SHRI S’AD VIDYA MANDAL INSTITUTE OF TECHNOLOGY

PREPARED BY:- PRAJAPATI URVESH

MANANI JAY

MISTRY JAYKISHAN

CHANDEL VIPUL

DEPARTMENT:- MECHANICAL-C

SEMESTER:- 3rd SEM

PRESENTATION ONDESTRUCTIVE TEST

CONTENTS

1. What is the Destructive Test.

2. Types of Destructive Test.

3. Description of types

1. What is Destructive Test

As the name suggests, destructive testing (DT) includes methods where your material is broken down in order to determine mechanical properties, such as strength, toughness and hardness. In practice it means, for example, finding out if the quality of a weld is good enough to withstand extreme pressure or to verify the properties of a material.

DESTRUCTIVE TEST

z

The types of Destructive are as follows;

a) Tensile Testing

b) Bend Testing

c) Impact Testing

d) Nick Break Testing

e) Hardness Testing

a) TENSILE TEST

• Tensile testing, also known as tension testing, is a fundamental materials science test in which a sample is subjected to a controlled tension until failure.

• The results from the test are commonly used to select a material for an application, for quality control, and to predict how a material will react under other types of forces.

• Properties that are directly measured via a tensile test are ultimate tensile strength, maximum elongation and reduction in area.

• For composite materials and textiles, biaxial tensile testing is required.

TENSILE TEST

b) BEND TEST

• Bending tests are carried out to ensure that a metal has sufficient ductility to stand bending without fracturing.

• A standard specimen is bent through a specified arc and in the case of strip, the direction of grain flow is noted and whether the bend is with or across the grain. 

• Bend testing provides insight into the modulus of elasticity and the bending strength or a material.

• Metallurgical offers three and four point bend setups with interchangeable rollers for a variety of test configurations. 

BEND TEST

c) IMPACT TEST

• Test of the ability of a material to withstand impact, used by engineers to predict its behaviour under actual conditions.

• Many materials fail suddenly under impact, at flaws, cracks, or notches.

• The most common impact tests use a swinging pendulum to strike a notched bar; heights before and after impact are used to compute the energy required to fracture the bar.

It has two types.

Charpy test.

Izod test.

Charpy test:-

In the Charpy test, the test piece is held horizontally between two vertical bars, much like the lintel over a door.

Izod test:-

In the Izod test, the specimen stands erect, like a fence post. 

ELEMENTS OF MOTION TRANSMISSION

6. Control elements In CNC m/c the control of all m/c functions is totally transferred to a computerized control system.

The control unit should be suited so that it is convenient for the operator to operate the m/c from the central place.

The facilities which a control unit should offer are:

• Indicate the current status & position of various m/c tool features & give feedback.

• Allow manual or semi-manual control of m/c tool elements.

• Enable m/c tool to be programmed.

The control unit part for allowing manual control & programming of the m/c may be housed on the m/c structure itself or separate control panel may be installed near the m/c.

7. Tool & work holding device

In general, a work holding device for CNC applications should have the following features:-

• It should restrict the linear & rotary motion of components.

• The component should not distort or deflect due to cutting forces in the process.

• It should quick facilitate quick loading & unloading of component.

• It should be fool proof.

• It should not interfere with the cutting tool.

• It should provide for easy removal of chips.

• It should be adaptable to automated loading/unloading of components.

• It should be safe.

TOOL & WORK HOLDING DEVICE

Automatic Tool Changer (ATC)

On the machining centers, ATC are provided to reduce the idle time between change from operation another.

The tool already fitted on the spindle is removed & replaced in the tool magazine

The tool change cycle consist of two parts:

a. Tool selection cycle

b. Tool transfer cycle

AUTOMATIC TOOL CHANGER (ATC)

8. Swarf removal Since the cutting time is much more in CNC m/c, the volume of swarf generated is also more.

Unless the swarf is quickly quality of the finished product. Also the swarf can’t be allowed to accumulate at the m/c tool because it may hamper the access to the m/c tool.

In addition some auxiliary functions like automatic component loading or automatic tool change may also be affected by accumulation of swarf.

To avoid these problem an efficient swarf control system should be provided with the CNC m/c tools with some mechanism to remove the swarf from the cutter & cutting zone & for the disposal of swarf from the m/c tool area itself.

SWARF REMOVAL