What are precision machines made of?

　Not familiar with lithography, only talking about mechanical equipment


No matter what kind of processing it is, the precision of the finished product is determined by measurement. When it comes to measuring precision products, one must first explain the principles of gauges and measuring tools.


For example, if we need a workpiece with a length of 10.0+/-0.01mm, how can we ensure the accuracy of this product during processing? Generally speaking, we require that the error of the inspection tool be 10% to 20% of the original error of the workpiece, so we need a "ruler" with an error of 0.001 to 0.002mm. With this ruler, we can know if the workpiece meets the specifications we need, and then leave the ones within the error range, such as scrapped ones and repaired ones, to ultimately obtain the workpiece we want.


But this measuring tool with an error of 0.001~0.002mm should be made with a precision of 0.0001? Isn't this not about striving for excellence


Endless? Of course, this is not feasible. At this point, we need to ask for various principles of proportional expansion to help.


Take a chestnut micrometer from Baidu Baike

According to the principle of spiral motion, when the differential cylinder (also known as the movable graduated cylinder) rotates one revolution, the micrometer screw advances or retreats by a pitch of 0.5 millimeters. In this way, when the differential cylinder rotates by one index, it rotates by 1/50 turn, and the screw moves along the axis by 1/50 × 0.5 mm=0.01 mm, therefore, use a micrometer


Can accurately read values of 0.01 millimeters.


Together, when we divide 0.5mm equally, the error is also divided equally. Assuming 0.5mm has a 0.05mm error (of course, the dial gauge used in actual production)

, which is much more accurate than the error I listed), each small cell is evenly divided into only 0.001mm, through a standardized piece that is close to the size


The calibration is carried out to minimize the errors caused by stacking each small grid in each revolution.


There are many types of proportional expansion like this, and by cleverly expanding the investigation, machinists can then make high-precision things and measuring tools from things with lower precision levels. With these things and measuring tools, we are able to mass produce other industrial products


.


Of course, the principle of spiral motion


It can also be directly used in production, and old-fashioned crank machine tools are based on this principle.


But it's just a mechanical linkage

The method used for measurement is far from enough to achieve the current level of industrial accuracy, thanks to physicists


On the basis of this technology, grating length measurement technology was invented, and the transmission gate is as follows:

Length measurement technology: grating length measurement technology


Simply put, this principle provides us with a natural bisection

If we have a gauge measuring 1 meter long and divide it into n=16238126 (or any number) grids, then the length of each grid is 1/N meter, and the distance of 1 meter is differentiated. Next, any length within 1 meter is just a process of counting grids. Most digital measuring tools use this principle. Similarly, the grating principle is also widely applied to a wide range of CNC equipment


In the direction control of.


With a ruler that uses these principles, the rest is just drawing inferences to select workpieces that meet our requirements. That's all.