5 Common Mistakes to Avoid When Using Hot Melt Adhesive

For many daily users of hot melt adhesives, there are numerous points to be mindful of.

Below are five common mistakes to avoid when using hot melt adhesives, which can serve as a reference：

1.Adhesive Tank Management Category：

1.❌ Overloading the glue tank

Mistake: Filling the entire tank with adhesive pellets at once.

Consequence: Excess glue melts prematurely, leading to oxidation, carbonization, and wasted material (up to 20% loss).

Solution: "Little and often" principle → Add pellets in small batches to match consumption speed.

2.❌ Mixing different adhesive types

Mistake: Mixing hot melt adhesives of different grades and formulations (e.g., EVA and PO-based)

Consequences: Phase separation leads to reduced bonding strength and equipment contamination

Solution: Thoroughly clean the glue pot, then let it sit for 15 minutes before switching adhesives

2.Substrate Treatment Category：

1.❌ Gluing dusty surfaces

Mistake: Substrate surface not cleaned (dust >50μg/cm²)
Consequence: Bond strength reduced by over 60%

2.❌ Ignoring substrate temperature

Mistake: Applying adhesive to cold surfaces (e.g. metal below 5°C).

Consequence: Rapid cooling causes poor wetting and bond failure.

Solution: Pre-heat substrates to >15°C or use low-temperature adhesives

3. Process Operation Category
1.❌ Incorrect bead size

Mistake: Glue bead diameter exceeds 1.5 times substrate thickness
Consequence: Glue overflow and prolonged curing time
Solution: Control glue bead diameter to 0.8-1.2mm (electronics) or 2-3mm (packaging)
2.❌ Moving parts too soon

Mistake: Moving components within 10 seconds after assembly (before instant adhesive cures)
Consequence: Bonded surfaces shift, causing weak adhesion

3.❌ Incorrect open time management

Mistake: Assembling parts after adhesive has cooled (exceeding open time).

Consequence: Bond strength drops by 30-50% due to lost tackiness.

Solution: Match assembly speed to adhesive's open time

4. Temperature Control Issues：
1.❌ Setting temperature too high

Mistake: Melting adhesive at temperatures exceeding standard by 20°C or more (e.g., using 180°C for 140°C adhesive)
Consequence: Adhesive carbonization, producing irritating fumes
Solution: Precisely control temperature within **±5℃ as labeled on the glue packaging**
2.❌ Nozzle Temperature Mismatch

Mistake: Nozzle temperature lower than glue tank temperature
Consequence: Stringing and adhesive breakage
Solution: Nozzle temperature should be higher than glue tank temperature

5. Storage Maintenance Category
1.❌ Storing adhesives in humid areas

Mistake: Storing glue in warehouses with humidity >70%RH
Consequence: Glue absorb moisture, causing bubble splatter
Solution: Store in sealed containers + desiccant (humidity <50%)
2.❌ Skipping nozzle purges

Mistake: Nozzle cleaning omitted after shutdown exceeding 4 hours
Consequence: Carbon buildup clogs nozzles, tripling maintenance costs
Solution: Daily 3-cycle cleaning with dedicated cleaning adhesive

3.❌ Neglecting equipment maintenance

Mistake: Running glue tanks at constant high temperature without cleaning.

Consequence: Carbon buildup clogs nozzles and degrades adhesive quality.

Solution: Clean tanks weekly with specialized purging compounds at 50% operating temperature.

If you have any questions about hot melt adhesives or need professional assistance, feel free to contact us anytime!