Fabrication

Action or process of manufacturing or inventing something

CNC MACHINE

CNC Machining is a process used in the manufacturing sector that involves the use of computers to control machine tools. Tools that can be controlled in this manner include lathes, mills, routers and grinders. The CNC in CNC Machining stands for Computer Numerical Control.

On the surface, it may look like a normal PC controls the machines, but the computer’s unique software and control console are what really sets the system apart for use in CNC machining.

Under CNC Machining, machine tools function through numerical control. A computer program is customized for an object and the machines are programmed with CNC machining language (called G-code) that essentially controls all features like feed rate, coordination, location and speeds. With CNC machining, the computer can control exact positioning and velocity.

First a CAD drawing is created (either 2D or 3D), and then a code is created that the CNC machine will understand. The program is loaded and finally an operator runs a test of the program to ensure there are no problems. This trial run is referred to as “cutting air” and it is an important step because any mistake with speed and tool position could result in a scraped part or a damaged machine.

There are many advantages to using CNC Machining. The process is more precise than manual machining, and can be repeated in exactly the same manner over and over again. Because of the precision possible with CNC Machining, this process can produce complex shapes that would be almost impossible to achieve with manual machining. CNC Machining is used in the production of many complex three-dimensional shapes. It is because of these qualities that CNC Machining is used in jobs that need a high level of precision or very repetitive tasks

WATERJET MACHINE

Working of Water Jet Machining (WJM):

  • Water from the reservoir is pumped to the intensifier using a hydraulic pump.
  • The intensifier increases the pressure of the water to the required level. Usually, the water is pressurized to 200 to 400 MPa.
  • Pressurized water is then sent to the accumulator. The accumulator temporarily stores the pressurized water.
  • Pressurized water then enters the nozzle by passing through the control valve and flow regulator.
  • Control valve controls the direction of water and limits the pressure of water under permissible limits.
  • Flow regulator regulates and controls the flow rate of water.
  • Pressurized water finally enters the nozzle. Here, it expands with a tremendous increase in its kinetic energy. High velocity water jet is produced by the nozzle.
  • When this water jet strikes the workpiece, stresses are induced. These stresses are used to remove material from the workpiece.
  • The water used in water jet machining may or may not be used with stabilizers. Stabilizers are substances that improve the quality of water jet by preventing its fragmentation.
 

Advantages of Water Jet Machining:

  1. Water jet machining is a relatively fast process.
  2. It prevents the formation of heat affected zones on the workpiece.
  3. It automatically cleans the surface of the workpiece.
  4. Excellent precision. Tolerances of the order of ±0.005iches can be obtained.
  5. It does not produce any hazardous gas.
  6. It is eco-friendly.

Basic Components and Operation:

High Pressure Pump 1 :

The pump generates a flow of pressurized water for the cutting process.

Articulated Cutting Head 2 :

As an add-on option to OMAX waterjets, this computer-controlled multi-axes cutting head permits angled cuts and can be used to automatically minimize taper for precise vertical cuts.

Abrasive Waterjet Nozzle 3 :

Inside the nozzle the pressurized water passes through a small-diameter orifice and forms a coherent jet of water. The jet then passes through a venturi section where a metered amount of granular abrasive is drawn into the water stream. The mixture of water and abrasive particles passes through a special ceramic mixing tube and the resulting abrasive/water slurry exits the nozzle as a coherent cutting stream of abrasive particles travelling at very high speed.

Catcher Tank 4 :

The water-filled catcher tank dissipates the energy of the abrasive het after it has cut through the material being machined.

Abrasive Hopper 5 :

The abrasive hopper and associated abrasive flow control system provide a metered flow of granular abrasive to the nozzle.

X-Y Traverse System 6 :

A precision X-Y motion system is used to accurately move the nozzle to create the desired cutting path.

PC-based Controller 7 :

Advanced motion controllers for abrasive waterjet systems are PC-based and permit production of accurate parts with minimal operator experience