A Tech Bite from Greener Vice-President & co-owner Matt Wojtech
“The Tortoise and the Hare” and “Slow is Smooth, and Smooth is Fast” are just two of many adages promoting the advantages of a slower, steady pace for solving problems and accomplishing goals. Does this strategy apply to your packaging lines?
This Greener Tech Bite explains how you can use the seal range of your flexible packaging material to determine the optimum machine speed on your flow wrappers and vertical baggers.
Sealing Jaw Temperature Cycles
During steady production, sealing jaw temperatures dip as they transfer heat to the package and then recover. These temperature cycles typically range within a few degrees.
When product feed rate fluctuates and production slows or is interrupted, sealing jaw temperatures cycle more widely.
Setup for Maximum Machine Speed
Flow wrappers and vertical baggers are often set up to run at maximum speed, with the intent to increase output. To maintain seal quality with the resulting shorter dwell times, sealing pressure is increased just short of the point where seals are crushed or split.
Steady Production Rate
Temperature is set to the highest possible level that keeps temperature cycles within the packaging material’s seal range—the span between the seal initiation temperature and distortion temperature. The seal range narrows as machine speed increases and dwell time is reduced.
Variable Production Rate
With machines set up for maximum speed, any fluctuation in product feed rate that slows production creates wider temperature cycles that can exceed the seal range.
This results in damaged and distorted packages with poor seal integrity.
Downtime accumulates as operators stop the machine to clean melted packaging material and product from the sealing jaws and fin wheels.
Maximum vs. Slower, Steady Machine Speed
Let’s look at some examples that compare scrap rate, downtime, and output levels for a flow wrapper and a vertical bagger set up to run at different speeds.
Flow Wrapper
A. Setup for Maximum Machine Speed
In situation A, a flow wrapper is set up to run at the maximum speed of 300 packages per minute. Over a ten hour production run, the wrapper only maintains this top speed for a cumulative total of five hours, or half the run.
During the other five hours, machine speed ramps up and down and occasionally pauses as the product feed rate fluctuates. With the wrapper set up to run at maximum speed, sealing jaw temperature cycles frequently exceed the seal range, increasing the scrap rate and downtime and limiting production to an average of 200 packages per minute.
Potential total output for the run is 150,000 packages, but actual output is limited to 117,000 packages.
B. Setup for Slower, Steady Machine Speed
In situation B the wrapper is set up to run at 225 packages per minute, which provides a broader seal range to accommodate wider temperature cycles when the product feed rate fluctuates.
This machine speed is maintained for most of the ten-hour run, with low scrap and downtime rates, and 129,600 packages are produced.
A: Maximum vs. B: Slower, Steady Machine Speed
Setting up for and running at this slower, steady speed improves seal quality and produces higher actual output than the setup for maximum speed.
Vertical Bagger
A: Maximum vs. B: Slower, Steady Machine Speed
Similar outcomes occur on vertical baggers where the product feed rate fluctuates. The setup for slower, steady machine speed produces more packages with better seal quality.
Slow is Smooth, and Smooth is Fast
To optimize setup on your flow wrappers and vertical baggers, use seal range and temperature cycles to determine what machine speed produces the highest output and best seal quality.
For cold seal applications where temperature and dwell time are not issues, setting machine speed to the maximum product feed rate can still cause problems that decrease output, such as frequent starting and stopping, empty packages, and product registration issues.
Dura-Therm and XR™* Sealing Jaws
You can increase the optimum machine speed on your flow wrappers and vertical baggers by updating to advanced sealing jaw designs.
* patent pending
Dura-Therm sealing jaws and XR™* Serration Technology reduce sealing jaw temperature variation, resulting in narrower temperature cycles that provide two types of opportunities:
Increase Output
To increase production output, you can increase machine speed and still keep temperature cycles within your material’s seal range to maintain seal integrity.
Convert to Sustainable and Less Expensive Packaging Materials
With Dura-Therm and XR™* sealing jaws, you can convert to sustainable or less expensive packaging materials with a narrower seal range without reducing machine speed or seal quality.
Slower and Steady Wins the Race
Setting up your packaging machines for slower, steady production and updating your sealing jaws can optimize production output and quality.
For help determining your optimum machine speed, or to learn how Dura-Therm and XR™* Sealing Jaws can improve your results, contact Greener Corporation.
We provide integrated parts and technical service solutions worldwide.
