Micro Array-dimples Produced By Electrochemical Micro-machining On Surface

In recent years, surface texturing is an attractive approach in the application of sliding contact elements. Array micro-dimples distributed on a frictional surface are expected to act as fluid reservoirs and help to promote the retention of a lubricating thin film between mating components. Compared to a lapped smooth surface without texturing, the samples with array micro-dimples successfully realized reductions in friction coefficient. Many processing methods have been used to machine array micro-dimples,such as laser machining, vibration machining, electro-discharge machining. Those methods have many disadvantages as well as inefficiency, remelt layer, tool-electrode wear,etc.Electrochemical machining (ECM) is an anodic dissolution process. It has many advantages such as its applicability regardless of material hardness, high material removal rate, absence of tool wear, smooth surface. It is always used for production of difficult-to-machine material.This paper focus on method of machining array micro-dimples by ECM. The following work has been done:1 Array micro-dimples on flat have been machined by through-mask electrochemical micromachining (TMEMM) which employs photolithographiy to produce circular micropatterns on photoresist-coated workpiece and then selectively dissolves substrates from unprotected areas. The results of experiments show that the position of micro-dimple center has microprotrusion. The cause of it has been expounded, through analyzing electrical field on the interface of workpiece by finite element method.2 Array micro-dimples on flat have been machined by process to transfer microscale patterns on fully exposed flat of anode. This process uses a metallic material with a resist circular pattern, which serves as cathode. The anode, which is fully exposed, is placed facing the cathode, with close inter-electrode gap. Electrolyte is pumped through the inter-electrode gap, to deliver fresh solution to the anode and cathode, as well as remove reaction byproducts. Array micro-dimples under the influence of electrical field have been discussed. The results show that array micro-dimples have good consistency.3 Array micro-dimples have been machined on flat by mobile-mask of electrochemical machining. Array micro-holes was machined on copper clad laminate (CCL). CCL has copper layer and insulating layer. Copper layer uses as cathode. The insulating layer surface was placed closely in contact with flat of workpiece to protect undissolved areas. Electrolyte is pumped through the holes of mask, to deliver fresh solution to the anode and cathode, as well as remove reaction byproducts. The results of experiments show that the position of micro-dimple center has microprotrusion. the cause of it formation has been expounded, through analyzing electrical field on the interface of workpiece by theoretical model.4 Array micro-dimples have been machined on cylinder surface by mobile-mask of electrochemical machining. Workpiece as anode installed on spindle, it drives the Workpiece to rotate, and mask throw closely in contact with workpiece. While workpiece rotated, machining circuit is broken to stop machining. After workpiece shifted some angle, circuit is opened to machine a row of micro-dimples. When workpiece rotated a period, the full micro-dimples of cylinder surface was machined. Array micro-dimples on cylinder surface have good consistency.