Screw Wire Guage Screw Wire GuageWIRING CHAPTER.pptx

Screw Wire Guage

1. ABOUT MYSELF INTRODUCTION NAME : AKASH SHARMA Adm no: 6660 Batch: II ELECTRICIAN CITS NSTI VIDYANAGAR HYDERABAD

2. Screw Guage (Micrometer) Screw gauge is a mechanical tool that allows precise measurement of the diameter, radius, or thickness of a thin wire or a thin metal sheet.  It is also known as a  micrometer screw gauge .

3. What is Screw Gauge ? Screw gauge is a measuring instrument made out of a calibrated screw used to measure small objects' dimensions. A screw gauge is a type of meteorological instrument used in machining, and mechanical engineering. A screw gauge is used for the precise measurement of thin wires and sheets. It consists of two scales: a  Pitch Scale  and a  Circular Scale .  Pitch scale  is the main scale that measures the distance traveled by the spindle per revolution (in millimeters). It is engraved with vertical lines on the barrel of the instrument. Circular scale  is horizontally engraved on the thimble. A revolution of the circular scale is equivalent to about half a millimeter of screw displacement. Total Screw Gauge Reading = Pitch Scale Reading + Circular Scale Reading x Least Count of the gauge

4. Working Principle of Screw Gauge Screw gauge operates on the principle of a screw. The screw gauge formula measures the rotation of the screw, thereby converting smaller distances into larger ones. Two parameters are used for screw gauge measurement – pitch and least count. The ratio of the moved distance to the number of rotations is known as the  pitch  of the screw gauge. The ratio of pitch to the total number of divisions that is there on the circular scale is known as the  screw gauge least count .

5. The main elements of a screw gauge are: Screw :  This is the screw gauge's key component that aids in measurement. Anvil :  The spindle is moved towards the object to be measured that is put on the anvil. Spindle :  The spindle will travel towards the anvil as the thimble is rotated. Thimble :  This is the rotating portion of the screw gauge. Thimble lock:  This element can be tightened to keep the spindle in position while measuring. It's sometimes referred to as a lock-nut or a lock-ring. Ratchet stop:  It's utilized to keep the thimble from rotating any further than it needs to. Barrel/Main Scale:  It's also known as a sleeve or stock, and it's a stationary component with linear or vernier markings on it as seen in the screw gauge diagram. The barrel of some screw gauge versions is a rotatable cylinder, which allows for zero value by adjusting the cylindrical barrel.

6. A differential screw is a crucial component of an analog screw gauge that enables small magnitudes. These screws have several threads, each corresponding to axial movement when spun one at a time. That is, each 360 degrees spin of the screw spans a minimal axial distance. This distance is referred to as the screw's lead or  pitch  of the screw gauge. Even if the object to be measured is tiny, the size of the thing can be determined by turning the thimble, which rotates the screw. The minute dimension is transformed into more extensive rotations that are much easier to comprehend. The dimension of the wire measured is displayed on an LCD screen in digital screw gauges.

7. Uses of Screw Gauge There are various uses of screw gauge which are as follows: With an accuracy of 0.001cm, a screw gauge is used to measure the diameter of circular objects, primarily wires. The radius of wires and other circular objects can be found using a screw gauge. A screw gauge is also used to determine the thickness of a piece of paper. Metal sheet and glass slab thickness can be identified using a screw gauge. Uniform thickness of any shape can be found using a screw gauge. 

8. Screw Gauge Measurement Using Micrometer The screw gauge measurement through a micrometer can be done using the screw gauge formula.   The following steps can be implemented to record the measurement: Clean the anvil and the spindle:  Take a clean cloth or paper and place it between the spindle and the anvil. Tighten the setup slightly until the paper or cloth becomes stuck, then pull it out while cleaning the setup. This step aids in obtaining an exact measurement. Place the object between the spindle and anvil:  Carefully place the thing between the anvil and the spindle. As the anvil is stationary, put the object that is to be measured against it. The object should be appropriately positioned so that it does not move while the measurements are taken. Rotate the ratchet counterclockwise to tighten it:  Make sure the thimbles' zero is parallel to the scale's line on the sleeve. Tighten the spindle with the object in the middle:  When you rotate the thimble, it clicks. Increase effort until it clicks three times. Lock the thimble:  While the object is in the middle, lock the thimble. The spindle can be moved even though the thimble is closed. This will help you get the precise measurement. Take the object out:  Carefully take out the object without compromising the accuracy of the screw gauge. Note the reading:  Before you unlock the spindle of the screw gauge, note the reading on it as seen in the screw gauge diagram.

9. Screw Gauge Measurement Example Let’s assume a screw gauge with the least count of 0.01 mm. What is its total reading ? Solution:  The main scale reading is 2.5 mm and the circular scale reading is 38. Thus, the total reading = MSR + CSR x LC = 2.5 + 38 x 0.01 = 2.5 + 0.38 =  2.88 mm