Prevention of webbing
Webbing is prevented just by setting on the machine:
– reduce compression speed,
– prevent too fast cooling down of material.
Webbing is prevented by screens in the clambing frame:
– limit forming area, so that geometrical compression conditions will be more favourable, … so that the “initial tent” will be smaller.
Webbing is prevented by design change:
– apply larger radii on the upper side of the mould so that geometrical compression conditions will be more favourable,
– change mould is such a way that webbing looks like purposely implemented reinforcement rib,
– create more surface in the lower section on that the webbing area can be used up.
Webbing is prevented by changing the mould in the waste area:
– build up mould higher so that webbing will form in the waste area ( this is only possible if the coresponding section will be severed),
– tear webs apart.
This can be effected with 2 artificial elevations ( e.g. hemispheres ), one right and left each of the web.
Similarly successful might be a wide recess below the web.
Webbing is prevented by means of the pre-stretching plug:
– according to the basic principle: ” you may press small webs, you have to pull large webs”,
– the pre-streching plug must be propably used in combination with negative moulds, especially for long, negatively formed groove-like recesses.
Webbing is prevented due to heavy sagging:
– if the surface of a heated materil is larger than the surface of the forming tool, there will be surface webbing. This is the case, when sagging is severe and the mould is flat,
– the solution is to mounth the mould at an increased height so that there will be a larger forming surface ( mould + increased height). It should be at least the size of the material surface generated by sagging.