Do you know what scraping adjustment is and what is it for?

As a result of the continuous use of a machine, the constant movement of its axes and elements could produce damages that would finally cause machining problems. For this reason, during the refurbishment of a machine tool, a manual adjustment is carried out by means of a tool called “scraper”, whose objective is to adapt two flat or curved parts so that they slide together with the most perfect contact possible. This process is called "scraping".

Process of manual adjustmen by Nicolás Correa Service

In the particular case of guides’ saddles wear in each axis (X,Y,Z), the adjustment process carried out by Nicolas Correa Service during the retrofitting of a second hand CNC milling machine, becomes an essential work bound to prevent possible plays that may affect the accuracy of the machine. Thus, during the refurbishing phase, the grinding of guides’ saddles of all structural elements is performed in first place, seeking a surface as flat and uniform as possible in each one of them. However, performing a manual scraping of all these elements becomes necessary in order to obtain their total adjustment and to assure that all axes meet geometry. The main purpose of this manual scraping of two pieces that have to slide together is, on one hand, to ensure a perfect sliding and adjustment necessary for each function. On the other hand, making small cracks so that the oil could flow through these two pieces in continuous friction will prevent them from being completely smooth and end up seizing.

To carry out this scraping process, the surface where the piece to adjust slides is painted with a fluid paste (Prussian blue) by our experienced technicians at NC Service. This paste is ideal to check adjustments of moulds and dies, among others, and marks the irregularities of the surfaces with a micrometric thin layer. The parts are assembled in the milling machine to make them slide together, and after dismantling, the paint remaining on the surface of the part to be adjusted will mark those areas with the greatest friction. This will allow our technicians to determine the need for adjustment and, if necessary, will show him where to make it, focusing in the most prominent areas marked in blue. If these parts have a uniform contact, except in the oil drain zone, and allows displacement, then we can say that they are well adjusted.

In this video we show you the scraping and adjust the Z-axis iron plate of a refurbished CORREA milling machine by Nicolás Correa Service. Don´t miss it!