Abstract: An apparatus is provided for electrolytically polishing the inside surface of tubular products such as rifled stock, or fiream or artillery barrels. The apparatus comprises a first and second reservoir in fluid communication through the tubular product with an electrolyte flow system. A cathode head is provided that is displaced from one reservoir to the other in the presence of flowing electrolyte and at a current density of between 1 and 5 amp-min/sq. in. A method of electrolytically polishing tubular products is also provided.

Abstract: An electro-erosion machine with an essentially cylindrical tank (14) for holding a liquid dielectric and divided longitudinally into at least two sections (18 & 20). The sections slide together and apart along the circumference.

Abstract: The invention relates to a process and apparatus for producing a rough and hard generated surface on a cylindrical body of rotation, more particularly a roll for metal strips. To rapidly obtain as uniform a surface roughness as possible, the body of rotation (2), acting as a cathode, is immersed over its whole length into an electrolyte (1) in a tank (3) only to such an extent that the immersed peripheral portion is narrower by a multiple than a plate-shaped anode (5) disposed opposite the body of rotation and extending over its whole length. The electrolyte can contain a substance suitable as a finishing deposit on the generated surface.

Abstract: A method and apparatus for forming lead frames and eliminating irregularities in the edge (22) of openings etched in the sheet metal from which the lead frame is formed. In a first process, a photo resist coated metal sheet (36) is first etched by a photo chemical process to define the lead frame, and then the lead frame metal sheet (36) is etched in an electrochemical process to remove edge irregularities. In a second process, the entire lead frame is formed in an electrochemical process.

Abstract: Precious metal-plated objects are cleaned by immersing them into a container filled with water. The electrical conductivity of the water is increased be adding an ion spender such as sodium carbonate therein. The positive terminal of a direct voltage source is connected to a metal plate such as aluminum plate immersed in the water bath. The precious metal-plated object to be cleaned is connected to the negative pole of the direct voltage source. The direct voltage is adjusted to between 1.5 and 9 V and the object is immersed for a few seconds. A kit for performing the method may be embodied as a battery-powered unit, or it may be provided with an a.c. adapter and an adjusting potentiometer allowing user-adjusted cleaning voltage.

Abstract: Masks for microelectronics technology are fabricated by electrochemical etching. Molybdenum sheet or foil is masked with patterned photoresist on one side, and a mating, mirror-image pattern of photoresist is applied on the other side of the foil in exact registration with the first pattern. The foil is immersed in electrolyte (an aqueous solution of sodium nitrate, sodium hydroxide, thiourea, and surfactant) along with nickel anode plates held parallel to the foil surfaces 1-3 cm away. The anode plate is made slightly smaller than the mask area of the foil. When voltage is applied across the cell, the foil is etched through to form vias. The electrolyte is pumped across the surface of the foil and uniform flow velocity over the foil surface is achieved.

Abstract: A system for making porous silicon on blank and patterned Si substrates by "immersion scanning", particularly suitable for fabricating light-emitting Si devices and utilizing an open electolytic cell having a cathode and an opposing anode consisting of a Si substrate on which the porous silicon is to be formed, both disposed, with their opposing surfaces in parallel, in an aqueous HF solution electrolyte contained in the cell. The substrate anode is mounted to be movable relative to the electrolyte so as to be mechanically cycled or scanned in and out of the electrolyte at a programmable rate during anodization. The uniformity, thickness and porosity of the resulting anodized layer on the substrate are determined by the scanning speed, number of cycles, current density, and HF-based electrolyte parameters of the system, and the Si substrate resistivity, conductivity type, and crystal orientation.

Abstract: A work tank for machine tools for receiving the machining fluid comprising a fixed part and a movable part which retracts to move the tank away from the work area when it is necessary to remove a workpiece.

Abstract: An electrolytic combined processing machine includes a grinding wheel spaced apart from and facing a workpiece, a current switching circuit for switching a coarse grinding to a fine grinding of the workpiece by the grinding wheel, and an infeed switching circuit for switching the infeed speed of an infeed table which allows the grinding wheel to relatively approach the workpiece. The switching operation is based on a measurement result obtained from a size measuring unit which measures a processing amount of the workpiece. During fine grinding, the infeed speed of the grinding wheel is the same as the speed of a passivation coating film generated on the workpiece. Workpieces, particularly of brittle materials, can be processed in a state of less processing distortion with improved surface roughness, flatness and efficiency.

