Slot Milling Operation Research Articles

Indicators for monitoring chatter in milling based on instantaneous angular speeds

The detection of chatter is crucial in the machining process and its monitoring is a key issue to ensure a better surface quality, to increase productivity and to protect both the machine and the workpiece. An investigation of chatter monitoring in the high speed machining process on the basis of the analysis of cutting forces and instantaneous angular speeds (IAS) in the angular domain is presented in this paper.Experimental cutting tests were carried out on slot milling operation of aluminum alloy. Our experimental set-up allows for, on the one hand, the acquisition of the angular cutting force and, on the other hand, the measurement of IAS. The latter is computed from the signal delivered by the standard encoder mounted on the spindle motors. The same signal is used as a base for synchronous angular sampling.The acquisition methodology is described and discussed in this paper. Data analysis confirms the relevance of cutting forces for chatter monitoring and the good correlation between cutting forces and IAS of the spindle. Two chatter indicators are developed in the angular domain from the periodic and residual parts of angular speed and cutting force signals. They are used successfully for the detection of the chatter phenomenon. The indicator based on IAS is very convenient because it does not require additional sensors and can be realized without increasing the cost of the manufacturing system.

Simulation and Experimental Study on Size Effect in Steel Micro Milling Machining Process

Size effect is a critical factor that needs to be considered when conducting micro mechanical machining processes. In this paper, a cutting process simulation technology is used to simulate a single tooth’s engagement with workpiece from the entry point to the exit point in a slot milling operation. The obtained specific cutting forces from simulation are employed to analyze the size effect and the minimum chip thickness with variable radii of tool edges. Micro machining experiments with different machining conditions are implemented by use of a high speed and high precision machining spindle to investigate the size effect on machined surface integrity and burr width. The optimal cutting parameters have been analyzed based on the simulation and cutting test results.

Modelling and Simulation of Milling Forces Using an Arbitrary Lagrangian–Eulerian Finite Element Method and Support Vector Regression

A new method is presented to predict milling forces synthetically. Firstly, the 3D simulation model of the milling process is established using the arbitrary Lagrangian–Eulerian finite element method. And the simulated accuracy is calibrated by milling tests. Then the simulation model is taken as a virtual milling test system to replace extensive real milling experiments. Secondly, the specific cutting coefficients in the mechanistic milling forces model are identified by the support vector regression method using the training sample generated from the established virtual milling test system. Lastly, this methodology was validated by the slot milling operation of 2024-T3 aluminum sheets. The results show that this new approach can dramatically eliminate the experimental machining work and achieve good estimation accuracy.

Cutting Mechanics of Bulk Metallic Glass Materials on Meso-End Milling

In this study, effect of feed rate on cutting force, burr formation, and surface roughness on milling of Zr-based bulk metallic glass (BMG) material was investigated at constant spindle speed, 5000 rpm. Uncoated 1 mm diameter solid-WC tools with two cutting edges were used for all tests. Cutting mechanics of helical endmill was examined. Specific cutting and edge coefficients for BMG-WC workpiece-tool pair were identified by using mechanistic approach. Analytically modeled forces converge to the experimentally measured forces with less than 10% error. Cutting forces of BMG were compared with SS304 stainless steel and Al6061-T6. BMG requires cutting force less than SS304 and more than Al6061 under the same conditions. Analyzing of burr formation of slot milling operations showed that the amount of deposited chip formation increases with the increasing feed rate. The rollover and the top burr type of burr formations were observed along the slot. This study concludes that Zr-based BMG can be achieved meso-machining with good surface roughness, (Ra = 0.113 µm), using conventional cutting tools.

Modelo matemático para la predicción del esfuerzo de corte en el mecanizado a alta velocidad

This paper presents cutting force-based models able to describe a high speed machining process. The model considers the cutting force as output variable, essential for the physical processes that are taking place in high speed machining. Moreover, this paper shows the mathematical development to derive the integral-differential equations, and the algorithms implemented in MATLAB to predict the cutting force in real time. MATLAB is a software tool for doing numerical computations with matrices and vectors. It can also display information graphically and includes many toolboxes for several research and applications areas. Two end mill shapes are considered (i.e., cylindrical and ball end mill) for real-time implementation of the developed algorithms. The developed models are validated in slot milling operations. The results corroborate the importance of the cutting force variable for predicting tool wear in high speed machining operations. The developed models are the starting point for future work related with vibration analysis, process stability and dimensional surface finish in high speed machining processes.

