Improvement in Drilling Performance of Micro Compound Tool

The present paper deals with the development of micro compound tools and their application to the micro drilling. The micro compound tool consists of a micro drill part and an electroplated part with a nominal finishing diameter of 100 µm and they are fabricated by grinding and electroplating processes. Fabricated tools are used in drilling tests with or without ultrasonic vibration. Influences of drill part geometry on burr formation and influences of diamond grit size on peeling of the electroplating layer are investigated. As the results, secondary cutting edges do not seem to have remarkable ability for reduction of burrs. And large size of diamond grit at the electroplated part of a micro compound tool with a small difference between a diameter of electroplated part and a diameter of drill part seems to be effective in preventing peeling of the electroplating layer and improving drilling performance.

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Influence of Drill Geometry Parameters on Helical Point Micro Drilling Performance

Materials Science Forum ◽

10.4028/www.scientific.net/msf.836-837.198 ◽

2016 ◽

Vol 836-837 ◽

pp. 198-204

Author(s):

Su Yan Zhang ◽

Zhi Qiang Liang ◽

Xi Bin Wang ◽

Tian Feng Zhou ◽

Pei Yan ◽

...

Keyword(s):

Thrust Force ◽

Helix Angle ◽

Contributory Factor ◽

Drilling Performance ◽

Micro Drilling ◽

Moderate Effect ◽

Drill Point ◽

Micro Drill ◽

Selection Of ◽

Small Point

Helical point micro-drill is characterized by a continuous helical flank instead of the piecewise planar flank, and its improved drilling performance is validated compared with planar drill point by some researchers. In this study, to analyze the effect of geometry parameters of helical point drill on the drilling performance, the micro-drills with different point angles, web thicknesses and helix angles of the flute are fabricated on a 6-axis CNC tool grinder, and a serial of micro-drilling experiments involving these drills on 1Cr18Ni9Ti austenitic stainless steel are carried out. In experiments, the drilling forces are measured and exit burrs are observed. Within a certain range of geometry parameters, thrust force increases with the increase of point angle and web thickness, and the decrease of the helix angle of the flute. The point angle is the main contributory factor for the thrust force followed by web thickness, while helix angle has a moderate effect on the force. Furthermore, poisson burr and rollover burr are generated with different point angles. Based on the results, a good selection of the helical point drill geometry parameters with small point angle, big helix angle and small web thickness are proposed to improve the micro-drilling performance.

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Mathematical Model and Simulation of Regrind Chisel Edge for Helical Micro-Drill

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.304-305.550 ◽

2006 ◽

Vol 304-305 ◽

pp. 550-554 ◽

Cited By ~ 2

Author(s):

W.J. Xiang ◽

Zhi Xiong Zhou ◽

S.J. Hu ◽

J. Yang ◽

J.P. Liang

Keyword(s):

Mathematical Model ◽

Geometric Model ◽

Drilling Performance ◽

Model And Simulation ◽

Kinematic Relationship ◽

Micro Drilling ◽

Novel Method ◽

Relationship Of ◽

Micro Drill ◽

Easy Operation

Micro-drills are becoming more and more important in precision and micro fabrications. They have been widely used in applications, e.g., precision and micro drilling. In this paper, a novel method is advanced and used for regrinding of chisel edges of helical micro-drills. In this method, a geometric model is established for the chisel edge regrinding. Based on the kinematic relationship of regrinding, the model simplifies machine movement so as to facilitate an easy operation. Computer simulation is applied to the regrinding process of the micro-drills. The results demonstrate that the proposed method is effective in regrinding chisel edges, which allows for a more reasonable distribution of the angles along the chisel edge of a drill, and enhances the drilling performance.

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A 5-Axis Coordinated CNC Grinding Method for the Flank of a Non-Coaxial Helical Micro-Drill with the Cylinder Grinding Wheel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1017.654 ◽

2014 ◽

Vol 1017 ◽

pp. 654-659 ◽

Cited By ~ 3

Author(s):

Zhi Qiang Liang ◽

Hong Chao Jian ◽

Xi Bin Wang ◽

Wen Xiang Zhao ◽

Su Yan Zhang ◽

...

Keyword(s):

Laser Scanning ◽

Grinding Wheel ◽

Three Dimension ◽

Drilling Performance ◽

Grinding Method ◽

Cnc Grinding ◽

Micro Drilling ◽

Drill Point ◽

Micro Drill ◽

Drill Tool

Micro-drilling become more widely used from precision mechanics to electronics. Nowadays, the main commercial tools are planar point micro-drills. However, that geometry often causes a high thrust force, high temperature, and rapid wear during micro-drilling. Furthermore, it is difficult to adjust the four flank surfaces to accurately intersect at one point, particularly when the drill diameter becomes smaller. To solve this problem, non-coaxial helical drills points have been proposed by some researchers, and is characterized by a continuous helical flank instead of the piecewise planar flank. Its drilling performance is improved compared with planar drill point. This study presents a 5-axis coordinated CNC grinding method of the non-coaxial helical drill flank. Mathematical models of the drill flank and its engagement line between cylinder grinding wheel and drill tool are established, and then the path of the grinding wheel with respect to the drill tool is obtained. In order to verify the availability of the proposed methods, three dimension (3D) grinding simulation of non-coaxial helical drills with diameter 0.5mm was carried out using the CAD software, and then were fabricated on a 6-axis Makino CNC tool grinder. The ground micro-drills examined by 3D laser scanning microscope show good identity with the simulated result. These indicate that the manufacturing model presented in this paper provides a practical and efficient method to grind the flank of a non-coaxial helical micro-drill.

