Hot Melt Trouble Shooting Tips
Problem~Possible Cause ~Solution
Stringing ~ Application temp. too low ~ Raise application temp. DO NOT exceed recommended application temp.
Viscosity of adhesives is HIGH ~ Raise application temp. DO NOT exceed recommended application temp.
Substrate is too far from applicator tip ~ Position substrate closer to tip.
Substrate temp. is too cold ~ Pre-warm substrate to increase surface temperature.
Poor nozzle shut off ~ Clean Nozzle and repair. If problem persists, contact equipment manufacturer.
Charring/Gelling in Reservoir ~ Reservoir temp. too high ~ Lower reservoir temperature
Faulty heating control Check control and replace
Surface oxidation ~ Maintain level of adhesive in reservoir. Keep reservoir covered; with some adhesives, nitrogen blanket may be necessary.
Dripping Nozzle ~ Worn needle or seat ~ Replace
Nozzle dirty ~ Clean or replace
Air in Adhesive at Applicator Tip ~ Extrusion head faulty ~ Consult with the manufacturer for a recommendation
Reservoir is out of adhesive. ~ Bleed lines and refill reservoir. Reset or replace valve.
Poor Adhesion ~ Adhesive bond shows that the glue film is mostly on one surface which is caused by improper penetration of the secondary surface.
A) Apply heavier glue film and/or apply adhesive hotter. Sometimes both approaches are necessary.
B) In the case of very conductive surfaces (metals) the substrate may have to be preheated to assure proper penetration of the secondary substrate.
Bond failure shows adhesive on both surfaces with leggy strains. Usually caused by disturbing the Bond during the setting stage.
A) Check compression to assure that there is no shifting during adhesive set up.
B) Apply less adhesive.
C) Lower adhesive Temperature.
Poor penetration of substrate coating:
A) Apply adhesive hotter.
B) Combine substrates quicker.
C) Lower adhesive temperature.
Glossy adhesive surface usually caused by poor contact with the secondary substrate. Temperature too low for proper wet out.
A) Adjust compression to assure intimate contact of substrates.
B) Increase adhesive temperature.
Substrates Popping open ~ Hot melt is not cooling rapidly enough:
A) Lower application temperature.
B) Decrease amount of hot melt adhesive applied.
Substrate is too hot to achieve proper cooling of adhesive ~ Cool substrates to room temperature if possible.
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