# Research on the Technologies of the Compressor Remanufacturing Process
## 4 Key Technologies for Compressor Remanufacturing
### Crankshaft Remanufacturing Technology  
The failure form of the compressor crankshaft is mainly friction damage, and the wear parts are the long shaft, short shaft, eccentric crank and thrust face, as shown in Figure 6. The wear of long shaft and eccentric crank is normally more serious, whereas that of the short shaft and thrust face is less so. Crankshaft remanufacturing mainly restores the shape tolerance, surface roughness and the reference size with fit requirements for the wear parts. The long shaft and eccentric crank have size fit requirements with the crankcase and connecting rod, respectively. However, the value of the connecting rod is low, and the economy of remanufacturing is poor. This fit gap can be repaired by replacing it with a new connecting rod. Therefore, the base size recovery aspect of the wear can only be for the long shaft diameter of the crankshaft for remanufacturing. Figure 6: Crankshaft wear diagram: (a) upper thrust face wear, (b) lower thrust face wear, (c) short shaft journal wear, (d) eccentric crank wear, (e) and long shaft journal wear. \begin{table}
\begin{tabular}{c c c c} \hline
**Cleaning Method** & **Cleaning Agent** & **Organic Contaminants (g)** & **Inorganic Contaminants (g)** \\ \hline \multirow{4}{*}{Spray + ultrasonic cleaning} & \multirow{4}{*}{Water-based cleaning agents (pure water)} & 0.0042 & 0.0407 \\  & & 0.0036 & 0.0418 \\  & & 0.0048 & 0.0392 \\  & & 0.0038 & 0.0377 \\ \hline \multirow{4}{*}{Immersion + ultrasonic cleaning} & \multirow{4}{*}{Organic solvents (industrial alcohol)} & 0.0014 & 0.0297 \\  & & 0.0024 & 0.0284 \\  & & 0.0016 & 0.0278 \\  & & 0.0017 & 0.0257 \\ \hline \multirow{4}{*}{Immersion + ultrasonic cleaning} & \multirow{4}{*}{Hydrocarbon cleaning agent (R141B)} & 0.0007 & 0.0066 \\  & & 0.0003 & 0.0081 \\ \cline{1-1}  & & 0.0013 & 0.0076 \\ \cline{1-1}  & & 0.0008 & 0.0089 \\ \hline \end{tabular}
\end{table} 
Table 3: Comparison of common cleaning agent properties of the motor stator. The compressor long shaft surface usually has a layer of 1.5-2.5 \(\upmu\)m thick manganese phosphate film. Long shaft normal wear depth usually does not exceed 10 \(\upmu\)m. Taking into account the quality requirements of the product, the experiments compared two long shaft repair methods: brushing + secondary phosphating and fine grinding + secondary phosphating. Table 4 shows the diameter (D) and cylindricity (C) of the long shaft before and after restoration. When the phosphate thickness exceeds 5 \(\upmu\)m, the phosphate efficiency decreases and phosphate layer denseness is reduced. This condition is not conducive to the product's antifriction characteristics. Therefore, the maximum repair of the crankshaft's reference dimensions by means of secondary phosphating should preferably not exceed 4 \(\upmu\)m on one side. The experiments showed that the remanufacturing solution of brushing + secondary phosphating does not improve the crankshaft shape tolerance significantly. It cannot completely change the impact of poor crankshaft shape tolerance on compressor noise and vibration characteristics. From the remanufacturing solution of fine grinding + secondary phosphating, the shape tolerance of the crankshaft can be improved significantly. Therefore, the remanufacturing solution for the compressor crankshaft should be fine grinding + phosphating + surface polishing. The crankshaft remanufacturing process is shown in Figure 7. The following aspects should be noted when remanufacturing.