Hydroerosive grinding is used as a finishing and inlet rounding operation of diesel nozzles to improve the engine performance. A mixture of hard particles suspended in a carrier fluid circulates through the injection holes to remove material until the required flow condition is achieved, although the time to reach this specification increases with time. The aim of this study is to analyze the process efficiency without renewal of solid particles. Results show that the removal efficiency decreased 20% after 150 hrs and this significant loss can be attributed to hydrodynamic interactions, particle size distribution change, and fluid viscosity reduction.

The hydroerosive grinding is one of the processes to manufacture diesel injection nozzles, being responsible for finishing injection holes. The process made use of an abrasive fluid under high pressure into these channels. Its efficiency depends on the physical properties of the abrasive fluid. Based on a previous investigation, this study verified the possibility of using a different particle size distribution of boron carbide to improve the process efficiency. All experiments were carried out in an industrial environment. The variation in process efficiency was compared with the maintenance of the viscosity along the production, and at the same time, the concentration of solids was constantly monitored. The alteration of particle size distribution was not suitable, causing an increase in the average particle size. In addition, we have verified that the concentration of solids presented a major influence on the process efficiency, being the lower the concentration, the lower the efficiency.