How much do you know about electric spindles?

I. Structural composition

The electric spindle is a new technology that combines the machine tool spindle and the spindle 

motor in the field of CNC machine tools in recent years. The main drive system of high-speed CNC machine tools eliminates the belt drive and gear drive. The main shaft of the machine 

tool is directly driven by the built-in motor, which shortens the length of the main drive chain of the machine tool to zero and realizes 

the "zero drive" of the machine tool. This type of transmission structure intergrating spindle 

motor and machine tool spindle, which makes the spindle components relatively independent from the drive system and overall structure of machine tool, so it can be made into a "spindle unit", commonly known as electric spindle or Motor Spindle.

The electric spindle is a set of components, which includes the electric spindle itself and its 

accessories: electric spindle, frequency conversion device, oil mist lubricator, cooling device, built-in encoder, tool changer, etc. The rotor of the motor is directly used as the main shaft of the machine 

tool, and the housing of the main shaft unit is the motor base, and other parts are integrated to realize the integration of the motor and the main shaft of the machine tool.

II.Driving method

The electric motor of the electric spindle adopts AC asynchronous induction motor. It is used on 

high-speed processing machine tools, so it needs to rise rapidly from static to tens of thousands of revolutions per minute or even hundreds of thousands of revolutions at startup. The starting torque is large, so the starting current must exceed the rated current of the ordinary motor by 

5 to 7 times.. There are two types of drive methods: inverter drive and vector control drive. 

III. Application of high-speed electric spindle in machine tool industry

1. Simplify structure and promote modular machine tool structure

The electric spindle can form standardized and serialized products according to the characteristics of use, structure, and performance parameters for the host to choose, thereby promoting the 

modularization of the machine tool structure.

2. Reduce machine tool costs and shorten machine tool development cycles. Standardized and serialized electric spindle products are easy to form professional and large-scale production, and can shorten the development cycle of machine tools, adapting to the current fast-changing market trend.

3. Improve machine performance and reliability.The CNC machine tool adopting the 

electric spindle structure has improved the reliability of the machine tool due to the 

simplified structure and the reduction of transmission and connection links; the electric 

spindle components with the mature technology, complete functions, excellent performance and reliable quality make the machine tool more reliable.

4. Realize the special requirements of some high-end CNC machine tools.Some high-end CNC machine tools, such as parallel kinematic machine tools, pentahedron machining centers, small hole and ultra-small hole processing machine tools, must use electric spindles in order to meet the 

complete functional requirements. The electric spindle system is directly driven by the 

built-in motor to meet the high-speed cutting’s requirements of “high speed, high precision, high reliability and small 

vibration” on the machine tool. The combination of electric spindle technology and motor frequency conversion, closed-loop vector control, and AC servo control technology can meet the needs of metal cutting processing such as turning, milling, boring, drilling, and grinding.

In September 1958, the spindle manufacturing department successfully developed China's first high-precision electric spindle. The electric spindle uses the speed of 30,000 ~ 60,000r / min for precision bearing grinding.

Through the efforts of several generations of spindle employees, ZYS has established its leading 

position in the field of high frequency Spindle spindle in China, and its research and development 

strength and spindles varieties rank first in China.

For more detailes of electrical spindle, please contact Mr. ZHANG by zys_zyj@163.com or visit www.zys-bearing.com.

Common faults and solutions for CNC machine tool spindles IV

Problem five:The spindle stops immediately after starts.

The cause of the failure and the solution:

1. System output pulse time is not enough: adjust the system's M code output time.

2. The inverter is in jog state: Refer to the instruction manual of the inverter and set the parameters.

3. The control components of the spindle line are damaged: check whether the contacts on the circuit are in good contact, check whether the DC relay is damaged which caused the contact can not self-lock. 

4. The spindle motor is short-circuited, causing thermal relay protection: find the cause of the short circuit and reset the thermal relay.

5. The spindle control loop does not have self-locking circuit, and the parameter is set to pulse signal output, so that the spindle can not operate normally: change the start and stop parameters of the system control spindle to the level control mode.

Problem six: the spindle rotation can not stop

The cause of the failure and the solution:

1. AC contactor or DC relay is damaged and uncontrollable: replace AC contactor or DC relay.

Common faults and solutions for CNC machine tool spindles III

Problem three: the rotating speed of the spindle without frequency conversion (shift spindle) is not controlled

The cause of the failure and the solution:

1. System has no S01-S04 control signal output: Check whether the system has shift control signal output. If no, it is system failure, replace the IC or send the factory for repair.

2. Connection line failure: If the system hasshift control signal output, check whether there is any open circuit or poor contact on each connection line, and check whether the DC relay or AC contactor is damaged.

