Ultrasonic machining

Ultrasonic Machining Process

1. Ultrasonic Machining(USM) Department of Mechanical Engineering Atria Institute of Technology Student names USN no. Veerendra T U 1AT18ME051 Vishal Sanjay Shivam 1AT18ME053 Yash G M 1AT18ME056 Yashwanth B 1AT18ME057 Course Coordinator- Anjan Kumar (Assistant Professor)

2. Contents 1.Definition 2.Working Principle 3.Schematic setup of Machine 4.List of equipment and its functions 5.Process parameters 6.Advantages 7.Limitations 8.Applications 9.Reference

3. Definition Ultrasonic machining  is a subtractive manufacturing  process that removes material from the surface of a part through high frequency, low amplitude vibrations of a tool against the material surface in the presence of fine abrasive particles ​. Ultrasonic machining is an abrasive process which can create any material into hard and brittle form with the help of its vibrating tool and the indirect passage of abrasive particles towards the work piece. It is a low material removal rate machining process. ​

4. Working Principle Working principle of Ultrasonic Machining  or Ultrasonic Impact Grinding is described with the help of a schematic diagram. The shaped tool under the actions of mechanical vibration causes the abrasive particles dipped in slurry to be hammered on the stationary workpiece. This causes micro-indentation fracture on the material.  Small abraded particles are removed along the surface which is perpendicular to the direction of the tool vibration. When the material is removed a cavity of the same profile of the tool face is formed. The abrasive particles gradually erodes as the machining process continues. As a result fresh abrasive particles are needed to be supplied in the machining zone. Abrasive particles associated with the liquid is fed to the machining zone and it ensures the removal of the worn out grains and material.

5. Schematic setup of Machine The schematic setup of Ultrasonic Machine is depicted below :-

6. List of equipment and its functions The equipments /components of USM and its functions are listed below :- 1) High-frequency generator -     An electronic oscillator is used to generate high-frequency alternating current. The frequency is in the ultrasonic range (20-40KHz).       2) Work piece - Workpiece of hard and brittle material can be machined by​USM.​ It is mounted on a vice, which can be located​at the desired position under the tool using a two axis table.​ The table can further be lowered or raised to​accommodate work of different thickness.​

7. 4) Abrasive slurry feeding arrangement -     A constant stream of abrasive suspension is flowed between to tool and  workpiece. This slurry consists of abrasive material like boron carbide, silicon carbide, diamond dust, etc. mixed with water or oil. The abrasive grit size is usually in the range of 100-1000 mesh size. The smaller size gives smoother surface finish, larger grain results faster machining. The flow of slurry carried away the debris during the machining. The slurry is cooled down by a cooling system.   3) Tool in a tool holder ​- ​ Tool is made of ductile material like mild steel, brass to reduce the tool ware. They are fastened to the tool holder by brazing to reduce fatigue. The cavity produced in workpiece has the same geometry of tool.​

8. 5) Transducer to generate vibration - ​​ Transducer used in USM converts the electrical energy into mechanical vibration. There are mainly two types of transducer is used in USM; piezoelectric transducer and magneto strictive transducer.​​ Tool is fed to the machining zone of workpiece .The tool is shaped as same to the cavity of be produced into the workpiece. The tool is fed to the machining area. The feed rate is maintained equal to the rate of enlargement of the cavity to be produced. ​ 6) Ultrasonic Oscillator​​ -      This operation uses high frequency electric current which passes to an ultrasonic oscillator and ultrasonic transducer. The function of the transducer is to convert electric energy into mechanical energy developing vibrations into the tool.​​ ​​ 7) Feed Mechanism -

9. Process Parameters The ultrasonic machining process parameters/variables are :-  1) Vibration frequency and amplitude - The frequency of vibration is directly proportional to the material removal rate. The increase in frequency increase the number blows by the tool per second and cut more material from surface. For many materials, the material removal rate is proportional to the square of amplitude of vibration.

10. 2) Static load on tool - The material removal rate increase with the static load on tool up to a maximum value. Beyond this point, the material removal decreases with the increasing static load. 3) Abrasive material, size -   The characteristics of abrasive like size, shape hardness, etc. are effects its cutting efficiency. The increase in grain size increases the material removal rate till grain size equal to the amplitude of vibration. Beyond this, the increase in grain size decreases the cutting rate.

11. 4) Slurry composition and property - The composition of slurry, the concentration of abrasive particle in slurry and  viscosity  of slurry effects the material removal rate. The abrasive grit worn out rapidly, so periodic replacement of slurry is required. Since the viscosity of slurry dampens the oscillation of grits, the material removal rate decreases as the viscosity increases. 5) Workpiece material and machining area and shape - The material removal rate depends on the characteristics of workpiece material like hardness, brittleness, etc. The shape depth of cut required also effects machining rate.

12. Advantages This process is used for drilling both circular and non-circular holes in very hard materials like carbide, ceramics, etc. This process is best suited for brittle materials. The machining operation is simple and requires less time. This process is economical. It is suitable for both conductive and non conductive  materials.  ​ A semi skilled operator can operate the machine. ​ Ultrasonic machining doesn’t require heating workpiece. If a workpiece is sensitive to thermal fluctuations it can be safely machined ​. High accuracy can be achieved.

13. Limitations The metal removal is slow due to micro chipping or erosion mechanism. The wear of sonotrode tip occurs more quickly. The machining of deep holes is not easy by this method because of the inability of abrasive slurry to flow at the bottom of the hole (Except rotary ultrasonic machining). Ultrasonic vibration machining can be used only to machine materials that have hardness value atleast 45 HRC. Low material cutting rate. High power consumption. Low penetration rate. The process is limited to the machined surface of a small size. Shorter tool life.

14. Applications 1) ​ Step Drilling 2)Grinding the brittle materials

15. 3) Threading 4) Engraving

16. 5) Machining glasses and ceramics 6)Slicing and Broaching hard materials

17. Reference https://www.youtube.com/watch?v=f9u8EnLM2X0 ​ https://www.youtube.com/watch?v=5w6szZtOg5w​ ​ https://www.youtube.com/watch?v=qVcwT0FfAIc ​​ https://www.youtube.com/watch?v=UyK7Ph6yosk ​​ https://www.youtube.com/watch?v=HTtnAXrzD4w ​ ​ The reference Youtube links of Ultrasonic Machining is given below-