There is no one-size-fits-all solution for the design of crimpers and sealing jaws on horizontal flow wrappers and vertical baggers; they should be specified according to the packaging film, products, and conditions of your packaging operation.
This post, the last in our four-part series, reviews design options for crimpers and jaws. The optimal combination of serration patterns, materials, and special features can dramatically improve seal quality and productivity when sealing across extra film layers at the end seal.
Transitions on the end seal between varying thicknesses of film created by the fin seal, lap seal, gussets, and wrinkles make it more difficult to maintain the operating window necessary for quality seals:
Too little pressure leaves gaps, or leakers, at these transition zones.
Excess pressure can easily crush or split the end seal.
Overheating distorts the seal and can cause poor hot tack, where the film springs back open at transition zones or “moons,” before the seal can set.
The end results can be packages that fail to protect the product or have little appeal to consumers, as well as lost production time spent attempting to meet package quality standards.
Set-up procedures for knives and anvils can vary according to the make and model of the packaging machine, knife adjustment style, and other factors. There are, however, some general principles that make these adjustments more effective and efficient, reducing downtime and parts costs.
♦ Optimize Knife Design
Knives ground on a diagonal, or bias–whether they have a zig zag or a straight cutting edge–require less pressure to cut so they are easier to set up and typically last longer.
Zig zag knives with smaller (more) teeth are also easier to set up and provide longer life.
Even experienced users of forming sets can, over time, become conditioned to accept the hidden costs and preventable constraints of their packaging equipment. As with all waste, however, careful diagnosis of the root causes will lead to implementation of effective solutions.
One such root cause is forming tube misalignment. This can occur if the forming set has been accidentally mishandled and damaged or if the forming set has not been properly designed and fabricated in the first place.Read more
Greener Corporation has published a series of white papers devised to help optimize package quality and productivity on horizontal and vertical form fill seal packaging lines. In addition to helping you solve problems, these technical articles provide foundational information you can use to implement proactive improvements—an approach that helps deter problems from occurring in the first place.
The first video in Greener Corporation’s “Tech Bites” series explains how adjusting backlash on horizontal flow wrappers helps prevent problems such as fractured end seals and premature failure of knives and anvils.