Milling Of H13 Steel Research Articles

Wear and breakage of coated carbide tool in milling of H13 steel and SKD11 hardened steel

In the present paper, the wear and breakage mechanisms of coated carbide tools are investigated in milling of H13 steel (HRC 30–35) and SKD11 hardened steel (HRC 58–62). The experiment results indicate that the hardness of workpiece has a dominant effect on tool failure patterns. Due to the low hardness of H13 steel, low-stress-repeated impact load on the tool induces the generation of cracks, but not enough to cause tool fracture. Thus, tool failure pattern is flank wear in milling of H13 steel. In contrast, the high-stress-repeated impact load facilitates the initiation and propagation of cracks and ultimately leads to breakage of rake face when milling SKD11 hardened steel. The geometry model of tool wear and breakage is established to explore the variation of tool angle. It is found that the flank wear reduces the clearance angle, while the breakage of rake face decreases the rake angle. In addition, the effect of tool wear and breakage on the cutting forces and chip formation is studied. The flank wear increases the friction coefficient between tool and H13 steel, and the breakage of rake face increases chip deformation and reduces the sharpness of cutting edge, both of which result in the increase in cutting forces. Furthermore, the wave-shaped chips are formed throughout milling of H13 steel, while the breakage of rake face results in the curling and separation of sawtooth chips when milling SKD11 hardened steel.

Investigation on plastic deformation behaviors in hard milling of H13 steel

Plastic deformation layer, as the topmost layer of machined surface, has a significant impact on the surface integrity. This research focuses on the plastic deformation behaviors in milling surface. First, the thermal model of machined surface and the classical infinitesimal milling force in hard milling process are developed, which were verified by a series of experiments. Secondly, the microstructure of plastic deformation layer is observed by a hard milling experiment and the scanning electronic microscopy analysis. Thirdly, based on the force model and thermal model, the reason that resulted in the nonuniformity of plastic deformation is analyzed by considering the mechanism of plastic deformation. Finally, the effect of cutting parameters on the thickness of plastic deformation is investigated; the results indicate that the more uniform plastic deformation can be obtained by employing the higher cutting speed and smaller feed rate in milling process. This research reveals the variation of plastic deformation layer, it is also helpful to optimize the cutting parameters so as to obtain the desired surface integrity.

Heterogeneous data-driven hybrid machine learning for tool condition prognosis

Cutting tool condition prognosis is critical to process stability and quality assurance, but affected by complex material-process interactions. This paper presents a hybrid machine learning method that integrates heterogeneous data (structured process parameters and unstructured power profiles and tool wear images) for tool condition prognosis. Surface and wear images are first analyzed by a convolutional neural network to identify surface roughness and wear severity. The results are subsequently fed into a recurrent neural network to reveal the relationship between tool condition degradation and power profiles. The fidelity of the method is validated in milling of H13 steel and Inconel 718.

An Experimental Investigation of Cutting Forces in Hard Milling of H13 Steel under Different Cooling/Lubrication Conditions

In the present research, an attempt has been made to experimentally investigate the cutting forces in hard milling of H13 steel with coated carbide tools under dry, MQL (minimum quantity lubrication) and MQCL (minimum quantity cooling lubrication) cutting conditions. Based on Taguchis method, four-factor (cutting speed, feed per tooth, radial depth of cut, and axial depth of cut) four-level orthogonal experiments were employed. It is found that the periodical fluctuation of the cutting forces caused by the variation of the undeformed chip thickness with the entry/exit of the cutting edge is an essential feature of the hard milling process. The empirical models for cutting forces are established, and ANOVA (analysis of variance) indicates that the quadratic models can well express the relationship between cutting forces and cutting parameters.

The stress distribution and thermal behavior of TiBN and TiBN/TiN coatings in milling AISI H13 work tool steel

The FEM model of TiBN and TiBN/TiN coated cutting tool in milling of H13 steel was developed. Process variables such as temperature and stress in the coating layer as well as in the substrate were analyzed. The efficacy of the present FEM analysis was verified by conducting controlled milling experiments on AISI H13 to collect the relevant tool life and force data. The results show that the stress in a coated tool can significantly be reduced compared to uncoated cutting tool, possibly due to surface coatings improving the tribological properties of cutting tools. Coating with good thermal properties also help to improve the thermal behavior of cutting tool.