How do you calculate injection pressure in injection molding?

How do you calculate injection pressure in injection molding?

A general calculation for determining press size needed is as follows: Pressure (lb/in2) x Projected Area (in2) = Force (lb.) Here are a few other important tips for calculating the right press size for your plastic injection molded part.

What is injection pressure in injection molding?

Injection pressure is the force applied by the reciprocating screw to push molten plastic resin into a mold cavity, up to about 95% of capacity. It’s balanced against the clamping pressure of the machine, and is calculated based on the size and shape of the part, as well as the size of the gate opening.

How is clamping tonnage calculated?

T = A x cf. For example, the projected area of the molded part is 150 sq/in times a clamp factor of 3 (tonnage needed/square inch from material data sheet). 150 x 3 = 450 tons needed. If you are running in a 500-ton press, try starting at 450 tons.

What is the unit of injection pressure?

For injection molding, the injection pressure can be between 15,000 and 20,000 psi (103–138 MPa). The average injection molding machine has 20,000 psi.

What is injection pressure definition?

1. n. [Well Completions] The pressure at which a treatment or test fluid can be injected into the formation matrix without causing a breakdown, or fracture, of the rock matrix. The injection pressure is commonly described as the surface pump pressure required to achieve injection.

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.

How do you measure for mold?

Fill the mold with water and then pour that water into a measuring cup. Multiply the number of fluid ounces of water by 1.8 to get the total cubic inches of the mold. For example, if your mold holds 12 ounces of water, 12 X 1.8 = 21.6 cubic inches.

How do you calculate injection molding tonnage?

Now you can calculate necessary tonnage based on the projected area times the clamp factor for the material used. T = A x cf. For example, the projected area of the molded part is 150 sq/in times a clamp factor of 3 (tonnage needed/square inch from material data sheet). 150 x 3 = 450 tons needed.

How do you calculate clamping force injection molding?

For example, a product has a projected area of 410 cm2 and material is PE, calculate clamping force. Calculated by above formula: P = Kp * S = 0.32 * 410*1.1 = 141 (T), 150 ton injection molding machine should be selected.

What is screw diameter in injection molding?

The screw diameter is important for 2 reasons. The first reason is that it determines the maximum available injection pressure, the smaller the diameter the higher the available pressure. This is critical for parts that have thin walls and a long flow length and for plastic materials that are difficult to inject.

How many zones are in injection molding machine?

The temperature profile in the three zones is dependent on the plastic type. The first zone is called the feed zone. The second zone is called the compaction zone. The third zone is called the metering zone.

How do I plot injection injection pressure vs time?

Once you have the graphics working, to plot injection pressure vs. time, go to the screen on your controller that deals with pack or second-stage velocity. If your machine calls it a velocity, the first thing you have to figure out is what pressure controls this pack velocity—first-stage set pressure or second-stage pressure.

How do you find the hold time on an injection molder?

To find the true hold time, the molder must subtract the actual fill time from the set time on the injection timer. A series-logic controller ignores any remaining time on the injection timer after first stage is reached and provides a second-stage time exactly at whatever is set.

What is fill time in plastic injection molding?

One of the important process parameters to establish and record for any injection molded part is its injection or fill time. Fill time is an indication of how fast the plastic is injected into the mold.

What is the ramp time to set pressure for molding?

From 0.1 to 5 mm/sec, the dip gets closer to the flat line; after 5 mm/sec, nothing changes This graph represents a typical ramp time to set pressure—when first-stage set pressure controls the velocity of pack and there is a time associated with it. This can definitely overpack and flash your mold.