There are two kinds of production process of plastic bottle cap, one is pressure plastic cap, the other is injection cap. There are many differences between these two processes. When selecting, we should pay attention to the selection according to the demand. In addition, there are some parameters that affect the size of the bottle cap, we should pay attention to it. Here for you to introduce the plastic cap production process and the impact of cap size of the pressure molding process parameters, let's have a look.
What is the production process of plastic bottle cap?
Generally speaking, the production process can be roughly divided into two types: the pressure plastic cover production process and the injection molding cover production process
1. Production technology of pressure plastic cover
The suction machine sucks the mixed materials into the barrel of the press molding machine. After heating the barrel to the semi melting and plasticizing state, it is quantitatively extruded into the mold cavity. The upper and lower molds are closed, molded, cooled, shaped and demoulded. After cutting the ring and adding cushion, the production of the pressure plastic cover is completed.
2. Production process of injection molding cover
The mixed materials are sucked into the barrel of the injection molding machine by the suction machine. After the barrel is heated to the melting and plasticizing state, it is injected into the mold cavity. The mold cavity is cooled and shaped, demoulded, and then the injection cover production is completed by cutting the ring and adding cushion.
What are the main differences between the production process of pressure plastic cover and that of injection molding cover?
1. The volume of injection mold is large, and the replacement of single cavity is troublesome; each cavity of compression molding is relatively independent and can be replaced separately.
2. There are no pouring points in the pressure plastic cover, so it has more beautiful appearance and better printing effect.
3. All cavities are filled with injection molding at one time, and one bottle cap material is extruded by pressing molding at a time. The extrusion pressure of compression molding is very small, but the pressure required for injection molding is relatively high.
4. The injection cover needs to heat the material to the melt flow state, the temperature is about 220 degrees; the pressure plastic cover only needs to be heated to about 170 degrees, so the energy consumption of the injection molding cover is higher than that of the pressure plastic cover.
5. Pressure molding processing temperature is low, shrinkage is small, cover size is more accurate.
What are the molding parameters that affect the cap size?
1. Cooling time
In the compression molding process, the cooling time mainly depends on the rotational speed of the equipment (i.e. the production speed). The slower the production speed and the longer the cooling time, the lower the temperature of the cap, and the larger the cap size after thermal expansion and cold contraction.
2. Raw material temperature
With the increase of raw material temperature and the same cooling time, the higher the cap temperature, the smaller the cap size after thermal expansion and cold contraction.
3. Mold temperature
The higher the mold temperature is, the worse the cooling effect of the bottle cap in the mold is under the same cooling time. The higher the temperature of the bottle cap is, the smaller the cap size is after thermal expansion and cold contraction.
4. Cap weight
A large number of experimental data show that with the increase of the weight of the cap, the temperature of the cap will increase and the size of the cap will decrease. But theoretically, the larger cap size will be obtained by increasing the cap weight.
The above is to introduce the production process of plastic bottle cap and the pressure molding process parameters that affect the size of bottle cap. You can go to find out and contact us if necessary.