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Learn about Injection Molding Machine (PART III)
2018/7/25
This article will show you more basic knowledge of injection molding machine from three aspects of right ways to operate the injection molding machine in a adjust the system and injection molding technics.
I. The right ways to operate the injection molding machine
1. Preparation before operation
(1) Prepare proper tools
(2) Check the manufacture data; revise the temperature and pressure
(3) Turn on the dryer and preheat the plastics
2. Check the safety device
(1) Check whether the low-pressure mold protection device is norwal
(2) Check whether the safety door is normal
(3) Check other safety devices
3. Turn on the machine
(1) Check whether the water circuit opens totally
(2) Check the electricity circuit
(3) Turn on the motor and open the mould; clean and lubricate the mould
(4) Check safety device
(5) Open the hopper when arriving at a certain the temperature; Clean up the over-heated plastic from the hopper
(6) Lock the mould and set manual, semi-automatic, automatic production
4. Turn off the machine
(1)Turn off the loader. Don’t turn off the machine until the products becomes defective, which means the plastic in the barrel is gone.
(2) If the machine is in the automatic mode or semi-automatic mode. Turn to the manual mode when the machine becomes defective.
(3) Clean the mould surface and spray protective agents. Drive backward the injection station when high pressure can’t be held.
(4) Turn off the power and clean the machine surface and surroundings.
5. Semi-automatic operation system
Before turning to semi-automatic operation system, operate in manual mode for several times. When the products meet the requirement, turn to the semi-automatic operation system.
6. Automatic operation system
Before automatic operation system, you must use manual and semi-automatic operation operation at first. Check whether the product can meet the automatic operation. If yes, you can turn into the automatic operation mode after several operation circuit in the semi-automatic mode.
II. Appropriate adjustment system
Injection part should be adjusted in an appropriate system, to achieve the ideal effects and efficiency.
1. Basic adjustment system are as below:
(1) Clean up the hopper, add the raw material and make sure the material type and whether the material is dried up;
(2) Adjust the hopper temperature from low to high;
(3) Adjust the injection pressure and injection rate according to the product and material;
(4) Estimate the material weight and save up some. (After adjustment, adjust the weight to an appropriate figure)
(5) Input the original time and revise it during the processing procedure until the product meets the requirement;
(6) Input the temperature of mould cooling water and heating mould, which depends on the requirement of the material.
2. Set-up of injection time
There are mainly two methods to set up injection time. The first one is to distinguish the quality from product outlook. The second one is to check from the weight of product.
III. Plastic injection process
Normal injection temperature
| Material |
Mould Temperature ℃ |
Barrel Temperature ℃ |
| I |
II |
III |
| PS |
10-75 |
150-160 |
200-260 |
200-280 |
| HIPS |
10-75 |
150-160 |
190-260 |
200-280 |
| ABS |
10-80 |
150-160 |
190-260 |
220-270 |
| LDPE |
20-60 |
130-200 |
220-300 |
230-310 |
| HDPE |
20-60 |
130-200 |
220-300 |
230-310 |
| PP |
10-80 |
140-180 |
220-290 |
220-325 |
| PC |
70-115 |
230-270 |
280-340 |
300-350 |
| PMMA |
30-70 |
140-170 |
190-220 |
190-240 |
| PA6 |
50-80 |
200-210 |
210-230 |
210-230 |
| PA66 |
50-80 |
190-250 |
250-280 |
250-280 |
| POM |
60-90 |
160-180 |
175-210 |
190-210 |
| PPO |
40-80 |
250-290 |
300-320 |
300-330 |
| PU |
40-80 |
170-200 |
180-210 |
190-240 |
| CP |
30-80 |
160-180 |
190-220 |
180-210 |
Basic injection condition
| Materail |
Pressure |
Injection |
| Injection Pressure Kg/cm2 |
Mould Holding |
Backpressure Kg/cm2 |
Injection Rate |
| PS |
- |
30-60% |
100-200 |
Depend on product shape |
| ABS |
1000-1500 |
30-60% |
100-250 |
Slow to fast |
| PE |
- |
30-60% |
150-250 |
Depend on product shape |
| PP |
1200-1800 |
50-70% |
120-200 |
High speed |
| PVC |
1000-1600 |
Not too high |
＜50 |
Not too fast |
| PC |
1300-1800 |
40-60% |
60-150 |
Depend on product shape |
| PMMA |
High pressure |
Long |
150-400 |
Depend on product shape |
| PA |
Not too high |
Not too high |
50-150 |
Fast seed |
| POM |
1200-1500 |
Depend on product condition |
100-200 |
Not too slow |
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