# Magnetic Abrasive Machining of Difficult-to-Cut Materials for Ultra-High-Speed Machining of AISI 304 Bars

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Principle of the UHSMAM Process

#### 2.1. Process Principle

#### 2.2. Magnetic Abrasives

## 3. Experimental Details

#### Selection of Process Parameters

## 4. Results and Discussion

#### 4.1. Effects of Process Parameters on the Machining Surface Roughness

#### 4.2. Effects of the Process Parameters on the Machining Micro-Diameter

#### 4.3. Optimization of the Objective Function

## 5. Conclusions

- When machining the surface roughness of the AISI 304 bar, the best machining conditions were found using analysis of variance. Here, the best conditions are a machining speed of 80,000 rpm, 60 s of machining time, a 10 Hz vibrational frequency, inert gas injection, a sharp magnetic pole type, and a 0.5 μm diamond particle mesh size. The best processing conditions yield an exceptionally smooth surface with features smaller than 0.03 μm.
- For machining, the micro-diameter of the AISI 304 bar, the best conditions are a machining speed of 80,000 rpm, 120 s of machining time, a vibrational frequency of 10 Hz, inert gas injection, a sharp magnetic pole type, and a 0.5 μm diamond particle mesh size. It is known that, as the processing time increases, the processing capacity also increases, and the relatively larger processed particles remove material with greater efficiency. After determining the best processing conditions for machining the micro-diameter of the workpiece, the effective processing efficiency was confirmed via regression analysis. Near the settings of the optimal condition, the amount of processing per unit of time is certain, and the regression equation can be used to budget the production corresponding to the desired processing capacity.

## Acknowledgments

## Author Contributions

## Conflicts of Interest

## References

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**Figure 2.**Two-dimensional magnetic force field lines holding particles operating on the workpiece [11].

**Figure 3.**Photographic view of the ultra-high-speed magnetic abrasive machining (UHSMAM) experimental setup.

**Figure 4.**Experimental conditions for the two kinds of magnetic pole types. (

**a**) The sharp shape; (

**b**) a 1 mm linear shape.

Mechanical Properties of AISI 304 | ||||||||

Workpiece(mm) | Ø 3 × 40 bar | |||||||

Provider | JFE Steel Corporation | |||||||

Density (g/cm^{3}) | 7.93 | |||||||

Electric resistance (Ω × cm) | 72 × 10^{−6} | |||||||

Magnetism | Non-magnetic | |||||||

Specific heat (J/Kg × °C) | 502 | |||||||

Young’s modulus (N/mm^{2}) | 193 × 10^{3} | |||||||

Ultimate tensile strength (MPa) | 515 | |||||||

Allowable stress (MPa) | At 30 °C, 183 | |||||||

Initial surface roughness (μm) | 0.32 | |||||||

Chemical Composition of AISI 304 | ||||||||

C | Mn | Si | P | S | Cr | Ni | N | |

0.030 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | 12.0 | 0.10 |

Level | A | B | C | D | E | F |

1 | 5000 | 30 | 5 | Inject | 0 | 1 |

2 | 30,000 | 60 | 10 | No-inject | 1 | 0.5 |

3 | 55,000 | 90 | ||||

4 | 80,000 | 120 | ||||

Expt No. | Rotational Speed | Machining Time | Frequency | Inert Argon Gas | Magnetic Pole Type | Diamond Particle Size |

