ABSTRACT Abrasive Jet Machining (AJM) or Micro Blast Machining is a non-traditional machining process, wherein material removal is effected by the erosive action of a high velocity jet of a gas, carrying fine-grained abrasive particles, impacting the work surface. The process is particularly suitable to cut intricate shapes in hard and brittle materials which are sensitive to heat and have a tendency to chip easily. As Abrasive jet machining (AJM) is similar to sand blasting and effectively removes hard and brittle materials. AJM has been applied to rough working such as debarring and rough finishing. With the increase of needs for machining of ceramics, semiconductors, electronic devices and L.C.D., AJM has become a useful technique for micromachining. Our project report deals with various experiments which were conducted to assess the influence of abrasive jet machining (AJM) process parameters on material removal rate and diameter of holes of glass plates using various types of abrasive particles. The experimental results of the present work are used to discuss the validity of proposed model as well as the other models. With the increase in nozzle tip distance (NTD), the top surface diameter and bottom surface diameter of hole increases as it is in general observation of abrasive jet machining process. As the pressure increases, the material removal rate (MRR) is also increased. The present study has been introduced a mathematical model and the obtained results have been compared with that obtained from the theoretical.
Fig.2.6 Effect Of Nozzle Tip Distance (NTD) On Diameter Of Hole The effect of SOD or NTD on material removal rate (MRR) is shown in fig.2.7 as the NTD increases the diameter of hole increases which is general observation in abrasive jet machining. Fig.2.7 Effect Of Nozzle Tip Distance (NTD) On Material Removal Rate The effect of abrasive flow rate (AMF) on material removal rate (MRR) is shown in Fig.2.8 as the abrasive massflow rate increases the material removal rate (MRR) increase which is also general observation in abrasive jet machining. Fig.2.8 Effect Of Abrasive Mass Flow Rate And Mixing Ratio On Material Removal Rate (MRR) The effects of standoffdistance on MRR and penetration rates have been reported by Ingulli, Sarkar and Pandey, VermaandLal. These investigations indicate that after a threshold pressure, the MRR and penetration rates increase with nozzle pressure. For brittle materials, normal impingement results maximum MRR and for ductile materials, an impingement angle of 15-20 degrees results in maximum MRR. The effects of abrasive grit size and mixing ratio which is the ratio of the weight of the abrasive powder to the weight of the abrasive powder and the air have been thoroughly investigated by many investigators. As the abrasive grit size and mixing ratio increase, the MRR and penetration rate increase but the surfaces finish value which is measured in Ra decreases. Fig.2.9 Graph Shows TheRelationship Between Pressure And Material Removal Rate (MRR) At Thickness 8 mm And NTD 12 mm
CHAPTER 4: EXPECTED OUTCOMES AND FUTURE SCOPE 4.1 Expected Outcomes We will be investigate the various process parameters of AJM by using different types of work material and abrasives by changing the other parameters of AJM like pressure, Nozzle tip distance, size of abrasive grains. From that we can decide the most appropriate condition for Material Removal Rate (MRR). 4.2 Future Scope It is very clear that AJM is greater Non-conventional machining process which is used as a multipurpose system. It is also a most effective among various affordable systems. This system is eco-friendly. Even some of the companies in India like ABB, L & T and ESSAR are already using this system with CNC programming. This system is also use as Water Jet Machining (WJM) in whichabrasives such as garnet, diamond or powders can be mixed into the water to make slurry with better cutting properties than straight water. Further development in WJM is called Hydrodynamic Jet Machining (HJM) which combines the principle of Water Jet Machining and Abrasive Jet Machining process. AJM is also used as Abrasive Flow Machining (AFM), Ultrasonic Machining (USM).