Friday, August 26, 2022

Step Motor Systems: The Benefits of Adding Encoders

Use Encoders to Enhance Step Motor System Performance

Because of their low cost, high resolution, precise positioning, minimal control electronics and low cost, step motors are popular in automation. Traditional step motors can be driven in an open loop system without the need to have sensors to send information back to a controller. However, open loop step motors pose challenges.



Complex projects such as quadcopters require enhanced position control. The stepper motors are designed to provide excellent precision and predictable performance. This is possible when both the gearbox ratio and step angle are known.

Stepper motors are now the preferred choice for many electronic devices.

Some engineers go one step further than the stepper motor's excellent visibility into velocity and position.

They have also added encoders in their motor systems to the stepper's open loop control.


The Motor Encoder: Closed Loop Control is essential

An Stepper Motor w/ Encoder can be attached to an electric motor. It can be attached to an electric motor shaft to provide closed-loop feedback signals.


This functionality may seem redundant at first. Is precision control not what the stepper does by itself? It seems that both yes and no. Recent research has demonstrated that even though it may seem unnecessary, the encoder can make a huge difference in the performance of a stepper motor.


Galil, a motion controller manufacturer, conducted side-by-side tests between closed and open loop stepper motors. The team found that an encoder can make a significant difference in performance metrics.


The closed loop system offers:

Significantly improved velocity smoothness

Reduction in overall consumption


Three-phase brushless motors with comparable torque outputs can produce higher torque at lower speeds than comparable three phase brushless servomotors.

Galil's researchers found that stepper motors could achieve "dramatic" performance improvements by integrating a positional-feedback device with a two phase brushless amplifier. Their website contains their testing methods and results.

These are exciting developments in the world of motion control. Engineers of all levels can make stepper motors more powerful and economically viable by using readily available encoder technology.


Which ENCODERS IS BEST?

Optic encoders are a well-established technology. They offer reliable and accurate performance with a wide range resolutions. However, they can be subject to degradation and loss due to oil, dust, and other contaminants. They work best in clean environments. Capacitive encoders use newer technology and offer similar benefits. They provide the same speed and position information as optical encoders. They are also immune to environmental contaminants.


Saturday, August 20, 2022

Tips on How to choose a CNC Spindle motor

It is important to choose the right spindle or milling head. A "toy" brush spindle with a plastic housing might be sufficient for use in plywood and soft plastics. It is not suitable for professional use, i.e. to make money. It is not suitable for professional use (CNC Spindle Motor). It can be completed in just a few hours with hard work, and it can take up to six months with economical work.




Professional spindles use ceramic bearings on brushless inductive spindles with tight engine compartments and absolutely with metal housings. There are many options for spindle revolutions, power and output.

The nominal spindle speed of the identification plate is 12.000, 15.000 and 18.000 respectively. However, this does not necessarily mean that the spindle spins with these revolutions. The inverter can control the revolutions, but it is important to keep in mind that spindle power is the torque multiplied with rotational speed. This means that while the spindle speeds can be reduced by half, the power also falls. Here is where we need to compromise.

There is no one spindle that works for all applications. The spindle speed limitation is caused by the higher spindle power and larger bearing diameters. A larger bearing diameter means that the ball's centrifugal force is greater, which causes more heat to be released. One way to decrease this effect is to use lighter ceramic balls. 40.000 rpm spindles can be made only in low power settings.

Materials such as aluminum and wood, composite materials and laminates require high speed. High speed is not recommended when machining steel, particularly stainless steel, thermoplastics, or drilling with HSS drill bit bits.

The primary criteria for power is the maximum milling cutter diameter and materials to be cut with them. The spindle can be used to machine aluminum, plastic, wood, or laminate up to 5mm. It has cutters that are up to 8mm in diameter, 12mm in diameter, 3.3kW spindle, 16mm in diameter, and 5.6kW spindle. We should choose a lower-rpm spindle for steel. This means cutters between 10mm and 3.3kW spindle, cutters between 12mm and 5.6kW spindle as well as cutters between 16mm to 7kW spindle and cutters between 20mm to 10kW spindle.(Spindle Motor Inverter)

You should always choose a stronger spindle if you plan to drill steel. For example, a 6mm drill with a 5.6kW spindle at 2000rpm can drill steel at 2000rpm. Because spindles have gears, it is impossible to compare their power with conventional milling machines. Another thing. These spindles can last up to 10 years.


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