Why The Coating Is Difficult To Process

       

For more information about the 3D
printing powder, spraying coat powder, or WC based powder, you may search
online wococarbide. Wococarbide.com provides various products and technical
questions and answers.The thermal spray coating is formed by the accumulation
of self fusible alloy powder with molten plastic particles passing through
high-temperature flame at high speed. Due to this unique formation method, the
spray coating has the following characteristics:

(1) The bonding between the spraying
layer and the part matrix basically belongs to mechanical bonding, and the
bonding strength is low, generally only 20 ^ - 30MPa. If the cutting force is
too large during machining, the coating may fall off. Therefore, this is an
important characteristic that should be paid attention to first.

(2) The matrix hardness of the coating
is medium, which is equivalent to that of general quenched and tempered steel,
but a large number of hard spots such as Cr, C: and WC are dispersed in the
coating matrix, and its microhardness is as high as 10480mp. 1607OMPa。 These hard spots cause serious abrasive wear on the cutting
tool, making the sharp edge blunt quickly.

(3) Because the coating of sand
blasting machine is porous and has a certain porosity, and because the coating
contains more nickel and chromium elements, the thermal conductivity of the
coating is very low, the cutting heat is difficult to be transmitted from the
workpiece and chip, and the heat is mostly concentrated on the tool tip. The
thermal effect during cutting aggravates the wear of the tool edge.

(4) The tensile strength of the coating
decreases, which is similar to that of gray cast iron.

From the above processing
characteristics, it can be seen that the tool is easy to cut into the coating,
but it is quickly blunt. The bonding strength of the coating is low. The
automatic sand blasting machine requires to keep the blade sharp during
cutting. The hardness of the hard points in the coating is high and the thermal
conductivity is low, which makes the blade blunt quickly. This contradictory
characteristic is the main reason why the coating is difficult to process.