Hot melt adhesive systems (HMS) have been a mainstay of production lines in a variety of businesses for many years, due to their, efficiency, reliability and versatility. These machines provide the ability to bond to difficult surfaces, an excellent capability for filling gaps, ease of storage, and an environmentally friendly method of applying adhesives without excessive waste.
However, hot melt systems are designed to dispense adhesive at high temperatures and pressures, so require careful attention to health and safety to protect operators. If used incorrectly, even the best HMS may not deliver the level of quality and consistency that you expect for your production standards.
To use your hot melt adhesive system safely and efficiently, here are some essential tips to consider:
1) Operating Temperature
Read the instructions carefully on your adhesive, and make sure you follow the recommended temperature range. Take care not to exceed the temperature advised, or you risk damaging your equipment with burnt adhesive and ruining your product. In contrast, if you set the temperature too low, you risk the adhesive setting too quickly and not bonding your substrates correctly.
2) Substrates
It’s important to clean the substrates you’re bonding, before applying the hot melt. If you try to use the hot melt adhesive on a dusty or soiled surface, or a highly textured surface – such as some paper products – you’ll compromise the bond. There are HMS solutions for all types of substrate, so please have a chat with your equipment supplier if you’re unsure of the right dispensing system to use on your project.
3) Metals
If you work with metals, you’ll need to check that the surface doesn’t carry oil or grease residues, which some metals have after being manufactured. If you feel the surface isn’t optimal, clean with an appropriate solvent before you apply the adhesive. Likewise, some metal surfaces carry a fine metallic dust, or scarf, as a residue from machining. This may affect glue adhesion if not removed.
4) Viscosity
Viscosity is a gauge of how dense the liquid adhesive becomes at various temperatures and pressures, and affects the delivery speed of the adhesive dispenser. As the temperature increases, the hot melt becomes thinner – i.e. the viscosity level lowers – and begins to flow faster. If you see the adhesive is flowing too slowly, very carefully raise the temperature on the HMS, but don’t go over the recommended range. At optimum viscosity, the hot melt should harden within about 15 seconds.
5) Add-On Level
‘Add-on level’ refers to the amount of hot melt you need to apply to a product to attain the required bond strength. And the more adhesive you use, the longer it will take for the glue to cool down to a temperature where it begins to cure, or harden. The cooling rate is a major factor in determining production time, so to maximise productivity and efficiency, a careful balance must be made between add-on level and cooling rate.
6) Compression
When you bond two substrates together, they require a certain amount of pressure for the glue to adhere. You’ll need to carefully apply just the right amount of force and time so that you don’t impact the final result and damage the substrate.
7) Know The Product
There are a variety of hot melts available and some work better with wood or metal, while others are perfect for fabric. Make sure you’re familiar with the performance profile of your chosen adhesive, and its compatibility with your HMS, so you get the best results possible.
Next Steps
At The Adhesive Laundry, we supply a range of advanced hot melt adhesive systems and application equipment for various industries. To discuss your requirements with one of our team, and for our recommendations on the most cost-effective solution for your production line, please get in touch today.
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