Several points to note when repairing injection molding machines:
1. Non-professional repair personnel or those without permission should not attempt to disassemble and repair the mold themselves.
2. Minor malfunctions during production can be addressed by the machine operator as needed.
For example: For mold sticking to the sprue: use a copper needle to tap it out at the sprue. Do not use steel needles or other hard objects to strike the mold. For minor mold marks in the cavity, choose polishing materials according to the cavity's smoothness. Do not use sandpaper or other polishing materials on textured surfaces; generally, use a copper brush dipped in diamond paste or corundum to clean the surface. This should be done by a professional repairman. For product sticking to the mold: generally, wrap the product and ejector area with hot plastic and eject it after cooling. If using fire, be careful not to damage the mold surface.
3. Professional repair personnel should not arbitrarily alter the mold structure. Any structural modifications must be approved by the quality engineering department.
4. Ensure repair quality by selecting appropriate equipment, materials, tools, and problem-solving methods to complete the repair as quickly as possible.
Injection molding machines are the culmination of mechanical, electrical, and hydraulic integration. They are electrically complex, with a complex network of hydraulic lines and a wide variety of controllers. From the 1980s to the present, the types of malfunctions they exhibit are diverse and varied, especially with imported injection molding machines, which are very expensive, costing tens to hundreds of thousands of US dollars each.
Large injection molding machines contain thousands of components. If even one component malfunctions, it can cause abnormal phenomena. Furthermore, even slight negligence in wiring connections can lead to problems. In addition, the large size of these machines, coupled with the lack of a temperature-controlled injection molding workshop, makes them highly susceptible to environmental influences that can easily cause malfunctions. Therefore, the problem of "difficult maintenance" for imported injection molding machines is a pressing one.
How to repair an injection molding machine?
1. Pressure but no movement: First, check if the indicator light on the mold opening valve on the output board is on. If it is, the computer output is normal, and the problem lies in the wiring from the computer to the mold opening valve. The simplest way is for one person to use a small test pen to push the mold opening valve while another person opens the mold. If the mold opens smoothly after pushing, the problem is confirmed to be a wiring issue; simply reconnect the wire (circuit problem).
2. Study injection molding machine electronic circuit materials extensively. Understand the characteristics and functions of various injection molding machine electronic circuit systems and PC/PLC programmable controllers; understand the alarms and troubleshooting methods of the injection molding machine's electronic circuit system; understand the meaning of PC/PLC injection molding machine parameter settings; understand PC/PLC programming languages; understand injection molding machine action programming methods; understand the operation of the injection molding machine control panel and the contents of each menu. There are often tons of materials; how do you read them all?
3. I believe the key is to focus on the essentials and understand the ins and outs. The key is to thoroughly understand the basic components and structure of the injection molding machine controller and master the block diagram. The rest can be browsed and read through, but each section should be understood and mastered with a focus on key points. Since the internal circuit diagrams of injection molding machine controllers are quite complex and manufacturers do not provide them, it's not necessary to understand them in detail. Focus on understanding the function of each part, the function of each board, the destination of the interfaces, the meaning of the LEDs, etc. Currently, there are many models of injection molding machine controllers, and they are updated rapidly; different manufacturers and different models often differ significantly. Understand their commonalities and individual characteristics.
4. Study and thoroughly understand the electrical diagrams of injection molding machines. For every electrical component, such as contactors, relays, time relays, etc., as well as the inputs and outputs of the PC and PLC, clearly label them on the electrical diagrams.
5. Study and deeply understand the hydraulic diagrams. For the mechanical and hydraulic diagrams of injection molding machines, understand their function and process. Mark them clearly on the drawings, such as which solenoid valve actuates the mold clamping? What are the corresponding PC and PLC outputs and inputs? The diagram should clearly show the entire process from electrical to mechanical action, with particular emphasis on understanding the closely related mechanical and electrical components. Modern injection molding machines use electro-hydraulic proportional technology; therefore, it's crucial to understand its function and operation, especially its adjustment methods and data. This includes understanding the proportional valve current and corresponding pump pressure in both static and dynamic states. A thorough understanding of both electrical and mechanical aspects, a mechatronics approach, and mastery of multiple skills will greatly enhance your problem-solving abilities.
Consult injection molding machine experts frequently. If you have the opportunity for training or for an expert to install and debug your injection molding machine, take advantage of it. This is an invaluable learning opportunity, providing access to a wealth of firsthand information and methods for debugging injection molding machines. If you don't understand something, find out. This period will be extremely rewarding, allowing you to obtain a significant amount of internal data and manuals (which are confidential to users). Even after the injection molding machine is put into production, maintain close contact with relevant experts.
6. After a malfunction occurs, understand the entire process of the injection molding machine failure: what alarms were generated, what components were operated, what was touched, what was modified, and what were the external environmental conditions? Based on a thorough on-site investigation and firsthand information, accurately listing the faults is half the battle won. Then, analyze and resolve the issues. Experienced and skilled injection molding machine operators are familiar with the machine's operation, processing procedures, and common problems. Close cooperation with them is highly beneficial for quickly troubleshooting.
Practice is essential; be bold and hands-on. Injection molding machine repair personnel must be bold yet meticulous, willing to take action. Simply talking without doing will not lead to successful repairs. However, always understand the situation before acting; avoid acting blindly, as this could escalate the problem, cause an accident, and have disastrous consequences.
7. The core of injection molding machine repair is fault diagnosis and troubleshooting. It involves a broad range of knowledge, is highly complex, and requires considerable depth (e.g., comprehensive professional knowledge). It requires basic knowledge of mechanical equipment repair, hydraulic repair, and electrical repair. In fact, injection molding machine maintenance is a challenging but also a process of continuous learning and improvement. As long as you master the basic working principles and methods of injection molding machines, regardless of the model, you can develop a set of maintenance procedures to ensure the normal operation of the injection molding machine.
