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Problem
Stringing
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Possible cause
Application temp. too low
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Suggested Solution
Raise application Temp. DO
NOT exceed recommended application temp.
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Viscosity
of adhesives is HIGH
|
Raise application Temperature, DO NOT exceed recommended
application temperature.
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Substrate
is too far from applicator tip.
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Position substrate closer to tip.
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Substrate
temp. is too cold
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Pre-warm substrate to increase surface temperature.
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Poor
nozzle shut off
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Clean Nozzle and repair. If problem persists, contact
equipment manufacturer.
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Charring/Gelling in Reservoir
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Reservoir
temp. too high
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Lower reservoir temperature
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Faulty
heating control
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Check control and replace
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Surface
oxidation
|
Maintain level of adhesive in reservoir. Keep reservoir
covered; with some adhesives, nitrogen blanket
may be necessary.
|
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Dripping Nozzle
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Worn
needle or seat
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Replace
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Nozzle
dirty
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Clean or replace
|
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Air in Adhesive at Applicator
Tip
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Extrusion
head faulty
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Consult with the manufacturer for a recommendation
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Reservoir
is out of adhesive.
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Bleed lines and refill reservoir. Reset or replace valve.
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Poor Adhesion
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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.
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Poor
penetration of substrate coating
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A) Apply adhesive hotter. B) Combine substrates quicker. C)
Lower adhesive temperature.
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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.
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Substrates Popping open
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Hot
melt is not cooling rapidly enough
|
A) Lower application temperature. B) Decrease amount of
adhesive applied.
|
|
Substrate
is too hot to achieve proper
cooling of adhesive
|
Cool substrates to room temperature if possible.
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