Generation of High Aspect Ratio Micro Holes by a Hybrid Micromachining Process

2007 ◽  
Author(s):  
Murali M. Sundaram ◽  
Sridevi Billa ◽  
Kamlakar P. Rajurkar
Keyword(s):  
Aspect Ratio ◽  
Ultrasonic Vibration ◽  
Machining Process ◽  
Hole Drilling ◽  
Micro Edm ◽  
Shape Distortion ◽  
Machining Time ◽  
Machined Surface ◽  
Electro Discharge Machining ◽  
Debris Removal

Drilling a micro hole with an aspect ratio above 10 is a challenging task for any-micromachining process. In micro electro discharge machining (micro EDM), a proven metallic micromachining process, this is due to the problems associated with debris removal. In such cases, where the capabilities of existing macro machining methods are constantly being challenged, innovative micro manufacturing approaches are required to make progress. Hybrid micromachining is one such approach in which the synergy of constituent processes is exploited to achieve desired results. In this paper, the results of ultrasonic vibration assisted micro electro discharge machining process are presented. This hybrid process is capable of deep hole drilling with aspect ratio of 20 in austenitic stainless steel by overcoming the limitations in the debris removal faced in the typical micro EDM process. Other benefits of ultrasonic vibration are the savings in machining time, and less tool wear. It is also noticed that the ultrasonic vibration causes some shape distortion and produces rougher machined surface.

High aspect ratio micro-hole drilling aided with ultrasonic vibration and planetary movement of electrode by micro-EDM

CIRP Annals ◽  
2009 ◽  
Vol 58 (1) ◽  
pp. 213-216 ◽  
Author(s):  
Z.Y. Yu ◽  
Y. Zhang ◽  
J. Li ◽  
J. Luan ◽  
F. Zhao ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Ultrasonic Vibration ◽  
High Aspect Ratio ◽  
Hole Drilling ◽  
Micro Edm ◽  
Micro Hole

Study on Machining Characteristics of Ultrasonic Vibration Assisted Micro-EDM

2012 ◽  
Vol 217-219 ◽  
pp. 2163-2166 ◽  
Author(s):  
Tomohiko Ichikawa ◽  
Wataru Natsu
Keyword(s):  
Ultrasonic Vibration ◽  
Machining Process ◽  
Hole Drilling ◽  
Micro Edm ◽  
Discharge Energy ◽  
Machining Speed ◽  
Micro Hole ◽  
Short Circuits ◽  
Small Discharge ◽  
Machining Characteristics

The existence of debris in the inter-electrode area in micro-EDM interrupts the machining process. Applying ultrasonic vibration to the machining fluid helps circulate the machining fluid and remove the debris from the gap area, and thus reduce short-circuits and abnormal discharges. In this study, the effect of applying ultrasonic vibration to machining fluid in micro-EDM was experimentally investigated. It was found that a significant increase in the machining speed was realized by applying ultrasonic vibration. Also, with the vibration of the machining fluid, micro-hole drilling with ultra-small discharge energy became possible.

scholarly journals Effect of Micro-EDM Parameters on Material Removal Rate of Nonconductive ZrO2 Ceramic

2013 ◽  
Vol 465-466 ◽  
pp. 1329-1333 ◽  
Author(s):  
Abdus Sabur ◽  
Abdul Moudood ◽  
Mohammad Yeakub Ali ◽  
Mohammad Abdul Maleque
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Pyrolytic Carbon ◽  
Carbon Layer ◽  
Machining Process ◽  
Machining Parameters ◽  
Micro Edm ◽  
Machined Surface ◽  
Electro Discharge Machining

Micro-electro discharge machining (micro-EDM) technique, an advanced noncontact machining process, is used for structuring of nonconductive ZrO2 ceramic. In this study copper foil as a conductive layer is adhered on the workpiece surface to initiate the sparks and kerosene is used as dielectric for creation of continuous conductive pyrolytic carbon layer on the machined surface. Voltage (V) and capacitance (C) are considered as the parameters to investigate the process capability of machining parameters in continuous micro-EDM of ZrO2. Different voltage pulses are studied to examine the causes of lower material removal rate (MRR) in micro-EDM of nonconductive ceramics. The results showed that in micro-EDM of ZrO2 MRR increases with the increase of voltage and capacitance initially, but decreases at higher values and no significant materials are removed at capacitances higher than 1nF.