Abstract: The technical field of the invention generally concerns electroerosively drilling small diameter holes, e.g. holes 6.0 mm in diameter and smaller. Such a small hole drilling apparatus includes a worktable for receiving a workpiece, together with a chuck and an electrode guide which receives and retains an elongated and thin tubular electrode. The drilling apparatus also includes a fluid supply and pump which delivers a first flow of machining fluid to an inner bore of the tubular electrode at a pressure of at least 20 kg/cm.sup.2. The drilling apparatus also includes a power supply for applying a series of electrical machining pulses between the tubular electrode and the workpiece. As material is removed from the workpiece, an electrode feed mechanism included in the drilling apparatus advances the tubular electrode into the workpiece to maintain the spacing between the tubular electrode and the workpiece.

Abstract: A fluid flushing device for an electroerosion apparatus for flushing a machining gap (32) with a dielectric fluid comprising a coupling block (46) having a supply conduit (19;45) connected to a supply source of dielectric fluid at one end. A pallet (1) for carrying the workpiece (14) includes a passage (17,28;41), and is equipped with a flexible hose (30) having a presetable flushing direction or orientation. The other end of the passage couples with the supply conduit when the automatic pallet changer (80) loads the workpiece on the apparatus through the pallet, so that continuous automatic operation can be realized.

Abstract: A wafer cutting device has a plurality of individually highly tensioned diamond impregnated wires that are mounted in a translatable head. Each wire has a tension monitor connected thereto for the purpose of insuring uniform tension and also alerting to breakage. Further, a differential DC voltage is applied to the wires and the crystal with the assistance of electrolytes to improve the removal of material for minimizing damage to the surfaces. The crystal is mounted on a two dimensional stage. During normal cutting the crystal is moved vertically into the cutting wire. The vertical cutting rate is adjusted due to the configuration of the crystal. At the end of cutting, the crystal is moved laterally so as to place a notch in the wafers for the purpose of removing the wafer in a clean break.

Abstract: An apparatus and method especially adapted for electropolishing reactive metal workpieces which require aggressive electrolytes. It incorporates a single, closed, pressure-tight polishing chamber into which metal workpieces are placed for a multi-step operation. All electrolyte cleaning and rinse fluids are pumped in and out of the chamber as required for sequential operations, and vacuum assisted purging and dying removes the electrolyte or polishing residue from the chamber after each step.

Abstract: A micromachined valve and valve array having one or more pores which are electrochemically opened and closed by dissolving and redepositing a barrier layer across a tiny opening or pore in substrate. The pore is spanned by two electrodes which apply a voltage to an electrolytic barrier layer material which dissolves in an electrolyte. Each open pore has a distinct flow rate related to its minimal cross-sectional area which together can form a binary sized array with each subsequent member in the array having a flow rate twice as large as the preceding member in the array. Any integral multiple of the smallest flow rate may be achieved by opening an appropriate combination of the pores with addressing logic. In a preferred embodiment, each bit in a binary representation of the desired flow rate acts as a switch for a pore having a flow rate corresponding to the bit position.

Abstract: An electrochemical fine processing apparatus for electrochemically performing an adding processing and a removing processing of a substance such as a metal or a polymer in a solution in order to produce a structure having a high aspect ratio. Removing electrodes for applying an electric potential opposite to that applied to an addition electrode are disposed around the addition electrode, whereby an excess portion of metal or polymer film pattern can be scraped electrochemically. In addition, alternate electric potential pulses are applied successively to the addition electrode and then to the removing electrodes. It becomes possible to form on the support a structure with sharp pattern edge portions and a high aspect ratio.

Abstract: The photoelectro-chemical etching system of compound semi-conductor is disclosed. The system comprises a laser generator, a shutter to cut off laser beam, a laser beam chopper, a secondary high reflection mirror, a beam expander, a waveform generator, a chopper controller, a potentiostat to apply the reverse or forward voltage to the optical glass cell. Instead of applying the reverse-bias voltage to a semiconductor material, the reverse and/or forward voltage with a uniform pulse period is applied so that homogeneous and damage-free surface is obtained and etching process is made available in a more efficient manner.

