The injection molding machine is one of the most commonly used equipment in the plastic processing industry, and usually it needs to work for a long time without interruption. So, no matter for the injection molding machine manufacturer or user, how to ensure the stable and continuous production of the injection molding machine is a very worthwhile goal to achieve. From the user’s point of view, selecting the correct injection molding machine model and effectively implementing regular preventive maintenance is the easiest way to ensure that the injection molding machine can continue to work normally without interruption. The so-called preventive maintenance is a series of prevention and inspection, which can find out the potential danger of failure in advance and effectively prolong the working life of the parts. Turn sudden outages into predictable routine maintenance and avoid sudden outages or overhauls; prepare in advance and find and replace parts that may be damaged soon, preventing sudden real damage that stops the machine from running or stopping Production Activities.
Injection molding machine`s hydraulic oil introduction:
The hydraulic transmission of the injection molding machine uses hydraulic oil as the working medium, and uses the pressure energy of the hydraulic oil in the sealed working volume to transmit energy, pressure or power or signal. The quality of hydraulic oil and seals directly affects whether the hydraulic system can work stably for a long time, and indirectly affects the quality of products. In order to prevent and reduce the failure of the hydraulic system, reduce the wear and prolong the service life, the hydraulic oil should be strictly used and maintained.
In general, 70% of hydraulic unit failures are due to incorrect or improper use and maintenance of hydraulic fluid. Maintaining good maintenance habits and preventive maintenance is the easiest and most effective way to reduce and prevent hydraulic failures in your machine. Therefore, careful maintenance of hydraulic oil and hydraulic system is very important.
When the machine we ordered from the injection molding machine manufacturer arrives at our workshop, please read the instruction manual of the injection molding machine provided by the manufacturer in detail, and strictly select the hydraulic oil model recommended by the manufacturer or the hydraulic oil with a higher specification.
The most important properties of hydraulic fluids are viscosity and cleanliness, as well as good resistance to oxidation, wear, foam, corrosion, and good lubricity.
The viscosity of hydraulic oil is expressed by the average kinematic viscosity at 40°C. Our commonly used No. 46 high-quality anti-wear hydraulic oil (46csT/40℃) means that the average kinematic viscosity of this hydraulic oil at 40℃ is 46m2/S.
The relationship between hydraulic oil viscosity and pressure and temperature is as follows: viscosity decreases with increasing temperature; while viscosity increases with increasing pressure.
1. Regularly test hydraulic oil performance. If the oil is contaminated or deteriorated, the life of the injection molding machine will be shortened and failure may occur. Therefore, regular oil testing is required to detect changes in oil properties. Based on this, it is possible to decide whether to change the oil. (If conditions permit, it is best to use the data value of professional laboratory testing) We can use a simple visual method to understand the state of the oil:
a). Appearance test: Put new oil samples and used oil samples into their respective test tubes, and compare their color, transparency, floating matter, and water sedimentation at the bottom of the test tubes.
b). Drop test: put the old oil drop on the filter paper (oil-absorbing paper) and observe it after one hour. Contamination is easy to observe if it is oily or visibly deteriorated.
c). Finger rubbing: Used oil can be rubbed on fingers. If the viscosity decreases and deteriorates, the hand feels rough and there is no sticky feeling. The oil droplets slide off the fingers smoothly with no sticky bounce.
Routine maintenance of the hydraulic system usually includes the following points (not limited to):
The working temperature of the hydraulic system of the injection molding machine should be between 45-50 °C. Since the hydraulic system is designed according to the viscosity of the oil and the selected pressure, the viscosity will vary with the oil. The liquid level changes, thus affecting the working components of the system, such as oil cylinders, hydraulic valves, etc., reducing the control accuracy and response sensitivity, which is more serious in precision injection molding machines.
Temperature will also accelerate the aging of the seal, making it harden and break;
If the temperature is too low, the processing energy consumption will be reduced and the working speed will be reduced.
