Motor accessories refer to the parts of the motor assembled in the motor manufacturer for the original parts of the motor, due to improper use or damage caused by wear and tear replacement parts called motor accessories. General parts life is not as long as the original life. Motor accessories can be divided into five parts. The classification of motor accessories can probably be classified according to the components of the motor, which can be divided into motor stator, motor rotor, stator winding, Motor Housing, end cover, motor blade, bearings and other parts. It can be manufactured by CNC Machining, Sand Casting, transparent acrylic(PMMA/PC) 3D Printing.

Electromagnetic DC motor consists of stator magnetic pole, rotor (armature), commutator (commonly known as commutator), brush, Housing, bearing, etc.
The stator magnetic pole (main magnetic pole) of an electromagnetic DC motor is composed of an iron core and an exciting winding. According to its excitation (the old standard is called excitation) mode can be divided into series excited DC motor, shunt excited DC motor, separately excited DC motor and compound DC motor. Because of the different excitation mode, the law of stator magnetic flux (generated by the excitation coil of the stator magnetic pole) is also different.
The excitation windings and rotor windings are connected in series by brushes and commutators, and the excitation current is proportional to the armature current, the stator's magnetic flux increases with the increase of the excitation current, the torque is approximately proportional to the square of the armature current, and the speed decreases rapidly with the increase of torque or current. Its starting torque can reach more than 5 times the rated torque, short-term overload torque can reach more than 4 times the rated torque, the speed change rate is large, and the no-load speed is very high (generally not allowed to run under no-load). Speed regulation can be realized by using external resistors in series (or parallel) with the series winding, or by connecting the series winding in parallel.
The excitation winding of shunt DC motor is in parallel with the rotor winding, the excitation current is relatively constant, the starting torque is proportional to the armature current, and the starting current is about 2.5 times of the rated current. The speed decreases slightly with the increase of current and torque, and the short-term overload torque is 1.5 times of the rated torque. The speed change rate is small, 5%~15%. Speed can be adjusted by the constant power of weakening the magnetic field.
The excitation winding of separately excited DC motor is connected to an independent excitation power supply, and its excitation current is also relatively constant, and the starting torque is proportional to the armature current. The speed change is also 5% to 15%. The speed can be increased by weakening the constant power of the magnetic field or reduced by reducing the voltage of the rotor winding.
In addition to shunt winding, series winding (with fewer turns) is also installed on the stator magnetic pole of the compound DC motor. The direction of magnetic flux generated by the series winding is the same as that of the main winding, the starting torque is about 4 times of the rated torque, and the short-time overload torque is about 3.5 times of the rated torque. The speed change rate is 25%~30% (related to series windings). The speed can be adjusted by weakening the magnetic field strength.
The commutator sheet is made of silver copper, cadmium copper and other alloy materials and molded with high strength plastic. The brush is in sliding contact with the commutator to provide armature current to the rotor winding. The brush of electromagnetic DC motor generally adopts metal graphite brush or electrochemical graphite brush. The core of the rotor is made of silicon steel sheet laminated, which is generally 12 slots and embedded with 12 groups of armature windings. After the windings are connected in series, they are connected with 12 reversing pieces respectively.