ABRASIVE JET MACHINING Prepared by B.BALAMURALI AP/MECH SNS COLLEGE OF ENGINEERING, COIMBATORE- 641 107.   DEPARTMENT OF MECHANICAL ENGINEERING   ABRASIVE JET MACHINING Prepared by B.BALAMURALI AP/MECH ME 6004- UMP / TOPIC-7 SNSCEME PRESENTATION

Factors considered for selection of process. RECAP Factors considered for selection of process. ME 6004- UMP / TOPIC-7 SNSCEME PRESENTATION

ABRASIVE JET MACHINING The mechanism of material removal is erosion or chipping action. The jet of inert gas and abrasive particles strike the work piece at high velocity (150-300 m/s). This can be employed for cutting, cleaning, etching, polishing, deburring and trimming. ME 6004- UMP / TOPIC-7

WORKING OF AJM ME 6004- UMP / TOPIC-7

WORKING OF AJM Gases like dry air, N2,CO2,helium are compressed to the pressure range of 0.2 to 1.4 Mpa before entering into the mixing chamber. Abrasive particles are sent to the mixing chamber. The proper mixing of gas with abrasives are ensured by inducing vibration to the mixing chamber through the vibrator. The gas abrasive mixture propels through the to nozzle orifice of diameter 0.075 to 1.0 mm at velocities of 200 -300 m/s. ME 6004- UMP / TOPIC-7

WORKING OF AJM Distance of the range 0.25 – 0.75mm is maintained between the nozzle tip and work surface which is named as standoff distance (or) Nozzle tip distance. The jet of gas-abrasive particles which is coming out from the nozzle strikes the work surface at high velocity ,erodes the material from the work piece. The process is usually performed manually by an operator who directs the nozzle at the work surface. ME 6004- UMP / TOPIC-7

ACTIVITY!!! DUBBING…………….. ME 6004- UMP / TOPIC-7

Hopper or Abrasive feeder Nozzle Abrasives Mixing Chamber ELEMENTS OF AJM Gas propulsion system Hopper or Abrasive feeder Nozzle Abrasives Mixing Chamber Machining Chamber ME 6004- UMP / TOPIC-7

ELEMENTS OF AJM Gas propulsion system - Dry air,N2,CO2,helium Hopper or Abrasive feeder - Control the quantity of abrasive particles Nozzle - Circular or rectangular cross section - Tungsten carbide(WC) -12 to 20 hours /Synthetic sapphire- Aluminium oxide (Al2O3) – 300 hours ME 6004- UMP / TOPIC-7

ELEMENTS OF AJM Abrasives - Hard & Brittle materials - Al2O3, Silicon carbide (SiC), Dolomite, glass beads, Crushed glass, Sodium bi carbonate. Type of Abrasive Recommended size Purpose Aluminium Oxide 10,25,50 microns Cleaning, cutting, Deburring Silicon carbide 25 microns Faster cutting of hard material Dolomite 200 microns Cleaning & etching Glass beads 0.3 – 0.6 mm diameter Polishing & Deburring Sodium bi carbonate Cleaning, cutting, Deburring of soft materials ME 6004- UMP / TOPIC-7

ELEMENTS OF AJM Mixing Chamber - Vibrator is provided at the bottom of the mixing chamber to ensure proper mixing of abrasive particles with air. Machining Chamber - Stand off distance is maintained @ 0.8mm (approx.) - If toxic material (beryllium) is machined ,special attention is given to dust collection system. ME 6004- UMP / TOPIC-7

NAME THE PARTS OF AJM ME 6004- UMP / TOPIC-7

ME 6004- UMP / TOPIC-7