Free Machining Steel—IV: Tools With Reduced Contact Length

1962 ◽  
Vol 84 (1) ◽  
pp. 89-98 ◽  
Author(s):  
E. Usui ◽  
M. C. Shaw
Keyword(s):  
High Speed ◽  
Solid Lubricant ◽  
Cold Work ◽  
Manganese Sulfide ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Cooling Capacity ◽  
Contact Length ◽  
Cutting Fluid ◽  
Undeformed Chip Thickness

Tools which provide controlled contact on the tool face are used to study the action of free machining steels. The mean normal stress on the tool face σc is found to increase with increased undeformed chip thickness (t = feed) or with a reduction in the controlled length of tool face contact. An increase in σc in turn is found to promote the stability of the built-up edge to higher speeds. The high-speed finish produced with a cut-away tool is thus found to be inferior to that produced with a conventional tool. Manganese sulfide is found to have a similar effect on surface finish, but lead tends to improve the finish obtained at a high cutting speed. The cut-away tool provides improved low-speed finish in all cases as does the addition of either manganese sulfide or lead to the steel. Manganese sulfide is found to become more effective with increased undeformed chip thickness t, while lead behaves in the opposite manner. This observation along with several others is in agreement with the idea that manganese sulfide is a poor solid “lubricant,” while lead is an effective solid lubricant. An optimum chip-tool contact length appears to exist at which the tool life will be a maximum at any combination of cutting speed and feed. From this it follows that an optimum combination of sulfur or lead content, degree of cold work, cooling capacity of cutting fluid, or extent of tool-face limitation exists, since all of these quantities influence the resultant length of contact between chip and tool.

Free Machining Steel: I—Tool-Life Characteristics of Resulfurized Steel

1961 ◽  
Vol 83 (2) ◽  
pp. 163-172 ◽  
Author(s):  
M. C. Shaw ◽  
N. H. Cook ◽  
P. A. Smith
Keyword(s):  
Sulfur Content ◽  
Tool Life ◽  
High Speed ◽  
Cold Work ◽  
Manganese Sulfide ◽  
Cutting Speed ◽  
High Speed Steel ◽  
Cutting Fluid ◽  
Low Sulfur Content ◽  
Hot Rolled

Tool-wear and tool-life characteristics of a series of five steels of different sulfur content are presented for different values of cutting speed, feed, cutting fluid, and cold work. While the presence of manganese sulfide in steel is generally found to extend tool life, certain combinations of speed and feed yield result that indicate the reverse effect. For the group of hot-rolled steels studied, sulfur was found to shorten tool life at certain cutting speeds when the feed was in the vicinity of 0.005 ipr. The hot-rolled steels of low sulfur content exhibit better tool life with high-speed steel tools than with carbide tools when the cutting speed is such as to give a tool life in the vicinity of 4 hr. A tracer device is described that is useful in exploring the nature and extent of the crater and built-up areas on the tool face.

Influence of Chip Curl on Tool-Chip Contact Length in High Speed Machining

2009 ◽  
Vol 626-627 ◽  
pp. 71-74 ◽  
Author(s):  
Xue Feng Bi ◽  
G. Sutter ◽  
Gautier List ◽  
Yong Xian Liu
Keyword(s):  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Contact Length ◽  
Radius Of Curvature ◽  
High Speed Machining ◽  
Uncut Chip Thickness ◽  
High Cutting Speed ◽  
Chip Formation Mechanism ◽  
The Relationship

The tool-chip contact length, as an important parameter controlling the geometry of tool crater wear and understanding chip formation mechanism, is widely investigated in machining. The aim of this paper is to study the influence of chip curl on tool-chip contact length by means of experimental observations with high cutting speed. The relationship between tool-chip contact length, chip radius of curvature and uncut chip thickness was investigated. Experimental results show the effect of increasing spiral chip radius on tool-chip contact length with low uncut chip thickness in high speed machining.

Free Machining Steel: II—Tool-Life Characteristics of Leaded Steel

1961 ◽  
Vol 83 (2) ◽  
pp. 175-180 ◽  
Author(s):  
M. C. Shaw ◽  
P. A. Smith ◽  
N. H. Cook
Keyword(s):  
Tool Life ◽  
High Speed ◽  
Cold Work ◽  
Cutting Speed ◽  
High Speed Steel ◽  
Cutting Fluid ◽  
Steel Tool

High-speed steel tool life results are presented and discussed for a leaded and nonleaded steel from the same heat. Variables investigated include cutting speed, feed, cutting fluid, and cold work.

