The rapid expansion of CNC machines in industry has lead to the need of special motors, capable of delivery high torque values and also to allow rapid variation of rotational speed. The answer was offered by the spindle motor together with the spindle drive. While the spindle motor offer a very low rotor inertia and high-peak-torque capability, its companion, the spindle drive allow the access to all motor benefits, implementing specific control techniques to get higher acceleration rates and also high torque values.
The challenge for the spindle drive is to maintain a constant force and a constant cutting velocity of the tool attached to the motor, regardless of the load during the operation. To provide this tight speed and torque control, a feedback device, typically an encoder or resolver, must be added to the motor, to allow the close loop required by the drive. The most common method implemented for spindle drive is a specific variable frequency control technique named vector control. This is implemented on AC synchronous and induction motors using a method called Proportional Integral Derivative control that makes sure the spindle has the current and torque it needs to maintain the rotational speed under various load conditions. Without this approach the motor will suffer a reduction in RPM when additional load is applied. Using vector control, speed regulation can be as accurate as 0.01% of set speed.
Usually a sudden decrease of the load could causes the motor to spin faster than nominal transform it into a generator, generating energy back into the driver unit, which should do something with that energy. Most of the spindle drive units dissipates this energy as heat via a dynamic braking resistor.
Most of the application of spindle units has high inertial loads or needs controlled fast stopping, so their drive implement a line-regenerative vector control. Such a drive puts the regenerated energy back into the ac power line, thus reducing energy costs.
The complexity and the computing power required to get the very tight specifications of the spindle drive make them difficult to repair units, requiring a vast experience from the technicians and also involving dedicated testing and debugging equipment.
Our team of highly qualified technicians can perform professional spindle drive repair. We have the experience required, and also the test equipment needed to find the problem of any unit, regardless of its complexity. After the fault is found we will provide you an estimation of the repair cost, leaving you to decide if the repair will be done. Usually the repair cost is less than 50% of the price of a new unit.
After the approval, we will repair the spindle drive and test it properly to assure the customer that the unit will comply with all the manufacturer specified characteristics. Whenever possible, the original drive parameters are saved and after the repair they are restored into the unit, so the customer could use the unit directly without the need of reprogramming. A good indicator of the quality of our services is the warranty return of the repaired units which is almost negligible. We will guarantee our repair with up to a full year warranty.