Injection moulding machines are crucial tools in the manufacturing industry, used to produce a wide range of plastic products. These machines rely on proper lubrication to ensure smooth operation and prevent wear and tear of essential components. However, lubrication failure can lead to costly downtime, decreased production efficiency, and even permanent damage to the machine. In this article, we will explore the common causes of lubrication failure in injection moulding machines and provide troubleshooting solutions to keep your equipment running smoothly.
Importance of Proper Lubrication
Before delving into troubleshooting, it is essential to understand the significance of proper lubrication in injection moulding machines. Lubricants act as a protective barrier, reducing friction between moving parts, and dissipating heat. This ensures the longevity of machine components, minimizes wear, and optimizes overall performance. Injection moulding machines generally have fixed resistance lubrication system and quantitative pressure lubrication system these two kinds.
Fixed resistance lubrication principle
Small injection moulding machine- more use fixed resistance injection moulding machine configuration with damping type distributor, when the lubricating oil pump work, from the oil pump outlet to the distributor of the oil circuit to produce pressure. When the lubricant pressure is higher than the damping pressure difference, the lubricant will overcome the damping and flow to each lubrication point until the lubrication time is over. The damping holes in the distributors vary in size and the amount of oil distributed to each lubrication point varies as required. If the pressure in the lubrication circuit does not reach the pressure set by the pressure relay during the lubrication time, the machine will give an alarm.
Quantitative pressure lubrication principle
Large injection moulding machine- adopts quantitative type The injection moulding machine is equipped with quantitative pressure distributor, when the oil pump works, the oil pump pressurises each distributor and pushes the lubricating oil from the upper cavity of the quantitative distributor to each lubrication point to lubricate each part evenly. When the pressure of the lubricating oil line reaches the pressure setting value of the pressure relay, the oil pump stops working and the computer starts the lubrication delay time, each distributor relieves the pressure and automatically replenishes the lubricating oil from the oil line to the upper cavity. After the lubrication delay time, the oil pump starts again and the cycle continues until the total lubrication time has elapsed. As the oil outlet holes of the distributors can be different, this ensures that the amount of oil at each lubrication point is also distributed as required. If the pressure of the lubricating oil circuit does not reach the pressure setting of the relay during the lubrication time, the machine receives a feedback signal and an alarm: lubrication failure!
Identifying Signs of Lubrication Failure
When it comes to injection moulding machines, proper lubrication is vital for their smooth and efficient operation. However, lubrication failure can happen, and it’s essential to recognize the signs early to avoid costly damages and downtime. Here are some common signs of lubrication failure:
Unusual Noises and Vibrations
If you notice unusual noises or vibrations during the machine’s operation, it could be a clear indicator of lubrication problems. Friction between components due to inadequate lubrication can lead to these unsettling sounds and vibrations.
Increased Energy Consumption:
When a machine lacks proper lubrication, its moving parts face more resistance, causing the motor to work harder. As a result, energy consumption increases, leading to higher operational costs and reduced efficiency.
Elevated Operating Temperatures:
Inadequate lubrication can cause excessive heat buildup within the machine. High operating temperatures not only decrease efficiency but also pose a risk of damaging vital components over time.
Reduced Performance and Output:
Lubrication failure can negatively impact the machine’s overall performance and output. The machine may not function as smoothly as it should, leading to a decline in productivity.
Visual Signs of Wear:
Regularly inspecting the machine for signs of wear can help identify lubrication issues. Look for signs of excessive wear, such as metal-to-metal contact, which can indicate insufficient lubrication.
Inconsistent Product Quality:
Lubrication failure can affect the quality of the products being manufactured. If you notice inconsistencies in product dimensions, surface finish, or other quality aspects, it could be linked to lubrication problems.
Frequent Equipment Breakdowns:
When lubrication is insufficient, the likelihood of equipment breakdowns increases. Frequent breakdowns not only disrupt production but can also lead to costly repairs.
Contaminated lubricants are a common cause of lubrication failure. If you find visible debris or foreign particles in the lubricant, it’s a sign that contamination is present.
Leaking lubricant may occur due to worn-out seals or improper lubricant application. Addressing leaks promptly is crucial to prevent further lubrication issues.
Shortened Equipment Lifespan:
If an injection moulding machine experiences lubrication problems over an extended period, it can significantly reduce the machine’s lifespan, leading to premature wear and tear.
Common Causes of Lubrication Failure
After introducing the principle of lubrication, the following common causes of lubrication failure are explained in the context of daily maintenance:
Low Oil Alarm:
When the oil tank is low on oil, the lube oil pump cannot work to absorb oil, the pressure is not enough, resulting in the alarm. Add semi-fluid grease (lubricating oil), manually lubricate, if there is no alarm again, it means the fault is well handled. If there is still an alarm, it is possible that the oil pump has inhaled air, the oil circuit has been caused by gas. At this point, disassemble the oil pump outlet, manual lubrication, from the oil exhaust tighten the oil pipe can be.
