What is matching production?
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When manufacturing hydraulic components, it is common to see references to custom fabrication on the drawings. What exactly does custom fabrication mean? Is it still necessary to develop a processing technique now?
Generally, the holes are machined first, followed by the pins, which are often machined in conjunction with the holes.
Generally, it involves two parts that need to fit together; one part is manufactured first, and the other is made to fit with it, and this manufacturing method is called matching production.
Primarily to ensure proper fit, the locations of the openings should be the same on the mating parts, so as to avoid failure to install them!
Generally, the purpose of such matching is to achieve a fairly high level of fitting or positioning accuracy without having to exert excessive effort. Its disadvantage is that they are not interchangeable. 1. Shaft and sleeve: First, machine the sleeve with the internal hole, then fabricate the shaft according to the actual dimensions of that internal hole; the machining and measurement of the outer surface are relatively easier ； 2. The machining of the positioning pin holes is usually done by custom fabrication. This post was last edited by Honor Angel on 2009-3-31 11:08.]
For the machining of some workpieces, it is necessary to carry out the processing accordingly. For example, when machining the holes for taper pins, it is required to assemble the two parts that the pin will connect between them first, then machine the pin holes, and finally insert the taper pins – this allows for precise positioning.
Generally, in assembly, when there are multiple fits or when a certain precision for the installation of a part is required, fitting is employed. Once fitting is completed, even if the parts are disassembled and reassembled, the desired installation precision can still be achieved. Fitting helps to reduce costs, as it is not necessary to use high-precision machining equipment to ensure that the required precision is met.
If the matching parts need to be replaced, they must be remade as well.
There are several machining positions that are related to each other (usually holes, steps, etc.), and the position and/or size of one of these positions is determined based on the position and/or size of another, which is what is meant by coordinated machining
It is mainly to ensure proper fit; although the current processing precision is very high, there are still tolerances, and fitting can ensure the accuracy.
The main purpose of fitting is to ensure the assembly accuracy of components that work together, but it has drawbacks as well: there is no interchangeability or only very limited interchangeability, and the cost of replacement parts is high.
As far as I know, there are mainly the following two aspects: 1. For shafts, bolts, nuts, etc., split pins need to be installed; drilling must be done after positioning or fastening, and in such cases custom fabrication is required； 2. During assembly, when matching shafts and holes, it is necessary to manufacture the shaft according to the dimensions of the hole or the hole according to the dimensions of the shaft; this is also a form of custom fitting. However, it is generally used only in single-unit production or maintenance, and is not adopted in mass production.
I saw it on an old drawing: the tolerances for shafts and holes were divided into three levels, with those having tolerances that were close to each other placed in red, yellow, and blue bags for matching during grinding. Unfortunately, that old drawing is no longer available, so I don’t know exactly how the tolerances were classified. If anyone knows, please explain in detail.
So that’s how it is. Thank you for your guidance, expert