The plunger and plunger sleeve are made of High-quanlity GCr15 and formed through the rough turning and the fine turning by CNC machine, straightness of the outer circle 0.001, roundness 0.0005, taper 0.001 and roughness 0.05; vacuum quenching process as the heat treatment makes the hardness reach HRC60-64, after formed, all through the gap test and the seal test to make sure the qualification rate. The service life is over 6 months.