Hot Melt News

During the last downturn in the US economy, we were invited to speak at a major hot melt supplier annual sales meeting. We discussed the use of lower cost hot melt adhesives as a cost saving measure for their customers. This was a viable alternative as a result of the “Melt on Demand” technology we provide.

Lower cost adhesives typically have more limited “pot life” than those of higher cost and quality. The “pot life” is the amount of time it takes for hot melt to start degrading when held at application temperature in a melt tank. These “Melt on Demand” hot melt tanks can process these lower cost adhesives because they melt and condition hot melt adhesive at lower temperatures than all other tanks.

The “Melt on Demand” tanks are tall and narrow with a high power melt grid in the bottom. They are specifically designed to melt hot melt as needed, rather than heating the entire tank of hot melt to application temperature. The “Melt on Demand” tank creates a graduated viscosity of the adhesive and it insures that the adhesive is used in a first in – first out order. Other tanks mix the adhesive, presenting an opportunity for the adhesive to exceed its “pot life”. In the standard 20 pound “Melt on Demand” tank, there is a temperature differential of 50 to 100 degrees F between the melt grid on the bottom of the tank and the top of the tank.

In addition to saving cost on adhesive, these “Melt on Demand” tanks help to reduce downtime due to system maintenance, while lowering the need for disposable spare parts, such as nozzles and filters. Finally, “Melt on Demand” tanks can dramatically reduce or eliminate the fuming of hot melt and decrease operator exposure to molten hot melt, providing a safer work place.

In today’s economy we are all looking for effective cost saving measures. The “Melt on Demand” technology provided by Glue Machinery is one way to have an immediate positive impact on your process as well as your bottom line.

Paper Bag Bottom Gluing is done on most bag machines with a glue paste pot containing a roller and a wheel with a rotating glue pad/stamping system. The paste is poured into the pot, transferred onto the wheel, then transferred again to the stamp.  The stamp contacts and then stamps the bag bottom as it comes through the machine, leaving an “I” pattern of glue on the bag bottom.  This pattern is required to insure thorough bonds for all folded substrates. The bag is then closed and stacked for distribution. The water-based adhesive has some initial tack, but the bond occurs mostly as a result of the adhesive being absorbed by the paper.

This method of applying water-based adhesive is accepted as the standard for the paper bag industry, even though it produces significant amounts of defective product, limits the speed of the machinery, all  while being maintenance intensive. Because the water-based glue dries quickly on the glue pad, it is difficult to insure that the quantity of adhesive is consistantly applied to each bag bottom.  Too little glue or too much glue have the same effect — not bonding the bag bottom. In addition, the varied glue patterns can allow excess adhesive to squeeze out and bond bags to each other. Another common problem is that the paste pot has a tendency to sling adhesive, as the adhesive viscosity varies with the wheel rotation.  This slinging has the effect of “Blocking” bags together and creating the need for excessive cleaning and maintenance on the machine.

New technology is available to bond bag bottoms using non-contact hot melt application systems. As the open bag bottom travels through the bag machine, precise dots and lines of hot melt are applied to the bag bottom from fixed high-speed hot melt guns with the patterns on very close centers. The compression of the bag bottom flaps spreads the hot melt adhesive, which quickly sets to form a permanent bond. Fixed high-speed glue guns insure that there is no pattern variability. The precision nozzles simply open and close according to the signal supplied by the variable speed controller and adhesive is vented into beads or dots onto the bag bottom.

The use of this high speed hot melt system was pioneered by bag manufacturers who specialize in plastic, metalized and coated bag material, where water-based adhesives would not work.  These nonporous substrates have more memory than paper substrates, and they are easily bonded by the aggressive hot melt adhesive applied in precise patterns.

The Bag Bottom Hot Melt Gluer does not touch the bag, does not require hourly maintenance, virtually eliminates product defects,and can easily increase the speed of any bag machine.  This system is versatile and can also be used in seaming applications.

Hot Melt adhesive is a viable and preferred alternative for paper bag bottom gluing. It offers significant improvements in product quality, manufacturing processes, and maintenance requirements.

