What is engineering tolerance? Types of mounting engineering tolerances

Mechanical manufacturing is an industry that requires high precision; the details must conform to standard engineering tolerances. So what is engineering tolerance. For more information on engineering tolerances, see the article below.

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What is engineering tolerance

Engineering tolerance is the allowable tolerance range, depending on the value of each product. The engineering tolerance value is equal to the difference between the maximum limit size and the minimum limit size; in other words, it is equal to the algebraic difference between the upper limit deviation and the lower limit deviation.

Things to know about engineering tolerances

On the detailed drawing, the designer writes the nominal size and then the engineering tolerance size behind; the upper limit deviation is recorded above, and the lower limit deviation is recorded below.

For special metal products, it should be noted that the product’s expansion is very sensitive to temperature, such as iron, steel, cast iron, stainless steel, etc. Measuring and checking the dimensions of the product within permissible tolerances shall be carried out at the standard temperature. In the precision mechanical processing industry, because the error is so small that it cannot be seen with the naked eye, you need to use measuring tools and equipment.

Thus, during the machining process, the worker will judge the size of the part to be processed based on his experience with the material and the ambient temperature.

Engineering tolerance is one of the important criteria to evaluate whether the part is satisfactory or not. This means that this is the tolerance range allowed when machining a particular product. Conversely, if the measured dimensions exceed the allowable tolerances, the product is unsatisfactory.

How much engineering tolerance is allowed depends on the drawing requirements or the party requesting the production of the product. Large or small tolerance does not depend on the fixed factor. Therefore, when processing, manufacturing products must pay attention to tolerances to check whether the product conforms to the standard or not.

Current types of mounting tolerances

During assembly, parts are fixed (screws, nuts, and bolts) or movable (pistons) to form joints. Surfaces used to assemble individual parts are called mounting surfaces. Assembly may result in errors. Currently, people have divided mounting tolerances into two types: keyed mounting tolerances and keyed mounting tolerances.

The assembly tolerance

Keyed tolerances are very common for fastening shaft components such as gears, pulleys, crankshafts, etc. and are used to transmit torque or give precise guidance when parts need to be moved. along the vertical axis. Then there are many types: equal, semicircle, etc.

Tolerance for mounting bolts

In particular, when it is necessary to transmit a large torque and require high precision between the shaft and the bearing, the key joint cannot be used. We must use the key joint. There are many types of keyed lips: rectangular teeth, trapezoidal teeth, triangular teeth, etc.

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How to limit errors in machining and assembly

In order for the measurement to be accurate, the manufacturer must consider the methods that can be used to limit errors. In fact, error detection is relatively complicated. Therefore, to overcome large errors that may affect the functional performance of the product, it is necessary to:

• Prepare carefully before measuring: Use a high-precision measuring machine to measure the part to be machined and check the accuracy of the machine part and coordinate system before measuring.
• Take multiple measurements to check the results for deviations.
• Processing results after measuring: It is necessary to use the method of compensation for opposites to make the product size more accurate.

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Hopefully, through the article, you can understand “What is engineering tolerance”. For useful information, do not miss the articles in The Tech. The Tech is a reliable supplier of electronic components, welding materials, etc.; if you have any questions, please contact us for the best advice!