Therefore, it is necessary to pay close attention to the working temperature of the hydraulic oil.
The shortage of hydraulic oil will cause the oil temperature to rise, and the air will easily merge into the oil and hydraulic oil, which will affect the normal operation of the system. The lack of fuel is usually caused by oil leakage. During maintenance, attention should be paid to check whether there is leakage on site, and replace the worn seals as soon as possible. parts, tighten the loose joints, and check the supply of hydraulic oil after repair.
There are various reasons for high oil temperature, but many are attributed to faulty or malfunctioning oil cooling system, etc.
In principle, change the hydraulic oil every 5000 hours of operation or at most once a year. No matter how good the hydraulic oil is, after a certain period of time, metal and rubber particles worn by moving parts such as pumps will enter the oil and form sludge and dirt. During normal maintenance, some contaminants can adhere to parts and be carried into the hydraulic fluid.
An important property of hydraulic fluids is their chemical stability, ie oxidative stability. Oxidation is the most important factor in determining the service life of hydraulic oil. The wood tar, sludge and insoluble substances such as carbon residue produced by oxidation will contaminate the hydraulic system, increase the wear of hydraulic components, reduce various gaps, block holes, and eventually lead to hydraulic system. Fault.
The oxidation rate depends on factors such as the hydraulic oil itself and working conditions, of which temperature is the main factor, so use appropriate hydraulic oil, and regularly check the degree of oxidation of the hydraulic oil (the color of the oil is determined by the depth), after a certain working hours An oil change is absolutely necessary to be proactive.
Even if the hydraulic oil is used correctly, its service life is generally considered to be one year, and it can be up to two to three years. Once spoiled, it must be replaced with new oil without hesitation. Good oil quality is the cornerstone to keep the hydraulic system stable.
Hydraulic oil is filled with a special oil filter truck, not a pumping unit with a pump. The author has seen many simple oil pump trucks with pumps, pumping waste water and waste oil, and adding new oil.
Pumps that have pumped waste water and oil have no strainers, and the dirtiest impurities lurk in the pump and pipeline, mixed with new oil and added to the tank. The author has used the box to observe many times, and the new oil that I just started to pump contains a lot of pollutants. These contaminants will only contaminate new oil and damage pumps and valves.
The filter accuracy of the professional oil filter car is usually 125um (micron), and there are generally two filters, which are double-protected and filtered to protect the cleanliness of the oil.
Hydraulic maintenance is not as simple as pumping out old oil, or just adding some new oil. Not only to replace the new oil, but also to clean the hydraulic equipment.
After the old oil is drained, do not wipe the oil tank with a rag to prevent the thread from clogging the filter. Using professional cleaners is expensive and leaves residue. The experience taught by the 20-year-old mechanic: ordinary flour is added with an appropriate amount of water to form a dry dough, and then divided into several pieces to apply oil stains, impurities, and powder in the metal oil tank. Clean and economical with no residue.
The magnetic frame and screen in the tank can be cleaned with kerosene and a copper brush; after that, they can be cleaned and dried with an air gun.
The air filter outside the tank makes it easy for the air in the tank to come in and out according to the change of the oil level in the tank. Every time the oil is changed and maintained, the air filter should be taken out, cleaned with kerosene, and dried with an air gun. If not cleaned, dirt may enter the fuel tank and affect the oil quality.
The oil filter plays the role of cleaning the hydraulic oil. The oil filter should be cleaned every three months to keep the oil suction pipe unobstructed. At the same time, check whether the oil filter net is damaged.
The hydraulic oil cooler should usually be cleaned once a year, or the interval between cleaning should be increased or decreased according to its own working environment and ability. Blockage or scaling inside the cooler will affect the cooling efficiency of both, and the cooling water should be clean. Clean soft water (mineral free) is preferred.
Tips:
1). The scale inside and outside the cooler tube should be cleaned with weak hydrochloric acid solution, rinsed with water, and dried with an air gun.