Effect of micro double helical grooved tools on performance of electric discharge drilling of Ti-6Al-4V

2021 ◽  
pp. 095440542199560
Author(s):  
Krupa Serah Jacob ◽  
G.L. Samuel
Keyword(s):  
Aspect Ratio ◽  
Electric Discharge ◽  
High Aspect Ratio ◽  
Hole Drilling ◽  
Electrode Wear ◽  
Machining Time ◽  
Debris Accumulation ◽  
Drilling Tools ◽  
Debris Removal ◽  
Complex Features

Machining of complex features and holes on superalloys is a topic of both industrial and academic interest. Though the demand for high aspect ratio holes on Ti-6Al-4V is high in aerospace, biomedical and chemical industries, machining the same is very challenging due to the low thermal conductivity and debris accumulation in the machining zone. The present-day methods of hole drilling by unconventional methods like Electric Discharge Machining (EDM) make use of electrodes with poor flushing capabilities. Hence the motivation of the present work is to develop a method to modify the geometry of Electric Discharge Drilling (EDD) tools in order to enhance debris removal. For the first time an attempt has been made to machine micro double-helical grooves on EDD tools in a single pass. Solid, single-helical and double-helical electrodes are developed and through-holes are drilled on a Ti-6Al-4V workpiece. A comparative analysis of the performance of these three types of tools with respect to the machining time, electrode wear rate and hole quality is carried out. From Computational Fluid Dynamics (CFD) simulations it is seen that the double-helical grooved tool is superior in debris removal. The best values of the machining time of 183.33 s, overcut of 2.19 mm, hole taper angle of 7.93° and area of recast layer of 6.66 mm2 are obtained on the holes machined using double-helical electrodes. The mentioned tool has the potential to overcome the problem of debris removal in high aspect ratio hole drilling and surpass the present-day electric discharge drilling tools.

Comparative Micro-EDM Studies on Ni Based X-Alloy Using Coated and Uncoated Tools

2018 ◽  
Vol 911 ◽  
pp. 13-19 ◽  
Author(s):  
Asma Perveen ◽  
M.P. Jahan
Keyword(s):  
Oil And Gas ◽  
Machining Process ◽  
Mechanical And Thermal Properties ◽  
Micro Edm ◽  
Discharge Energy ◽  
Machining Time ◽  
Coated Tools ◽  
Electro Discharge Machining ◽  
Wide Range ◽  
The Difference

Nickel based alloys have found their wide range of applications in the automotive, oil and gas, and aerospace industries due to their excellent mechanical and thermal properties. However, these alloys impose greater challenges to conventional machining techniques due to their extreme hardness. Therefore, non-traditional machining process like micro-electro discharge machining, which is a non–contact machining process, comes into consideration. In this study, the machinability of Ni based X-alloy was investigated using micro-EDM process with the aid of coated and uncoated tools. From the experimental results, it was evident that the machining time was reduced with the increase of discharge energy for both the coated and uncoated tools. Increase in discharge energy also resulted in enlargement of entrance diameter and overcut. However, the non-conductive nature of coating caused in the reduction of overcut for machining using coated tools. The tool wear was found to reduce with the increase of discharge energy due to shorter machining time at higher discharge energy. Finally, crater size also increased with the increased discharge energy. The coated tools resulted in bigger crater sizes than uncoated tools at 1000 rpm, however, for higher tool rotation the difference was not significant.

scholarly journals Effect of Laser Parameters on Sequential Laser Beam Micromachining and Micro Electro-Discharge Machining

2021 ◽  
Author(s):  
Mir Akmam Noor Rashid ◽  
Tanveer Saleh ◽  
Wazed Ibne Noor ◽  
Mohamed Sultan Mohamed Ali
Keyword(s):  
Laser Beam ◽  
Laser Power ◽  
Short Circuit ◽  
Scanning Speed ◽  
Hole Drilling ◽  
Machining Time ◽  
Research Attention ◽  
Pilot Hole ◽  
Electro Discharge Machining ◽  
Input Parameters

Abstract Laser beam micromachining (LBMM) and micro electro-discharge machining (µEDM) based sequential micromachining technique, LBMM-µEDM has drawn significant research attention to utilizing the advantages of both methods, i.e. LBMM and µEDM. In this process, a pilot hole is machined by the LBMM and subsequently finishing operation of the hole is carried out by the µEDM. This paper presents an experimental investigation on the stainless steel (type SS304) to observe the effects of laser input parameters (namely laser power, scanning speed, and pulse frequency) on the performance of the finishing technique that is the µEDM in this case. The scope of the work is limited to 1-D machining, i.e. drilling micro holes. It was found that laser input parameters mainly scanning speed and power influenced the output performance of µEDM significantly. Our study suggests that if an increased scanning speed at a lower laser power is used for the pilot hole drilling by the LBMM process, it could result in significantly slower µEDM machining time. On the contrary, if the higher laser power is used with even the highest scanning speed for the pilot hole drilling, then µEDM processing time was faster than the previous case. Similarly, µEDM time was also quicker for LBMMed pilot holes machined at low laser power and slow scanning speed. Our study confirms that LBMM-µEDM based sequential machining technique reduces the machining time, tool wear and instability (in terms of short circuit count) by a margin of 2.5 x, 9 x and 40 x respectively in contrast to the pure µEDM process without compromising the quality of the holes.

