Choosing between EVA and PUR glue is no longer a sticking point – thanks to Biesse’s new Hybrid Glue Head, users can easily switch between the two in a matter of minutes.

A tale of two glues

The last few years have seen the market moving away from EVA and towards PUR adhesive, which offers better bond strength and a thinner glue line. A further advantage of PUR is that it is water- and heat-resistant, making it a practical choice for bathroom and kitchen furniture.

As an example, it is beneficial to use PUR to edgeband the panels used in an oven housing, as heat might reactivate EVA glue, causing the edging tape to come away.

The downside of PUR is that it is more expensive than EVA and comes with a greater maintenance responsibility, as after PUR sets, it is very difficult to remove. A failure to purge PUR can result in a hefty repair bill.

In addition, PUR must be protected from moisture when it is not being used, which means the tank must be removed and stored correctly during extended downtimes.

Hybrid Glue Head

The ideal scenario, therefore, is to use EVA for edgebanding less aesthetically critical panels, and PUR for outer fascias and door fronts, where a high-quality finish is essential. The problem is that switching between the two either requires the glue pots to be taken off the machine and cleaned, which results in significant downtime, or the operator to stock spare glue pots that can be swapped in, which is cost prohibitive.

Biesse has eradicated these issues with the development of its Hybrid Glue Head, available on the Akron 1300 series upwards, which allows users to change from one type of glue to another in less than 20 minutes, or to execute a colour change in less than 15 minutes, thanks to an in-built CIP (Clean In Place) system.

There is no need to remove the head from the machine for cleaning or to replace it with a different one. To switch from PUR to EVA, just purge the PUR, add a cleaner, run the cleaning cycle and then add EVA. To switch from EVA to PUR, simply purge the EVA and add PUR.

TM20 Pre-Melting Unit

Mess-free operation, fast changeovers and in-situ cleaning are the key advantages of Biesse’s Hybrid Glue Head. In addition, whereas on some systems the residual adhesive flows from the glue pot and has to be collected manually, Biesse’s system incorporates an automatic system that drains the glue from below.

NC control matches coat weight to substrate

The Hybrid Glue Head can also be supplied with NC (Numerical Control) of the glue gate to optimise the amount of glue that is applied according to the material that is being edgebanded. For example, chipboard and MFC are more porous than MDF and plywood, which means they require slightly more adhesive.

Rather than relying on the operator to manually adjust machine settings for each material, NC control allows the user to pre-programme the optimum coat weight for each substrate, so the operator simply makes a selection from a menu of presets. This not only saves on adhesive, but also assists with the quest to minimise the glue line.

Flexible configurations

The Hybrid Glue Head has two options – a 0.8kg and a 1.5kg glue head. Operations that use a high volume of PUR glue can opt to combine with Biesse’s TM20 pre-melter. This supports continuous, high-speed production, as whenever the glue level drops, the pre-melter replenishes the glue head.