Hot-cut Bag Making Machine vs Cold-cut Bag Making Machine
Hot-cut: Hot sealing knife completes sealing and cutting at the same time; the cut edge is fused together.
Cold-cut: Separate heat sealing first, then cut by unheated mechanical flying knife. The cut edge is open without fusion.
Hot-cut Bag Making Machine
A heated knife (around 200°C) presses down. It melts and seals the film while cutting it off in one action. After cooling, the cut edge sticks together.
Cold-cut Bag Making Machine
Heat sealing knife and cutting knife are two independent mechanisms.
The heat sealing knife seals the bottom of bags first. Then a set of unheated upper & lower flying scissors cuts the film mechanically. The cutting blade has no heat.
Appearance of Finished Bags
- Hot-cut: The edge has fused rim and slight curling. The cut position is sealed and not easy to fray. Improper temperature may cause yellowing or film burn-through.
- Cold-cut: Clean and straight cut edge. The cut is open with no fusion. No burning on printed patterns. It will get burrs if film is too thick or tension is unstable.
Applicable Materials & Bag Types
Hot-cut
✅ Suitable: Normal PE T-shirt shopping bags, garbage bags, ordinary PE flat bags, thin PE film.
❌ Not suitable: Color printed laminated bags, OPP bags. High temperature may smudge printed surface.
Cold-cut
✅ Suitable: Color printed bags, laminated film bags, OPP garment bags, thick PE flat bags, bags with high printing requirements.
✅ 4-line cold-cut: 4 lanes at one time, for mass production of flat bottom-sealed bags.
4. Advantages & Disadvantages
Hot-cut
Advantages: Fused edge, bag edge not easy to crack; simple structure.
Disadvantages: Strict temperature control; thin film easy to wrinkle or yellow; not good for fine color printing bags.
Cold-cut
Advantages: Smooth cut edge, no damage to printing; stable parameters for thick films.
Disadvantages: Cut edge is not fused; blade needs regular sharpening.
5. Quick Selection Guide
- Supermarket T-shirt bags, ordinary garbage bags → Hot-cut machine
- Color printed flat bags, OPP clothing bags, high-volume 4-line production → Cold-cut machine
