Enter the injection force (lb) and the projected area (in^2) into the Calculator. The calculator will evaluate the Injection Pressure. 

Injection Pressure Formula

IP = F/PA

Variables:

  • IP is the Injection Pressure (psi)
  • F is the force (lb)
  • PA is the projected area (in^2)

To calculate Injection Pressure, divide the injection force by the projected area.

How to Calculate Injection Pressure?

The following steps outline how to calculate the Injection Pressure.

  1. First, determine the force (lb). 
  2. Next, determine the projected area (in^2). 
  3. Next, gather the formula from above = IP = F/PA.
  4. Finally, calculate the Injection Pressure.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

force (lb) = 400

projected area (in^2) = 700

FAQs

What is injection pressure and why is it important in injection molding?

Injection pressure is the force per unit area applied by the injection machine to push the molten material into the mold cavity. It’s crucial in injection molding as it affects the quality of the molded parts, including their consistency, strength, and appearance.

How does the projected area affect the injection pressure calculation?

The projected area is the surface area of the part in the direction of the injection force. It directly affects the injection pressure calculation since the pressure is inversely proportional to the projected area. A larger projected area requires less pressure to fill the mold cavity with the same amount of force.

Can the injection pressure be too high? What are the consequences?

Yes, the injection pressure can be too high. Excessive injection pressure can lead to several issues, such as flash (excess material that escapes from the mold cavity), stress marks on the molded parts, and damage to the mold itself. It’s essential to optimize the pressure to avoid these problems.