Cause

Remedy

Not enough hot melt or coat too thin

Increase the spreading temperatur by increasing the melting temperature. If possible measure the spreading temperature at gun outlet and control it

Malfunction of temperature regulator or heating

Repair/ replace the corresponding parts

Aggregate carbonized, consequently bad head transmission

Clean the units

Insufficient contact to surfaces to be stuck

Improve contact pressure; check contact pressure on duration and interruption

Open time of hot melts is too short

Increase the working temperature; increase the coating quantity; reduce the time between spreading of the hot melt and contact pressure; check the surfaces to be coated, whether they are too cold, too wet; pre-heating, if necessary; use hot melt with a longer unsealed time. Apply hot melt with higher hot-tack

Change in quality of the surfaces to be stuck (e.g. cating, water content, stroke, painting, etc.)

Check the surface of the packing material

Speed of the parent machine too low

Increase the speed of the machine. Choose another hot melt. If necessary, increase temperature. Preheat the packing material by touching on warm air

Use on polyolefine surfaces too small

Preheat electrically

Cause

Remedy

Working temperature too low

Increase working temperature

Distance between spreading unit and packing material too large

Reduce distance if possible

Ambient temperature too low, e.g. due to draught

Change ambient condition (e.g. stop draught, increase ambient temperature)

However, special types of hot melt or spreading methods also become threaden during normal working conditions

Mounting of a hot ait nozzle or heating wire just after spreading or provide special machine devices

Hot melt too viscous

Use hotmelt with a lower viscosity

Cause

Remedy

Too much hot melt was spread on

Reduce spreading quantity

Working temperature too high

Reduce temperature

Insufficient contact pressure of the surfaces to be stuck

Check contact pressure: spread the hot melt onto the optimum contact of the adhesive surfaces; e.g. there where the packing allows enough backpressure. Avoid surfaces to be stuck to get out of place during the contact pressure

Open time of the hot melt material too long

Reduce working temperature; reduce applied quantity; lengthen contact pressure time; use hot melt material having a higher hot-tack

Spreading surface too small, hence initial adhesive power too small

Increase the coating surface

Reaction forces too high

Lengthen the contact pressure time for a short moment of time and/or increase the coating surface. On long term improve the material (grooving). Consider relocating the sticking area of the packing material. If necessary, use another melting material

Hot melt closings get out of place during the setting time

Adjust contact pressure and if necessary, check the synchronization of the belts.

Cause

Remedy

Heating or temperature regulation in the melting basin; conveying system or spraying valve are defefective. Valve control device defective, conveying system defective

Checking and repair of the unit at the corresponding positions

Filter blocked, nozzle blocked

Cleaning of the unit, respectively of the corresponding components. Provide preventive servicing, check the purity of the hot melt and check the temperature sensors

Pressure of pump too low

Regulate the pump-pressure

Nozzle too small

Use a bigger size

Cause

Remedy

Pressure of pump too high

Regualate the pressure

Cause

Remedy

Local overheating of the melting mass

Adjust the temperature regulation

Lack of melting material in the tank

Empty and bleed the conduction

Melting material too viscous (at wheel coating)

Increase the temperature or use melting material with a lower vicosity

Melting material contains water

Dry

Cause

Remedy

Spreading temperature too low

Increase the spreading temperature and/or preheat the packing material

Type of the melting material is not suitable for the surface of the packing material

Co-ordinate hot melt and packing material surface: contact hot melt dealer for suitable hot melt

Spread on quantity too small, hot melt is already cold before touching the surface of the packing material

Increase quantity of coating

Causes

Remedy

Soiling of coating elements by filling material, parts of packing material and so on

Clean the unit, if necessary. Prevent soiling by change of construction

Causes

Remedy

Temperature of melting tank too high (faulty temperature regulator)

Reduce the temperature of the melting tank (Repare or replace the regulator if defective)

Oxidation of the hot melt by air

Keep the melting tank covered; if necessary, use intergas