Abstract: A method and apparatus are provided for marking orthodontic products. The method includes the steps of coupling the orthodontic product with the anode of a power source, placing an electrolyte in electrical contact with the cathode of the power source, and selectively exposing portions of the orthodontic product to be marked to the electrolyte. The apparatus includes a hand marker connected to the cathode of a power source. A sponge pad soaked with an electrolyte is attached to the hand marker. A workplate provided for holding the orthodontic product is coupled to the anode of the power source. A stencil is also provided to enable selective portions of the orthodontic product to be exposed to the electrolyte and thereby be marked.

Abstract: A method and apparatus for electrochemically machine lapping a matched set of fixed and orbiting scroll members for use in a scroll compressor. The orbiting scroll member is orbited in a short stroke relative to the fixed scroll member while an electrolyte is pumped between the scroll wraps. An electric current is passed through the fixed and orbiting scroll wraps to thereby electrochemically machine away high profile areas on corresponding metal wear surfaces. During the machining process, the clearance spacing between the scrolls is tightly controlled to prevent contact between the scrolls.

Abstract: A method of electrochemically machining a workpiece made of electrically conductive material so as to provide a radius on an edge of the workpiece comprises, (a) providing a cathodic tool comprising a cathode section sandwiched between two anode sections and separated therefrom by insulation, (b) locating the tool adjacent to but separate from the workpiece so that the cathode section is positioned centrally over the edge of the workpiece to be radiused and the anode sections lie facing opposite sides of the edge, (c) causing electrolyte to flow between the tool and the workpiece, (d) applying a cathodic voltage to the cathode section, (e) applying preselected anodic voltages simultaneously to the workpiece and the anode sections so that electrical field null points between the cathodic tool and the workpiece lie either side of the edge to be radiused, and (f) varying the electrical field between the tool and the workpiece so as to cause the null points in the electrical field to move with respect to each oth

Abstract: A hardmetal object is cathodically protected from corrosion by a protective electrode during the spark-erosion process, which protective electrode is electrically connected to the hardmetal object via an external power source. The protective electrode is preferably plate-shaped.

Abstract: An optical fine processing apparatus for forming a structure having a high aspect ratio even on a workpiece having high heat conductivity. Light, such as a laser beam, is irradiated onto the workpiece in an electrolytic solution through a light guide to deposit a substance such as a metal or a polymer. A plurality of removal electrodes are allowed to have an electric potential for removing a part of the deposited substance. The removal electrodes are disposed in a rotation ring which is rotatable about the optical axis of the irradiating light onto the sample so as to adjust the width of a predetermined pattern to be scraped by changing the rotation angle of the removal electrodes with respect to the optical axis. By scanning the light guide and the removing electrodes above the workpiece surface, it is possible to form any desired pattern on the workpiece.

Abstract: The invention is a process for making sharp tips. A computer controlled instrument and process characterizes the tip while in formation and reliably produces tips having a radius of curvature of approximately 100 nm. In the invention, the position of the wire during the etching operation is mechanically controlled while the etching current is monitored. When the current reaches a predetermined level, the process is halted.

Abstract: The present invention describes a high speed, high precision electrochemical micromachining tool, chemical solution and method for the one sided through-mask micropatterning of conducting foils and films supported by insulating material. The tool of the present invention can include either a movable plate means allowing for the movement of the workpiece to and fro above the cathode assembly, or a movable cathode assembly means allowing for the movement of said cathode assembly to and fro beneath the workpiece. Said cathode assembly also consists of a nozzle assembly from which the electrolytic solution emerges as electrolytic shower and impinges upon the workpiece. Methods to resolve the problems related to the loss of electrical contact during the electrochemical micromachining process are also described.

