September/October 2012 | Volume 31, No. 5

Massman's machinery is engineered, fabricated and assembled
in an advanced, fully air-conditioned modern manufacturing facility.

Pleated filter seaming has been around a long time. What continues to change is how the first and last pleats have been held together. From the simple overlap, to the use of a metal clip, to hot melt and now ultrasonic weld seaming, the progression has been good for both the environment and to have a reliable impermeable closed seam.

Each seaming method can have its inherent drawbacks. Simple overlaps although environmentally friendly have a virtual open path to bypass filtration; metal clips have a considerable blow-apart resistance but are not incineratable; hot melts are incineratable but the high-tech polyamide adhesives which withstand oil, gasoline and alcohol are more difficult and problematic to dispense. The champion of the domain is the ultrasonically welded seam. Ultrasonic welds are environmentally friendly by being completely incineratable, easy to apply and provide a premium end pleat attachment.

Change Can Be Slow
Although all these seaming methods are still used today, the change to the ultrasonically welded seam can be slow due to the steps needed for approvals in the end users specifications. If it is mandated that a metal clip be used, a metal clip is often what continues to be used even when a more environmentally friendly and comprehensive seaming method is available. The end user is often not the driving force behind making changes unless it is tied to a direct financial advantage, and in the case of ultrasonic welding there is a cost per filter monetary advantage too.

Monetary Advantage
With a metal clip there is a constant fluctuating and repeated cost of the purchase of 70-pound coils of metal material that is used in clipping each filter. Hot melt seams require a never ending procurement of 40-pound bulk bags of adhesive and the continued cost of hot melt dispenser maintenance. In contrast, ultrasonic welding of the end pleats can be made without any additional materials if the plastic content of the media being welded is of at least a 65% plastic content. For cellulose medias, ultrasonic weld seams can be made with the introduction of a minuscule amount of synthetic string, sold in 8-pound spools, sandwiched between the end pleats. When the weld is applied the synthetic string flows and creates a contiguous premium seam.

Technical Advantage
Like metal clip seams, ultrasonic weld seams can capsulate numerous multilayers of media; whereas hot melt seams are not suited for multilayer filters due to only the inner layer of the joint being adhered.

Ultrasonic welds are electronically controlled and each weld is verified to give a 100% assurance that the appropriate amount of energy required is imparted, providing a contiguous good weld. In contrast, hot melts can sputter the adhesive dispense, leaving a gap for blow-by, and metal clip applications can mechanically fail and have an incomplete compressed clip for a by-pass under the passively attached clip.

Automation Equipment
Each seaming method has its advantages in automation also. Assuming the most basic level of equipment needed to manual apply a seam, the metal clip seam requires the least amount of upfront cost with only a metal bender and a press being needed. In comparison, higher level equipment is required for hot melt and ultrasonic weld seaming with the required purchase of either a hot melt dispenser or ultrasonic welder, respectively.

In an automation cost comparison, clipping is initially the least expensive to automate but the saving are quickly lost due to the expense of the metal material needed for each filter and overtime becomes the most costly method of seaming.

Automated seaming with hot melt typically has the highest product throughput (highest cycle rate per automatic machine), but coupled with the high initial equipment cost, the continued expense of hot melt material and the regular hot melt dispenser care, operation procedures, and even component replacement, automated hot melt seaming is much more trouble when looking at expenses not just within a 2 year justification window.

Only ultrasonic weld seaming provides a low cost after equipment purchase solution. Like hot melt seaming there is an initial automation equipment expense, but ultrasonic weld seams have less after purchase procurement and operational cost, little hassle and less maintenance issues. Automated ultrasonic weld seam cycle speeds are marginal in comparison to both metal clip and hot melt seaming, however, when considering the failsafe assurances of the ultrasonic seam, automation expenses beyond 2 years, reliability and trouble free operation, ultrasonic weld seams will more than make up for any additional equipment needed to fill production volumes.

Good automation equipment will – improve quality, mitigate unequal pleat spacing, decrease scrap, limit downtime and lessen operator intervention, while increase volume throughput. Good seam technology will improve your products and lessen the realized per filter cost. If your pleated filter can be ultrasonically welded, you will be in the trending marketplace to switch to the ultrasonically welded seam.

For more information contact:
Massman Automation Designs, LLC
PO Box 84, 1010 East Lake Street
Villard, MN 56385, U.S.A.

Tel: 1-320-554-1000 x602 | Sales: 1-651-315-7787