12)3.
- To get the total volume in cubic feet, convert from cubic inches using the formula ft3 = in3 × 0.000578704.
- Gallons can be found using the cubic feet to gallons formula:
- gallons = h × π × ((2 × r22) + r12)3 × 7.480507.
What is barrel capacity?
When used to denote a volume, one barrel is exactly 42 US gallons and is easily converted to any other unit of volume. As the US gallon since 1893 is defined as 3.785411784 litre, a volume of one barrel is exactly 158.987294928 litres.
How do you calculate molding?
Divide the total number of inches by 12 to convert from inches to linear feet. For example, if your wall measured 40 inches in length, and you are installing molding on the top and bottom, 40 x 2 = 80 inches. Divide 80 by 12 to get 6.66 linear feet.
What are the disadvantages of polycarbonate?
The main disadvantage of polycarbonate is that it isn’t resistant to scratches. For example, if a branch should happen to fall on a patio canopy made of polycarbonate, it may be scratched. This problem can be solved by polishing the polycarbonate.
Is polycarbonate hard or soft?
Polycarbonate is a durable material. Although it has high impact-resistance, it has low scratch-resistance. Therefore, a hard coating is applied to polycarbonate eyewear lenses and polycarbonate exterior automotive components.
What is the plasticizing capacity?
What is plasticizing effect?
Plasticization, in general, refers to a change in the thermal and mechanical properties of a given polymer which involves: (a) lowering of rigidity at room temperature; (b) lowering of temperature, at which substantial deforma- tions can be effected with not too large forces; (c) increase of the elongation to break at …
What is the residence time of plastic resin?
Plastic residence time is the time that plastic or resin is subjected to heat during fabrication. An injection system features a hopper, barrel, reciprocating screw, and injection nozzle. The shot size is the maximum amount of plastic injection mold that can be injected in one molding cycle.
What do you need to know about polycarbonate?
One of the most important elements which you have to know when dealing with polycarbonate parts is tolerance. You see, there is a need for getting a polycarbonate part that has a tight tolerance for the effectiveness of the application.
Is the transmittance of polycarbonate plastic Unbreakable?
Also, PCs are virtually unbreakable. Transmittance – PC is an extremely clear plastic that can transmit over 90% of light as good as glass. Polycarbonate sheets are available in a wide range of shades that can be customized depending on an end-user application.
How to calculate the residence time of a shot?
To be on the safe side, you could say there are eight shots in the barrel. Multiply eight by the cycle time to get the residence time of the plastic in the barrel. As an example, if the cycle time is 40 sec then the residence time would be 8 × 40 = 320 sec or 5.4 min.