The Importance of Including Size Effect When Modeling Slot Milling

This paper presents a detailed mechanistic force analysis that includes size effect for slot milling operations. Existing studies of the milling process have modeled the slot end milling operation as a simple geometric extension of peripheral end milling models with constant values for the specific energies used to predict forces for a given cutter geometry and cutting conditions. This paper addresses the limitations of this approach for accurate predictions of the instantaneous cutting force variation, particularly for steady-state slotting with four-flute cutters. It is shown through a comparison of model simulations and experimental results that significantly improved predictions of the cutting force variation are obtained by properly accounting for the size effect in slotting. The dependence of the cutting force variation on axial depth of cut and helix angle is demonstrated. Practical implications of selecting helix angle and axial depth of cut based on the improved slot end milling model are also discussed. Modeling approaches other than the mechanistic approach considered here are also noted in this light.

Frequency versus time domain parameter estimation: Application to a slot milling operation

The time domain recursive least squares estimation of parameters in the presence of additive output noise of harmonic form leads to biased estimates. However, frequency domain least squares parameter estimation, where the frequency range contaminated by the noise is eliminated, can be used to obtain good parameter estimates. Both the time domain and frequency domain methods are described, and applied to the example of a slot milling operation. A model of the resultant force response to feedrate changes in slot milling, based on previously reported experimental studies, is presented. The force measurement is corrupted by harmonic noise arising from runout on the milling cutter. Simulation studies are performed, using a flat band width multi-frequency test signal to persistently excite the system. The time domain approach leads to poor estimates as expected, while the frequency domain approach gives good parameter estimates. The advantages and disadvantages of both methods are discussed.

Machining Performance of High-Rate Face-Milling Cutters with SWC Application

Summary To develop milling tools for high-rate machining of steels, prototype cutters with a special double-rake edge design using the SWC(Silver White Chip) cutting principle have been evaluated in milling tests of the low carbon steel SS41 generally used for weldments and the SCM440 chromium-molybdenum steel. Three kinds of indexable-type prototype cutters with ISO M2 grade inserts have been tested: they are, so-called “type-U” face-milling cutter intended for rough machining of The low carbon steel, “type-S” face-milling, cutter for medium carbon steels and alloy steels, and “type-SL” cutter for slot milling operation. Test results show that when proper cutting conditions are selected so as to form the built-up edge on the primary rake face, the cutting edge is free from the fragile chipping, and therefore the high-rate milling is possible. A double-rake edge of the prototype cutters is operated normally and attainstool life from 2000 to 10,000 cuts per edge at the metal removal rate several times greater than that of a convertional cutter edge. Machining power required by the SWC cutters is reduced by 20 to 38 to that by the conventional cutter. It will be possible to design cutters for practical use based on those test results.

ＳＷＣ切削法の応用による高能率フライスカッタの切削性能

To develop milling tools for high-rate machining of steels, prototype cutters with a special double-rake edge design using the SWC (Silver White Chip) cutting principle have been evaluated in milling tests of the low carbon steel SS 41 generally used for weldments and the SCM 440 chromium-molybdenum steel. Three kinds of indexabletype prototype cutters with ISO M 2 grade inserts have been tested: they are, so-called “type-U” facemilling cutter intended for rough machining of the low carbon steel, “type-S” face-milling cutter for medium carbon steels and alloy steels, and “typeSL” cutter for slot milling operation. Test results show that when proper cutting conditions are selected so as to form the built-up edge on the primary rake face, the cutting edge is free from the fragile chipping, and therefore the high-rate milling is possible. A double-rake edge of the prototype cutters is operated normally and attain tool life from 2 000 to 10 000 cuts per edge at the metal removal rate several times greater than that of a conventional cutter edge. Machining power required by the SWC cutters is reduced by 20 to 38% to that by the conventional cutter. It will be possible to design cutters for practical use based on those test results.