1. What is an Injection Molding Tonnage Calculator?

Definition: This calculator estimates the required clamping force (in tons) for an injection molding machine based on part geometry and material properties.

Purpose: It helps manufacturers select the appropriate machine size to prevent mold flashing and ensure quality parts.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( T \) — Clamping force (tons)
• \( A \) — Projected area of part (in²)
• \( P \) — Injection pressure (psi)
• \( SF \) — Safety factor (typically 1.5-2)

Explanation: The projected area multiplied by injection pressure gives the total force, which is then adjusted by a safety factor and converted from pounds to tons.

3. Importance of Tonnage Calculation

Details: Proper tonnage selection prevents mold flashing (too little force) while avoiding excessive machine wear (too much force).

4. Using the Calculator

Tips: Enter the part's projected area (including runners), typical injection pressure (default 5000 psi), and safety factor (default 1.5). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is projected area?
A: The maximum cross-sectional area of the part and runner system as seen from the direction of mold closure.

Q2: How do I determine injection pressure?
A: Material suppliers typically provide this. Common ranges: 3000-5000 psi for easy-flow materials, 8000-12000 psi for engineering resins.

Q3: When should I increase the safety factor?
A: Use higher factors (1.8-2.0) for thin-walled parts, high precision requirements, or materials with high viscosity.

Q4: Why divide by 2000?
A: This converts pounds (from psi × in²) to tons (2000 lbs = 1 ton).

Q5: What if my part has complex geometry?
A: Use the maximum projected area in the direction of mold opening, or consult with mold flow analysis software.