High Speed Hot Melt Retrofit Package for Bag Machinery

Hot Melt bonds all bag substrates for production of wider range of bags

visit Glue Machinery Corporation to discuss your project and how we can improve your ‘bottom’ line today.

In manual assembly and packaging applications, the actual hot melt adhesive usage is often twice as much as is required.  Precise manual application of hot melt can be difficult; therefore operators apply additional adhesive to insure a sufficient bond.  Packaging and/or product failures are more expensive than the cost of adhesive overuse, so managers simply accept higher adhesive consumption as a cost of doing business.

With skyrocketing raw material and shipping costs pushing the average cost of hot melt to more than $2.00 per pound, it makes sense to take another look at hot melt consumption.

Tips to Control Hot Melt Adhesive Consumption:

1. TRAINING — Operators have the ultimate control over adhesive usage.  Thorough documentation and training on approved assembly procedures will help operators gauge the correct amount of adhesive usage.
2. EVALUATION — Regular quality control checks should be performed to ensure that the appropriate amount of adhesive is being applied.  If not, additional communication and training with operators might be necessary.
3. EQUIPMENT – There are many options within adhesive application equipment.  Melting, pumping and applying capabilities of equipment should match assembly requirements.  Under-specified hot melt equipment may require operators to overheat the system in order to maintain sufficient melt rates.  This overheating can degrade adhesive and affect subsequent bonds.  In addition, this can lead to increased system maintenance requirements.
4. ADHESIVE – It is critical that the adhesive have the appropriate open time, set time and bond strength for the application.  This can only be accomplished with thorough testing.  If any characteristic of the adhesive does not match the application, consumption will certainly be affected.  Keep in mind that more adhesive does not necessarily mean a better bond; the amount of adhesive affects set times and subsequent bonds.
5. ERGONOMICS – Make it easy for operators to manipulate their tools.  Ease of operation enables operators to apply consistent patterns.
6. ASSEMBLY TIME – Operators need to have sufficient time to focus on the application.  This will allow for correct and standardized adhesive patterning on each package.
7. AUTOMATION – Consider ways to go “Hands Free.”  Benchtop units and XY Tables can provide more consistent and controlled adhesive application.

With proper training, monitoring, supplies and tools operators can produce better products, in less time with less adhesive.  Please visit www.gluemachinery.com/ergo-erector for an example of a system that has produced significant adhesive usage reductions in the case erecting industry.

Be sure to check in next month for information about reducing adhesive consumption in auto glueing applications.

Contact Pierce Covert to discuss your particular process and application needs to find out how we can improve your consumption rates.

Most padded and upholstered seats or seat backs used in the transportation industry are assembled with a solvent based contact adhesive. In this process the fiberglass or steel base of a seat or seatback is bonded to foam, which is then bonded to re-enforced fabrics, and finally covered with cloth. Due to the high traffic of these seats, they typically have a seven + year duty cycle. Given these conditions it is often required that lamination between these substrates be permanent.

Most assembly and recovering companies that perform this service are looking for alternatives to flammable spray products such as contact cement. Along with the need for adhesive alternatives, the need to have easier removal of the foam cushioning from the fiberglass or steel bases has been expressed.

Glue Machinery proposes that PUR reactive hot melt is a good alternative. It is easily sprayed onto one side of each component, it bonds quickly, and it cures to a very strong bond. When it is time for this component to be re-upholstered, the materials can be removed with high heat as the PUR bond is softened at temperatures over 300 F.

PUR Upholstering on YouTube

PUR is also available for smaller jobs or spot welding in 10 ounce cartridges, which are processed by PUR Cartridge Spray guns. For larger volume applications the heated five gallon pail unloader TOF20 Mini with heated swirl hose and handgun is used to dramatically increase output and cut the cost of the PUR hot melt.

Email Pierce Covert (info@gluemachinery.com) at Glue Machinery Corporation to discuss your specific needs and how we can improve or streamline your upholstering process.

Further information:

Champ 5 with GIA1051 Hot Melt

Beads of GIA1051 hot melt applied to different density EPS Foams.

Beads of GIA1051 at 334 F burn very little into substrate.

GIA1051 has a long open time that also gives good initial tack.

Bond between substrates is repositionable.

Bonds between EPS foams are permanent and destructible bonds.