Tool Posture Planning Method for Low Rigidity Workpiece Considering Elastic Deformation Caused by Cutting Force

2020 ◽  
Author(s):  
Jun'ichi Kaneko ◽  
Yuki Okuma ◽  
Shumpei Sugita ◽  
Takeyuki Abe
Keyword(s):  
Cutting Force ◽  
Elastic Deformation ◽  
Feed Rate ◽  
Machining Process ◽  
Machining Time ◽  
Machined Surface ◽  
Nc Program ◽  
Blade Shape ◽  
Tool Posture ◽  
The Moment

Abstract In machining process for a workpiece with low rigidity such as a blade shape, it is required to consider elastic deformation of the workpiece shape itself due to cutting force. Conventionally, reduction of the cutting force in machining process is achieved by optimization of feed rate value in NC program. On the other hand, since a decrease in the feed rate causes an increase in machining time. So, other optimization algorithm is required. In this paper, a new method to suppress the elastic deformation of the workpiece by changing tool posture in multi-axis controlled machining is proposed. The proposed method is intended for finish machining process for blade shape with a ball end mill. In the proposed method, first, the cutting force loaded on the workpiece surface in a certain posture candidate is predicted, and an instantaneous cutting force at the moment when the machining surface is generated is estimated by model-based computer simulation. Based on this results, the amount of elastic deformation on the machined surface is estimated by FEM. This process is repeated at each cutter location and tool posture candidate, and the new tool posture that can minimize machining error caused by the elastic deformation is determined at each cutter location.

Performance of Micro-Hole Drilling by Ultrasonic-Assisted Electro-Chemical Discharge Machining

2012 ◽  
Vol 445 ◽  
pp. 865-870 ◽  
Author(s):  
Meifal Rusli ◽  
Katsushi Furutani
Keyword(s):  
Ultrasonic Vibration ◽  
Removal Rate ◽  
Glass Plate ◽  
High Amplitude ◽  
Machining Process ◽  
Hole Drilling ◽  
Tool Electrode ◽  
Conductive Materials ◽  
Electrolyte Level ◽  
Micro Hole

Electro-chemical discharge machining (ECDM) is one of nontraditional processes for micro-fabrication of non-conductive materials. A high applied voltage is preferable to form a gas film and to generate discharge in the film. However, accumulation of discharge heat often causes cracks of the surface because non-conductive materials have low heat conductivity. In this study, the effect of ultrasonic vibration and the electrolyte level on the performance of gravity-feed drilling by ECDM was investigated. Ultrasonic vibration was applied to a glass plate. A tungsten rod as a tool electrode was fed by gravity. Ultrasonic vibration changed the discharge behavior and improved electrolyte circulation. Although high amplitude ultrasonic vibration caused very dense and wide current pulses consistently during machining process, it decreased removal rate significantly. In addition, electrolyte levels affect single bubble size and the resistance in the electrolyte. Low electrolyte level will cause higher resistance, and higher temperature of the tool electrode and workpiece. A high bias current flew at a low electrolyte level without ultrasonic vibration. In this case, removal rate decreased and surface integrity was improved.

Optimization Method of Rotational Axis Motion in 5-Axis Controlled Machining to Keep Command Tool Feed Rate

2020 ◽  
Author(s):  
Takayuki Nakamura ◽  
Kohei Ichikawa ◽  
Masanobu Hasegawa ◽  
Jun'ichi Kaneko ◽  
Takeyuki Abe
Keyword(s):  
Surface Roughness ◽  
Feed Rate ◽  
Machining Process ◽  
Rotational Axis ◽  
Feed Speed ◽  
Machining Processes ◽  
Machining Time ◽  
Machined Surface ◽  
Lead Angle ◽  
Tool Posture

Abstract In recent machining processes, 5-axis controlled machine tool is widely used for machining complicated workpiece shape with curved surface. In such process, to achieve high productivity, planning method of cutting conditions to satisfy both following the commanded tool feed rate in machining process and realization of good surface roughness are required. In conventional study, it is known that lead angle of tool posture against local machined surface influence the surface roughness. Then, common commercial CAM systems have already functioned to avoid interference and control the lead angle in each cutter location. However, in the generated cutter locations by the conventional algorithms, when the tool posture changes rapidly, there is a problem that actual feed rate does not reach the command value and machining time becomes longer than expected. In this paper, we propose the new tool posture correction algorithm. In the proposed method, first, the rotational axis that causes the feed speed rate decline is specified by preliminary experiments. And, the jerk value that is the threshold for the feed speed decline is investigated. After that, for the NC program, the command value of the target axis is modified within a range where interference of cutting tool does not occur, thereby preventing a decline in the actual feed rate. This paper describes an outline of the proposed modification method and the effect of the modification of the target axis positions on the lead angle and the actual feed rate.

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