ADVANCED MICRODRILLING PROCESS

THERE IS AN INCREASING NEED FOR IMPROVEMENTS IN THE FABRICATION OF SMALL DIAMETER ORIFICES IN HARDENED METAL COMPONENTS. THIS NEED IS PARTICULARLY ACUTE IN THE FABRICATION OF FUEL INJECTORS FOR GASOLINE AND DIESEL ENGINES. IN THOSE ENGINES, THE INJECTORS ARE USED TO BOTH METER AND ATOMIZE THE FUEL. FOR A GIVEN PRESSURE DROP, THE FLOW THROUGH THE INJECTOR ORIFICES VARIES INVERSELY WITH THEFOURTH POWER OF THE ORIFICE DIAMETER. THEREFORE, SMALL VARIATIONS IN HOLE DIAMETER RESULT IN LARGE VARIATIONS IN FLOW. EXISTING MICRODRILLING TECHNIQUES (EDM, LASER AND ELECTRON BEAM DRILLING, AND OTHERS) HAVE MARGINAL ACCURACY AND PRODUCE A ROUGH RECAST LAYER WHICH RESULTS IN BURRS AT THE INLET AN EXIT OF THE ORIFICES. POOR INJECTOR HOLE QUALITY LEADS TO VARIATIONS IN FUEL-TO-AIR RATIO RESULTING IN POOR ENGINE PERFORMANCE AND INCREASED POLLUTION. THIS PROPOSAL ADDRESSES AN IMPROVED MICRODRILLING PROCESS. THE PROPOSED PROCESS IS A DERIVATIVE OF ELECTROCHEMICAL MACHINING (ECM) AND HAS THE POTENTIAL TO PRODUCE BURR-FREE HOLES WITH TIGHT DIMENSIONAL CONTROL AND LOW CYCLE TIMES. THIS TECHNIQUE WOULD REDUCE COSTS AND IMPROVE THE PRODUCTIVITY AND QUALITY OF THE INJECTOR MANUFACTURING PROCESS. IN PHASE I WE WILL DEMONSTRATE THE FEASIBILITY OF THE CONCEPT THROUGH SCOPING ANALYSES AND PROOF-OF-CONCEPT TESTS.