Machining of SiC ceramic matrix composites: A review

Abstract Fiber-reinforced composites have become the preferred material in the fields of aviation and aerospace because of their high-strength performance in unit weight. The composite components are manufactured by near net-shape and only require finishing operations to achieve final dimensional and assembly tolerances. Milling and grinding arise as the preferred choices because of their precision processing. Nevertheless, given their laminated, anisotropic, and heterogeneous nature, these materials are considered difficult-to-machine. As undesirable results and challenging breakthroughs, the surface damage and integrity of these materials is a research hotspot with important engineering significance. This review summarizes an up-to-date progress of the damage formation mechanisms and suppression strategies in milling and grinding for the fiber-reinforced composites reported in the literature. First, the formation mechanisms of milling damage, including delamination, burr, and tear, are analyzed. Second, the grinding mechanisms, covering material removal mechanism, thermal mechanical behavior, surface integrity, and damage, are discussed. Third, suppression strategies are reviewed systematically from the aspects of advanced cutting tools and technologies, including ultrasonic vibration-assisted machining, cryogenic cooling, minimum quantity lubrication (MQL), and tool optimization design. Ultrasonic vibration shows the greatest advantage of restraining machining force, which can be reduced by approximately 60% compared with conventional machining. Cryogenic cooling is the most effective method to reduce temperature with a maximum reduction of approximately 60%. MQL shows its advantages in terms of reducing friction coefficient, force, temperature, and tool wear. Finally, research gaps and future exploration directions are prospected, giving researchers opportunity to deepen specific aspects and explore new area for achieving high precision surface machining of fiber-reinforced composites. 

https://link.springer.com/content/pdf/10.1007/s11465-022-0680-8.pdf

Fiber-reinforced composites in milling and grinding: machining bottlenecks and advanced strategies

/pdf/fiber-reinforced-composites-in-milling-and-grinding-fhcdm1c7.pdf

Modelling and grinding characteristics of unidirectional C–SiCs

Environmentally friendly grinding of C/SiCs using carbon nanofluid minimum quantity lubrication technology

C/SiC has excellent mechanical properties and is extensively utilized in the aerospace field. Meanwhile, it is a typical intractable material in virtue of its special intrinsic structure. To investigate the grinding force and material removal mechanism of fiber reinforced CMC, a unidirectional C/SiC composite material was designed and prepared. A series of particular surface grinding experiments were carried out, and then the grinding force model was established based on multiple-exponential function method. Furthermore, the surface morphology and grinding mechanism of the composites were analyzed. The results show that the grinding parameters (wheel speed, grinding depth, feed speed) have a significant impact on the grinding force, and the order of grinding force is as follows: Normal>Longitudinal>Transverse. The R2 (Goodness of fit) values of the grinding force model are all above 0.9, which demonstrates the models can reliably predict the grinding force of the unidirectional C/SiC composite grinding. Besides, the dominant removal mechanism of C/SiC composites is the brittle fracture, and its failure modes are the combination of matrix cracking, fiber breakage and interface debonding. Then, the factors affecting the grinding force in surface grinding of the composite are revealed. The research results can provide theoretical support for improving grinding efficiency and precision machining of composites.

Influence Factors on Grinding Force in Surface Grinding of Unidirectional C/SiC Composites

Three-dimensional Hashin failure criterion and material stiffness degradation model were compiled by VUMAT subroutine. The Abaqus/Explicit solver was performed to establish progressive damage model of cutting force for CFRP high-speed milling, and high-speed milling experiments with different cutting parameters were carried out. Further, the impact mechanism of fiber cutting angle and cutting parameters on cutting force, stress, and material failure during milling was explored, and the material removal mechanism in high-speed milling of CFRP was revealed. The results show that the error between the experimental and simulated of cutting forces is less than 5%, which indicates that the progressive damage model is feasible. The fiber cutting angle has significant influence on cutting force and stress in cutting process, and the cutting direction has a significant influence on cutting force. In addition, cutting parameters play a critical role in cutting force, and the feed per tooth is the most significant factor affecting the cutting force. Simultaneously, the progressive damage model predicts that the shear failure of materials mainly concentrates in the cutting area and extends along the feed direction. Finally, the material removal mechanism of CFRP in high-speed milling was revealed combining cutting force experiment.

