# Research on the Technologies of the Compressor Remanufacturing Process
## 4 Key Technologies for Compressor Remanufacturing
### Crankshaft Remanufacturing Technology
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Index**} & \multicolumn{2}{c}{**Waste Crankshaft**} & \multicolumn{2}{c}{**Crankshaft**} & \multicolumn{2}{c}{**Crankshaft after**} & \multicolumn{2}{c}{**Scondary**} & \multicolumn{2}{c}{**Surface Polishing**} \\ \cline{2-10}  & **D (mm)** & **C (\(\upmu\)m)** & **D (mm)** & **C (\(\upmu\)m)** & **D (mm)** & **C (\(\upmu\)m)** & **D (mm)** & **C (\(\upmu\)m)** \\ \hline
1 & 18.001 & 3.17 & 17.998 & 3.32 & & & 18.007 & & 18.004 & 3.01 \\ \hline
2 & 18.000 & 4.82 & 17.996 & 4.05 & & & 08.004 & & 18.001 & 3.62 \\ \hline
3 & 17.997 & 1.57 & 17.992 & 1.46 & & & 18.001 & & 17.999 & 1.42 \\ \hline
4 & 17.994 & 5.66 & 17.991 & 5.42 & & & 17.999 & & 17.996 & 4.87 \\ \hline
5 & 17.998 & 1.64 & 17.994 & 1.52 & & & 18.003 & & 18.000 & 1.55 \\ \hline
6 & 18.001 & 7.14 & 17.996 & 5.94 & & & 18.004 & & 18.002 & 5.12 \\ \hline
7 & 18.000 & 4.96 & & & & 17.902 & 1.73 & 18.002 & & 17.999 & 1.65 \\ \hline
8 & 17.998 & 5.89 & & & & 17.901 & 1.82 & 18.000 & & 17.998 & 1.72 \\ \hline
9 & 17.996 & 6.51 & & & & 17.990 & 2.04 & 18.000 & & 17.998 & 1.68 \\ \hline
10 & 17.995 & 4.41 & & & & 17.990 & 1.46 & 17.998 & & 17.995 & 1.52 \\ \hline
11 & 18.000 & 4.78 & & & & 17.992 & 0.93 & 18.001 & & 17.998 & 0.84 \\ \hline
12 & 17.999 & 3.54 & & & 17.992 & 1.11 & 18.000 & & 17.997 & 0.96 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of the long shaft repair methods. Figure 7: The crankshaft remanufacturing process: (**a**) crankshafts, (**b**) phosphating treatment, (**c**) fine grinding, and (**d**) crankshaft tolerance measurement. 1. The fine grinding of crankshaft mainly fixes the size accuracy and shape tolerance of the wear parts of the crankshaft, namely, the long shaft and eccentric crank. The fine grinding of the long shaft is processed by the coreless grinder, and the grinding volume should be controlled below 15 \(\upmu\)m. The fine grinding of the eccentric crank is processed by eccentric grinder, and the grinding volume must consider the requirements of the crankshaft eccentric size, which can be controlled at approximately 30-50 \(\upmu\)m. The quality of fine grinding of the crankshaft is not only ensured by the machining accuracy of the machine tool but also by the design of the positioning tool, the size of grinding wheel, the speed of the grinding wheel and the choice of the grinding fluid selected. 2. The phosphate treatment serves to increase the crankshaft antifriction properties and fix the shaft diameter size. Phosphating treatment uses a manganese phosphating agent, and the film thickness is controlled at 4-5 \(\upmu\)m. The acidity, temperature and phosphating time of the phosphating solution during phosphating have an evident effect on the thickness and quality of the phosphating film [23]. The total acidity of the phosphating solution should include control at 35-45 points, free acidity at 4-6 points, a phosphating temperature of 85-90 \({}^{\circ}\)C and a phosphating time of approximately 8-10 min during crankshaft remanufacturing. The resulting phosphate film has a uniform and detailed appearance, and it has a continuous film layer and a thickness of approximately 4-5 \(\upmu\)m.
3. Surface polishing removes contaminants and larger phosphate particles from the crankshaft surface and improves the surface roughness of the crankshaft. crankshaft polishing can be performed with a polishing machine steel brush type. Polishing treatment can only change the surface quality of the parts and not the shape tolerance of the parts. After the remanufacturing of the waste crankshaft according to the process scheme, its shape tolerance and roughness were significantly improved. However, the long shaft diameter became slightly smaller and should be matched by part staging to achieve the fit clearance requirements. The key data comparison before and after crankshaft remanufacturing is shown in Table 5.