What are the possible reasons why the injection molding machine does not lock the mold?

In the busy workshop of injection molding production, the injection molding machine suddenly does not lock the mold, just like a key musical instrument suddenly “loses its voice” in a symphony performance, and the entire production process comes to an abrupt end.Understanding the reasons behind it is the key to getting production back on track quickly.
1. Mechanical transmission failure: "intestinal obstruction” of power transmission
First of all, the tie rod of the clamping mechanism is the key support to ensure the tight closure of the mold.If the tie rod is bent and deformed, it may be caused by long-term stress or external impact.This is like the load-bearing beam of a house is crooked, and the mold cannot be accurately aligned and closed, so it is naturally impossible to lock the mold.During daily inspections by operators, professional measuring tools can be used to measure the straightness of the tie rod. Once the deviation is found to exceed the standard, it should be replaced or straightened in time.
The loose connection between the piston and the piston rod in the clamping cylinder is also a common “cause”.Frequent reciprocating movements cause gaps in the originally fastened connection parts, and the power transmission is greatly reduced, causing the clamping force to be unable to be applied normally.Maintenance personnel need to disassemble the cylinder and re-fasten the connecting parts to ensure the smooth transmission of power from the cylinder to the mold.
The guide post and guide sleeve serve as the “guide rail” of the clamping mechanism. If the lubrication is poor, the friction will increase sharply, which will hinder the normal opening, closing and locking of the mold.Regularly check the lubrication status of the guide post guide sleeve and supplement with special grease to make the mold “glide” smoothly and avoid blocking the clamping.
2. Hydraulic system problems: the “cut-off” crisis of pressure
The failure of the hydraulic pump can be called the “confidant” of the hydraulic system.When the parts in the pump are worn out, such as the blades and plunger, they are damaged and cannot output sufficient pressure, just like the blood supply to the heart is insufficient, and the high-pressure oil required for clamping cannot be supplied.With the help of professional pressure testing equipment, monitor the outlet pressure of the hydraulic pump. If it is lower than the rated value, repair or replace the pump in time.
The hydraulic valve is a “transportation hub” that controls the flow direction and pressure of oil.If the reversing valve is stuck, the oil passage cannot be accurately switched, or the relief valve fails and the pressure cannot be stably adjusted, the clamping action will fall into chaos.Clean or replace the faulty hydraulic valve to ensure the orderly “dispatching” of oil.
The condition of hydraulic oil cannot be underestimated.If the oil is contaminated, impurity particles may clog the oil channel and wear the seal; if the oil temperature is too high, the viscosity of the oil decreases, and the risk of leakage increases. Both will lead to the loss of clamping pressure.Regular filtration and replacement of hydraulic oil and control of oil temperature are the basis for the normal operation of the hydraulic system.
3. Electrical control system failure: the dilemma of “lost contact" of instructions
The relay that controls the clamping is like the commander's ”messenger". If the contacts are stuck or ablated, the clamping instructions will be misinterpreted or blocked.Use a multimeter to detect the on-off status of the relay, and replace the failed relay in time to ensure that the instructions are unimpeded.
The stroke switch is the “scout” of the mold position and is responsible for feedback to the control system on the state of the mold opening and closing.When it fails and misjudges the position of the mold, the control system will “command in chaos”, and there is no way to talk about the clamping operation.Check, clean or replace the stroke switch to accurately control the position of the mold.
Aging, short-circuiting or disconnection of electrical lines is like “paralysis” of communication lines and signal transmission is interrupted.Investigate along the electrical lines, repair damaged wires, fasten loose joints, and rebuild the electrical system “communication network”.
4. Mold-related factors: hidden dangers of “misalignment” of adaptation
If there are foreign objects on the parting surface of the mold, even tiny plastic debris and iron shavings, the parting surface will be propped open to prevent the mold from closing and locking.After each mold opening, carefully clean up the parting surface to ensure that it is smooth and smooth, so that the mold can be “seamlessly connected”.
The mold design is unreasonable, such as uneven distribution of clamping force, excessive force in some areas, and local deformation, resulting in the overall inability to lock the mold.Communicate with mold manufacturers, optimize mold design, rationally allocate clamping force, and ensure stable mold closure.