hot melt glue does not have a single melting point like a crystalline metal. Most industrial hot melts are blends of polymers, tackifiers, waxes, and stabilizers that soften through a transition range. In practice, the temperature you “need to melt” hot melt glue is the temperature that produces the right viscosity for application and wet-out while preserving adhesive stability. That range depends on the base polymer, the formulation, and the process. The guidance below summarizes typical temperature windows used by manufacturers of packaging, woodworking, bookbinding, hygiene, and industrial assembly adhesives.
When teams say “melting temperature,” they usually mean one of two things. The first is the softening point measured by ring-and-ball, where the solid transitions to a flowable state. The second is the recommended application temperature that delivers target viscosity at the nozzle. Production decisions should be based on the application window rather than a single softening value, since viscosity governs wet-out, penetration, and bond formation.
| Hot melt type | Typical softening range °C | Recommended application temp °C | Notes on use and performance |
|---|---|---|---|
| EVA hot melt | 80–110 | 160–180 | Workhorse grade for packaging and woodworking with balanced open time and cost. Overheating above 190 can cause oxidation and charring. |
| Metallocene polyolefin | 95–120 | 150–170 | Clean-running with low char and stable viscosity for high-speed case and carton sealing. |
| APAO/polyolefin | 90–120 | 150–170 | Good low-temperature flexibility and creep resistance for assembly and filter media. |
| Pressure-sensitive HMPSA | 70–110 | 120–160 | Remains tacky after set. Used for labels, tapes, hygiene. Equipment often runs cooler to control cold flow. |
| Polyamide hot melt | 125–160 | 180–210 | High heat and oil resistance with fast green strength. Requires tighter thermal control to avoid gelation. |
| Reactive PUR hot melt | 80–110 | 110–140 | Moisture-cures after cooling for structural strength and heat resistance. Lower application temps protect heat-sensitive substrates. |
| Low-temperature EVA | 70–90 | 120–150 | Designed for temperature-sensitive packaging and some assembly tasks to reduce substrate thermal stress. |
Values reflect common production practice. Always verify against the technical data sheet for the specific grade.
If a product lists 150–170°C, begin at 160°C and evaluate bead appearance, wet-out, and stringing. Increase in 5–10°C steps if viscosity feels too high and the bead does not level. Decrease if you see smoking, excessive penetration, or scorching.
Higher temperature lowers viscosity and often extends open time. On fast packaging lines, a slightly higher setpoint can improve fiber tear and reduce pop-opens. On slow manual assembly, dropping 5–10°C can reduce soak-in and control stringing.
Cold cartons or metal parts act as heat sinks. Preheating the substrate or elevating glue temperature by 5–15°C helps maintain a wet film long enough to form a bond. For temperature-sensitive films or foams, use low-temperature grades and limit glue to the lower end of the window.
Wood and paper need enough viscosity to prevent over-penetration that starves the bond line. If fiber tear is low and the glue line looks dry, lower the temperature or select a higher-viscosity grade.
Extended residence above the recommended range accelerates oxidation. For EVA and polyolefin, sustained exposure beyond 190–200°C increases char, gels, and filter clogs. Use covered tanks, nitrogen blankets when available, and follow purge schedules.
Tank temperature set to the adhesive application target. Maintain within ±5°C to keep viscosity stable over long runs.
Hose temperature often 5–10°C lower than the tank to reduce thermal aging during residence time.
Gun or nozzle temperature equal to the tank to prevent viscosity spikes and cold plugs at the tip.
Substrate temperature ideally above 15°C for packaging and above 20°C for wood assembly. When the plant is cold, a short preheat or infrared panel near the compression station stabilizes bond quality.
Stringing at the nozzle suggests temperature is too low or pressure too high. Raise setpoint 5–10°C or reduce pressure.
Poor wet-out and skip bonds suggest viscosity too high. Raise temperature and confirm nozzle is not restricted.
Excessive soak-in and squeeze-out indicate temperature too high. Lower setpoint or switch to a higher-viscosity grade.
Odor, smoke, or amber darkening indicate oxidation. Reduce temperature, check tank lid and headspace, and remove char through filtration.
Pop-opens after cooling often result from too low a temperature or too short compression time. Raise temperature slightly and lengthen compression dwell.
For EVA and metallocene case-seal adhesives, 160–175°C is a common starting point. For cold-room packing or recycled board, push toward the upper end to maintain wet-out. For temperature-sensitive laminates, a low-temperature EVA around 130–150°C reduces warping.
EVA for woodworking runs near 170–190°C depending on viscosity and feed speed. PUR hot melt improves heat and moisture resistance while running at 110–140°C. Keep moisture control practices in place for PUR to ensure full cure.
HMPSA grades are usually applied between 120 and 160°C to maintain tack and avoid thermal degradation. Calibrate coat weight with viscosity to reach target peel and shear.
APAO and specialty polyolefins often run at 150–170°C for good creep resistance and flexibility. For nonwoven hygiene, temperature is tuned tightly to avoid odor and color shift.
Use an in-line viscosity check or measure Brookfield viscosity at the setpoint during lot qualification.
Adopt color and char inspections during tank cleaning to catch early oxidation.
Maintain filters and screens and record pressure differentials to detect gel formation.
Log setpoint, ambient, and substrate temperatures with each shift change and major order to track seasonal drift.
Implement PM on hoses and guns to prevent cold plugs that mimic low-temperature defects.
Wear heat-resistant gloves and eye protection when handling molten adhesive.
Keep water away from open tanks. Contact with water can cause violent foaming and spattering.
Use fume extraction if operating near the top of the temperature window.
Store adhesive in a cool, dry area and keep containers sealed to prevent moisture uptake for reactive grades.
What temperature actually melts hot melt glue Most grades soften between 70 and 120°C, which is adequate to move and pump the adhesive. The functional application temperature is higher, typically 120–210°C depending on the chemistry, so the adhesive attains the target viscosity and wets the substrate before setting.
Can I run the adhesive hotter to speed the line Moderate increases can extend open time and improve wet-out, but excessive temperature accelerates oxidation and can reduce bond strength over time. Increase in small steps and monitor color, odor, and char.
How do I switch from EVA to metallocene polyolefin Start 10–15°C lower than your EVA setpoint, verify viscosity at the nozzle, and tune compression dwell. Expect cleaner running with less char at comparable bond strength.
What if my plant is cold Raise adhesive temperature by 5–10°C, precondition cartons or parts, and extend compression time. For severe cold, consider a low-temperature grade designed to run closer to 130–150°C.
Why does my nozzle clog Thermal degradation produces gels that lodge in screens and tips. Lower setpoint within the recommended window, reduce residence time, keep lids closed, and follow a routine for purging and filter replacement.
EVA for cartons and general assembly: 160–175°C
Metallocene PO for clean-running packaging: 150–170°C
APAO for assembly and filters: 150–170°C
HMPSA for labels and hygiene: 120–160°C
Polyamide for oil and heat resistance: 180–210°C
PUR for structural woodworking and assembly: 110–140°C
The temperature needed to melt hot melt glue is best understood as an application window that delivers the correct viscosity and open time for your process. For most EVA and polyolefin adhesives used in packaging and woodworking, that window centers on 150–180°C. For pressure-sensitive grades, the range is lower. For polyamide, the range is higher. For reactive PUR, the range is lower due to the chemistry and cure mechanism. Select a target within the recommended band for the specific grade, verify bond quality on your substrates, and manage residence time and equipment settings to protect adhesive stability. This approach minimizes defects, reduces maintenance, and ensures consistent performance for high-speed production.
