| 1. |
- Bonilla Hernández, Ana Esther, et al.
(författare)
-
Integrated optimization model for cutting data selection based on maximal MRR and tool utilization in continuous machining operations
- 2016
-
Ingår i: CIRP - Journal of Manufacturing Science and Technology. - : Elsevier BV. - 1755-5817 .- 1878-0016. ; 13, s. 46-50
-
Tidskriftsartikel (refereegranskat)abstract
- The search for increased productivity can be interpreted as the increase of material removal rate (MRR). Namely, increase of feed, depth of cut and/or cutting speed. The increase of any of these three variables, will increase the tool wear rate; therefore decreasing its tool life according to the same tool life criteria. This paper proposes an integrated model for efficient selection of cutting data for maximal MRR and maximal tool utilization. The results show that, it is possible to obtain a limited range of cutting parameters from where the CAM Programmer can select the cutting data assuring both objectives.
|
|
| 2. |
- Eynian, Mahdi, et al.
(författare)
-
Sensitivity of Axis Tracking Errors of Machine Tools to Tool Wear in Drilling
- 2016
-
Ingår i: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings. - Lund : Swedish Production Academy. ; , s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- Axis Tracking Errors (ATEs) of the active and inactive axis of numerically controlled machine tools are presented as new means of detection of tool wear that forgo expensive sensors or modifications of the machining structure, however, very little has been published about their capabilities or limitations as signal source for monitoring. In this paper the ATEs and cutting forces in drilling tests in two different machine tools, with drills of varying wear levels are measured. The sensitivity to wear is compared by introducing Percent Deviation from New Tool (PDFNT) factor, which is applied to the peak-to-peak values of the signals. While the ATEs are very small in magnitude, they are highly sensitive to wear levels, with PDFNTs reaching to 1000% for some axis. In addition, the standard deviation of PDFNTs calculated in drilling of seven holes with the same tool represents the repeatability of ATEs. The PDFNTs for ATEs are rather repeatable, but less repeatable than the PDFNTs of the axial drilling force. Furthermore it is shown that ATEs of different machine tools have different levels of sensitivity to wear levels which necessitates calibrating of monitoring systems using ATEs for each machine tool separately.
|
|
| 3. |
- Hoier, Philipp, 1988, et al.
(författare)
-
Characterization of tool wear when machining Alloy 718 with high pressure cooling using conventional and surface-modified WC-Co tools
- 2016
-
Ingår i: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings. - Lund : Swedish Production Academy. ; , s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- Coolant supplied by high pressure into the cutting zone has shown to lower thermal loads on the tool when machining difficult-to-cut materials as Alloy 718. In this study, we investigate how the combination of high pressure cooling and tool-surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant-tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by ~ 12%. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45% for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivityof metal cutting processes.
|
|
| 4. |
- Holmberg, Jonas, et al.
(författare)
-
Grit Blasting for Removal of Recast Layer from EDM Process on Inconel 718 Shaft : An Evaluation of Surface Integrity
- 2016
-
Ingår i: Journal of materials engineering and performance (Print). - : Springer Science and Business Media LLC. - 1059-9495 .- 1544-1024. ; 25:12, s. 5540-5550
-
Tidskriftsartikel (refereegranskat)abstract
- The heat generated during EDM melts the work material and thereby allows large amounts to be removed,but an unfavorable surface of a recast layer (RCL) will also be created. This layer has entirely different properties compared to the bulk. Hence, it is of great interest to efficiently remove this layer and to verify that it has been removed. The main objective of this work has been to study the efficiency of grit blasting forremoval of RCL on an EDM aero space shaft. Additionally, x-ray fluorescence (XRF) has been evaluated asa nondestructive measurement to determine RCL presence. The results show that the grit-blasting processing parameters have strong influence on the ability to remove RCL and at the same time introduce beneficial compressive stresses even after short exposure time. Longer exposure will remove the RCL fromthe surface but also increase the risk that a larger amount of the blasting medium will get stuck into the surface. This investigation shows that a short exposure time in combination with a short grit-blasting nozzle distance is the most preferable process setting. It was further found that handheld XRF equipment can be used as a nondestructive measurement in order to evaluate the amount of RCL present on an EDM surface.This was realized by analyzing the residual elements from the EDM wire.
|
|
| 5. |
- Repo, Jari, et al.
(författare)
-
Detectability of various machining conditions by using internal encoder signals
- 2016
-
Ingår i: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings. - Lund : Swedish Production Academy. ; , s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- Automated Tool Condition Monitoring (TCM) often relies on additional sensors sensitive to tool wear to achieve robust machining processes. The need of additional sensors could impede the implementation of tool monitoring systems in industry due to the cost and retrofitting difficulties. This paper has investigated the use of existing position encoder signals to monitor a special face turning process with constant feed per revolution and machining speed. A signal processing method by converting encoder signals into a complex-valued form and a new vibration signature extraction method based on phase function were developed to analyze the encoder signals in the frequency domain. The cumulative spectrum indicated that the spectral energy would shift from the lower to the higher frequency band with increasing cutting load. The embedded vibration signatures extracted from the encoder signals provided additional detectability of the machining condition with distinguishable spectral modes. This paper confirms the sensitivity of the encoder signals and more signatures could be extracted for tool wear detection in the future work.
|
|
| 6. |
- Repo, Jari, 1976-, et al.
