The following troubleshooting guide will help you:
- analyze some of the problems encountered in the manufacturing of films
- determine the potential causes
- find solutions
Sharkskin or orange peel
| Causes |
Solutions |
- The high viscosity melt leaves the die above a critical shear stress,
which leads to film surface irregularities or even cracks.
- This phenomenon is predominantly encountered with LLDPE.
|
- Lower the melt viscosity by using higher processing temperature
- Decrease output
- Use processing aids (e.g. fluoropolymers)
- Increase die gap
|
Agglomerates on film surface
| Causes |
Solutions |
- Undispersed pigment
- Polymer gels
- Oxidized particles
|
- Contact masterbatch supplier, review masterbatch selection
- Check resin quality
- Ensure machine is clean
- Use thermally stabilized raw materials
- Use antioxidants during shut-down period
|
Poor homogeneity
| Causes |
Solutions |
- Insufficient distributive mixing
|
- Optimize extrusion conditions e.g. increase back pressure by using finer screen packs, reduce temperature
- Review masterbatch selection with regards to rheology and compatibility with dilution polymer
|
Low opacity
| Causes |
Solutions |
- Too low pigment
or masterbatch
dosage
- Wrong pigment selection
|
- Increase level of pigment
- Select pigment with higher opacifying power
|
Lensing or fish eye
| Causes |
Solutions |
- Excessive
amount of
moisture in
raw materials
|
|
Die build-up
| Causes |
Solutions |
- Die design and
geometry
- Process conditions
- Melt rheology
- Compatibility between
raw materials
- Presence of low
molecular weight
species
- Thermal stability of
raw materials
|
- Reduce extrusion temperature
- Use highly compatible and thermally stable polymers and additives
- Use processing aids such as fluoropolymers
|
