What is manufacturing?
Simply, Manufacturing is the making of goods by hand or by machine. Items used in manufacture may be raw materials or component parts of a larger product. The manufacturing usually happens on a large-scale production line of machinery and skilled labour.
Manufacturing process are the steps through which raw materials are transformed into a final product. The manufacturing process begins with the product design and materials specification from which the product is made. These materials are then modified through manufacturing processes to become the required part.
- Labeling and Painting
- Addictive manufacturing
Mainly above process are done on raw materials or components to create final products. Above each processes have their own steps to follow. Product quality management and safety precautions should be followed while during these processes.
Before starting discussion about these manufacturing processes there is another topic to be discussed. That’s measuring instruments. Measuring instruments play a major role in manufacturing part. Because all the manufactured products are created under analyzed measurements and also under universal standard measurements. So all of us have to aware about measuring instruments very well.
Measuring is very important in Manufacturing. Most products are manufactured to standard sizes and shapes. Standardization is a necessity for interchangeable parts and is also important for economic reasons. Products are inspected either during/ after manufacture either manually or automatically. Inspection of products/items can be done in two ways.
- By attributes: In manufacturing, particularly in mass production it may not be necessary to know the exact dimensions of a part, only that it within previously established limits. Limits can often be determined more easily than specific dimensions by the use of attributes type instruments called gauges. Gauging is the term for determining whether the dimension is larger or smaller than the established standard or range of acceptability. Gauges can be used for both linear and angular dimensions and can be used manually or automatically
- E.g.: Plug gauges, Ring gauges, Thread gauges, Radius gauges
- By variables: Use of calibrated instruments to determine the actual dimensions of the product for comparison with the size desired.
- E.g.: Vernier callipers, micrometre screw gauges etc.
Variable types of inspection generally take more time and are more expensive than attribute inspection but they give more information because the magnitude of the character is known in some standard unit of measurements
Linear measuring instruments
- Direct reading:- Object being measured can be read directly on this scale
- E.g.: Ruler, Vernier calliper, Micrometer screw gauge
- Indirect reading:- Used to transfer the size of the dimension being measured to a direct reading scale thus obtaining the desired size and information indirectly.
- E.g.: Calipers
Linear Measurement (Direct reading)
- Simplest and most commonly use for making linear measurements.
2. Vernier Caliper
- Consists of a graduated beam and a sliding jaw with a Vernier
- Available in various sizes
- Can be used to measure outside diameters, inside diameters and depth measurements.
- Least count: – The least distance, which can be measured by Vernier callipers.
- When the jaws are closed, the Vernier zero mark should coincide with the zero mark of the main scale. If the Vernier zero mark should not coincide with the zero mark of the main scale, is said to have a zero error. If the zero mark of the Vernier scale is on the right of the zero mark of the main scale then the zero error is reduced from the observed reading to obtain the actual reading. If it is on the left of the zero mark of the main scale then the error is added to the observed reading.
- Observed reading = Main scale reading + Vernier scale reading ± zero error
3. Micrometer screw gauge
The micrometre screw gauge is used to measure even smaller dimensions than the vernier callipers. The micrometre screw gauge also uses an auxiliary scale (measuring hundredths of a millimetre), which is marked on a rotary thimble. It is a screw with an accurately constant pitch (the amount by which the thimble moves forward or backward for one complete revolution). The jaws can be adjusted by rotating the thimble using the small ratchet knob. This includes a friction “clutch” which prevents too much tension being applied. To measure an object, the object is placed between the jaws and the thimble is rotated using the ratchet until the object is secured.
Note that the ratchet knob must be used to secure the object firmly between the jaws, otherwise the instrument could be damaged or give an inconsistent reading. The lock may be used to ensure that the thimble does not rotate while you take the reading.
4. Depth gauge
The depth micrometre is an accurate and reliable tool to use for depth measurement. The depths of holes, slots, shoulders, and projections can be measured accurately. When using a depth micrometre, two points must be kept in mind. Depth micrometres measure from a reference plane to a point. The large base of the depth micrometre makes up the reference plane. The very small area of the measuring rod makes up the point of contact. Measuring distance is from the reference plane to the contact point.
5. Height gauge
Linear measurement (Indirect reading)
For this kind of linear measurements, firstly the readings are taken to the specially designed tools and then that readings are measured by measuring instruments. This procedure is called as indirect reading.
Generally, each calipers are designed to do a special task. For an example outside spring, calliper is used to get the reading of outside diameters of circles which can’t be measured directly using instruments.
Accurate angle measurements are usually more difficult to make than linear measurements. Angles are measured in degrees and decimal subdivisions of a degree. The primary unit of angular measurement is the degree. There are 360 degrees in a complete circle. Each degree is divided into 60 parts and these parts are known as minutes. Each minute is also divided into 60 parts. These parts are known as seconds.
1. Bevel Protractor
This instrument is contained with two blades which allows to measure angle directly on Vernier scale
2. Sine bar
Sine bar is a bar which has known length. When gauge blocks are placed under one end the height can be measured and the bar is inclined to a specific angle. From those readings, Sin inverse is calculated and that value will be the inclined angle.
Above article gives a basic idea about manufacturing engineering.
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