injection mold process stages:
Clamping, glue, pressure maintaining and cooling, mould and products.
The above process, again and again, can batch periodically to produce products. Thermosetting plastic and rubber molding including the same process,
but a thermoplastic material barrel temperature is low, the injection pressure is higher, the mould is heated, finished material injection in the mold of the subject to curing or curing process, and then strike off the membrane.
The trend of the current processing technology is developing towards the direction of the high and new technology, these technologies include micro injection molding, high filling compound injection, water injection, mixed with a variety of special injection molding process, foam injection molding,
mold technology, simulation technology, etc.
The temperature control
Injection molding equipment and mold manufacturing in china
1．Nitrogen-treated barrel temperature, injection molding process, the need to control the temperature of the
cylinder temperature, nozzle temperature, and mould temperature, etc. The first two main influence plastic plasticizing temperature and flow,
and then the temperature are mainly influenced by plastic flow and cooling. Each kind of plastic flow with different temperature, the same kind of plastic,
due to different sources or brand, the flow temperature, and decomposition temperature is little different, this is due to the different average
molecular weight and molecular weight distribution, plastic in different type of injection machine of plasticizing process is also different, so choose the cylinder temperature is not
the same.
2. The nozzle temperature, nozzle temperature is usually slightly lower than expected tube maximum temperature, this is to prevent the molten
material in straight through the nozzle may be "salivate phenomenon". Nozzle temperature also cannot too low, otherwise, it will cause the early setting
of melting and the nozzle clogging, or due to early coagulation material into the cavity affect the performance of the products.
3．Pictures of injection molds temperature, mold temperature inner performance and apparent impact on the
quality of products. Mold temperature is determined by the size of the plastic, of crystalline products and structure, performance requirements,
and other process conditions (melt temperature, injection speed, and injection pressure, molding cycle, etc.).
Pressure control
In the process of injection molding pressure including plasticizing and injection pressure, and directly affects the quality of plasticizing and plastic products.
1．plasticizing pressure: (back pressure) adopts a screw injection machine, screw at the top of the molten material in the screw rotating backpressure is called the plasticizing, which is also called backpressure. The size of the
pressure can be found on the overflow valve to adjust the hydraulic system. In injection, the size of the plasticizing pressure is depending upon the
design of the screw, the product quality requirements, and the type of plastic and needs to change, if the situation and the screw rotation speed is
constant, increase plasticizing pressure will strengthen shearing action, which will raise the temperature of the melt, but will reduce the plasticizing efficiency, increase the current and leakage flow, increase the driving power.
In addition, increase plasticizing pressure often can make the melt temperature uniformity, color mixing and discharge gas in the melt. general Injection molding in the operation of the pressure curve, the plasticizing pressure shall be on the premise of guarantee the quality of the product is lower, the better,
the specific values vary with the varieties of the plastic, but usually rarely more than 20 kg/cm2.
2. Injection molding pressure: in the current production, almost all the injection pressure of the injection machine is in piston or screw at the top of the plastic on the pressure (by oil pressure conversion) shall prevail. Injection pressure in injection molding, the role of is, to overcome the flow resistance
of plastic flowing from the cylinder cavity, given the rate of molten material molding and compaction of molten material.
