Slitter blades will rub with boards during operation, resulting in blade blunding. Therefore, it is neccessary to shapen blades with grinding wheels. lcknife Slitter blades made of different materials should be sharpened with correspondinggrinding wheels. For example, you can choose CBN(cubic boron nitride) grinding wheel for high-speed steel thin blade, with particle size ranging from 100#-150#; While tungsten steel thin blades should be sharpen with SCD(diamond) grinding wheels, with particle size ranging from 180#-240#.

AC cooling fan introduction - Chungfo Electronic

AC cooling fan is the major aspects of different varieties of industrial products, including electrical machinery and electronic digital products which all demands cooling fan as the major device for energy managing. By developing the environment flow, cooling fan provides cool air to decrease the temperatures of your industrial equipment, also, will help the industrial electrical or electronic digital projects to hold our prime effectiveness as well as its performance is definitely not minimized due to the heat produced.

As the part of the electronic digital components, AC cooling fans are widely developed in the home appliance or different varieties of industrial electronic digital machinery. It is because AC coolinf fan offers stable air movement consistently, which assists to stable the machinery performance, hence the machinery is definitely not from operate due to the overheat.

AC cooling fan works with AC power, and by operating of your impellers to generateair flow to decrease the temperatures of your machinery, which will help prevent the machinery from overheat. The many between AC fan and DC fan is – AC cooling fan air flow is stable and consistently, that may typical the machinery temperatures. Also, by changing the fan speed to meet the objective of energy managing.

AC coolinf fan could be categorized in 2 major models, depending on its design –

AC axial fans – the air flow it creates is vertical with the fan impeller, the air in and out is in the same direction. AC axial fans’ main advantages are – big air flow, easy assembly, high efficiency, and high speed. With multiple product selection with different air flow and speed, it allows the users to choose the axial fans meets their requirements most. External rotor axial fans provides stronger air flow and higher speed, and with metal impeller design, it fits better for customers who need to use the fans in a rugged circumstance.

AC cross-flow fan the air-in direction is horizontal with air-out. The design of impeller and air-out area is narrow, which fits most to install on the flat machines, like elevators, air conditioners,electronic equipment and so on.

If you need to know more about Chungfo AC fan,please don’t hesitate to contact with us.

AC, DC, EC fans Features

When it comes to cooling fans, it is estimated that everyone is very familiar with them. They are indispensable in our life, such as household appliances, electronic products, digital computers, medical equipment, etc. They will be used as long as they need cooling and exhausting. Cooling fans can be divided into AC fans, DC fans and EC fans. Here, I will explain the difference between AC / DC / EC fans:

AC fan is what we call AC cooling fan. The principle and manufacturing method of this kind of fan are very simple. Its characteristic is that the power frequency is fixed and will not change with the positive and negative voltage.

DC fan and EC fan belong to DC cooling fan, but there are some differences between them. A simple summary: DC input is DC, EC can input AC, which converts AC into DC.

Advantages of AC fan:

1. Provide stable and continuous air volume.

2. Hot air can be discharged and colder air can be inhaled.

Advantages of DC fan:

1. Minimal electromagnetic interference.

2. Low energy consumption.

Advantages of EC fan:

It has the characteristics of high intelligence, high energy saving, high efficiency, long service life, low vibration, low noise and continuous work.

We are Chungfo, a professional manufacturer of cooling fans. We prodece DC axial fan, DC blower fan, DC frameless fan, AC fan, AC / DC cross flow fan, EC fan and so on.

In addition to the DC brushless motor, there is another type of shaded pole induction motor in the exhaust cooling fan.

As the name suggests, Induction motors is because electromagnets in the stator induce magnetism in the rotor. They induce magnetism in the rotor because, unlike the rotor in a brushless DC motor, the rotor in an induction motor contains no magnets.

A separate small winding is used in the stator, called the shielded coil. The electromagnets in the stator are formed by coils around steel laminations. The shading coil is wound around a small section of the laminations. When ac is supplied to the main winding, a portion of the resulting magnetic flux links to the shading coil. This induces a current in the shading coil which behaves like the secondary of a transformer. The induced current, in turn, produces its own (weak) magnetic flux which lags the magnetic flux in the main portion of the stator. Consequently, there is a time and space displacement between the two fluxes. This time and space displacement sets up the conditions for a rotating (or shifting) magnetic field. The rotating magnetic field is what starts and keeps the rotor turning.

Some shielded pole motors do not use shielded coils. Instead, they use a small gap in the lamination, which is enough to generate the hysteresis magnetic field needed to rotate the rotor.

The advantage of AC cooling fan shaded pole motors is that they are inexpensive because they have a pretty simple construction. But the problem is that they are inefficient, mainly because of the lossy linkage between the shaded coil and main winding. The efficiency of shaded pole motors generally is only between 15 and 30%. And the power factor is rather low as well.

