Types of Chips | Chips That are Formed During Machining

TYPES OF CHIPS

There are three types of chips:

01 - Types of chip - chip formation

1. CONTINUOUS CHIP

During cutting of ductile materials, a continuous chip is produced due to the presence of tool cutting edge in compression and shear. These types of chip are in the form of long coil and have the same thickness throughout the length.

This type of chip is required, since it gives a good surface finish, improving the tool life and less power consumption. However, chip disposal is not easy and the surface finish of the finished work gets affected.

The following condition favours the formation of continuous chips.

1. Smaller depth of cut.

2. High cutting speed.

3. Large rake angle.

4. Proper cutting fluid.

5. Low friction between tool face and the chips.

2. DISCONTINUOUS CHIP OR SEGMENTAL CHIP

Discontinuous chip are as shown in the figure, which are produced while machining brittle materials such as grey cast iron, bronze, high carbon steel at low cutting speed without fluids when friction exists between the tool and chip.

During machining, the brittle materials lack its density which is necessary for plastic chip formation. But, it should be less. This will result in formation of discontinuous chip. In continuous chip formation the shearing occurs at head of cutting tool continuously without fracture whereas in discontinuous chip formation, intermittently rupture occur which will produce segment of chips.

Handling of these chips is easier and it can be easily disposed off, since they are having small length. Also , it will not spoil the finished work piece surface as they do not interfere.

The following condition favours the formation of discontinuous chips.

1. Machining of brittle materials.

2. Small rake angle.

3. Higher depth of cut.

4. Low cutting speed.

5. Excess cutting fluid.

6. Cutting ductile material at very low feeds with small rake angle of the tool.

3. CONTINUOUS CHIP WITH BUILT-UP EDGE

During cutting process, the interface temperature and pressure are quite high and between tool-chip interface the friction is also high. It causes the chip material to weld itself to tool face near the nose as shown in the figure. This is called “built-up edges”.

Formation of built-up edges in continuous chip is a transient and not steady phenomenon. The collected built-up of chip material will then break away, part adhering to the undesired of the chip and part to the work piece. Thus, the process will result in a poor surface finish on the machined surface and accelerated wear on the tool face.

However, this type of chip having some advantage, the one important favour of it is that, from the wears the rake face of the tool is protected due to moving chip and the action of heat. It may result in the increasing of tool life.

The following condition favours the formation of continuous chip with built-up edges.

1. Low cutting speed.

2. Small rake angle.

3. Coarse feed.

4. Large uncut thickness.

5. Insufficient cutting fluid.

Ultrasonic Machining Process | Application of Ultrasonic in Industries

ULTRASONIC DRILLING PROCESS

       Ultrasonic waves are used for making holes in very hard materials (eg. glass, diamond). a powerful ultrasonic generator is fitted with a drill bit and used for this purpose.

       A thin fluidic paste of carborundum powder and water is made to flow between the drill bit and plate in which the hole is to be made.

01 - ULTRASONIC DRILLING PROCESS - USE OF ULTRASONIC IN METAL CUTTING PROCESS

       Ultrasonic generator causes tool bit to vibrate rapidly and gives momentum to the slurry. The material is removed from the plate by the slurry particles below the drill bit. By this technique a hole is drilled on the hard material.

ADVANTAGES

· Brittle material can also be used for drilling process.

· Final finishing is not required after drilling process.

· It is a noise less operation

· A hole of any shape can be made.

· Low cost operation.

ULTRASONIC WELDING

       Some materials change their properties when heated so they cannot be welded by conventional electric or gas welding. In those conditions ultrasonic is used to weld the metal pieces at room temperature. A hammer is attached to a powerful ultrasonic generator. The metallic sheets which are to be welded are placed under the tip of the hammer. This hammer is made to vibrate in a very high frequency.

01 - ULTRASONIC WELDING - PROCESS OF ULTRASONIC WELDING

         As a result of high frequency vibration it presses the two metallic sheets rapidly and the makes the molecule of one meta to collide with the molecule of another metal. This makes the molecule to diffuse. So the metallic sheets are welded without using the heat. This process is also called as cold welding process.

ADVANTAGES

1. It does not require any additional welding material.

2. The process is very safe and fast.

3. No fumes and flames are produced

4. The process is noiseless operation.

5. Its cost is low.

ULTRASONIC SOLDERING

          Metals like Aluminium cannot be directly soldered without usi ng flux. However, it is possible to solder such metals by ultrasonic waves.

01 - ultrasonic soldering - ultrasonic in mechanica engineering

           An ultrasonic soldering iron consists of an ultrasonic generator with a tip fixed at the end. The tip is heated individually by an electrical heating element.

         During the working process, the tip of the iron melts the solder on aluminium and the ultrasonic vibrator removes the aluminium oxide layer. Now, the solder gets joined to clear metal without any difficulty.

ADVANTAGES

1. This process does not require any flux.

2. Since the flux is not used, the flame is not produced.

3. It is very safe and fast process

4. It’s cost is less.

ULTROSONIC CLEANING

        Ultrasonic cleaning setup is shown in the picture. It consists of a transducer attached to the bottom of a tank.

01 - ultrasonic cleaning - ultrasonic washing

       The object to be washed is immersed in a detergent cleaning solution in the tank. The ultrasonic waves are produced in the fluid by the transducer. Now the bubbles are formed due to cavitation. These bubbles get collapse at a tremendous rate.

01 - ultrasonic cleaning process - ultrasonic washing

      The high energy ultrasonic waves acts on the impurities in the object and removes them from it. Thus, the object is cleaned.

ADVANTAGES

1. It is the cheapest technique for cleaning.

2. The various part of machine, electronic components can be cleaned.

3. The smaller parts can be cleaned in an efficient manner.