2). The dirt on the baffle should be cleaned with a copper brush.
First, the dirt outside the valve can be cleaned with a waste cloth and an air gun. You can remove the plug and remove the oil valve. The sludge and debris on the valve core and valve body can be cleaned with a kerosene brush and dried with an air gun. Care should be taken to avoid upside-down spool installation and loss of O-rings.
After disassembling the clamping, thimble, base, and plastic injection cylinder, use kerosene to clean the cylinder block and piston, and replace the worn and damaged oil seal, dust seal, and O-ring. The reasons for dismantling the oil cylinder, checking the oil seal and replacing it are as follows:
1. The stability of the injection pressure is the main factor determining the quality of the finished product. The sealing and wear rings should be replaced every 20,000 hours of machine operation or a maximum of five years. Although the five-year-old oil seal is not seriously damaged, it must also be replaced. It cannot be repaired until there is an oil leak, carbonation or pressure relief, or the machine fails.
2. Check whether the piston rod is loose.
3. Cleaning equipment parts is also a maintenance method.
The connector will not be tightened, and the wires at the connector will be damaged if there is heat or sparks, and bad connectors will also affect the transmission of signals;
The movement of the contactor joint is easier due to vibration and electromagnetic release, so the position and tightening of the cable joint need to be checked regularly.
General motors are air-cooled, and the accumulation of dust will cause heating problems, so they should be cleaned regularly every year. Usually, there is a motor overload cut-off device in the circuit. The current limit of the protection device is adjustable, and the power consumption should be based on needs. Appropriate selection, once the overload protection is activated, it should be checked whether there is a phase loss, poor contact, or the position switch is restored after the oil temperature is high.
The heating pipe should be tightened and checked to ensure effective heat transfer, and heat is generated invisibly in the normally burning barrel. Pay attention to the work of the thermostat and judge whether it is normal from the heat pipe.
Another common damage to the heating tube is the cable connection. Due to the poor joint, the contact resistance increases, so the connection to the local overheating causes the interface to be oxidized and damaged.
The contactor acts more frequently on the electrical part, because its loss rate is also relatively fast. If the melting point of the main contactor is overheated, it may lead to poor control of the heating temperature of the bonding, so if the contactor is found to be overheated or broken, it will make a clicking sound. , then the damaged contactor will be replaced as soon as possible when the fire is large.
With the application of computer control technology in injection molding machines, computer electronic board parts and related auxiliary components have put forward higher requirements for working power supply voltage fluctuations, temperature and humidity of the working environment, installation earthquake interference, and the outside world for high-frequency signals. The ventilation fan of the control box is used for the work, and it is powered by a high-precision voltage stabilizer.
To reduce external vibration of the control box, the Effectively address these issues and check them regularly.
The template best reflects the clamping state of the parallel part, the template will not cause the failure of the product and increase the wear of equipment and tooling in parallel.
The parallelism of the template is a preliminary analysis reflected by the movement of the end of the pressing plate and the appearance of the product, but the specific situation such as equipment testing needs to be derived from the dial table.
The steps of the template should be adjusted in parallel by a person familiar with it, otherwise the machine will be more damaged by improper adjustment.
The mold thickness should be adjusted regularly using the system, and the module thickness should be adjusted from the thickest to the thinnest to ensure the smooth long-term production of the machine and the same mold. This inspection must be carried out to avoid failure.
The central lubrication system is an indispensable part of injection molding. The central oil lubrication system should always check whether it is filled, and the lubricating oil used should be clean and free of impurities to ensure that Lubricating oil supply to all parts is normal.
If the water pipe is found to be blocked or leaking, it should be replaced or repaired immediately.
Most mechanical wear occurs due to lack of lubrication, so the importance of adequate lubrication is self-evident.
Smooth motion or vibration may be caused by improper speed adjustment, inconsistent speed change and time, or mechanical and hydraulic adjustments.
Such shocks will accelerate the wear and loosening of mechanical components, and tightened screws should reduce and prevent vibration.
