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why the molding temperature of the compression molding process is lower
Feb 11, 2018

Why the molding temperature of the compression molding process is lower?

In plastic bottle cap industry, it is well known the compression moulding have much more  advantages than the injection molding process, such as cap quality good consistency and molding process is stable, low energy consumption, simple color changeover, etc., it is these advantages make the compression molding process become a mainstream plastic cap industry trend.

Today,Guangzhou Jeepine Intelligent Compression Molding Machine Co.,Ltd has carefully analyzed the energy consumption, and why the molding temperature of the molding process is lower than the molding temperature of injection molding.

Plastic cap Injection molding VS Plastic cap Compression moulding

Let's see the following on the injection molding process from molding thermometer, you can see, the plastic melt temperature setting is about 220 ℃, mold cooling water temperature is 10 ℃.

Let's look at the compression molding process of forming thermometer, everyone should can be seen at a glance, the temperature of the molding process set is much simpler than the temperature of the injection molding process Settings, no hot runner temperature Settings, cylinder temperature section number is less.Plastic melt temperature setting is about 180 ℃, the mould cooling water temperature of 15 ℃.

In general, the compression molding process temperature setting has the following characteristics:

The cylinder temperature around 40 ℃ lower than that of the injection molding process, molding process of the heating energy consumption advantages highlighted immediately.

Mold cooling temperature is about 5 ℃ higher than injection molding process, so the molding process of refrigeration, cold water machine without consuming too much energy to even available room temperature water cooling, this aspect also saves considerable energy consumption.

For two different molding process, now we are already in the heating temperature and cooling temperature has been very clear contrast data, now, we try to analyze, why injection molding process to such a high melt temperature and the cooling temperature so low?Why does the compression molding process do not require too much melting temperature and low cooling temperature?

Injection is a very complex molding process, injection molding machine needs a screw high-speed propulsion and will melt the plastic injection cylinder mouth, and then into the hot runner, by very small needle point hot nozzle, the last to enter the mold cavity, the process of melt plastic will encounter a lot of resistance, needs very high pressure to injection molding, plastic must keep very good flow state to achieve this purpose.To attain such a good plastic flow state, plastic particles from the hopper into the screw at that moment, the screw will have to spend a lot of energy to high-speed rotation, plastic particles in up to 220 ℃ environment, carried out in a screw with a nitrogen-treated barrel wall friction and shear in order to achieve full state of melt, can achieve the status of suitable for injection molding.

If will set a lower melt temperature, injection molding process of plastic melt state is relatively poor, injection molding machine screw even use maximum pressure cannot make plastic by injection mold cavity smoothly, will cause the cap missing glue problem, the following chart:

Injection molding process need high molding temperature, so the cooling water must be low temperature to take away the heat of the mold, and because of that, cold water machine the compression system requires more energy to cooling and at lower temperature, so the energy consumption also follow.

Instead, compression molding process is a very simple, different with injection molding, screw without frequent and rapid advance and retreat, also need not spin with shear plastic granules, and no hot runner molding process, also do not have the needle point into the gate, and melt the plastic without any resistance almost can smoothly into the mold, so the cap compression molding process does not require the plastic flow in a very good state, only the plastic can reach state, so the compression molding process of the melt temperature Settings can be low, thereby saving a large amount of energy consumption, low melt temperature, mold heat relatively is not so much, also need not too low temperature of cooling, the mechanism of cold cold water demand is low, thereby saving considerable energy consumption

After a careful analysis of the above comparison, I believe a lot of bottle cap manufacturing enterprises in the new production line will tend to choose the compression molding technology, compression molding machine is known as the cap industry the highest ratio of printing presses, save energy consumption in production for a long time will greatly enhance the profitability of the cap making factories.

Guangzhou Jeepine Intelligent Compression Molding Machine Co.,Ltd have the powerful cap compression molding machine manufacturing team,While guaranteeing the production and quality of the bottle cap making machine, we will devote a lot of energy to research and development, and continue to share the technological achievements with the main bottle cap making factories.

Jeepine plastic cap compression moulding machine’s Advantages:

Main machine Feature: 

A.Rotary muti compression molding process and advanced hydraulic system bring the highly stable and accurate production

B.Muti-cavity continuous high speed rotation, short cycle time, and high production efficiency

C.Low energy consumption in heating and cooling process.No hot runner, save energy effectively

D.No raw material wasted in spilling and hot runner circuit, Every single granule of raw material is fully used

E.Safe machine door interlock,emergency stop switch,rigid machine housing, U/L certified

D.Fully automatic in line production, no hand touching, avoid contamination

Compared with injection moulding machine and other plastic closure making machine manufacturers,Jeepine’s plastic closure compression molding machine have the following advantages:

Plastic closure Compression molding technology as a well known technology around the world in plastic closure production.

Energy saving

Less Energy Consumption,Overall energy savings per cap can be as high as 45%.

Because plastic closure compression moulding machine need lower heating temperature,which means less energy consumption in both heating and cooling.

High specific density and less shrinkage

Equal molding pressure, lower molding temperature allows the result of a higher density. Furthermore, less heating and cooling temperature gap accomplish less shrinkage of caps.

Quick color changeover without hot runners,only with the extruder.

Shorter cycle time (2 seconds) and therefore higher productivity

Due to lower extrusion temperature, caps are more quickly to be cooled down 

in mould.It makes shorter cycle time, thus capacity rises.

Easy and flexible maintenance 

Independent molds make it easier to change molds, only with hand tools but not crane.

Less material waste    

Advantages of compression cap mold:

1.High Quality 

The major cap mold material has excellent wear resistance, high

corrosion resistance and high machinability, high coating hardness

2. High Precision 

All the molds can precisely meet the dimension tolerance of cap


Jeepine has professional manufacture equipment, dedicated to

mold design and development, absolutely cope with your needs

Guangzhou Jeepine Intelligent Compression Molding Machine Co.,Ltd 

Address:C4 Building of Scientific&Technogical Enterprise Accelerator,11# Kaiyuan Avenue,Science Town of Luogang Development Zone,Guangzhou,China