With regard to the manufacturing of innovative hard-machining super alloys (i.e., Inconel-800), a potential alternative for improving the process is using a novel cutting fluid approach. Generally, ...the cutting fluids allow the maintenance of a better tool topography that can generate a superior surface quality of machined material. However, the chemical components of fluids involved in that process may produce harmful effects on human health and can trigger environmental concerns. By decreasing the cutting fluids amount while using sustainable methods (i.e., dry), Near Dry Machining (NDM) will be possible in order to resolve these problems. This paper discusses the features of two innovative techniques for machining an Inconel-800 superalloy by plain turning while considering some critical parameters such as the cutting force, surface characteristics (
), the tool wear rate, and chip morphology. The research findings highlight the near-dry machining process robustness over the dry machining routine while its great potential to resolve the heat transfer concerns in this manufacturing method was demonstrated. The results confirm other benefits of these methods (i.e., NDM) linked to the sustainability aspects in terms of the clean process, friendly environment, and permits as well as in terms of improving the manufacturing characteristics.
A brazed chip breaker capable of controlling the chip curling and flow is proposed on the rake face of a polycrystalline diamond (PCD) tool to obtain ideal chip shape of aluminum alloy materials. Two ...new position parameters, the breaker-point distance and the rotation angle of chip breaker, are proposed for positioning the chip breaker on the rake face of PCD turning tool. Influences of two position parameters of the chip breaker on the chip curling and chip flow direction are studied through finite element simulations and cutting experiments. The appropriate breaker-point distance can improve the up-curling and back-flow of the chip, and control the chips flow to the tool flank face to form a C-shaped chip. After setting the appropriate breaker-point distance, increasing the rotation angle of chip breaker can promote the trend of side-curling and side-flow of the chip, which is beneficial to the formation of short helical chip. Based on the chip-breaking criterion and the geometric relationship between the chip breaker and tool rake face, the equations of two position parameters of chip breaker are established, and effective chip breaking can be achieved within the reasonable range of chip breaker position parameters calculated by the established equations. The proposed chip breaker which position parameters are convenient to measure and install can be brazed on turning and drilling tools to obtain needed chip shape of aluminum alloy materials.
•Proposed two position parameters of chip breaker for PCD turning tools.•Derived a set of equations to determine the effective range of the two position parameters.•Analyzed the influence of the position parameters on the chip curl, chip flow direction and chip shape.
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•Motion conditions for chip breaking of the LFV proposed as a new vibration cutting method was geometrically derived.•The LFV is not constrained in processing shape unlike ...conventional vibration cutting.•The specific cutting force of LFV when the cutting force was decreased compared with that of conventional cutting at the same feed rate.•Experiments show the effectiveness of LFV for difficult-to-cut materials such as stainless steel, which tends to generate long chips.
In turning process, long continuous chips are often generated and become entangled in both the tool and the machine. It can cause scratches on the product surface, adversely affect the tool life, or cause the machine to stop. To solve the problems in the turning process caused by long continuous chips, Low frequency vibration-cutting (LFV) was developed. LFV applies the vibration in the tool feed direction and can synchronously control the vibration in the tool feed direction and the spindle rotation. The vibration is composed of a combination of the two vibration axes, the X axis and the Z axis, of the lathe. Therefore, unlike in conventional vibration cutting, LFV has a big advantage in that it can be applied to all shapes processed with a lathe such as a taper or an arc. In this paper, we proposed a motion conditions formula for breaking chips using the operating parameters of LFV, and carried out cutting experiments on SS304 stainless steel using LFV and conventional cutting. As a result, it was found that LFV can discharge chips of a shape corresponding to the motion conditions. The cutting force of LFV drew a trapezoidal shape, and it was confirmed that periods during which the cutting force became zero periodically appeared. It was revealed that the specific cutting force of LFV when the cutting force becomes maximum was decreased compared with that of conventional cutting at the same feed rate. These results indicated that LFV can be useful for difficult-to-cut materials such as SS304.
High-pressure cutting fluid supply is a proven technology for chip breaking when turning difficult-to-cut materials, such as Inconel 718. However, the technology is usually not suitable for the ...finish turning of safety-critical parts in aero engines. The acting force of the cutting fluid jet on the back of the chip causes chip breaking. The broken chips are then accelerated by the cutting fluid jet towards the workpiece surfaces where they cause damage on impact. One approach to minimize surface damage is a specific increase in the chip length. The center of gravity of the chips with an adjusted length is shifted out of the focus where the cutting fluid jet hits the chips. Hence, the already finished surface is subjected to fewer impacts of the chips. In this study, the adjustment of the chip length by pulsating high-pressure cutting fluid supply to prevent surface damage was investigated. A valve unit was used to generate two alternating cutting fluid supply pressure levels in certain time intervals. During the low-pressure stage, the force of the cutting fluid jet does not lead to chip breakage and the chip length increases until the valves switch and the high-pressure stage is released. The focus of this work was the analysis of the relationship between the duration of the low-pressure and high-pressure time intervals and the chip length. Additionally, the influence of the depth of cut, the feed, and the cutting speed on the chip length during pulsating high-pressure cutting fluid supply was investigated. Finally, a case study was carried out to evaluate the effectiveness of the pulsating high-pressure cutting fluid supply technology. Therefore, the shoulder surface of a demonstrator part was finished by face turning. Following, the cylindrical surface was finished with a continuous and pulsating high-pressure cutting fluid supply with varied supply parameters. Microscopic analyses of the surface prove that the pulsating high-pressure cutting fluid supply prevents the surface from being damaged by the impacts of chips.
