The first step: tin plating. In order to achieve the release of the coating, a low-melting metal tin is firstly plated in the inner hole of the tire, and heated during the demolding to melt the tin, thereby separating the tire and the coating. The coating is as thin as possible to meet the requirements of smooth demoulding to ensure the final size and shape accuracy of the reamer. The acid bright tin plating solution has high cathode current efficiency, fast deposition speed and good leveling performance, so it is used.

The second step: sand. The main task of this stage is to make the diamond particles uniform, single layer, and firmer. Since the composite plating of diamond particles is performed in the inner hole, the sand burying method is employed.

The tin plating is made of metal tin so that the plating solution can be replaced and cleaned. In addition, the use of tin on the tin plating is very advantageous for the subsequent demolding. This layer of metal is also removed during the cutting stage, so the quality of the coating has no effect on the performance of the tool.

The thickness of the tin plating should be well controlled when sanding. The coating is too thick, and there are too many solidified diamond particles, which is prone to agglomeration and nodulation, which not only causes waste, but also reduces the flatness of the surface of the subsequent plating layer, and accurately determines the bonding position of the arbor when bonding the coating and the arbor. The size brings difficulties. After a series of tests, it is concluded that the thickness of the upper sand is 12% to 15% of the average diameter of the diamond. This can ensure that the sand is washed back and forth from the hole with a slightly hard brush after unloading the sand. After removing the floating sand, a layer of sand is evenly distributed on the wall of the hole, and the sand will not fall off by hand.

The third step: unloading sand. After the sand is finished, remove the excess sand from the hole in the tire. One is to save the emery, but also to facilitate further plating thickening later. After that, replace the plating solution and thoroughly clean the plating unit.

The fourth step: initial thickening. In order for the diamond particles to be firmly wrapped by the coated metal, it should be thickened on the basis of the front plating. The thickness of the coating depends on the size of the diamond particles to prescribe the diamond particles. When the reamer is working, the layer of metal is the working layer of the tool, and its physical and mechanical properties and the degree of fusion with the diamond particles have a decisive influence on the performance of the tool. Compared with nickel plating, nickel-cobalt alloy has good hardness and wear resistance, and the 30% cobalt-containing alloy plated in the sulfate solution is the highest hardness nickel-cobalt alloy (41-42HRC), so it is used as The working layer of the reamer is advantageous for improving the performance of the reamer. The composition of electroplated nickel-cobalt alloy is shown in Table 4, and the process specifications are shown in Table 5. Due to the influence of diamond particles, the current density at this stage should not be too large. Otherwise, the plating layer is irregularly crystallized, and the crystal lattice of the original plating layer cannot be well grown for epitaxial growth, and the internal stress is large. After the test, Ic is preferably 1 to 15 A/dm2. The cobalt ion in the plating solution is supplemented by a continuous dropwise addition of a cobalt salt solution.

Step 5: Further thicken. In order to ensure the quality of the connection between the coating and the shank, the coating should be further thickened by about 08 to 1 mm. The coating at this stage requires less wear resistance and hardness, and it is more desirable to reduce stress, increase ductility, and increase deposition speed. Based on the above considerations, the watt-type nickel plating solution is used in this stage. The composition of the thick plating solution is shown in Table 6. The process specifications are shown in Table 7. Since there is no diamond particle effect, the current density can be increased to 5A/dm2 or higher to reduce the plating time. Since the thicker plating solution of the previous step does not adversely affect the plating solution of this process, the cleaning system is not required after the plating solution is replaced. When the thickness of the coating reaches the required level, the DC power supply can be turned off, the tire is removed, and cleaning is performed. At this point, the entire electroplating process is over.

Polyurethane Pump Parts

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