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Interpretation of Injection Curve of Die Casting Machine, Fault Diagnosis of Speed, Boosting, and Pressure Curve

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  • Release time: 2026-11-07

Interpretation of Injection Curve of Die Casting Machine, Fault Diagnosis of Speed, Boosting, and Pressure Curve
The injection curve is the electrocardiogram of the die-casting process. Understanding the curve, quickly distinguishing between mold problems, aluminum liquid problems, and machine hydraulic problems, is a necessary skill for foreign trade process debugging.
1、 Three core stages of injection curve
Slow injection stage: low-speed propulsion, smoothly pushing the aluminum liquid through the material cylinder and discharging the air inside the cylinder; Fast injection stage: reaching the set trigger position, accelerating the filling of the cavity; Boosting stage: The cavity is filled, the pressure rises rapidly, the aluminum liquid is compacted, and shrinkage and looseness are replenished. The pressurization and pressure holding time of the alloy wheel mold hub should match the solidification speed of the thick walled hot joint.
2、 Typical normal curve characteristics
Slow injection is stable without fluctuations; Quick pressure shooting with clean takeoff and stable peak speed; After the filling is completed, the pressure rises steadily at the boosting take-off point, and during the holding phase, the pressure remains stable without any drop.
3、 Faults corresponding to abnormal curves
Quick injection and early jump: Insufficient filling of the barrel, insufficient aluminum liquid, and easy gas entrapment; Continuous oscillation of fast injection speed: unstable runner resistance and temperature fluctuations of aluminum liquid; Unable to increase pressure, rapid pressure drop: material leakage on the parting surface, seal failure of the slider, premature solidification of the gate; Boosting too late: The cavity has already solidified, compaction is ineffective, and there is frequent shrinkage.
4、 The linkage between curve and mold design
The resistance of the sprue is high, the fast injection load is high, and the curve pressure rises significantly; Exhaust blockage, sudden change in resistance at the end of filling, and abnormal peaks in the curve. The same set of molds, different machines have different hydraulic responses, and the curve shape cannot be directly copied.
5、 Differences in Low Pressure Casting Curves
Low pressure refers to a constant pressure rise and holding curve, without a high-speed injection section. It monitors the rise pressure, holding pressure, holding time, and high-pressure injection curve in two completely different systems. Google's "die casting shot curve analysis" is aimed at process engineers.
FAQ
Does the higher the boost pressure, the denser the casting?
The premise is that the casting has not solidified yet; Pressurizing after solidification is ineffective and will only cause mold expansion.
2. How to adjust the jump position for fast pressure shooting?
Adjust according to the length of the material handle and the filling rate of the material cylinder.
3. When the curve fluctuates greatly, what should be the priority for checking?
Aluminum liquid temperature, barrel lubrication, hydraulic oil pressure, oil contamination.
4. If the pressure cannot be increased, is it necessarily due to mold flash?
It is also possible that there is internal leakage in the hydraulic system or insufficient pressure in the accumulator.
5. What is the pressure holding time set according to?
CAE solidification simulation can assist in accounting based on the hot spot solidification time.
Is it normal for two machines to have different curves for the same mold?
Normal, hydraulic response, accumulator, and valve group are different.
7. If the curve is qualified, will there still be porosity in the casting?
Aluminum liquid hydrogen exceeds the standard, mold release agent produces gas, and the melting end problem cannot be seen from the curve.
8. If the material handle is too thin, where will it be reflected in the curve?
The slow injection stage enters the fast injection stage ahead of schedule.

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