High-speed milling of CFRP composites: a progressive damage model of cutting force

After the damaged blade is repaired by laser cladding, the quality of the recontouring by milling determines its working performance in reservice. Ti-6Al-4V, titanium alloy, commonly used as the ma...

MILLING FORCE AND SURFACE TOPOGRAPHY OF Ti-6Al-4V TITANIUM ALLOY CLADDED BY THE LASER

Deep-holes are typical parts of aircraft structures, which is difficult to be machined. Boring assisted with ultrasonic vibration-assisted cutting has been proved to greatly enhance machining performance, especially for Ti6Al4V aviation alloy. This paper focuses on the machining extra-large aspect ratio (exceeding 20) of Ti6Al4V aviation deep-hole with the axial ultrasonic vibration-assisted boring (AUVB) method. First, the kinetics of the AUVB process is analyzed and a retrospective of its separation cutting feature is provided. Subsequently, a multi-stepped cantilever beam model of boring bar is established to analyze its static rigidity and dynamic stability. The aperture error is deduced, and then size coefficient is put forward to represent the static rigidity of the boring bar, which is inversely proportional to the diameter. In addition, two different vibration cases, namely modal-coupling vibration and regenerative vibration are considered for dynamic stability analysis. Next, the morphology of bored surface is analyzed, and the geometric height of peaks formed by AUVB and CB are calculated. Phase shift φ= π is suggested for obtaining a better surface in AUVB. Finally, the feasibility of AUVB on the machining of extra-large aspect ratio Ti6Al4V titanium alloy aviation deep-hole is verified through systematic experiments. Results demonstrate that AUVB has obvious advantages in reducing boring force, improving boring accuracy, suppressing vibration and promoting surface quality. Furthermore, the aperture error decreases to 50% and vibration amplitudes decrease to only 20–25%. The overall surface roughness of the deep-hole part stays below Ra=0.8μm with rotational speeds of 60r/min and 80r/min, and the surface residual stress state is transferred from the tensile state to a compressive one. As a result, not only AUVB can provide better boring accuracy and surface finish, but it also can enhance the surface fatigue properties.

Feasibility study on machining extra-large aspect ratio aviation deep-hole Ti6Al4V part with axial ultrasonic vibration-assisted boring

The invention relates to a self-adaptive positioning method for aero-engine blade repair. The method comprises the following steps: establishing a speckle vision measurement system; point cloud coordinates of all parts of the blade are obtained through non-contact measurement; The self-adaptive positioning method for the aero-engine blade under under-positioning clamping comprises the steps of calculating coordinates of a mark point and a center point of a measuring head, splicing integral point cloud data of the blade based on the mark point, calculating the pose relation of all positioning coordinate systems, modeling in a CAM system and generating a repair path and a to-be-machined program, so that the self-adaptive positioning method for the aero-engine blade under-positioning clampingis realized. The self-adaptive positioning of the engine blade to be repaired in the five-axis machining center can be effectively achieved, the repairing machining efficiency and precision of the blade for different shapes are improved, the maintenance cost is reduced, and the self-adaptive positioning method has wide application prospects.

Lifeng Zhang

Papers

Influence Factors on Grinding Force in Surface Grinding of Unidirectional C/SiC Composites

High-speed milling of CFRP composites: a progressive damage model of cutting force

MILLING FORCE AND SURFACE TOPOGRAPHY OF Ti-6Al-4V TITANIUM ALLOY CLADDED BY THE LASER

Feasibility study on machining extra-large aspect ratio aviation deep-hole Ti6Al4V part with axial ultrasonic vibration-assisted boring

A self-adaptive positioning method for aero-engine blade repair