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Mathematical Modeling of Cutting Forces in Micro-Drilling

ASME 2012 International Manufacturing Science and Engineering Conference ◽

10.1115/msec2012-7399 ◽

2012 ◽

Author(s):

Kumar Sambhav ◽

Puneet Tandon ◽

Shiv G. Kapoor ◽

Sanjay G. Dhande

Keyword(s):

Mathematical Modeling ◽

Chip Thickness ◽

Rake Angle ◽

Cutting Mechanism ◽

Line Field ◽

Slip Line Field ◽

Effective Rake Angle ◽

Micro Drilling ◽

Micro Drill ◽

Secondary Cutting

In drilling, the primary cutting lips and the secondary cutting lips of the drill shear the material while the central portion of the chisel edge indents the workpiece, making the cutting process complex to understand. As we go for micro-drilling, it exhibits an added complexity to the cutting mechanism when the edge radius gets comparable to chip thickness at low feeds. The presented work models the forces by the primary cutting lip of a micro-drill analytically using slip-line field that includes the changes in the effective rake angle and dead metal cap during cutting for cases of shearing as well as ploughing. To study the variation of forces experimentally, the primary cutting lip and chisel edge forces are separated out by drilling through pilot holes of diameter slightly above the drill-web thickness. Finally, the analytical and experimental results have been compared and the model has been calibrated.

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The Study of High Speed Micro-Drilling Performance and Machining Quality of Coated Micro-Drills with Zr-C:H Coatings

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.591-593.342 ◽

2012 ◽

Vol 591-593 ◽

pp. 342-346 ◽

Cited By ~ 2

Author(s):

Wen Hsien Kao ◽

Yan Liang Su ◽

Sun Hui Yao ◽

H.C. Huang ◽

M.S. Chen

Keyword(s):

High Speed ◽

Printed Circuit Board ◽

Circuit Board ◽

Hole Drilling ◽

Closed Field ◽

Machining Performance ◽

Machining Quality ◽

Drilling Performance ◽

Micro Drilling ◽

Micro Drill

The Zr-C:H coatings with various C2H2 flow rate were deposited on micro-drills (a diameter of 0.2 mm) used a closed field unbalanced magnetron sputtering system. The ultrahigh speed (drilling speed of 160000 rpm) through-hole drilling printed circuit board tests used to evaluate the drilling performance of the coated micro-drills. The rejection criteria of service lives of the coated micro-drills were evaluated using two different criteria: (1) a nail head ratio greater than 1.5; (2) a drilled hole surface roughness greater than 25.4 μm. Adopting a service life criterion of a nail head ratio of 1.5, the Zr-C:H-5 coating possesses the optimal high-speed machining performance, which yields a micro-drill lifetime of above 6000 drilled holes. It represents a three-fold improvement on that of an uncoated micro-drill and it also improves machining quality.

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An In-Process Intervention to Mitigate the Effect of Built-Up Edges in Micromilling

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4037574 ◽

2017 ◽

Vol 5 (4) ◽

Cited By ~ 1

Author(s):

Robert G. Altman ◽

James F. Nowak ◽

Johnson Samuel

Keyword(s):

Machining Process ◽

Burr Formation ◽

Tool Runout ◽

Part Geometry ◽

Intervention Technique ◽

Mechanical Removal ◽

Working Volume ◽

G Code ◽

Critical Process Parameters ◽

Critical Process

This paper is focused on developing an in-process intervention technique that mitigates the effect of built-up edges (BUEs) during micromilling of aluminum. The technique relies on the intermittent removal of the BUEs formed during the machining process. This is achieved using a three-stage intervention that consists first of the mechanical removal of mesoscale BUEs, followed by an abrasive slurry treatment to remove the microscale BUEs. Finally, the tool is cleaned using a nonwoven fibrous mat to remove the slurry debris. An on-machine implementation of this intervention technique is demonstrated, followed by a study of its influence on key micromachining outcomes such as tool wear, cutting forces, part geometry, and burr formation. In general, all relevant machining measures are found to improve significantly with the intervention. The key attributes of this intervention that makes it viable for micromachining processes include the following: (i) an experimental setup that can be implemented within the working volume of the microscale machine tool; (ii) no removal of the tool from the spindle, which ensures that the intervention does not change critical process parameters such as tool runout and offset values; and (iii) implementation in the form of canned G-code subroutines dispersed within the regular micromachining operation.

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