Abrasive Jet Machining ( AJM ) Fig : Schematic illustration of Abrasive Jet Machining 1. AJM is a metal removal by mechanical erosion caused by the use of a high speed stream of abrasive particles carried by a high pressure gas or air, impinging / impacting, through a shaped nozzle on to the work piece

Abrasive Jet Machining ( AJM ) 2. The filtered gas is supplied under a pressure of 2 to 8 kg/cm 2 to the mixing chamber containing the abrasive powder and chamber is vibrating at 50 Hz. 3. This abrasive and gas mixtures comes out of convergent nozzle at high speed of 150 to 300 m/min in the form of a jet. With repeated impact of jet, small bits of material gets loosened and material removal takes place.

Abrasive Jet Machining ( AJM ) Disadvantages : Material removal rate is low Abrasive powder cannot be reused Machining accuracy is poor Nozzle wear rate is high Abrasive particle : Al 2 O 3, SiC Usually performed manually by operator who directs nozzle Applications : Normally used as a finishing process rather than cutting process Used for trimming, cleaning, polishing Work materials : thin flat stock of hard, brittle materials Advantages : Very less heat generation Low capital cost

Water Jet Machining / Water jet cutting

Stand off distance : distance between nozzle tip and work piece = 0.5 mm to 1.5 mm Exit velocity of water jet = 920 m /s Water pressure = M pa

1.Thin jet of high pressure and high velocity is used to machined work piece. Water jet ( with or without abrasives ) can be used for machining. 2. Water is sent to intensifier where intensifier raises pressure of water further. From the pump/intensifier, water goes to an hydraulic accumulator. 3. Hydraulic accumulator acts as an energy reservoir, since the cutting action may not be continuous. During the idle periods, energy is stored in the accumulator and given out only during machining. From the accumulator, the water goes to nozzle through tube. 4.When high pressure water jet emerges out of a orifice of a nozzle, it attains a large kinetic energy. When this high velocity jet strikes the work piece, its kinetic energy is converted into pressure energy inducing high stress in the work material. When this induced stress exceeds the ultimate shear stress of the material, erosion occurs. Water Jet Machining Water Jet Machining ( WJM )

Water Jet and Abrasive Water Jet Cutting Nozzle blast during cutting

Water Jets & Abrasive Water Jets Water jets are used for soft material Abrasive water jets for hard material An abrasive element is added to the water beam to assist cutting Abrasive Water Jet Nozzle Diagram

Water Jets & Abrasive Water Jets Abrasive Water-Jet Machining

Water Jets & Abrasive Water Jets Water Jet Machinable Materials –Soft rubber, foam, tin foil, carpet, soft gasket material Abrasive Water Jet Machinable Materials –Titanium, aluminum, hard rubber, hardened tool steel

Water Jet Machining Process

Cutting under water to reduce noise and splash.

Water Jet Machining : Water Jet Machining : Pure Water Applications:

Abrasive Water jet and Water jet Part Ceramic part cut with an abrasive water jet Applications:

Advantages of Water Jets Cuts all sorts of material with a single tool Minimum heat generation, material properties unaffected (unlike most other machining equipment) Makes it own start holes (unlike Electro Discharge Machining ) Smooth finish Cheaper than most machining options Programmable systems make accurate shapes with very good tolerances (+/ inches) Disadvantages of Water Jets Tolerances deteriorate with material hardness and thickness Abrasive water jet nozzles are subject to heavy wear hence increasing the maintenance cost