Hot Melt News

Erecting and sealing cases, cartons and boxes with hot melt adhesive is standard practice in the packaging industry. This is usually accomplished by spreading hot melt over case flaps in a series of parallel beads. Using smaller parallel beads on close centers bonds much faster than using a large bead or two. These smaller beads also offer a much stronger lamination bond, rather than the less effective point of contact bond.

T Nozzle on High Flow Manual Bead Hotmelt Handgun

“T” nozzles, or spreader nozzles, have been used as a low cost method of channeling hot melt into multiple patterns from one applicator. Hot melt adhesive flows under pressure into this “T” or spreader nozzle and is channeled into a series openings on close centers. The “T” nozzle or spreader nozzle is used with hot melt stick guns, hot melt bulk guns as well as automatic hot melt guns.

T Nozzle on ChampStick400 available from Glue Machinery Corporation

The “T” nozzle is not suitable for precise application requirements, as there can be a tendency for temperature variations within the nozzle. The “T” nozzle is much larger than a standard nozzle, so the adhesive temperature varies as it moves through the nozzle and further from the heat source. This can create poor patterning and hot melt stringing. The use of low viscosity
hot melt will result in better flow from the “T” nozzle.

Frequent and consistent use of the gun and nozzle, will also improve patterning, as the hot melt flow through the nozzle actually heats the nozzle making for more consistent temperatures from gun to substrate.

Contact Pierce Covert at 410.761.2727 to discuss this simple alternative to improving your case sealing operation. Also see: Ergo Erector Basic Case Sealer

Improved efficiency is an overriding concern in today’s competitive environment.  An easy place to start is with adhesive usage.  Most automatic hot melt applications can be adjusted to operate with less hot melt adhesive. When planned and executed properly, adhesive reduction can offer significant long term cost savings.

Before making any changes to your hot melt system or adhesives, you should produce sample blanks with non-compressed hot melt and glued samples for evaluation by your hot melt adhesive and hot melt machinery suppliers.

To make thorough recommendations for your adhesive process, it is important to include the following information with your samples:

• Hot Melt System Temperatures
• Air Pressure Used for the Pump
• Nozzle Tip Orifice Size
• Adhesive Specification Sheet
• Current Consumption per Package
• Type of Hot Melt System Currently in Use
• Speed of Operation
• Frequency of Hot Melt System Maintenance
• Pattern Coverage Requirements.
  To include:
  • Number of Beads
  • Bead Profile
  • Centers Between the Beads

It can also be helpful to have your engineering, maintenance, and production personnel review these same samples. They are often able to provide valuable insight into your adhesive application and consumption process.

Too often, hot melt adhesive is used to compensate for other deficiencies in the production process. Dirty and/or poorly maintained hot melt systems can result in reduced adhesive bond quality. Nozzle cloggage issues can merely be the result of an incorrect orifice size on the nozzles. Another point to consider with regard to potential adhesive waste is hot melt application temperature.If the temperature is too hot, the adhesive is too thin, and this can result in excess amounts of adhesive being dispensed.

The case, carton, corrugated box sealing and erecting industry is one that has seen significant improvements on adhesive savings with the use of professional and in-house adhesive consumption consultation. It is important to note that incorrect compression of the adhesive and substrate on the erector or sealer can affect the sealing capacity of hot melts between substrates.

Be sure to also read our article, “Use Lower Cost Hot Melt” to learn about the benefits of using “Melt on Demand” Hot Melt Tanks and how they too can reduce your production costs.

Contact Glue Machinery Corporation today to discuss your application and how we can improve your adhesive savings.

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.

Heated hoses are used to convey hot melt (thermoplastic) adhesives in the typical adhesive application system from the melt tank to the dispensing valves. The hoses are temperature controlled by means of a sensor, located on the outside of the hose core, usually between the hose heater and the hose outer wall. Remote temperature controls are capable of holding temperatures fairly close to the setpoints today, as compared to years ago.

There is still a problem with contamination over time within the hose itself, despite manufacturer’s efforts to minimize this tendency. Some adhesives can virtually eliminate charring within the hose, but most of the standard hot melt adhesives today have some limit in terms of ‘pot life’. This is the length of time that a material can be held at a given temperature before signs of degradation begin to occur. This period of time can range from several hours to almost indefinitely, depending on the adhesive and its formulations. The average hot melt has a pot life of 50-100 hours at application temperature, often 350F.