(författare)
-
In-Process Tool Wear Detection Using Internal Encoder Signals for Unmanned Robust Machining
- 2016
-
Ingår i: High Speed Machining. - : De Gruyter Open. - 2299-3975. ; 2:1, s. 37-50
-
Tidskriftsartikel (refereegranskat)abstract
- Automated Tool Condition Monitoring (TCM) often relies on additional sensors sensitive to tool wear to achieve robust machining processes. The need of additional sensors could impede the implementation of tool monitoring systems in industry due to the cost and retrofitting difficulties. This paper has investigated the use of existing position encoder signals to monitor a special face turning process with constant feed per revolution and machining speed. A signal processing method by converting encoder signals into a complex-valued form and a new vibration signature extraction method based on phase function were developed to analyze the encoder signals in the frequency domain. The cumulative spectrum indicated that the spectral energy would shift from the lower to the higher frequency band with increasing cutting load. The embedded vibration signatures extracted from the encoder signals provided real-time detectability of the machining condition with distinguishable spectral modes. The embedded vibration signatures extracted from the encoder signals provided additional detectability of the machining condition with distinguishable spectral modes. In particular, tool chipping manifested itself as significant amplitude changes at a specific frequency band 20-30 Hz in the extracted vibration signatures. A new monitoring metric based on the XY-plane modulations combined with statistical process control charts was proposed and shown to be a robust tool wear and tool wear rate indicator. The results show that when tool chipping occurred, it could be detected in real-time when this this tool wear rate value jumped in combination with breach of the control limits. This confirms that internal encoder signals, together with the proposed metric, could be a robust in-process tool wear monitor.
|
|
| 7. |
- Tamil Alagan, Nageswaran, 1990-, et al.
(författare)
-
Investigation of Modified Cutting Insert with Forced Coolant Application in Machining of Alloy 718
- 2016
-
Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271 .- 2212-8271. ; 42, s. 481-486
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract In the last decades machining methods have witnessed an advancement in both cutting tools and coolant/lubrication, sometimes in combination with high pressure jet. The aim of this work is to investigate a modified cutting insert with forced coolant application, FCA, how it influences the tool-chip contact in the secondary shear zone and how it affects the tool wear when turning Alloy 718. During the machining process the main and frequent problems are heat generation and friction in the cutting zone, which has a direct impact on the cutting tool life. High pressure jet cooling have headwayed the cutting technology for the last five decades, showing an improvment of tool life, reduced temperature in the cutting zone and better surface integrity of the workpiece. These developments have practically enhanced the capability and quality in machining of superalloys. This paper is an advancement of the previous work, increasing surface area of the insert, with a additional channel design to improve the coolant reachability in the tool-chip contact area on the rake face. The influence in tool wear has been investigated. Through a set of experiments, a channel design insert with forced coolant application, has shown about 24-33% decrease in tool wear compared to only a textured insert. Hybrid inserts with its cooling and channel features have even widened the operational cutting region with significantly less tool wear.
|
|
| 8. |
- Tamil Alagan, Nageswaran, 1990-, et al.
(författare)
-
Next Generation Insert for Forced Coolant Application in Machining of Inconel 718
- 2016
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 836-837, s. 340-347
-
Tidskriftsartikel (refereegranskat)abstract
- Machining technology has undergone an extensive evolution throughout the last decades in its capability to machine hard-to-cut material. This paper will discuss about the next generation insert with cooling feature coupled with forced coolant in machining Inconel 718. The geometry of the insert was changed in a way which has enlarged the surface area approximately 12% compared to regular insert named as nusselt insert. The idea applied in “nusselt insert” was the relation of increase in surface area to heat dissipation. Forced coolant application has become a way to improve existing metal cutting concepts and improve their current material removal rates without any need for a reengineered machining process. Experiments conducted on the inserts is that the first experiment of its kind in machining technology together with forced coolant and tested in four different inserts. The primary focus of the work was the investigation of the relation between the heat dissipation with an increase in surface area/mass ratio in the cutting interface based on its influence on tool wear. The experimental results showed the nusselt insert have better ability for heat dissipation which has led to significant reduce in tool wear and successfully facing Inconel 718 at vc 105 m/min, f 0.3 mm/rev and ap 1 mm where the regular insert had a catastrophic failure at vc 90 m/min, f 0.1 mm/rev and ap 1 mm. Nusselt insert has shown to increase MRR significantly compared to regular insert.
|
|
