Cutter Materials Research Articles

Investigation of the cooling effect of heat pipe-embedded cutter in dry machining with different thermal conductivities of cutter/workpiece materials and different cutting parameters

Traditional cooling methods used to irrigate coolants are not environment friendly and economical. An innovative idea, which is environment friendly, is to integrate a transcalent device without outer driving-heat pipe, into the structure of cutter. Cutting parameters directly affect removing material efficiency and shape of the cutting chip, which affects flow of cutting heat. Thermal conductivities of cutting tool and workpiece affect heat transmission and distribution across the machining system. In this paper, cutting experiments and finite element simulations were carried out to explore the impact of workpiece and cutter materials and three cutting parameters on the cooling effect of heat pipe-embedded cutter. Cooling effect of the heat pipe embedded into cutter was significantly higher than the ordinary cutter. About 40 % of the heat flowing into the cutter was transferred by the heat pipe; temperature at the measurement point of rake face decreases by about 50 ∘C; highest temperature of cutter decreased by about 200 ∘C. Cooling effect of the embedded heat pipe was affected by the materials of workpiece and cutter, and cutting parameters as well. The heat pipe transfers heat more efficiently when there is a large heat flux causing a more efficient decrease in the temperature of tool bit when difficult-to-cut metal was machined. Compared to other cutting parameters, cutting speed has a dominant effect on the cooling of the heat pipe.

The Current Status and Future Directions of Cutting Tool Materials

This paper introduces the performance and application of various cutter materials including high-speed steel, cemented carbide, ceramic and super-hard material. The current status and prospect in the tool materials are discussed.

Laboratory Simulation of Drill Bit Dynamics Using a Model-Based Servohydraulic Controller

Drilling costs are significantly influenced by bit performance when drilling in offshore formations. Retrieving and replacing damaged downhole tools is an extraordinarily expensive and time-intensive process, easily costing several hundred thousand dollars of offshore rig time plus the cost of damaged components. Dynamic behavior of the drill string can be particularly problematic when drilling high strength rock, where the risk of bit failure increases dramatically. Many of these dysfunctions arise due to the interaction between the forces developed at the bit-rock interface and the modes of vibration of the drill string. Although existing testing facilities are adequate for characterizing bit performance in various formations and operating conditions, they lack the necessary drill string attributes to characterize the interaction between the bit and the bottom hole assembly (BHA). A facility that includes drill string compliance and yet allows real-rock/bit interaction would provide an advanced practical understanding of the influence of drill string dynamics on bit life and performance. Such a facility can be used to develop new bit designs and cutter materials, qualify downhole component reliability, and thus mitigate the harmful effects of vibration. It can also serve as a platform for investigating process-related parameters, which influence drilling performance and bit-induced vibration to develop improved practices for drilling operators. The development of an advanced laboratory simulation capability is being pursued to allow the dynamic properties of a BHA to be reproduced in the laboratory. This simulated BHA is used to support an actual drill bit while conducting drilling tests in representative rocks in the laboratory. The advanced system can be used to model the response of more complex representations of a drill string with multiple modes of vibration. Application of the system to field drilling data is also addressed.

Experiment and Analysis on Near-Dry Cutting System in Titanium Alloy Deep-Hole Drilling

This paper depicts a boring and trepanning association (BTA) deep-hole drilling system with near-dry cutting technique. The cutting tests are carried out in view of the machining performances under the condition of applying the compressed air and atomized cutting fluid for drilling deep holes on titanium alloy which is difficult to cut. Several cutter materials have been utilized in the tests. The reasonable material of the deep-hole drilling cutter has been determined by analyzing the cutting force, the cutter wear and the surface finish. Environmental pollution decreases owing to little cutting fluid consumption in near-dry cutting system.

Extracting cutting constants via harmonic force components for a general helical end mill

Mechanistic cutting constants serve well in predicting milling forces, monitoring the milling process as well as in helping to understand the mechanistic phenomena of a machining process for a unique pair of workpiece and cutter materials under various types of cutting edge geometry. This paper presents a unified approach in identifying the six shearing and ploughing cutting constants for a general helical end mill from the dynamic components of the measured milling forces in a single cutting test. The identification model is first presented assuming the milling force is measured with a known phase angle of the cutter spindle. When the phase angle of the cutter rotation is not available, as is the case for most milling machines, it is shown that the true phase angle can be identified through the theoretical phase relationship between the different harmonic components of the milling forces measured with an arbitrary phase angle. The numerical simulation and the experimental results for ball and cylindrical end mills are presented to demonstrate and validate the identification methods.

Drilling process optimization for graphite/bismaleimide–titanium alloy stacks

In this study, the drilling process of graphite/bismaleimide-titanium alloy (Gr/Bi–Ti) stacks was optimized in terms of machined hole quality and machining cost. The drilling experiments were conducted by using two different cutter materials, HSS-Co and carbide. Drilled hole quality parameters include surface texture, titanium burrs, hole diameter, cylindricity, and roundness deviation. Machining cost was estimated through drill wear experimentations. A multiple objective linear program was used to optimize drilling feed and speed not only to maximize each hole quality parameter to the greatest extent possible but also to minimize machining cost. Optimum process conditions for achieving desired hole quality and process cost were found to be a combination of low feed and low speed when using carbide drills, and high feed and low speed in drilling with HSS-Co drills. The sensitivity of weighting factors on the feasible process conditions depends on the optimal point position and distribution of each objective.

A study on the drilling of composite and titanium stacks

An experimental study on drilling of graphite/bismaleimide (Gr/Bi) titanium (Ti) stacks was conducted by using different cutter materials with a standard geometry to understand and characterize the process. The tool materials used were high-speed steel (HSS), high-speed cobalt (HSS-Co), and carbide. It was observed that at the interface of Gr/Bi–Ti, high temperatures induced material damage near and around the hole region. Dissimilar mechanical and thermal properties affected the tool life and allowed for increased matrix degradation and burr formation in Ti, regardless of the cutting tool material. As a result, fewer holes were produced when high spindle speeds and slow feeds were used. It was also found that carbide drills outperformed all other tools in terms of tool life, minimal surface damage, and heat induced damage on both workpiece materials.

Drilling of Graphite/Bismaleimide Composite Material

Drilling study of graphite/bismaleimide composite material was conducted by using different cutter materials (high-speed steel, carbide, and polycrystalline diamond) and drill geometries. It was found that polycrystalline diamond tools outperformed all other tools in terms of minimal surface damage, delamination, and fiber pullout. The drilling forces exerted in machining graphite/bismaleimide were recorded by using a dynamometer, and the morphology of drilled surfaces was evaluated with surface profilometry and optical and scanning electron microscopy. The drilling characteristics were evaluated in terms of cutting forces, tool wear, and surface morphology.

High Technology Options for Sheep Shearing: Improved Shearing Devices

Wool production is a very important factor in the Australian economy, representing $3 billion in exports. Nevertheless, rising production costs and growing competition from manmade fibres necessitate increased attention to all aspects of productivity if the industry worldwide is to remain viable. As some 80 per cent of labour content is involved in harvesting wool, improvements in the shearing process potentially offer particular opportunities for economies. This article reviews the results of a widely based Australian research programme which has investigated the fundamental physics of wool severance, especially in terms of energy requirement, leading to improved design of shearing devices incorporating more efficient motors and novel cutter materials. Subsequent articles will review the process of automated mechanical shearing and chemical and biological defleecing.