1. What is Injection Molding Tonnage?

Injection molding tonnage refers to the clamping force required to keep the mold closed during the injection process. It's measured in tons and is a critical factor in selecting the right injection molding machine for a specific part.

2. How Does the Calculator Work?

The calculator uses the tonnage formula:

Where:

• \( Area \) — Projected area of the part including runners (in²)
• \( Pressure \) — Injection pressure (psi)
• 2000 — Conversion factor (lbs to tons)

Explanation: The formula calculates the clamping force needed to counteract the injection pressure acting on the projected area of the mold.

3. Importance of Tonnage Calculation

Details: Proper tonnage calculation ensures the selected machine can produce quality parts without flash (excess material) while avoiding excessive machine size that increases costs.

4. Using the Calculator

Tips: Enter the total projected area (part + runners) in square inches and the injection pressure in psi. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is projected area?
A: The total area of the part and runners as seen when looking directly at the mold along the axis of clamp force.

Q2: How do I determine injection pressure?
A: Injection pressure depends on material and part design. Typical ranges are 3,000-20,000 psi. Consult material specifications.

Q3: Should I add a safety factor?
A: Yes, it's common to add 10-20% safety margin to the calculated tonnage to account for variations.

Q4: What if my part has complex geometry?
A: Complex parts may require higher tonnage due to uneven pressure distribution. Consider consulting with mold flow analysis.

Q5: Does material affect tonnage requirements?
A: Yes, materials with higher viscosity (like PC) require more pressure than low-viscosity materials (like PP), affecting tonnage needs.