Zebra Chip disease vectored by the potato psyllid
Bactericera cockerelli
(Šulc) was first reported in Idaho and the Columbia Basin of Oregon and Washington in 2011. Since then growers have incurred ...significant costs for managing the disease. Thus, we conducted an expert opinion survey to estimate expenditure on insecticides dedicated to controlling potato psyllids in the largest potato producing regions of Idaho, Oregon, and Washington. Results highlight a total of about 9 million US dollars spent on active ingredients targeted at psyllid control. When application costs are added to the cost of insecticides, expenditures total about 11 million US dollars.
In this study, control research of chip morphology and removal is conducted theoretically and experimentally on the basis of the low-frequency vibration-assisted drilling process of titanium alloy. ...The chip morphology prediction model is established on the basis of the modified kinematic model, in which the shear angle variation, critical cutting thickness, and stiffness of a vibration generator system are considered. In terms of chip removal monitoring, a new monitoring method based on high speed camera is proposed in this paper. And the reliability of the new method is verified by comparing the signals obtained by the power sensor and the force sensor. An empirical prediction model for chip removal is also established on the basis of the modified kinematical model, the chip morphology prediction model, and the force balance analysis of fragmental chips. Validation experiments show that the mean error of chip radian, which can reflect the difference between the predicted chip morphology and the experimental one, is 6%. The mean error of the predicted chip removal index compared with the experimental one is 10.4%. The results obtained show that chip removal can be controlled effectively by low rotation speed, small chip radian, light chip weight, high minimum quantity lubrication cooling pressure, and high oscillation frequency. On the basis of the prediction model of chip removal, the effects of drilling parameters on chip removal behavior are analyzed, and the optimal drilling parameter combination with highest processing efficiency is given.
There are several methods of monitoring metal cutting processes. In this study, the combination of various methods in order to define an overall “cutting state” of a turning process is discussed ...along with an application to use these methods for adaptive fuzzy feed rate and cutting speed optimising control. For this purpose, different methods of monitoring individual cutting phenomena such as chip length and vibration level are aggregated and the combination of this information is considered to be the cutting state of the process. Expert data has been collected from a series of experiments concerning the apparent state of these phenomena as well as required control action. An adaptive optimizing fuzzy controller has been designed based on the concept of the cutting state and collected expert rules. The automatically classified cutting state as well as the control action based on this state is compared to expert data. There are notable differences which are analysed and solutions and further research are suggested based on the points requiring further improvement.
In the modelling approach of bar turning, the accurate prediction of the Chip Flow Direction represents a real challenge; it directly affects the axial and radial components of the cutting forces, ...and consequently the temperature distribution in the rake face. Chip flow direction is one aspect of chip control which is an important key factor in turning operations optimization. The aim of the present work is to propose an analytical approach of modelling to determine the chip flow direction in bar turning. Experimental tests and results complete the study and validate the proposed model.
Mechanics of Chip-Guiding Cutting with Grooved Tools AOKI, Tomoya; SENCER, Burak; SUZUKI, Norikazu ...
Journal of the Japan Society for Precision Engineering,
2016/01/05, Letnik:
82, Številka:
1
Journal Article
Odprti dostop
The mechanics of “chip-guiding cutting” with grooved tools are investigated in the present study. The chip-guiding cutting has been proposed by the authors to realize continuous chip disposal. It has ...been clarified in the previous study that chips can be guided successfully into desired directions with the grooved round-nose tools, but the mechanics of the new cutting process with the guide grooves has not been clarified. Fundamental chip-guiding cutting experiments are carried out with grooved straight-edge tools in this study. An analytical model for the chip-guiding cutting process is developed. Effects of the chip-guiding on the process parameters such as cutting forces are investigated accurately by the proposed model and validated by cutting experiment. Both experimental and analytical results unveil that chip flow direction can be controlled by chip-guiding forces generated by the side-walls of the groove structure engraved on the rake face. It is shown that as the chip flow direction can be altered to the various guide directions from the original one, and the proposed model predicts that as the guiding force increases, shear angle decreases and thus resultant cutting force is increased only slightly. Therefore, when the guide direction is not dramatically different from the original chip flow direction, the resultant cutting force is not increased significantly, which make the process favorable. These results support the fact that proposed model captures the critical cutting mechanics accurately.
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