Home > Events >BFS(Blow-Fill-Seal)Extrusion Molding
BFS(Blow-Fill-Seal)Extrusion Molding
BFS
technology is an advanced technology for producing the plastic-packaged
preparations, by which the whole process of blowing, filling and sealing can
be completed at once under a sterile environment. Compared to the conventional
filling lines, it has great advantages. However, due to the complexity of
such equipment, more factors will affect the product quality, in which the
plastic bottle molding problem is the most prominent one.
The
plastic bottle molding is affected by various factors, such as plastic
performance and melting temperature, vacuum setting, compressed air pressure
setting, cooling setting, equipment maintenance level, device operation
motion setting parameters as well as the experience of operators. Firstly,
this article aims to seek the best extruding temperature through the
experiment of adjusting the temperature of the extruder so as to guarantee
the quality of the plastic bottle molding. Secondly, this article details analysis
on the factors causing the abnormal bottle molding and provides corresponding
solutions. At last, this article provides the suggestions how to guarantee
the stable operation of production, how to improve the product percent of
pass and how to reduce the production cost.
Extruder Temperature Experiment
lEquipment &
Materials
BFS-310
equipment manufactured by Tofflon has been adopted to conduct the contrast
experiment, which can produce 30 2ml bottles at once, with the production
capacity of 9000 bottles/ hour. The plastics particles selected in this
experiment is 3020D low density polyethylene (LDPE) produced by BASELL, a
German company.
lExperiment Method
The
plastic particles are put into the hopper on top and then get melted. After
that, the melted liquid goes through the screw and is pushed into the die, in
which a set of 30 bottles is blow-molded. The drug liquid is transported from
the preparation room to the overhead of the system through pipelines. After
the empty bottles are cooled inside the die, the drug liquid is injected into
the bottle through multi-head filling port, and then the bottles get sealed.
After the whole process of blowing, injection and sealing have been
completed;
the bottles come out from the equipment. In the process of extruding and
molding, the temperature control has a significant impact on the molding
process and molding quality. Through increasing the extruder’s heating
temperature, it is helpful to reduce the melt’s viscosity, to improve the
melt’s fluidity and reduce the power consumption of the extruder. Through
increasing the screw speed, it is beneficial to improve the product’s
intensity, brightness, and transparency. The main parameters of the 3020D
plastic particles are shown as below:
The
experiment adjusts the extruding temperature setting within the temperature range
of the extruder and makes comparison in respect
of the yield, bottle weight, thickness, light transmittance and the other
quality indicators of the products.In
the circumstance that the heating temperature of the extruder increases
appropriately, the melt’s viscosity will be reduced and its fluidity will be
improved. It is good for the molding.
However, with the increase of the temperature, the plastic may have
cross-linking reaction, which has an impact on the light transmittance. The
experimental data shows that the higher extruding temperature is good for the
bottle molding and the product yield coefficient. However, with the increase of
the temperature setting, the light remittance of the bottle wall will be
reduced. Especially, after the high temperature sterilization, the light
remittance will be far lower. Therefore, through comprehensive consideration,
170℃ is an appropriate extruding temperature to get the relatively good
product quality.The pass rate of light
remittance under different temperature conditions as below:
Data
on bottle shapes tested under different extruding temperatures.
Reasons
for Causing Abnormal Bottle Molding and The Corresponding Solutions
From
the data of the experiment results, it can be analyzed that 3020D presents
the relatively data within the temperature range of 70℃~175℃. When the temperature within this range increases appropriately,
the melt fluidity speed increases and the bottle wall thickness will have a
slight increase correspondingly.
In
the actual operations, there will be more factors to affect the bottle
molding. Besides the extruding temperature, the defected bottle molding can
also be related to the stability of the equipment and the operation skills of
the operators. The defected bottle molding is the main problem to lower the
percent of pass. Simultaneously, it is also of great importance to correctly
set the equipment parameters and well grasp the technology standard. In
addition, the defected bottle molding and the protective machine halt will
not only reduce the yield coefficient, but also, more importantly, bring
environmental risks since the human intervention will affect the aseptic
conditions. The table below shows the analysis on the reasons of causing the
abnormal bottle molding and provides the detailed adjustment solutions.
Abnormal item
Reason
Solution
Curving tube billet
Wrong adjustment of the throttle valve of the tube
billet
Adjust the throttle valve of the tube billet
Different lengths of tube billets
Wrong adjustment of the feedstock throttle valve of the
tube billet; the clearance between the die core and die sleeve are different
Adjust the feedstock throttle valve; adjust the height
of the die core
Folded bottles inside the die
The tube billets are blown too
large
Adjust the blowing throttle valve of the tube billet;
increase the evacuation time of the tube billet.
Uneven thickness of the tube billet’s circumferential
wall
The extruding die core and die sleeve are eccentric; the
tube billets are blown too large and the air cannot be well exhausted.
Check and adjust the die core and die sleeve to be
concentric; adjust the tube billet’ blowing and evacuation time.
Leakage of the bottle head
The parallel misalignment of the left and right diesis
too large;
The filling needle is dripping liquid.
Check
the installment of the die and the filling needle.
Dents on the bottle wall; W strips at the bottom of the
bottle
The air vent of the die is clogged
Add a vacuum hole to exhaust air; Use the texturing on
the surface of the die to increase air evacuation.
Scratches inside and outside the bottle; The stripes
are too prominent.
The extruding head or the discharge hole is unclean;
impurities exist in the die core and die sleeve.
Clean the extruding head; Clean the discharge hole of
the tube billet.
Foreign matters on the bottle wall
Foreign matters are mixed in the plastic particles; the
extruding head or the discharge hole is unclean.
Check the plastic particles; clean the discharge hole
of the tube billet.
In
addition to the extruding system, there is another important factor to
influence the percent of pass of the bottles, and that is, the die. After the
extruder produced the qualified tube billet, die is the most important place
for bottle molding. The bottle shape design, the temperature control, the
vacuum control, the installment, and the clamping pressure control of the die
will all have effect on the molding quality of the bottles.