Driven by motor to transport the products from one location to another, conveyors are generally used in all stages of the factory production – filling, packaging, labelling and distribution. They have become a key element in all automated facilities and applications today, responsible for orientating and metering out product, providing buffering and staging between processes.
3 types of conveyor system are commonly used on labelling machines: Green belt conveyor, black belt conveyor and plastic top chain (PTC) conveyor. They are equipped with different characteristics and have been used for different labelling purposes.
- Materials:
Black belt conveyors are made of synthetic belt that use a combination of fabric and polyester material; the material for green belt conveyors is similar to black belt but PVC material is applied instead. Plastic top chain conveyor is assembled with modular plastic parts into conveyor belt.
- Mechanism:
Black belt and green belt conveyors move with the friction created between the belt surface and the motor-driven conveyor pulley. This allows them to operate in fast speed with low noise generated.
PTC conveyors move via positive drive where the plastic sprocket under the belt propel it forward, fast conveyor speed is anticipated from the low friction generated from the positive drive. However, loud noise generated from the vibration when runs in higher speed is unavoidable, making it unfeasible for certain noise sensitive production environment.
- Application/Usage:
As friction drive was used for both black belt and green belt conveyors, heavy objects are not recommended on them as it will increase the belt friction result in slower operation and more susceptible to breakage in long run. Green belt conveyor with PVC surface has higher friction relative to black belt, making it a more appropriate choice for feather light products on top labelling machine such as egg trays, plastic bags and empty plastic trays. Whereas black belt with moderate friction is commonly used for round bottle on wrap around labelling machine to avoid too much friction applied while bottles are being rotate for labelling process.
On the contrary, PTC conveyors are usually employed for heavy objects such as detergent bottles, jerry cans, or edible oils for the durability and hard surface derived from plastic that allows product to stay still on conveyors during transport whilst providing sufficient support on products weights. Light weight products are not recommended on PTC due to the strong vibration and lack-of-grip surface as products might topple during the process.
- Maintenance
Black belt and green belt conveyor both faced a major drawback – the ability for the belt to stay centered. Any alteration of the belt width and length will require proper design and tuning in order for the belt to be centered. Adding guides at the belt bottom could help to stay centered but might impair on performance due to additional friction.
As for PTC, the conveyor is always centered thanks to the positive drive. Conveyor runaway is impossible unless the teeth are broken. The cost for PTC conveyor is higher because of the way it is fabricated. Although the plastic module used to fabricate PTC is inexpensive, however, the cost is very much driven by the manpower required to assemble the component.
In term of maintenance, the entire black belt and green belt requires to be replaced while the modular design of PTC requires only a section of the component to be replaced if damage occur.