(rpm) | (s) | (Hz) | (-) | (mm) | (μm) | |

1 | 5000 | 30 | 5 | Inject | 0 | 1 |

2 | 5000 | 60 | 5 | Inject | 0 | 1 |

3 | 5000 | 90 | 10 | Inject | 0 | 0.5 |

4 | 5000 | 120 | 10 | No-inject | 1 | 0.5 |

5 | 30,000 | 30 | 5 | Inject | 1 | 1 |

6 | 30,000 | 60 | 5 | No-inject | 1 | 1 |

7 | 30,000 | 90 | 10 | Inject | 0 | 0.5 |

8 | 30,000 | 120 | 10 | No-inject | 0 | 0.5 |

9 | 55,000 | 30 | 10 | No-inject | 0 | 1 |

10 | 55,000 | 60 | 10 | Inject | 0 | 1 |

11 | 55,000 | 90 | 5 | No-inject | 1 | 0.5 |

12 | 55,000 | 120 | 5 | Inject | 1 | 0.5 |

13 | 80,000 | 30 | 10 | No-inject | 1 | 0.5 |

14 | 80,000 | 60 | 10 | Inject | 1 | 0.5 |

15 | 80,000 | 90 | 5 | No-inject | 0 | 1 |

16 | 80,000 | 120 | 5 | Inject | 0 | 1 |

Factors | Degree of Freedom | Sequential Sum of Squares | Adjusted Mean Squares | F-Ratio | p-Value |
---|---|---|---|---|---|

A | 3 | 0.003241 | 0.001080 | 21.31 | 0.003 |

B | 3 | 0.000819 | 0.000273 | 5.38 | 0.050 |

C | 1 | 0.000006 | 0.000006 | 0.12 | 0.740 |

D | 1 | 0.000056 | 0.000306 | 1.11 | 0.340 |

E | 1 | 0.000306 | 0.000001 | 6.04 | 0.057 |

F | 1 | 0.000001 | 0.000051 | 0.01 | 0.911 |

Error | 5 | 0.000253 | - | - | - |

Total | 15 | 0.004683 | - | - | - |

Factors | Degree of Freedom | Sequential Sum of Squares | Adjusted Mean Squares | F-Ratio | p-Value |
---|---|---|---|---|---|

A | 3 | 0.003671 | 0.001224 | 6.85 | 0.032 |

B | 3 | 0.001971 | 0.000657 | 3.68 | 0.097 |

C | 1 | 0.000839 | 0.000839 | 4.69 | 0.082 |

D | 1 | 0.000388 | 0.000388 | 2.17 | 0.200 |

E | 1 | 0.000039 | 0.000039 | 0.22 | 0.659 |

F | 1 | 0.004881 | 0.004881 | 27.33 | 0.003 |

Error | 5 | 0.000893 | 0.000179 | - | - |

Total | 15 | 0.012683 | - | - | - |

A | B | C | D | E | F |
---|---|---|---|---|---|

(rpm) | (s) | (Hz) | (-) | (mm) | (μm) |

80,000 | 60 | 10 | Inject | 0 | 0.5 |

A | B | C | D | E | F |
---|---|---|---|---|---|

(rpm) | (s) | (Hz) | (-) | (mm) | (μm) |

80,000 | 120 | 10 | Inject | 0 | 0.5 |

Factors | Degree of Freedom | Sequential Sum of Squares | Adjusted Mean Squares | F-Ratio | p-Value |
---|---|---|---|---|---|

Regression | 1 | 550.827 | 550.827 | 1526.71 | 0.000 |

Error | 5 | 1.804 | 0.361 | - | - |

Total | 6 | 552.631 | - | - | - |

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## Share and Cite

**MDPI and ACS Style**

Wang, R.; Lim, P.; Heng, L.; Mun, S.D.
Magnetic Abrasive Machining of Difficult-to-Cut Materials for Ultra-High-Speed Machining of AISI 304 Bars. *Materials* **2017**, *10*, 1029.
https://doi.org/10.3390/ma10091029

**AMA Style**

Wang R, Lim P, Heng L, Mun SD.
Magnetic Abrasive Machining of Difficult-to-Cut Materials for Ultra-High-Speed Machining of AISI 304 Bars. *Materials*. 2017; 10(9):1029.
https://doi.org/10.3390/ma10091029

**Chicago/Turabian Style**

Wang, Rui, Pyo Lim, Lida Heng, and Sang Don Mun.
2017. "Magnetic Abrasive Machining of Difficult-to-Cut Materials for Ultra-High-Speed Machining of AISI 304 Bars" *Materials* 10, no. 9: 1029.
https://doi.org/10.3390/ma10091029