Development of Cutting Tools With Micro-Textured Surface for High Speed Machining of Ti-6Al-4V

2021 ◽  
Author(s):  
Mitsuru Hasegawa ◽  
Tatsuya Sugihara
Keyword(s):  
Tool Life ◽  
High Speed ◽  
Metal Cutting ◽  
Failure Process ◽  
Cutting Tools ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Cutting Fluid ◽  
Textured Surface ◽  
Textured Surfaces

Abstract In cutting of Ti-6Al-4V alloy, the cutting speed is limited since a high cutting temperature leads to severe tool wear and short tool life, resulting in poor production efficiency. On the other hand, some recent literature has reported that various beneficial effects can be provided by forming micro-textures on the tool surface in the metal cutting process. In this study, in order to achieve high-performance machining of Ti-6Al-4V, we first investigated the mechanism of the tool failure process for a cemented carbide cutting tool in high-speed turning of Ti-6Al-4V. Based on the results, cutting tools with micro textured surfaces were developed under the consideration of a cutting fluid action. A series of experiments showed that the textured rake face successfully decreases the cutting temperature, resulting in a significant suppression of both crater wear and flank wear. In addition, the temperature zone where the texture tool is effective in terms of the tool life in the Ti-6Al-4V cutting was discussed.

A Comparison of the Simulated Dynamics of Various Models Used to Predict Undeformed Chip Thickness in High-Speed Low-Radial-Immersion Milling Processes

2013 ◽  
Author(s):  
Josiah A. Bryan ◽  
Roger C. Fales
Keyword(s):  
High Speed ◽  
Chip Thickness ◽  
Milling Process ◽  
Precision Machining ◽  
Traditional Model ◽  
Cnc Milling ◽  
Undeformed Chip Thickness ◽  
Milling Tool ◽  
Tool Damage ◽  
Low Radial Immersion

Various models have been proposed to estimate the undeformed thickness of chips produced by a CNC milling tool, in order to calculate the forces acting on the tool. The choice of model significantly affects the simulated dynamics of the tool, thereby affecting the dynamic stability of the simulated process and whether or not chatter occurs in a given cutting scenario. Simulations of the dynamics of the milling process can be used to determine the conditions at which chatter occurs, which can lead to poor surface finish and tool damage. The dynamics of a traditional model and a more detailed numerical model are simulated here with particular emphasis on the differences in their chatter bifurcation points. High-speed, low-radial-immersion milling processes are simulated because of their application in industrial high-precision machining.

Ultra High-Speed Micro-Milling of Aluminum Alloy

2015 ◽  
Author(s):  
Said Jahanmir ◽  
Michael J. Tomaszewski ◽  
Hooshang Heshmat
Keyword(s):  
Aluminum Alloy ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Micro Milling ◽  
Burr Formation ◽  
Ultra High Speed ◽  
Cut Quality ◽  
Tool Diameter ◽  
Cutting Speeds

Small precision parts with miniaturized features are increasingly used in components such as sensors, micro-medical devices, micro-fuel cells, and others. Mechanical micromachining processes, e.g., turning, drilling, milling and grinding are often used for fabrication of miniaturized components. The small micro-tools (50 μm to 500 μm diameter) used in micromachining limit the surface speeds achieved at the cutting point, unless the rotational speeds are substantially increased. Although the cutting speeds increase to 240 m/min with larger diameter tools (e.g., 500 μm) when using the highest available spindle speed of 150,000 rpm, the cutting speed with the smaller 50 μm tools is limited to 24 m/min. This low cutting speed at the tool tip is much smaller than the speeds required for efficient cutting. For example, in macro-milling of aluminum alloys the recommended speed is on the order of 60–200 m/min. The use of low cutting speeds limits the production rate, increases tool wear and tendency for burr formation, and limits the degree of dimensional tolerance and precision that can be achieved. The purpose of the present paper is to provide preliminary results that show the feasibility of ultra high-speed micro-milling of an aluminum alloy with respect to surface quality and burr formation. A new ultra high-speed spindle was used for micro-milling of an aluminum alloy with micro-end-mills ranging in diameter from 51 μm to 305 μm. Straight channels were machined to obtain an array of square patterns on the surface. High surface cutting speeds up to 340 m/min were achieved at 350,000 rpm. Inspection of the machined surfaces indicated that edge quality and burr formation tendency are related to the undeformed chip thickness, and therefore the cutting speed and feed rate. The quantity of burrs observed on the cut surfaces was generally small, and therefore, the burr types were not systematically determined. Cutting with the 305 μm tool at a cutting speed of 150 m/min produced an excellent cut quality using a chip thickness of 0.13 μm. However, the cut quality deteriorated as the chip thickness was decreased to 0.06 μm by increasing the cutting speed to 340 mm/min. This result is consistent with published data that show the dependence of bur formation on ratio of chip thickness to tool tip radius. The channel widths were also measured and the width of channels cut with the small diameter tools became larger than the tool diameter at higher speeds. The dependence of the channel widths on rotational speed and the fact that a similar variation was not observed for larger diameter tools, suggested that this phenomena is related to dynamic run-out of the tool tip, which increases the channel width at higher speeds.

