Q1. What is “tonnage,” and how much do I need?

Tonnage = Clamping Force, which keeps the mold closed during injection. Too low leads to flash or short shots; too high wastes energy.

Quick estimate: Projected Area (cm²) × Cavity Pressure (kg/cm²) ÷ 1000 = Required Tonnage (Ton)

Example — Projected area: 120 cm²; Material: PA (Nylon), est. pressure: 400 kg/cm² → 120 × 400 ÷ 1000 ≈ 48 tons → Recommended machine: about 80–100 tons for safety margin.

Q2. What is the “injection unit,” and why is shot size important?

The injection unit includes the barrel and screw, which melt and inject material into the mold. The key parameter is shot size (in cm³ or grams), which must match your part size.

• Best practice: your part volume should be 30–80% of the machine’s shot size.
• Too small → can’t fully fill the mold.
• Too large → residence time increases; risk of discoloration or degradation.

Q3. My part weighs 110 g (PA + 10% glass fiber). What injection unit fits?

1. Material density ≈ 1.25 g/cm³
2. Part volume: 110 g ÷ 1.25 ≈ 88 cm³
3. Add ~20% for runner/scrap: 88 × 1.2 ≈ 105 cm³

Q4. How do I check if the screw size fits?

Refer to the machine spec sheet or consult your supplier. Typical reference values:

Q5. Anything else to consider?

• For glass-fiber–filled materials, use wear-resistant screws (e.g., bimetallic or nitrided).
• If you plan multi-cavity molds or product upgrades, leave capacity headroom.
• Special applications (e.g., optics or medical) may need custom screw profiles or specific temperature zones.