If the bearing makes different sounds during operation, or the internal temperature rises, it means that the bearing is worn. It should be checked or replaced in time, and the grease should be refilled.
The injection screw, inspection ring and barrel constitute the heart of the injection molding machine, which determines the processing quality and efficiency of the injection molding machine, and we must keep them in good working condition.
First of all, it is necessary to take necessary measures to prevent non-plastic chips from mixing into the flow of plastic. When adding, pay attention to check the gap between the screw and the barrel, and check whether the gap between the ring and the barrel is correct. When the gap is normal, it should be able to return and generate the plasticizing shears required for sealing. When it is found that the melt is slow, the melt spots and black spots, the molding is unstable or the product is worn, the wear of the screw, ring and barrel should be checked.
Injection molding machines are generally used for long time working, hence, it is import to do the ordinary maintenance, to prevent from any machine breakdown to delay the production and delivery.
Effectively arranging the maintenance is necessary and it could greatly reduce the failure and improve the efficiency. For example, you can arrange daily maintenance for the most frequent failures, and weekly maintenance for less frequent items.It is essential to arrange a specific personnel to be in charge of the maintenance, which would ensure the work is effectively done as scheduled. It is necessary to record the finished items, in order to make future evaluation accordingly.Let’s follow the injection molding machine preventive maintenance checklist below. For the ordinary hydraulic injection molding machines, the daily maintenance mainly starts from the following aspects:
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Timing belt (For inspection method, refer to section 6.2 Timing Belt Inspection)
A. Check that the timing belt is not loose.
B. Check that the belt and pulley have no wearing or damage.
A. In consideration of service lives of screw tip assembly, packing, and electric equipments (heater, timers), make preparation for replacement. The guarantee period for these equipments is six (6) months.
B. Inspect fans inside the control cabinet for rotating normally. And inspect fans for existence of abnormal noise or insulation status.
DANGER: Securely turn off the power and measure voltage at inspection points to check power off before inspection.
C. Lubrication
Inspect the inside bearing in operation of the clamp unit, ejection device, mold thickness setter, injection unit, nozzle touch drive unit for existence of abnormal noise or for wearing on bushing and sliding face of slide ways.
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An abnormally high oil temperature may be normal, or it may be the result of heat generation that prevents hydraulic cooling system components from working.
1. The cooling system is abnormal
a). The water supply of the cooling system is insufficient, the water valve is not fully opened, and the water pressure or water pump flow does not meet the needs.
b). Pipe blockage, such as filter, cooling tower or water blockage.
c). The cooling water temperature is too high, such as the cooling tower cooling capacity is insufficient, or damaged or the temperature is too high.
a). The pump is damaged, and the internal parts wear and generate heat during high-speed rotation.
b). Improper pressure regulator, excessive pressure in the hydraulic system, overheating for a long time.
c). There is leakage inside the hydraulic components, such as damage to the direction of the valve or damage to the sealing ring, which heats the small space through which the high-pressure oil flows.
Abnormal noise is produced, and parts are damaged or improperly adjusted. If there is a noise problem, the cause should be identified and repaired in time.
a). When the hydraulic oil is insufficient, the dirt inhaled by the oil pump or oil filter can block the air, which can cause the pump to starve, causing the air to leave a noise impact when the oil is discharged. The solution is to check the oil, prevent the air from being sucked in and clean the oil filter .
b). The viscosity of hydraulic oil is high, which increases the flow resistance and properly replaces the hydraulic oil.
c). When the noise of the concentricity deviation of the coupling is caused by the damage of the pump or motor bearing or vane, the concentricity should be adjusted or the parts should be replaced.
d). The direction of the solenoid valve fails but the function still does not respond. For example, the heart valve is worn, internal leakage, and the burr block does not move freely. When the solenoid valve fails, noise will be generated due to insufficient current.