A low power factor and efficiency is probably ok for applications where there is only one small cooling fan (shaded pole motors are generally 40 W or less). But consider an application like a data center, which includes racks and racks and racks and racks of severs, and each of those servers has its own fan. It is not advisable to have hundreds or even thousands of fans all operating at only 30% efficiency. Brushless motor technology and its efficiency of 90% are more suitable for these applications.

Motors that power ventilation cooling fans are usually divided into brushless motors or induction motors.

Brushless motors are sometimes called electronically commutated motors. Commutation refers to the act of switching the electrical connection from one motor winding to the next one. Motor windings in the DC cooling fan motor  is generally located in the stator or stationary portion of the motor. Then the rotor contains a magnet with alternating poles. (DC motor with the magnets in the rotor are sometimes called outrunner. There are other possible configurations but they are not as widely used as outrunners.)

The brushless DC fan motor uses an electronic controller to sequentially energize the stator windings, turning them into electromagnets, in a sequence that turns the rotor. First, one set of coils (that is, a coil and the coil located 180º away from it) would be energized to become electromagnets. This causes the opposite poles of the rotor and stator to be attracted to each other. As the rotor nears the energized coil, the next coil is energized and the coil nearest the rotor pole is switched off. As the rotor rotates near the next coil on the stator, the coil nearest the rotor pole is switched off. This sequence repeats as the rotor runs. The point to note is that there is always one set of coils pulling the rotor, causing it to rotate.

In fact, the set of coils behind the set pulling on the rotor is energized in a way that pushes on the rotor rather than pulls it. So there is a combined effect of pulling and pushing on the rotor which gives this motor high efficiency. The combined effect is that most of the coils in the stator act on the rotor nearly all the time.

One aspect of brushless motor operation is the necessity of knowing the position of the magnetic poles in the rotor. In order to fire the right stator coils at the right time, the controller must sense the position of the rotor. The controller reads the rotor position sensor to decide what coils to energize.

The usual way to sense the rotor position is with a Hall Effect sensor. It’s also possible to measure the back-EMF in the undriven coils to infer the rotor position, thus eliminating the need for separate Hall effect sensors, but that scheme is a bit more complicated. The efficiency of brushless motor is usually 85% to 90%, mainly because most of the energy entering the coil actually drives the rotor.

Brushless DC (BLDC) fans are the most common type used to cool electronic equipment. Many cooling fans now have additional functions which provide greater control the fan speed and operation, thus improving the system performance. Having a fan run constantly even when maximum cooling is not required, does not result in an efficient system and can reduce the service life of a fan. If the average speed of the fan is reduced to 50% of its rated maximum speed, its service life can be approximately doubled, thus improving the reliability and availability of the whole system and reducing the maintenance costs.

Fan speed controller ICs are available for use in designing forced-air thermal management systems. Besides simple fan speed control, those ICs can include several important functions, such as detecting fan failure and closed-loop fan speed control for improved system performance. Cooling fan speed control options include:

Auto-restart

If the fan can't start due to obstacles, this may cause thermal lag problems or failure conditions. To solve this problem, most modern DC cooling fans feature auto-restart protection, which can detect when the fan motor is prevented from rotating and automatically cut off the driving current.

Tachometer Signal

Cooling fan motor and sensor for the tachometer share the same supply voltage. The tachometer signal can also detect fan failure or identify an impending failure of the fan. Detects rotational speed of cooling fan motor and provides a pulsed output. If motor stops, output stops pulsing and stays at logic high or low.

3-wire fans have a locked-rotor signal in place of the tachometer output. The locked-rotor signal indicates when the fan stops spinning but does not provide the tachometer’s detailed speed information of a tachometer.

Rotation Detector

Doubles as a lock sensor where output remains at logic low during normal operation, but is driven to logic high if fan motor stops.

PWM Control Signal

4-wire fans have all of the connections of 3-wire fans and add a PWM speed-control input and provide the ability to control the speed of the fan. Instead of modulating the power to the fan, the PWM input is used to control fan speed. That means that the power to the fan is continuously available, making the tachometer output continuously available. Duty cycle of this input determines speed of fan’s rotation, relationship between duty cycle, and whether fan’s speed is linear.

4-wire PWM cooling fans can be operated at frequencies above the audible frequency range, eliminating audible noise. The recommended PWM frequency for these fans is typically between 15kHz and 30kHz, but some can operate as high as 100kHz. The PWM speed-control input is usually compatible with 3.3V or 5.0V logic.

When used with a microcontroller one can create a sophisticated thermal management solution used to adapt to system conditions and provide more efficient operation.

1. When purchasing cabinet cooling fans, first confirm the size of the cabinet, select the appropriate fan model and appearance for installation, and then determine the parameters such as voltage, airflow, speed, current, noise and other parameters.

2. Cooling fan voltage, which can be divided into DC voltage 5v, 12v, 24v and 48V; AC voltage 110V, 220v, 380v. If the wrong voltage is connected, the cooling fan will be burned out, and the cabinet will also be damaged, causing adverse effects.

3. Confirm the service life of the cabinet cooling fan. The service life of sleeve bearing is about 30,000 hours, the service life of the hydraulic bearing is about 40,000 hours, and the service life of the ball bearing can reach about 80,000 hours.

