Mechanical milling as a technology to produce structural and functional bio-nanocomposites

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

Bone cutting is an important procedure in most surgery operations; therefore, understanding the mechanism by which the chip forms is important to design tools for optimising the surgery process. However, only very few studies to address this issue exist. In this paper, a transition from shear cutting, shear-crack cutting and fracture cutting modes with the increase of uncut chip thickness in orthogonal bone cutting was presented. To address these phenomena, a fracture mechanics based cutting model was proposed for the chip formation and cutting process. The influence of the anisotropy of bone to the orthogonal cutting was studied in reference to chip formation and thus, considered in the model to explain the chip morphologies in different cutting directions relative to the bone fibres (i.e. osteon). The experimental result shows to be consistent well with the proposed model yielding a maximum error of predicted transition uncut chip thickness of 10%. On the other hand, analysis of surface morphology revealed that significant differences exist in material damage mode related to the cutting mode and direction. Moreover, the proposed bone orthogonal cutting mechanism was also validated by the cutting force analysis from both static and dynamic components points of view. Based on this study, a maximum uncut chip thickness in a unique anisotropic material as bone to guide the selection of more advanced cutting process (e.g. drilling, milling and sawing) was proposed.

On chip formation mechanism in orthogonal cutting of bone

The influence of anisotropy in numerical modeling of orthogonal cutting of cortical bone

Mechanistic modeling of bone-drilling process with experimental validation

Excessive drilling forces can result in drill breakage, bone breakthrough, and thermal necrosis during bone drilling process. However, the effect of drilling process parameters, drill geometry parameters, and bone material type on drilling forces have not been fully investigated. Three designs of experiments are introduced separately to study single factor's effect on drilling forces, identify significant geometry parameters and possible interactions for drilling forces, and formulate direct relationship between drilling forces and process parameters. The results show that thrust force and torque are increased with feed rate, drill diameter or web thickness. The effect of spindle speed, point angle, helix angle, and chisel edge angle on drilling forces is complex. The results also show that the drilling forces are affected by bone type significantly, which are highest for bovine cortical bone, and lowest for Sawbones 3401. The levels of significance of geometry parameters are identified and different for thrust force and torque, which can assist new surgical drill development. Quadratic regression equations obtained by response surface methodology can predict thrust force and torque accurately in a wide range of process parameters, which can be used to control drilling conditions for robot assisted surgeries to realize safe drilling.

Experimental Study of Thrust Force and Torque for Drilling Cortical Bone.

Multi-grooved cutting tool to reduce cutting force and temperature during bone machining

In orthopedic operations, no sound solutions exist to avoid conditions like tool breakage, bone fracture/cracks and thermal necrosis for lacking understanding of the mechanics of the bone cutting process. In this work, analysis of variance (ANOVA) and regression analysis were performed to investigate effects of cutting conditions on cutting and thrust forces based on a full factorial design. Then applicability of Merchant's analysis for calculating cutting force with respect to rake angle and feed was evaluated by comparison with experiments. Finally, the friction coefficient was evaluated by calculation. ANOVA shows that forces are much more sensitive to feed, cutting direction and rake angle than to cutting speed. Regression equations including all four factors were obtained by introduction of dummy variables. Cutting forces from experiments and from Merchant's analysis are partially comparable (maximum relative error = 34%) when feed and rake angle are changed. Friction coefficient was affected by rake...

Jianbo Sui

Papers

Mechanistic modeling of bone-drilling process with experimental validation

Experimental Study of Thrust Force and Torque for Drilling Cortical Bone.

Multi-grooved cutting tool to reduce cutting force and temperature during bone machining

Force analysis of orthogonal cutting of bovine cortical bone

Relationship of microstructure, mechanical properties and hardened steel cutting performance of TiSiN-based nanocomposite coated tool