ABRASIVE JET MACHINING q WHAT IS ABRASIVE JET

ABRASIVE JET MACHINING

q WHAT IS ABRASIVE JET MACHINING ? v It is the material removal process where the material is removed by high velocity stream of air/gas or water and abrasive mixture. v An abrasive is small, hard particle having sharp edges and an irregular shape. v High velocity jet is aimed at a surface under controller condition.

q COMPONENTS OF ABRASIVE JET v Abrasive delivery system v Control system v Pump v Nozzle v Mixing tube v Motion system MACHINING

1. ABRASIVE DELIVERY SYSTEM Auto abrasive delivery system has the capability of storing abrasive & delivery the abrasive to the bucket. It’s works auto programming system by help of once measuring record & no adjustment or fine tuning system. High sensitive sensor gives extremely reliable & repeatable.

2. CONTROL SYSTEM v The control algorithm that computes exactly how the feed rate should vary for a given geometry in a given material to make a precise part. v The algorithm actually determines desired variation in the feed rate & the tool path to provide an extremely smooth feed rate.

3. PUMP v Crankshaft & intensifier pump are mainly use in the abrasive jet machine. v The intensifier pump was the only pump capable of reliably creating pressures high. v Crankshaft pumps are more efficient than intensifier pumps because they do not require a power robbing hydraulic system ultra high pressure &

4. NOZZLE v All abrasive jet systems use the same basic two stage nozzle. First , water passes through a small diameter jewel orifice to form a narrow jet. v The abrasive particles are accelerated by the moving stream of water & they pass into a long hollow cylindrical ceramic mixing tube. v Generally two type of nozzle use , right angle head & straight head.

Ø FIG. OF NOZZLE

5. MIXING TUBE v The mixing tube is where the abrasive mixes with the high pressure water. v The mixing tube should be replaced when tolerances drop below acceptable levels. v For maximum accuracy , replace the mixing tube more frequently.

6. MOTION SYSTEM v In order to make precision parts , an abrasive jet system must have a precision x-y table and motion control system. v Tables fall into three general categories. ü Floor-mounted gantry systems ü Integrated table/gantry systems ü Floor-mounted cantilever systems

q WORKING PROCESS v High pressure water starts at the pump , and is delivered through special high pressure plumbing to the nozzle. v At the nozzle , abrasive is introduced & as the abrasive/water mixture exits , cutting is performed. v Once the jet has exited the nozzle , the energy is dissipated into the catch tank , which is usually full of water & debris from previous cut.

q FIG. SCHEMATIC DIAGRAM OF AJM

q AJM FEATURES v There are main features of AJM Ø Obtainable tolerances Ø Material to machine Ø Material thickness Ø Accuracy of table Ø Stability of table Ø Control abrasive jet

q MACHINE ASPECTS Around curves Ø Inside corner Ø Feed rate Ø Acceleration Ø Nozzle focus Ø Speed cutting Ø Pump pressure Ø Hardness & thickness Ø Software controlling the motion Ø Power at the nozzle Ø

q TYPES OF ABRASIVE MATERIALS v Different types of abrasive are used in abrasive jet machining like garnet , aluminum oxide , olivine , silica sand , silicon carbide , etc. v Virtually any material can be cut by using abrasive jet machining method , i. e harder materials like titanium to steel. v Abrasive particles must be hard , high toughness, irregular in shape & edges should be sharp

q ADVANTAGES Extremely fast setup & programming Ø No start hole required Ø There is only one tool Ø Low capital cost Ø Less vibration Ø No heat generated in work piece Ø Environmentally friendly Ø

q DISADVANTAGES Low metal removal rate Ø Due to stay cutting accuracy is affected Ø Abrasive powder cannot be reused Ø Tapper is also a problem Ø

q CONCLUSION v The better performance , and the applications represented above statements confirm that ABRASIVE JET MACHINING is continue to expand. v The new software’s used to minimize time and investments , there by making it possible for more manufacturers of precision parts to install AJM centers.