2.2  Cutting force principle
 By the work piece during the cutting action of the cutting forces on the tool called the cutting forces. Directly determines the cutting force cutting heat generation and affect tool wear, breakage, tool life, machining accuracy and quality of the machined surface. In production, the cutting force is calculated cutting power, to develop cutting, cutting state monitoring, design and use of machines, tools, fixtures necessary basis. Therefore, the study rules and calculation methods of cutting force, cutting mechanism will facilitate analysis, and actual production has important practical significance. 
Under the action of the tool, the cutting layer of metal (chips) and the machined surface layer of the metal to be elastically deformed, and plastic deformation of the cutting force source has two aspects: one is cutting metal layer, the surface layer of the metal chip and the elastic deformation and plastic deformation resistance generated twenty tool and the chip, the surface friction between Ffa, Ffb. In order to facilitate the measurement, calculation and research, often cutting force F is decomposed into three orthogonal components: the main cutting force Fc, cutting force in the movement direction of main component, consistent with the cutting speed of VC, it is the main basis for calculating the cutting power and machine design; back force Fp , Is the cutting force F to force direction in a surface processing method, turning round when Fp is not work, but it will cause the deformation of the work piece or cause vibration, affect the machining precision and surface quality of machined; the feed force cutting force is Ff, F in the feed direction of the force, which is parallel with the direction of feed, the role of Ff in feed mechanism, is the design of feed mechanism or feed system for checking the strength of components on the basis of. The largest Fc in the three components, Fp and Ff small. The relationship between Fp, Ff and Fc as Fp = (0.15 ~ 0.7)Fc ， Ff = (0.1~ 0.6)Fc. Experience is widely applied in actual production of formula [2]：
Type: AP, F, VC respectively for the cutting depth (mm), feed rate and cutting speed (mm/r) (mm/s);
The cutting force coefficients CFc, CFp, CFf and work piece materials and experimental conditions related to the;
KFc, KFp, KFf, experimental conditions and calculation conditions are not at the same time correction coefficient. 
Calculate the empirical formula of cutting force is obtained by experiment, in the process can be found in a number of different manual working conditions parameter values in the formula for calculating the size of experience in cutting force. Machining practice, there exist some unknown factors, to obtain accurate numerical cutting force, also needs to make the real-time measurement of a measurement system. In the automatic production, the cutting force signal real-time monitoring and optimization of cutting process can be measured with a force measuring system.

3. Experimental setup
 3.1 Monitoring system
Fig. 3 shows the micro cutting and monitoring systems used for the experiments. The micro cutting system has the same structure as a three-axis machine tool, and consists of three-axis linear stages (X, Y, and Z-axis) and a high-speed spindle that can rotate at a maximum speed of 100,000 rpm. The cut-ting force monitoring system is composed of a micro tool dynamometer, an acceleration sensor, and current hall sensors. A three-axis micro tool dynamometer (Kastler) is used to obtain the reference cutting force components in comparison with the signals obtained using the acceleration sensor and current hall sensors during the experiments. The three-axis acceleration sensor (SA12ZSC-TI) was attached to the main spindle housing, and the current hall sensors were connected to the motor inlet cables (U and V lines). In this research, all sensor signals were obtained through 10 kHz low pass filters to remove high-frequency noise. The filtered sensor signals are acquired simultaneously through an A/D conversion board (PCI-NI 9133). 切削力的间接测量英文文献和中文翻译(2):http://www.751com.cn/fanyi/lunwen_40859.html