At the PMMI Innovation Stage at Pack Expo 2016 in Chicago, Aurizon Ultrasonics and Zip-Pak collaborated on a presentation to demonstrate why rotary ultrasonics is the most fitting solution for the zipper crushing process. They discussed benefits of the technology including a higher process rate, shorter seal times and increased quality of the zipper crushing process.
Using a rotary ultrasonic process to perform zipper crushing provides a zone on a zipper web that has been reduced in thickness. This thinning or “crushing” allows a faster cross seal of the product downstream in the process. If the zipper is full thickness at the cross seal process, it takes longer for the cross sealer (typically a heat seal) to make a complete and hermetic seal. Crushing or thinning this zone allows that seal to be made in a much shorter time, thus increasing the process rate capability.
Aurizon Ultrasonics’ zipper crushing equipment is comprised of a rotary ultrasonic horn acting on a lobed anvil with two high spots. The anvil is servo driven and camming software is utilized to locate the crush zone in the appropriate place on the product. This control process allows the customer to make grade or size changes electronically without having to change equipment.
The initial reason for applying rotary ultrasonics to the zipper crushing process was to find a solution that increased line speeds in a continuous process. Using a heat crush or stationary blade system would require that the web be stopped, which was functional but not ideal. In continuous flow wrap applications, using rotary ultrasonics increased speeds by nearly 50% – from 125 to 185 bags per minute.
Other advantages of the rotary ultrasonic solution include the following:
Rotary horn to anvil contact is acceptable
- Contact often leads to converter or horn failure in a stationary system.
Rotary horn systems accommodate varying thicknesses
- Stationary systems can be challenged by sealing over back seals or gussets.
Rotary horn fly-wheel effect
- Only a portion of the working surface is loaded at any given moment.
- The freely vibrating portion of the horn minimizes amplitude sag during peak loading.
- Potential to eliminate “heat seal” layer
- Materials self-heat, which means that films that melt at high temperatures are sealable
Rolling contact helps remove residual product from the seal zone
- Both styles of ultrasonics are effective at sealing through residual product.
- Rotary ultrasonics helps clear some materials instead of capturing them in the seal.
Adjustable cross direction width capability
- Traversing rotary horn can be programmed to package size
- A single rotary horn can be used for seals that are longer than the typical size
For more information, see Aurizon’s previous posts regarding Replacing Heat or Glue-based Processes with Rotary Ultrasonic Technology in an Industrial Application and Comparing Rotary Ultrasonic and Stationary or Blade Technologies or contact us here.