Daily patrol machine to develop a good habit of checking the lubricant tank, observe the use of lubricants, active refuelling or early detection of hidden lubrication problems, can not wait until the lack of oil alarm to passive refuelling.
Oil tank with oil alarm:
The oil pump filter is clogged, causing the oil pump to be unable to take in oil, resulting in insufficient pressure and the alarm being triggered. The most common cause of this fault is the use of dirty, old or poor quality oil. Remove the strainer from the oil pump, clean the strainer and oil suction hole with a copper brush and paraffin, clean the oil tank and replace with qualified oil (grease).
Low oil pressure alarm:
Use a flat screwdriver to turn it clockwise inwards to adjust the amount of oil discharged. Then turn it counter-clockwise to adjust the amount of oil discharged. Then turn it counter-clockwise to adjust the amount of oil discharged. The oil relief port must have oil overflow, neither large, large, the oil pressure at the outlet will be small; no oil drain, it is easy to burst the oil pipe because of the large oil pressure, but also not conducive to lubrication again when the starting pressure. Relief valve mouth oil overflow moderate for appropriate
If there is still no improvement, some oil pumps are equipped with spring and ball structure in the relief valve mouth, may be spring ball is stuck impurities, remove the cleaning can be.
Clean the strainer and adjust the relief valve. After cleaning, although there is oil flowing from the oil pump outlet, the pressure gauge shows insufficient pressure and the machine alarms. It is likely that the oil pump is a long-term use of waste oil, old oil after wear and tear leakage, resulting in insufficient pressure. Repair or replace the oil pump.
There are many cases where companies use used hydraulic oil or waste oil for lubrication to save costs. The old oil has not been finely filtered and dewatered, just simply precipitated, directly added to the tank. Old hydraulic oil impurities, viscosity is not enough, in fact, can not play the role of proper lubrication. It will only accelerate the wear of the oil pump and mechanical parts.
Oil line leak:
Oil is leaking from a point in the oil circuit where the oil pipe fitting has fallen off or broken, causing the pressure relay not to sense. After locking the mould, manually lubricate and observe, find the oil leakage point and repair the oil line.
Damaged or blocked oil manifold:
If the distributor does not detect the pressure relay, clean the distributor with paraffin and adjust the adjusting nut on the quantitative pressure distributor so that the telescopic rod can be pressed against the relay switch. If it still does not work, replace the distributor with a new one.
Damage to the pressure relay switch:
Test the switch with a multimeter and replace it with a new one if it is broken.
Signal cable broken or poor contact:
Use a multimeter to locate the fault, repair the damaged cable or tighten the terminals.
Incorrect parameter setting:
Lubrication failure alarm during the production process, check the pump, oil, line, no abnormalities. Check the computer signal, found that the computer controller no signal output, manual lubrication is still no response, which may be a parameter setting problem. Lubrication modulus set value is small, lubrication modulus has reached its set value, you can enter the system screen with the password, find the lubrication modulus, set the value of the larger can be.
Constant pressure type lubrication time is actually lubrication alarm time, lubrication time should also be appropriately long, there is enough time to ensure that the pressure relay pressure, so as to avoid setting the lubrication alarm time is too short and false alarm. In fact, the machine has been scientifically and reasonably set before leaving the factory, it is not recommended that the computer is not preferred to change the settings of the relevant lubrication parameters, so as not to affect the lubrication of the machine.
Troubleshooting Lubrication Failure
Troubleshooting lubrication failure in injection moulding machines is essential to maintain their efficiency and prevent costly breakdowns. Here are some troubleshooting steps you can take to address lubrication issues:
Regular Lubrication Schedule:
Establish a regular lubrication schedule based on the manufacturer’s guidelines and the specific requirements of your injection moulding machine. Stick to this schedule to ensure consistent protection of vital components.
Selecting the Right Lubricant:
Choose a high-quality lubricant that is suitable for your machine and its operating conditions. Consider factors such as temperature, load, and speed when selecting the appropriate lubricant.
Proper Lubrication Application:
Ensure the correct application of lubricant, avoiding over-lubrication or under-lubrication. Use the right tools and techniques to apply the lubricant precisely where it is needed.
Regular Maintenance and Inspection:
Perform routine maintenance and inspections to identify potential issues before they escalate. This includes checking for lubricant contamination and assessing the condition of machine components.
Proper lubrication is paramount for the efficient and reliable operation of injection moulding machines. Understanding the signs of lubrication failure and the common causes behind it is the first step in troubleshooting. By implementing a regular lubrication schedule, using high-quality lubricants, and conducting routine maintenance, you can prevent lubrication-related problems and prolong the life of your valuable equipment.