The solution is to clean the spool and replace the worn parts of the spool with a new one, so that the current is stable and sufficient.
e). Damaged hydraulic components or blocked oil pipes indicate that noise is generated when hydraulic fluid flows at high speed.
f). Mechanical failure, lack of lubrication or wear of mechanical bearings or loose parts, the cause of the fastening parts should be found out or replaced – make sure there is enough oil.
In a stable production cycle, unstable product quality occurs, possibly caused by wear or improper adjustment of mechanical components.
a). The screw, check ring and barrel are worn.
b). Fuel injection causes seal leakage and damage.
c). The temperature control of the heating tube is unstable.
d). The pressure and speed control parts are disordered.
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A bit late since the move should meanwhile be over, but still. There is absolutely no way you could, or should do this, for too many reasons to even know where to start.
But of course, there's theory and there's practice. In reality, showing good will but having a little "accident" early on that day and calling in sick for the remainder might be the smartest thing to do. Unluckily, with that sprained ankle, you can do no lifting.
Because, you know, the person who complains first about very reasonable concerns is the first to be fired. That's life. So, although you are absolutely entitled to refuse this crazy endeavor, it will come down onto you negatively if you are the trouble man (even moreso as you seem to have what looks like a "typical US-style management"). If nothing else, you get a negative rating at the end of the FY. Nobody likes the trouble man. We want solutions, not complaints. Pussy.
Moving typical "machinery" on their typical little wheels (at that weight, probably cast metal) works -- if the ground is even. Otherwise, no way, forget it. Pitted road? Got suicide tendencies? The possibly best thing that can happen is one of the wheels getting stuck in a pit and the machine becoming unmovable thereafter. That's the absolutely best thing that can happen (and something much more desastrous is more likely).
The idea of moving something of any considerable weight, let alone 450kg, up a 45° pathway for half a block on pitted ground as pointed out in an explanatory comment is just outright hilarious. Even assuming that this may work is unreal. Try and walk 45° uphill for half a block with no weight.
Some of the steepest roads on the planet have an inclination of around 35%, which is a mere 17-18°. Usually, there's warning signs for as little as 10% already (for good reason!). So you are going to push half a ton of weight on cast wheels (presumably?) uphill on a path three times as steep. You need not be a rocket scientist to see that this will either not work at all, or end badly. Makes you wonder what forklifts were invented for.
There is this thing called due diligence. Whatever your boss tells you, you still have due diligence or you get in trouble when something happens (note the wording when, not if). In a situation like this, due diligence can be assumed not to be present, so when something happens, your indemnity insurance won't pay. And of course, the blame (from management, for the lost machine) will be on the person/people having touched the machine last. So, don't be that person, don't touch it.
What could happen? I am not even going to start about this thing rolling downhill or toppling and crushing someone underneath. It's enough if someone gets his toes under one of the unforgiving wheels. I've seen people lose a couple of toes due to considerbly less heavy stuff rolling over their unprotected foot. You do wear metal-cap boots in your office, don't you... :)
Let's not think about getting yourself a hernia or a bad back either, lifting around crazy heavy stuff as an untrained office guy, without proper equipment. Nothing's gonna happen, right.
What's worst, you do not even need to get the weight on top of a part of your body to get serious harm. Once 450kg are moving, it's enough to have your hand in the wrong place (between machine and wall, or door). You cannot shout "stop" fast enough, and if you could, your co-workers couldn't stop the thing before your fingers are pulp.
Even if no body parts are in the way, you cannot shout "stop" fast enough before the rolling monster turns the entrance door to rubble. Or the photocopy machine, or whatever comes in its way. Who's going to pay?
Getting the machine onto the truck is actually a lot easier than you would think (I've done that, never having done it before). But it's still a needlessly dangerous thing, and do you really want to have the responsibility for whatever happens when that thing falls off, even without killing someone?
Anything but hiring professionals for such a thing is outright insane. Of course, there's no way you can tell that your manager, so there's the solution with that sprained ankle.