Experimental Investigation of the Characteristics of Dynamic Cutting Process

1977 ◽  
Vol 99 (2) ◽  
pp. 410-418 ◽  
Author(s):  
M. M. Nigm ◽  
M. M. Sadek
Keyword(s):  
Experimental Investigation ◽  
Theoretical Model ◽  
High Speed ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Rake Angle ◽  
Experimental Results ◽  
High Speed Photography ◽  
Cutting Coefficients

The dynamic response of the shear plane and the variations of the dynamic cutting coefficients are experimentally investigated at various values of feed, cutting speed, rake angle, clearance angle, frequency, and amplitude of chip thickness modulation. Wave generating and wave removing cutting tests, in which high-speed photography is used to investigate the geometry of chip formation, are carried out. The theoretical model of dynamic cutting developed in [1] is assessed with reference to these experimental results. A comparison between this model and previous models in relation to the experimental results is also presented.

Free Machining Steel: III—Cutting Forces; Surface Finish and Chip Formation

1961 ◽  
Vol 83 (2) ◽  
pp. 181-192 ◽  
Author(s):  
M. C. Shaw ◽  
E. Usui ◽  
P. A. Smith
Keyword(s):  
Cutting Force ◽  
Surface Finish ◽  
Solid Lubricant ◽  
Manganese Sulfide ◽  
Contact Length ◽  
The Other ◽  
Common Belief ◽  
Complex Curves ◽  
Other Hand ◽  
Made In

Tests upon a variety of friction sliders reveal that, contrary to common belief, manganese sulfide is a poor solid lubricant relative to air. Lead, on the other hand, is found to be an excellent solid lubricant. An analog tool is introduced to enable surface finish studies to be made in the absence of feed marks. Cutting force results are presented for a wide variety of cutting conditions for both resulfurized and leaded steels. The built-up edge and thermal softening along the tool face lead to complex curves of cutting force versus speed. Additions of sulfur are found to promote the formation of a small built-up edge that is stable to much higher values of speed than that normally experienced with a nonresulfurized steel. Lead, on the other hand, tends to prevent built-up edge formation. Both lead and sulfur are found to produce thinner chips, promote chip curl, and to give rise to a shorter contact length between chip and tool. A discussion of the significance of the observed changes in contact length will be found in part 4 of this series.

Finite Element Modeling of Chip Formation in the Domain of Negative Rake Angle Cutting

2003 ◽  
Vol 125 (3) ◽  
pp. 324-332 ◽  
Author(s):  
Y. Ohbuchi ◽  
T. Obikawa
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Rake Angle ◽  
Undeformed Chip Thickness ◽  
Element Modeling ◽  
Single Grain ◽  
Serrated Chips

A thermo-elastic-plastic finite element modeling of orthogonal cutting with a large negative rake angle has been developed to understand the mechanism and thermal aspects of grinding. A stagnant chip material ahead of the tool tip, which is always observed with large negative rake angles, is assumed to act like a stable built-up edge. Serrated chips, one of typical shapes of chips observed in single grain grinding experiment, form when analyzing the machining of 0.93%C carbon steel SK-5 with a rake angle of minus forty five or minus sixty degrees. There appear high and low temperature zones alternately according to severe and mild shear in the primary shear zone respectively. The shapes of chips depend strongly on the cutting speed and undeformed chip thickness; as the cutting speed or the undeformed chip thickness decreases, chip shape changes from a serrated type to a bulging one to a wavy or flow type. Therefore, there exists the critical cutting speed over which a chip can form and flow along a rake face for a given large negative rake angle and undeformed chip thickness.

Finite Element Analysis of Cutting Forces in High Speed Machining

2006 ◽  
Vol 532-533 ◽  
pp. 753-756 ◽  
Author(s):  
Jun Zhao ◽  
Xing Ai ◽  
Zuo Li Li
Keyword(s):  
Finite Element ◽  
Cutting Force ◽  
Cutting Forces ◽  
High Speed ◽  
Fem Simulation ◽  
Chip Thickness ◽  
Cutting Conditions ◽  
Cutting Process ◽  
Undeformed Chip Thickness ◽  
High Speed Cutting

The Finite Element Method (FEM) has proven to be an effective technique to investigate cutting process so as to improve cutting tool design and select optimum cutting conditions. The present work focuses on the FEM simulation of cutting forces in high speed cutting by using an orthogonal cutting model with variant undeformed chip thickness under plane-strain condition to mimic intermittent cutting process such as milling. High speed cutting of 45%C steel using uncoated carbide tools are simulated as the application of the proposed model. The updated Lagrangian formulation is adopted in the dynamic FEM simulation in which the normalized Cockroft and Latham damage criterion is used as the ductile fracture criterion. The simulation results of cutting force components under different cutting conditions show that both the thrust cutting force and the tangential cutting force increase with the increase in undeformed chip thickness or feed rate, whereas decrease with the increase in cutting speed. Some important aspects of modeling the high speed cutting are discussed as well to expect the future work in FEM simulation.

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