Sealing Over Extra Layers of Film at the End Seal (part 4 of 4): Optimizing Crimper & Sealing Jaw Design

Matt Wojtech horizontal flow wrappers, sealing, vertical FFS baggers January 15, 2018crimpers, downtime, Dura-Therm, Easy Seal, flexible sealing face, flow wrapper, fractured end seal, heat, leakers, mooning, packaging film, pressure, projects, sealing jaws, sealing theory, vertical bagger

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.

Package Quality Issues_vertical baggers_Greener Corp

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.

Crimper and Sealing Jaw Design Options

Troubleshooting Extra Layers of Film at the End Seal (Part 1 of 4): Refining and Eliminating Wrinkles and Creases on Horizontal Flow Wrappers

Matt Wojtech forming, horizontal flow wrappers, sealing February 14, 2017crimpers, fin seal wheels, flow wrapper, heat, leakers, packaging film, pressure, seal quality, serrations, wrinkles & creases

Varying thicknesses of film at the end seal can cause sealing problems, especially at the transition point between two and four layers created by the fin seal, gussets, wrinkles and creases, as well at the corners. Applications of pressure and heat (if applicable) must be great enough to cause the sealant layer to flow into and seal off these voids. Excess pressure can easily crush or split the end seal, while overheating distorts the seal and can cause poor hot tack, where the film springs back open, or “moons,” before the seal can set.

Package Quality Issues_Greener Corporation

The operating window for creating quality seals can be elusive, resulting in packages that leak, are distorted, and have little appeal to consumers.

An important step in troubleshooting these issues is to eliminate unintended wrinkles and creases. This post, the first in a four-part series, will examine this process on horizontal flow wrappers; Part 2 considers these issues on vertical baggers.

Optimizing Knife and Anvil Set-Up on Horizontal Wrappers

Matt Wojtech cutting, horizontal flow wrappers September 21, 2016anvil, cleaning, clearance, downtime, Easy Seal, flow wrapper, heat, knife, pressure, shim stock, training

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.

♦ Set Up the Crimpers First

Clearance and Pressure Adjustments required to create a good seal can impact the knife and anvil set-up.

HEAT: Improving Seal Quality and Consistency

Matt Wojtech horizontal flow wrappers, sealing, vertical FFS baggers June 22, 2016crimpers, Dura-Therm, flow wrapper, heat, mooning, seal quality, sealing jaws, temperature, vertical bagger

For heat seal applications, each packaging film structure has a Seal Initiation Temperature (SIT), at which the sealant layer is heated enough to flow into and seal off gaps in the end seal and provide a minimally acceptable seal, and a Maximum Temperature, beyond which the film distorts, fractures, or has inadequate hot tack (seal strength and integrity while the seal is still warm). The temperature range between the minimum and maximum is the film’s Operating Window.

For a number of reasons, regulating heat is not as straightforward as simply adjusting the temperature setting within the operating window for the film you are running.

♦ The sealing face of crimpers and sealing jaws is often hotter in the middle than at the ends, where heat dissipates more quickly. These inconsistencies are readily apparent in the thermal profile shown below:

Stainless Steel Crimper Thermal Profile

Case Study: Packaging Material Cost Reduction

Matt Wojtech horizontal flow wrappers, sealing January 1, 2016anvil, collaboration, crimpers, Easy Seal, flow wrapper, fractured end seal, knife, packaging film, productivity, projects, seal quality, seal reduction profile

Project Goals

The corporate engineering department at a large, international company commenced a project to reduce material costs for a variety of products that are individually packaged on horizontal flow wrappers. Greener Corporation was invited to participate in a series of meetings that defined the project’s initial goals:

To reduce the cut-off length for each package by reducing the overall seal width, thus allowing the product envelope to remain unchanged.

To achieve material savings without degrading seal integrity or productivity levels.

To achieve a project payback period of twelve months or less.

White Papers: From Problem Solving to Proactive Improvement

Matt Wojtech cutting, forming, horizontal flow wrappers, sealing, vertical FFS baggers March 16, 2015anvil, crimpers, downtime, flow wrapper, forming set, fractured end seal, Greener Corporation, knife, seal quality, sealing jaws, sealing theory, serrations, vertical bagger

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.

End Seal Leaks at the Fin Seal Fold

Serration Pattern Design