Study on the burr formation process in micro-milling of high aspect ratio structures

Abstract High-aspect-ratio (HAR) micro-structures of harden steel (SKD11) are widely used in the national defense and electronic fields. Micro-milling is a suitable method for machining HAR micro structures, however the inevitable generation of burrs deteriorates the machined surface. Previous studies have mostly focused on the burr formation process of shallow grooves, but have ignored HAR grooves. This paper investigated the burr formation mechanism in HAR (2:1) grooves on harden steel (SKD11). Due to the fact that the burr formation process was difficult to be observed in the actual micro-milling process, a finite element model was established. A corresponding experimental research was conducted, which revealed a good consistency between simulation and experimental results. Moreover, a new burr type was formed on the sidewall of the HAR groove, which was transformed from top burrs and was named as side burr. The results demonstrated that the chip flow on the rake face of the micro-mill was hindered by the sidewall, which caused chip crumbling, chip accumulation, and surface scraping, seriously affecting the burr formation mechanism. This paper revealed the burr formation mechanism for HAR grooves, and provided research direction for improving the machining accuracy of HAR grooves.

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Investigations on burr formation mechanisms in micro milling of high-aspect-ratio titanium alloy ti-6al-4 v structures

International Journal of Mechanical Sciences ◽

10.1016/j.ijmecsci.2020.105884 ◽

2020 ◽

Vol 185 ◽

pp. 105884 ◽

Cited By ~ 2

Author(s):

Yang Wu ◽

Ni Chen ◽

Rong Bian ◽

Ning He ◽

Zhenjun Li ◽

...

Keyword(s):

Titanium Alloy ◽

Aspect Ratio ◽

High Aspect Ratio ◽

Micro Milling ◽

Burr Formation ◽

Formation Mechanisms

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Laser hybridizing with micro-milling for fabrication of high aspect ratio micro-groove on oxygen-free copper

Precision Engineering ◽

10.1016/j.precisioneng.2021.01.012 ◽

2021 ◽

Vol 70 ◽

pp. 15-25

Author(s):

Xiuqing Hao ◽

Wenhao Xu ◽

Mengyue Chen ◽

Chen Wang ◽

Jinjin Han ◽

...

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Micro Milling

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Surface Textured Drill Tools—An Effective Approach for Minimizing Chip Evacuation Force and Burr Formation During High Aspect Ratio Machining of Titanium Alloy

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4048432 ◽

2020 ◽

Vol 143 (4) ◽

Author(s):

S. Niketh ◽

G. L. Samuel

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Sliding Friction ◽

Thrust Force ◽

Research Work ◽

Machining Process ◽

Cutting Fluid ◽

Burr Formation ◽

Burr Height ◽

Drill Tool

Abstract The real challenge pertaining to high aspect ratio drilling is the rapid increase in chip evacuation force due to the chip clogging phenomenon occurring at higher drilling depths. The clogged chips will further impede the reachability of cutting fluid at the machining zone leading to the tool temperature buildup. This will eventually result in the catastrophic failure of the tool. Hence, in the present work, an attempt has been made to minimize the chip evacuation force by functionalizing the drill tool surfaces based on the laser microtexturing principle. Microscale textures in the form of circular dimples were created on the flute and margin side of the drill tool with an objective to control the sliding friction, thereby minimizing the chip clogging effect. The effectiveness of the functionalized drill tools were assessed mainly based on the variation in thrust force and torque. Drilling experiments showed a net reduction of 17.18% in thrust force and 26.98% in torque while machining Ti–6Al–4V using the flute and margin textured tool, which justified the effectiveness of micro scale textures in minimizing the chip evacuation forces. The experimental analysis was further extended in terms of burr height evaluation, where FMT tools were found to be highly effective in burr height reduction (1.29 mm), showing a net reduction of 54.26% when compared with the non-textured tool. The outcomes from this research work will be highly beneficial for the manufacturing industries including aerospace, automobile, and spacecraft as high aspect ratio drilling of titanium alloys are still categorized to be the most challenging machining process owing to its lower thermal conductive property.

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Investigation on micro-milling of micro-grooves with high aspect ratio and laser deburring

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405419893491 ◽

2019 ◽

Vol 234 (5) ◽

pp. 871-880 ◽

Cited By ~ 2

Author(s):

Yinfei Yang ◽

Jinjin Han ◽

Xiuqing Hao ◽

Liang Li ◽

Ning He

Keyword(s):

Aspect Ratio ◽

Tool Wear ◽

Surface Quality ◽

High Aspect Ratio ◽

High Conductivity ◽

Cutting Fluid ◽

Micro Milling ◽

Free Alcohol ◽

Processing Efficiency ◽

Machined Surface

High aspect ratio micro-grooves are critical structures in the micro-electromechanical system. However, problems like rapid tool wear, low processing efficiency, and inferior machined quality in micro-milling of high aspect ratio micro-grooves by length–diameter ratio tools are particularly significant. In this work, a combined micro-milling method based on water-free alcohol as the cutting fluid and laser deburring is proposed to investigate the high aspect ratio micro-groove generation of oxygen-free high-conductivity copper TU1. Parametric experiments and high aspect ratio micro-groove experiments were conducted to investigate the surface quality, cutting forces, and tool wear. The water-free alcohol was employed to improve the tool life and machined surface quality. In the case of the oxygen-free high-conductivity copper TU1 material, a satisfactory high aspect ratio micro-groove (groove-width = 0.2 μm and aspect ratio = 2.5) with a nanoscale surface roughness ( Ra = 68 nm) was obtained under the preferred machining conditions. Furthermore, the deburring process of the high aspect ratio micro-groove by the laser technology was conducted to achieve ideal machined quality of the top surfaces.

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