The issues begin to occur within hoses that are not kept in continuous production first, but can eventually affect all hoses over time. When the material is not flowing within the hose, the hot melt that is in contact with the hose wall is the hottest material in the hose. The adhesive, over time, if exposed to high heat will eventually begin to break down, often leading to an increase in viscosity, gelling, and ultimately charring which forms over time on the hose interior walls. The use of ‘cleaning fluids’ to try and dislodge this ‘char’ often is not fully effective, rather loosening and removing some, but leaving the rest to become dislodged after the hose is put back in service.

Users can minimize problems with hoses over the long term by using the newer ‘standby’ feature on hot melt tanks which  lower the hose temperatures when not in use. Other options are to manually lower hose and gun temperatures or simply turn off the entire system to minimize periods where they are kept hot but material is not being dispensed. It is recommended to replace hot melt hoses every 3 or so years, depending on system usage and materials being used, to ensure clean system operation and minimized downtime due to clogged nozzles and filter maintenance.

Hot Melt Hose Operation by John Neu at Glue Machinery Corporation

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.

Recently, a customer having two identical units was experiencing problems with only one of the units, despite the fact that both were similarly configured and running the same materials. After investigation of his error code (OV-C), we asked him to check his supply voltage. What was discovered was that the voltage source for each unit was from a separate feed. The transformer output that was supplying the roll coater was providing 240v, but was spiking as high as 300V during operation. Relocating the unit to a more stable power source corrected this condition and the customer was able to resume work at full capacity.

Glue Machinery Corporation Hot Coat and Hot Coat Plus industrial hot melt roll coaters have several diagnostic fault codes that may be displayed on the motor speed control (inverter) in case of system error. This feature is one of the many built in benefits and features of Glue Machinery Corporation equipment. Aside from our proven customer service and service department, we also provide superior product documentation with all our products. As always, technical support is just a phone call away. (Ask for Les, Matt, or John in the service and repair department at 1-888-202-2468)

Hot Coat Motor Speed Control Diagnostic Location

A list of fault codes and corrective actions are listed below for your reference.

OC-S Over current during start. Motor is shorted. Check and fix motor or Motor has ground fault - Locate and correct ground fault

OC-A Over current during accel. Accel time is too short - extend accel time

OC-C Over current during constant speed mode. Excessive load changes - check load condition

OC-D Over current during decel. Decel time is too short - increase decel time

OV-C Over voltage during constant speed mode. Input voltage fluctuation - check AC supply to motor/unit, verify that it is constant and not over rated voltage

LV-C Low voltage during constant speed mode. Input voltage drop - verify that the incoming AC supply meets minimum voltage requirements

OH-C Overheat during constant speed mode. Load is too high - investigate load condition

OH-1 Braking resistor overload . Decel time too short - increase decel time -or- frequent starting and stopping of unit - prolong run/stop cycle

OL-1 Motor overload. Load is too high - investigate load on roller, correct if needed

OL-2 Inverter overload. Load is too high - investigate load on roller, correct if needed

OL-3 Over torque. Load is too high - investigate load on roller, correct if needed

Hot melt hoses should be replaced every couple years.  The frequency of replacement depends on amount of time used, temperatures of operation, and adhesive used.

Our experience shows that customers will service their hot melt system and guns regularly and continue to use the same hoses for many years after they should have been replaced.  To protect your investment and insure optimal production standards, Glue Machinery Corporation recommends replacing your old hoses after three years of continuous operation.

Charred hot melt often builds up in hoses and this debris will dislodge and clog filters and nozzles in your adhesive system.

The inside of the hose is Teflon lined but degraded material tends to build up at the ends where fittings are swaged onto the hose.

Recirculating purge through the hose and back to the tank can help extend the life of the hose but can also lead to debris dislodging from the inside of the hose while the system is on line- causing further damage to the previous mentioned filters, nozzles, and guns.

Hot Melt Hose Debris

Contact the Glue Machinery Corporation Service Department to evaluate your particular Hot Melt Hose and how we can be of service to help you maintain optimal performance. 1-888-202-2468 or email:info@gluemachinery.com