Cutting Devices for Extrusion Blow Molding Machines

Cutting devices on an extrusion blow molding machine are usually divided by function: cutting the unformed parison and trimming the semi-finished product neck. Parison cutting options include hot cutters, cold pointed cutters, and cold cutters with sealing mechanisms. Neck trimming options include on-machine spin trimmers, independent spin trimmers, linear neck trimmers, and centrifugal trimmers.

1. Hot cutter: An electrically heated blade with adjustable temperature. It cuts and melts at the same time, so it works with many materials. The trade-off is electricity use and the need for proper maintenance.
2. Cold pointed cutter: A sharp customized blade set matched to the number and spacing of die heads. It pierces and cuts the parison at high speed, but it is less flexible across different die-head layouts and must be maintained carefully.
3. Cold cutter with sealing: Front and rear blades close together to cut the parison while a sealing mechanism closes the lower opening. This supports parison support air, which is useful for square products and corner strength. The mechanism is more complex and usually costs more.
PP, EPET, and PETG normally require hot cutting because the parison can break or tear if cut cold.

A neck trimmer removes the dome or head from a semi-finished bottle. On-machine spin trimmers are mounted beside the blow molding machine and trim as the bottle moves and rotates, but heavy bottles or large necks may tilt without bottom support. Independent spin trimmers use the same principle but operate as separate units with their own conveyor and control box. Linear neck trimmers support the bottle from below through a longer cutting path, so they are more flexible for different bottle sizes. Centrifugal trimmers are installed with the machine and are suitable for very thin or soft products. Heating options can be added for materials such as PET.