4. The quality of the stator and copper wire will also affect the quality of the cooling fan of the cabinet. (Copper wire includes pure copper wire, aluminum clad copper, and even iron clad copper. The stator is also divided into pure steel and steel strip). The quality of copper wire and stator directly affects the service life of the cooling fan. Good copper wire and stator increase the speed and directly affect the service time of the cabinet.

5. The power line is also very important. Confirm the required length of the line. If the power line is peeled off or copper wire is exposed at the welding place, do not use it. It will cause personal injury and electric shock if the consequences are serious.

6. Generally, the frame and blades of DC cooling fans are made of PBT material. Usually, the operating temperature of the cooling fan is between -10 ~ +70°C, and the humidity is between 20% ~ 85%. Beyond this range, the AC cooling fans made of aluminum alloy can be selected.

The characteristics of the cooling fan itself are different from other products. Brushless cooling fan actively stirs the air and accelerates the airflow, so it also sucks in dust. There are two main aspects of inhaling dust. One is sucked into the bearing and the other is sucked into the rotor and stator. Inhalation of dust more or less affects the cooling fan, causing the fan to slow down and even stop the fan in severe cases.

Commonly used dust-proof cooling fan design methods generally have the following three aspects:

1. When designing, increase the height of the outer frame where the motor is installed to allow the motor to sink, reduce the distance between stator and rotor, and reduce dust entry.

2. Using double ball bearings, the balls have a certain degree of dust resistance, and the bearings are not susceptible to serious interference.

3. Add a dust-proof net cover to the cooling fan, which is durable and can effectively prevent dust from entering the fan blade area.

The above three aspects can effectively protect the cooling exhaust fan from the influence of dust, particles, etc., causing the damage of the fan or hindering the rotation of the blades. Compared with ordinary fans, dust-proof cooling fans have more stable running speed, better heat dissipation performance and longer relative service life.

The basis of a centrifugal fan is a rotating blade wheel called an impeller, which drags the incoming air or gas into a circular motion. It is then pushed out of the fan by the centrifugal force created by the rotation. When entering and exiting the fan, the airflow changes direction. This is the centrifugal fan principle.

In order to ensure the normal operation of the fan and improve the service life of the fan, we often carry out regular maintenance and maintenance on the various parts of the fan.

1. From the principle of the centrifugal fan, it can be seen that the impeller is an important component, so the maintenance of the impeller is essential. First, the impeller must be checked for cracks, wear and other defects from time to time. Second, the impeller must be kept clean, and the dust and rust on it should be brushed off regularly with a wire brush, because with the increase of operating time, these dusts cannot evenly adhere to the impeller, which will cause the impeller to lose its balance and cause the rotor to vibrate. Third, as long as the impeller is repaired, it needs to be dynamically balanced. If possible, you can use a portable test balancer for field balancing.

2. We also cannot ignore the maintenance of the casing and the air intake chamber. In addition to regularly checking the casing and intake chamber for severe wear and heavy dust accumulation, also regularly check that all fastening bolts are tight.

3. Bearing maintenance is equally important. In daily use, it is necessary to check the oil supply of bearing lubricating oil frequently. If there is oil leakage in the tank, you can slightly tighten the bolts of the end cover. If that doesn't work, you may have to replace it with new packing.

4. If we do not use the centrifugal fan for a long time, what maintenance work can be done? 1. When the ambient temperature is lower than 5 °C, the remaining water in the equipment and pipelines should be drained to prevent the equipment and pipelines from freezing. 2. Coat the surface of main parts such as bearings with anti-rust oil to avoid corrosion.

Guangdong Chungfo Electronic Technology Co., Ltd. focuses on the cooling needs of equipment in various industries, specializing in the research and development and supply of cooling fans such as DC cooling fans, AC cooling fans and DC blowers. For example, 5v centrifugal fan, 12v centrifugal fan, etc., we can provide professional customization of cooling fans according to customer needs.

DC cooling fan has two positive and negative power lines. When installing the cooling fan, if the positive and negative lines are connected reversely by wrong operation, will the cooling fan burn out?

Whether the axial cooling fan is burnt out or not is mainly related to the IC Design of the cooling fan. In general, the drive IC with double wire winding method has internal protection design. If the positive and negative power lines are connected reversely, it will show the phenomenon of short circuit. At this time, the current of the cooling fan will be much higher than that under normal conditions. The motor current is large and its temperature rise is high. When the temperature reaches a certain degree, the driving IC will be damaged due to overheating and the cooling fan will be burned out.

Some of the single winding drive IC has no internal polarity protection. If the motor stator PCB is not designed with polarity protection, it may burn out the IC instantly when connected.

In order to prevent the ventilation cooling fan from burning out due to positive and negative polarity connection, a diode is added on the PCB of the cooling fan to design polarity protection, that is, when the polarity of the cooling fan is connected reversely, the current is zero, showing no power supply, so it can protect the cooling fan from burning out.