What are the factors affecting the hollow blow molding machine/blow molding
1. Blowing pressure
Compressed air in blow molding has two functions, inflation and cooling. Low
viscosity, low volume or thick wall parts should use low air pressure; high
viscosity, large volume or thin wall parts should use higher pressure.
2. Blowing speed
In order to shorten the blowing time, in order to facilitate the product to
obtain a more uniform thickness and a better surface, the inflation speed should
be as large as possible, but the speed is too fast to easily produce the
following phenomena: ① Create a vacuum at the air inlet, so that this part of
the parison When the parison is completely inflated, the diaphragm part will
form a diaphragm; ② The parison of the die part may be pulled off by the
extremely fast air flow.
3. Blow-up ratio
Usually controlled at 2-4 times, if the inflation ratio is too large, the
shape stability of the product is poor, and if it is too small, it will easily
cause uneven wall thickness.
4. Mold temperature and cooling time
If the mold temperature is too low, the plasticity of the plastic at the jaw
will be reduced, it is not easy to swell, and the part will be thickened, and it
is difficult to form; the mold temperature is too high, the cooling time is
extended, and the production cycle is long. The cooling time is too short, the
cooling is not It is easy to cause deformation of the product, shrinkage
increases, and the surface is dull.
5. Molding cycle
Including extruded parison, intercepted parison, mold clamping, blowing,
cooling, deflation, mold opening, product removal and other processes. The
selection principle of the molding cycle is to shorten as much as possible on
the premise of ensuring that the product can be shaped.