Vertical Injection Moulding Machine Silicone Injection Molding
Machine
The key to realize the precise injection molding of LSR liquid
silica gel
LSR is different from traditional thermoplastic materials in
shrinkage, demoulding, mold material, cold runner system and
temperature control, which makes LSR more difficult to process than
ordinary thermoplastic rubber.
The water-proof silicone rubber ring of smart phone is mostly
formed on the original metal or plastic accessories. At the same
time, its volume is smaller than that of the general use of
silicone ring, and its matching degree with the shell and
accessories is higher, so it needs to adopt more precise (micro)
injection molding technology.
Machine Model Parameter
| TYM-L5058 Vertical LSR injection molding machine | | Injection Unit | | Shot Volume | 165 g | | Injection Rate | 30 g/s | | Injection Pressure | 19.6 T | | Clamping Unit | | Clamping Force | 130 T | | Opening Stroke | 250-550 mm | | Tie-Bars Pace | 500*580 mm | | Ejection Force | 7.8 T | | Ejection Stroke | 150 mm | | Others | | Pump Pressure | 21 Mpa | | Motor Power | 12.1 KW | | Heater Power | 9 KW | | Mould Orientation Ring Diameter | Φ 100 mm | | Machine Weight | 6 T | | Machine Dimension | 2.5*1.6*3.6 m |
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The key points for LSR to realize precision injection molding are
as follows:
(1) Full mixing of liquid silica gel
➀ accurate mixing proportion: LSR is a and B two-component raw
materials. Before injection molding, it must be fully mixed
according to the accurate 1:1. If it is a colored liquid silica gel
product, the color paste proportion must also be accurately
controlled.
➁ mixer: the static mixer is the key part in the injection molding.
Only after the static mixer is fully and evenly mixed, can the
liquid silica gel injected into the mold be fully vulcanized.
(2) Sealing and temperature control of injection molding machine
parts
➀ due to the low viscosity of LSR, the screw must be sealed in
order to consider the backflow and leakage of materials;
➀ since the mold is heated during LSR forming, in order to prevent
LSR from curing, the water-cooled nozzle can be used to ensure the
temperature is low enough.
(3) Finished product control in injection molding process
➀ parting line: the position and accuracy of parting line shall be
considered in advance, which is helpful to avoid air entrainment
and welding and burr;
➁ shrinkage: Although LSR does not shrink in injection molding, it
usually shrinks by 2% - 3% after demoulding and cooling due to its
high thermal expansion coefficient;
➂ location of glue injection port: actual product shrinkage shall
be considered;
➃ vacuumizing: when designing the parting line, ensure that the
mold is closed, and the vacuum pump vacuumizes all cavities through
the clamps under the mold switch;
➄Demoulding: generally, demoulding technology of fractionating
column tray, push pin and air push is adopted, or manual demoulding
is adopted.
➅ mold temperature: LSR is vulcanized in the heating process, and
the temperature distribution in the mold must be controlled evenly.
The temperature difference shall be controlled at + / - 10 ℃
