Problem |
Caused by |
Solution |
|
Thickness variations in traverse direction towards the machine
|
Maladjusted nozzle
|
Adjust the screws of the nozzle (the opening of the nozzle should generally be set to 110% and 120% of the wanted sheet thickness)
|
|
Adjust header's restrictor bar, keeping all nuts tight.
|
|
Decrease the temperature of the header in thicker areas and increase it in thinner areas
|
| |
Variations in melting temperature
|
Check melting temperature fused in the sheet
|
|
Check the performance of the thermocouples
|
|
Check that resistances are not burnt
|
|
Check the pyrometers
|
| |
Presence of foreign bodies in header's rims and/or in the opening of first rollers
|
Clean the lips of the header
|
|
Adjust the restrictor bar and/or the opening of the lips with the purpose of optimizing the material flow from the header |
|
Check the existence of flow pulsations
|
|
Adjust the temperature in the header to guarantee the flow uniformity
|
| |
Temperature controllers malfunctioning in the header
|
Check the temperature in the header
|
|
Check the controllers
|
| |
Polishing rolls group poor adjustment
|
Adjust the opening of the rollers (the opening among the first rollers should be set to 1% or 2% higher than the wanted thickness, the opening among the last rollers should be equal or lower to the wanted thickness)
|
|
Elevate the pressure of the first roller with the purpose of distributing the flow inconsistencies from the header
|
|
Check if the bearings are in good condition
|
| |
| Thickness variations in machine's direction |
Temperature variations in the extruder areas |
Check that resistances are not burnt
|
|
Check that the temperature set is the appropriate one
|
|
Check the connections of the thermocouples and their contact with metal
|
|
Check that the pyrometers are working well
|
|
Check that there isn't material pumping
|
| |
Inconsistency in feeding
|
Check temperature in the different barrel areas
|
|
To Check that the screw is cool, if there's one.
|
|
Check the formula used
|
|
Check the feeding of solids to the extruder
|
|
Check the chute
|
|
Check the feeding of grinded material and its concentration
|
| |
Poor mixture
|
Check the homogeneity of the ingredients in the formula
|
| |
Variations in the speed of the extruder or in pulling system
|
Check the stability of the extruder
|
| Check that there isn't material pumping |
| |
Screw design
|
Check that the screw was designed for the resin that's being processed
|
| Check the quantity of grinded |
| Check additives concentration |
| |
Belts sliding
|
Check the belts tension
|
| Check the belts condition |
| |
Material accumulation between first rollers
|
Increase the speed of the polisher rollers
|
| Reduce the extrusion speed |
| Increase the opening among the first rollers |
| Clean the polisher rollers |
| Check the waste of the polisher rollers |
| Check the concentricity of polishing rollers |
| Check the pressure among the polishing rollers to make sure that enough force is exercised to maintain a constant spacing among them |
| |
The power of the coiler is superior to that of the pulling rollers
|
Adjust the tension of the coiler
|
| Increase the pressure among the rollers of the pulling system |
