Double Spring Snap-on Gripper Chain, also known as VFFS Vertical Form Fill Seal Film Pulling Chain, is a specialized gripping chain designed for flexible film traction in food packaging equipment.

Base Chain Specification

• Base chain model: 08B
• Pitch: P = 12.7 mm (1/2 inch)
• Standard version: 08B-2SS
• Main material: 304 stainless steel

Structure & Working Principle

The core design is an independent double-spring gripping unit. Each gripper jaw set is equipped with two springs, and each spring provides approximately 30 N of force. Together, the two springs deliver uniform and stable clamping force.

The grippers are opened and closed by a side cam mechanism. As the chain runs along the guide track, the cam presses the tail of the gripper jaw to open the clamping mouth and allow film insertion. After leaving the cam zone, the double springs automatically close the jaws and firmly hold the film, ensuring synchronous traction during operation.

Advantages of the Double-Spring Design

Compared with single-spring gripper chains, the double-spring structure provides more balanced force distribution, significantly improves spring fatigue life, and reduces the risk of one-sided loose clamping, slippage, and film deviation.

This is the flat jaw version. The flat clamping surface is suitable for thin PE film, laminated film, and packaging roll stock, while minimizing the risk of film surface damage.

Main Features

• Full stainless steel construction: Link plates, rollers, pins, gripper jaws, and springs are all made of stainless steel.
• Hygienic design: Resistant to rust, water, and washdown cleaning, suitable for food packaging environments.
• Stable and adjustable clamping force: Different spring stiffness can be selected to adapt to thin soft film, thick stretch film, aluminum foil, and other materials.
• Good synchronization: Based on the standard 08B roller chain base, it matches standard sprockets for accurate transmission.
• High-speed capability: Less prone to tooth jumping or position loss during high-speed film pulling, suitable for high-speed VFFS machines.
• Low maintenance: Self-lubricating options are available to reduce oil contamination on food-contact films.
• Modular structure: Each gripper unit is independent. If one gripper is damaged, it can be replaced individually without replacing the entire chain.

Typical Applications

• VFFS Vertical Form Fill Seal Packaging Machines: Vertical film pulling and forming for snacks, granules, powders, frozen food, and similar products.
• Thermoforming Packaging Machines: Base film conveying for vacuum packaging and modified atmosphere packaging lines.
• Pharmaceutical pouch packaging and daily chemical sachet packaging equipment.
• Other flexible web handling: Continuous traction of aluminum foil, laminated film, thin plastic film, and similar flexible materials.