3. The spindle motor is damaged or open circut : Check the spindle motor.

4. Machine is not linked: hang up the gear.

Problem four: the spindle has no brake

The cause of the failure and the solution:

1. Abnormal brake circuit or strong electrical components damage: Check whethr bridge stack, fuse or AC contactor is damaged; check if the high-voltage circuit is open.

2. Braking time is not long enough: adjust the braking time parameter of the system or inverter.

3. System has no brake signal output: replace internal components or send to the factory for repair.

4. The inverter control parameters are not adjusted: Check the inverter manual and set the inverter parameters correctly.

Common faults and solutions for CNC machine tool spindles II

Problem two: the spindle with the inverter does not turn​

The cause of the failure and the solution:

1. Mechanical transmission failure: Check whether the driving belt is broken or whether the machine tool is in neutral.

2. Three-phase power supply to the spindle is missing: Check the power supply and exchange any two power lines.

3. The inverter control parameters of the CNC system are not open: see the system manual to understand the inverter parameters and change them.

4. Line connection error between the system and the inverter: Check the connection manual of the system and the inverter to ensure the connection is correct.

5. The analog voltage output is not normal: Check whether the analog voltage output by the system is normal with a multimeter; check whether the analog voltage signal line connection is correct or the contact is good, and the analog voltage received by the inverter matches.

6. High-voltage control part is disconnected or component is damaged: Check whether the connection of each contact of the spindle power supply is reliable and whether the DC relay is damaged or the fuse is burnt out.

7. Inverter parameters are not adjusted: The inverter contains control mode selection, which is divided into inverter panel control spindle mode, NC system control spindle mode, etc. If NC system control mode is not selected, we can not control spindle with system; check if the relevant parameter settings are reasonable or change them if necessary. 

The use of the surface layer of the metal melting and re- solidification

Solid state phase transition, by the method of rapidly heating the surface layer part of the surface hardening treatment machine tool spindle is called a heat treatment , known as surface hardening . Including flame hardening , high ( in ) frequency induction heating quenching, laser heating or electron beam heating quenching. KOYO bearing characteristics of these methods are: local heating surface hardening , the workpiece deformation ; heating speed, high production efficiency ; heating time is short, very slight surface oxidation and decarbonization . This method especially for improving the  wear resistance to withstand certain impact loads and fatigue strength effects of large  and extra large bearing parts significantly The use of certain elements into  solid state diffusion to change the chemical composition of the metal surface layer , deep groove ball bearings to achieve surface hardening High speed Spindle method called chemical heat strengthened, also known as diffusion heat treatment . Including boriding metals , carburizing and carbonitriding , nitriding and nitrocarburizing , sulfide and Sulphonitrocarburizing , Chromizing , aluminized and chrome aluminum silicon permeation , diffusion layer graphite , etc. , a wide range of different characteristics . Or dissolved into the matrix metal element forming a solid solution with other metals or elements  to form compounds. I.e. short change the chemical composition of the elements into the surface layer , and a different phase structure can be obtained . Surface treatment process and carburizing bearing KOYO bearing sleeve nitrided steel parts are enhanced handling this type of fortification .
The use of the surface layer of the metal melting and re- solidification , to give the desired composition of the surface hardening treatment or tissue enhancement technique called surface metallurgy . Including the surface from the insoluble alloy or composite powder coatings, crystalline or amorphous surface melting , surface alloying methods. Deep groove ball bearing is characterized by rapid heating to a high energy density , the surface of the metal layer or metal coating on the surface of the alloying material is melted and then solidified by cooling to obtain their particular structure or particular properties of the reinforcing layer . This particular structure is perhaps the crystal structure refinement , or maybe supersaturated phase , metastable phase , even non- crystal structure , depending on the process parameters and methods of surface metallurgy . Rolling industry in miniature bearing surface enhanced laser heating has done research to good effect.
Application of physical or chemical methods , the coating on the metal surface bearing a different material properties of the matrix to strengthen the film , the film referred to as surface hardening. It includes electroplating , electroless plating ( chrome, nickel, copper, silver , etc. ) as well as composite plating, brush or transformation processing , including in recent years, the rapid development of high-tech : as CVD, PVD, P-CVD , etc. vapor deposition and ion implantation method to strengthen the film surface enhancement technology ( also known as atomic metallurgy ) and so on. Their common feature is the film can form specific performance in the work surface to enhance the wear resistance of the surface resistance, fatigue resistance, corrosion resistance and self-lubricating properties. Such as ion implantation technology to strengthen the deep groove ball bearing surface , enabling the bearing surface wear , corrosion resistance, and resistance to contact fatigue performance have been significantly improved , so that the service life of bearings KOYO grow exponentially .