1. What is Gate Size in Mold Design?

The gate size in injection molding refers to the cross-sectional area where molten plastic enters the mold cavity. Proper gate sizing is crucial for controlling flow, preventing defects, and ensuring quality parts.

2. How Does the Calculator Work?

The calculator uses the gate size formula:

Where:

• \( \text{Volume} \) — Volume of material to be injected (cm³)
• \( \text{Shear Rate} \) — Desired shear rate at the gate (1/s)

Explanation: The formula calculates the optimal gate size based on the volume of material and the desired shear rate, which affects material flow and quality.

3. Importance of Gate Size Calculation

Details: Correct gate sizing prevents flow marks, reduces shear stress, controls filling time, and minimizes pressure drops in the injection molding process.

4. Using the Calculator

Tips: Enter volume in cm³ and shear rate in 1/s. Both values must be positive numbers. Typical shear rates range from 10,000 to 50,000 1/s for most applications.

5. Frequently Asked Questions (FAQ)

Q1: What happens if gate size is too small?
A: Too small gates cause excessive shear heating, material degradation, and may lead to short shots or flow marks.

Q2: What happens if gate size is too large?
A: Oversized gates can cause excessive gate vestige, longer cycle times, and may require secondary trimming operations.

Q3: How does material affect gate size?
A: Different materials have different viscosity and shear sensitivity, requiring adjustments to gate size calculations.

Q4: What are typical gate sizes?
A: Gate sizes typically range from 0.5mm to 6mm depending on material, part size, and wall thickness.

Q5: Should gate size be adjusted for multi-cavity molds?
A: Yes, balancing runner systems and gate sizes is critical for uniform filling in multi-cavity molds.