[VIDEO] VFFS machine maintenance: How to change the cutoff knife blade
March 26, 2021
Each month, one of our expert packaging machine technicians walks you through a common maintenance task.
On the docket this month: How to change the cutoff knife on a vertical form fill seal (VFFS) machine.
What is a cutoff knife blade?
First, let's talk about the cross-seal jaws. Located on the bottom part of a VFFS machine, these two pairs of heated seal bars come together once per cycle to bond the sealant layers of the packaging film together to create a horizontal seam.
The cross seal jaws are composed of four sealing bars. The lower two bars create the top seam on the bag that has just been formed, while the top two bars create the bottom seam on the next bag. The cutoff knife is mounted in between the two sets of sealing jaws, connected to an air cylinder that drives its motion.
What does a cutoff knife blade do?
As bags are produced on a VFFS packaging machine, each bag is still connected to the one created after it. To separate the bags, once per cycle the cutoff knife will move forward quickly from in between the cross seal jaws, making a clean cut to release the current bag from the next one.
How to change the cutoff knife blade on a VFFS machine
CAUTION: Always follow your company's lockout/tagout and PPE procedures when performing machine maintenance. The cutoff knife is sharp and can cause serious injury. The jaw area may be hot and can cause serious burns.
Before you begin, make sure the cross seal jaws are in the fully open position.
- Remove the product stager to uncover the front jaw cover plate. The stager is held on my two 13mm bolts.
- Remove the two large flat head 5mm bolts and take off the front jaw cover plate.
- Underneath you will find where the knife blade is mounted to the air cylinder for the knife. Remove the two bolts with a 5mm Allen wrench.
- Carefully remove the knife blade.
- To re-install the knife blade, reverse the previous steps.
Recommendation: Keep spare knife blades on hand
Over time, with use, the knife blade will get dirty or start to dull and you will notice a dip in cutting performance. Many packaging machine owners choose to have an alternate blade (or two) ready to rotate in to keep production going and minimize downtime. If you do not have a spare blade, contact your packaging equipment manufacturer's spare parts department.
Get 5 expert maintenance & parts tips >>
Watch more packing machine maintenance videos
Check out the other videos in our VFFS Maintenance Quick Tips series:
How to change a vacuum pull belt on a high-speed machine >>
How to set up automatic film tracking >>
How to set up film registration & train photo-eye sensor >>
Stick to a comprehensive parts & maintenance plan
Machine preventive maintenance and managing your spare parts inventory effectively are two of the most important things you can do to ensure a long, productive life for your packaging line. Download our comprehensive VFFS machine preventive maintenance planner for daily, weekly, monthly, and yearly recommended maintenance tasks:
