| 1. |
- Svenningsson, Inga, et al.
(author)
-
Exploring the mechanics of adhesion in metal cutting
- 2023
-
In: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 127, s. 3337-3356
-
Journal article (peer-reviewed)abstract
- The deterioration of the cutting edge during machining influences production cost and productivity. The adhesion is one of the main wear mechanisms. This study delves into the adhesive mechanism in the context of turning, milling, and drilling, focusing on three different cutting materials: 34CrNiMo6, 1.437 stainless steel, and ductile iron. Building upon previous research on the adhesive process in turning, a dynamic model was developed to understand the mechanism further. The results showed that adhesion is a general phenomenon occurring in all tested work materials, but with varying intensity levels. Intermittent cuts did not greatly impact the adhesive mechanism, and cutting data, coolant, and chip breaking also showed little effect. However, the presence of graphite in ductile iron temporarily inhibited adhesion. The source of the adhesive sound was found to be the pivoting movement of the chip as it binds and rips off the cutting tool, leading to a frequency shift upon detachment. The adhesive wear was found to be a thermal mechanism, where chemical reactions between the SiO2 in the work material with the cutting tool caused thermal cracks and low-frequency fatigue.
|
|
| 2. |
- Svenningsson, Inge, et al.
(author)
-
On the mechanism of three-body adhesive wear in turning
- 2021
-
In: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 113, s. 3457-3472
-
Journal article (peer-reviewed)abstract
- The paper reveals a hypothesis regarding the adhesive mechanism in metal cutting and its mechanical dynamics. One steel grade, 34CrNiMo 6, 285 HB, and one set of coatings on the cutting tool are reviewed. The adhesive mechanism is a transient vibration, including a feedback system limited by the plastic deformation in the chip. The vibration shows as a cluster of waves with stochastic duration in time. It starts up again after a stochastic lapse of silence. The cycle frequency is around 12.5 kHz and the internal excitation is twice that frequency, as the cutting speed and feed are 200 m/min and 0.2 mm, respectively. The adhesive frequency and amplitude are influenced by the cutting speed and the current wear status. The adhesion is monitored by the sound waves emanating from vibrations in the chip, the part still in the workpiece.
|
|
| 3. |
- Tatar, Kourosh, 1973-, et al.
(author)
-
Effect of chamfer width and chamfer angle on tool wear in slot milling
- 2022
-
In: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 120, s. 2923-2935
-
Journal article (peer-reviewed)abstract
- The tool geometry is generally of great significance in metal cutting performance. The response surface method was used to optimize chamfer geometry to achieve reliable and minimum tool wear in slot milling. Models were developed for edge chipping, rake wear, and flank wear. The adequacy of the models was verified using analysis of variance at a 95% confidence level. Each response was optimized individually, and the multiple responses were optimized simultaneously using the desirability function approach. The Monte Carlo simulation method was applied to tolerance analysis. All milling tests were conducted at dry conditions; the chamfer width and the chamfer angle varied between 0.1 and 0.3 mm, and 10 and 30°, respectively. Optimal chamfer geometry for minimizing chipping and rake wear was small chamfer width and chamfer angle. The flank wear reached the minimum value for the tool with 0.18 mm chamfer width and 10° chamfer angle. The obtained composite model predicted good edge strength and minimum overall wear when the chamfer was 0.1 mm wide at a 10° angle. Thermal cracks were observed on the tools. They were small on the edges with the finest and least negative chamfer but were more significant on the more negative and greater chamfer. A great chamfer width and chamfer angle also resulted in insufficient chip evacuation. The results show how the edge geometry affects the tool’s reliability and wear and may help manufacturers minimize tool cost and downtime.
|
|
| 4. |
- Tatar, Kourosh, 1973-, et al.
(author)
-
Estimation of the in-plane vibrations of a rotating spindle, using out-of-plane laser vibrometry measurements
- 2016
-
In: Mechanical systems and signal processing. - : Elsevier BV. - 0888-3270 .- 1096-1216. ; 72-73, s. 660-666
-
Journal article (peer-reviewed)abstract
- A method for estimating the in-plane vibrations of a rotating spindle using out-of-plane laser vibrometry measurements is described. This method enables the possibility to obtain the two orthogonal radial vibration components of a rotating spindle. The method uses the fact that the laser vibrometer signal is a total surface velocity of the measurement point in the laser direction.Measurements are conducted on a rotating milling machine spindle. The spindle is excited in a controlled manner by an active magnetic bearing and the response is measured by laser vibrometer in one of the two orthogonal directions and inductive displacement sensors in two orthogonal directions simultaneously. The work shows how the laser vibrometry crosstalk can be used for resolving the in-plane vibration component, that is the vibrations in the laser vibrometer cross direction. The result is compared to independent measurement signals from the displacement sensors.The measurement method can be used for vibration measurements on rotating parts, for example, where there is lack of space for orthogonal measurements.
|
|
| 5. |
- Tatar, Kourosh, 1973-, et al.
(author)
-
Investigation of cutting conditions on tool life in shoulder milling of Ti6Al4V using PVD coated micro-grain carbide insert based on design of experiments
- 2020
-
In: Heliyon. - : Elsevier. - 2405-8440. ; 6:6
-
Journal article (peer-reviewed)abstract
- Tool life prediction is generally of great importance in all metal cutting processes, including milling titanium. In this paper, tool life testing was performed based on full factorial design. The cutting speed and width varied between 100 and 120 m/min, and 10 and 70 percent of tool diameter, respectively. All cutting tests were performed in Ti6Al4V under wet conditions using Physical Vapor Deposition (PVD) coated milling inserts. The wear limit was set to 0.2 mm. The data were analyzed using multiple regression analyses, where the method of least squares was applied. A mathematical tool life model was established. Roughly, for each one percent increase in cutting width, tool life decreases on average by one percent, and an increase in cutting speed by a percent leads to a decrease in tool life by four percent. The adequacy of the model was verified using analysis of variance at 95% confidence level. Tool life contour in cutting width and speed was generated from the model. The results can be used for selecting optimum cutting parameters for providing a desired tool life or maximum metal removal rates for a favored tool life.
|
|
