Hot Melt Extrusion (HME) is applying heat and pressure on polymer pellets over their melting point. It is an established technology used in several industries like case sealing, carton sealing, tray forming, and diaper manufacturing.
Hot melt also has a long shelf life, rapid solidification, minimal volatile organic compounds and minimal waste. No wonder then that the North America hot melt adhesives market size stood $1.86 billion in 2021 and is expected to surge to $2.80 billion by 2029, representing a CAGR of 5.1%.
It is necessary to have control of the nozzle to optimize the hot melt extrusion procedure. Choosing the correct nozzle is imperative since every adhesive has a unique viscosity. Each nozzle will come with different hole configuration for precise application. Here’s a guide on choosing an appropriate one to complete your project.
Hot Melt Nozzles
Hotmelt adhesives are used in numerous industries like bookbinding and specialty applications. Serving unique markets requires different degrees of volume, velocity and direction on a substrate. This explains why selecting the right product is necessary for high-quality outcomes and minimizing waste. Nozzles are interchangeable and come in many sizes and designs for dispense applications. These are quite useful to finish the work quickly and efficiently with long-lasting results.
The most common are, swirl-spray nozzle, zero cavity nozzle, single and multi-orifice nozzle. But you must have a clear idea of how to pick the best-suited one for your extrusion needs.
It is a common misconception that the bigger the better. The orifice size does have a direct correlation with the dispensed glue. Generally, smaller orifice nozzle applies more precise beads and minimal dripping from the nozzle as it closes. Most nozzles come under:
Single Orifice Nozzle: This produces a single or intermittent pattern of hot melts. It is usually ideal for manufacturers working with high-speed lines, flexible patterns and precision application.
Swirl-Spray Nozzle: This kind of hot melt nozzle dispenses adhesives in different diameters and widths. You can expect a narrow to a wide-angle hollow cone. A spray nozzle can bind two big surfaces like in the construction of a foam-lined box for shipping delicate items.
Multi-Orifice Nozzle: A single nozzle will be able to dispense multiple beads. It gives you the freedom and flexibility to set up specific patterns with a wide variety of beads. The use of a multi-bead nozzle reduces cost as it can replace the need for two or more expensive heads.
Having a thorough idea of how each one works will help you make an informed choice. Make sure to read about the challenges like clogging and charring and how to handle them. It will ensure safe and useful glue work.