Abstract: An apparatus for electrochemically machining a workpiece having first and second platforms and an airfoil extending transversely therebetween includes a first cathode trio having a center cathode disposed between first and second cathodes. The center cathode is configured for electrochemically machining a first side of the airfoil, and the first and second cathodes are configured for electrochemically machining at least the first and second platforms adjacent to the airfoil first side. The first and second cathodes are movable relative to the center cathode so that they move away from each other and toward the opposing platforms during machining. A second cathode trio is provided for electrochemically machining the airfoil second side.

Abstract: In a process of surface-roughening of an aluminum support for a printing plate using an AC electrolytic etching apparatus, changes of the current waveform, particularly changes of the time required for the current to reach its peak value due to variations of the load on the power supply are prevented. Also, the voltage load on the gate turn-off thyristors used for generating an alternating current is prevented from going beyond the withstanding voltage capacity of the thyristors. In accordance with the invention, an electrolytic surface-roughening treatment apparatus is provided in which an alternating current is supplied by a power supply having a circuit for generating the alternating current using a current inversion control circuit so as to perform electrochemical treatment, wherein the electrolytic surface-roughening treatment is performed with either a parallel circuit or a series circuit of a capacitor and a diode bridge inserted in parallel with the load on the power circuit.

Abstract: The present invention relates to an electropolishing tool for the removal of metal from a workpiece, said electropolishing tool comprising a container means for retaining an electrolytic solution, a cathode assembly in the shape of a pyramid the height of which is adjustable, a power supply means including a negative terminal and a positive terminal with said negative terminal being electrically connectable to said cathode assembly, a plate means for holding the workpiece and for forming an electrical connection to the workpiece, said plate means connected to the positive terminal of said power supply means, and an enclosure means placed over the workpiece leaving only the surface of the workpiece which is to be polished exposed to the electrolytic solution such that when the workpiece is secured to said plate means and said cathode assembly is connected to the negative terminal of said power supply means and is placed over the said enclosure means directly facing the workpiece enclosed therein, that portion

Abstract: An apparatus for electrochemical marking of a flat or arced, preferably cylindrical metallic surface of a workpiece, which is connected to one pole of a voltage source, has a tool provided with a metallic pin, which is connected with the other pole of the voltage source. The pin is held in a tool holder of an electrically non-conducting material, which is movable in relation to the workpiece surface. A liquid electrolyte becomes effective between the tool and the workpiece surface.

Abstract: The internal quality of continuously cast and other steel samples in the form of ingots, billets, blooms, slabs and bars is determined in rapid manner to enable potentially problem-causing casting conditions to be identified and corrected in timely manner. A steel sample from the casting, after grinding to remove any heat-affected zone and to provide a desired degree of surface roughness, is anodically etched using dilute hydrochloric acid at ambient temperature to etch away metal from the surface to reveal the internal quality. After removal of the sample from the etching apparatus, the sample is washed, dried, and visually examined to determine the internal quality.

Abstract: A micromelt structure is provided on a probe tip by contacting the probe tip with a foil of the material from which the micromelt structure is to be formed and passing an electric current through the contact point to melt the foil and cause the molten foil material to collect on the tip of the probe where, by surface tension, it is drawn into a microsphere shape and homogeneously solidifies. The probe with the micromelt tip is highly reproducible and uniform and is particularly effective for use as a probe in scanning microscopy.

Abstract: A machine for electrochemically machining (ECM) a workpiece having a stacking axis and first and second opposite sides includes a pair of cathode tools. The first and second tools have first and second longitudinal axes, respectively, disposed substantially perpendicularly to the workpiece stacking axis. The first and second tools also include the first and second transverse axes, respectively, disposed perpendicularly to the first and second longitudinal axes, respectively, and substantially parallel to the workpiece stacking axis. The machine is effective for practicing an improved method of moving the first and second tools along the first and second longitudinal axes and along the first and second transverse axes, respectively, toward the workpiece for the electrochemical machining thereof. By moving the respective cathode tools along both longitudinal and transverse axes, a selectively variable resultant feedrate direction is obtained which is inclined relative to the workpiece stacking axis.

Abstract: Probe tips are produced from electrically conductive wire by electrolytic machining of a zone of the wire above a free end utilizing a liquid electrolyte layer in contact with this zone, a ring electrode surrounding this zone, and a layer of an insulating fluid into which the free end extends. The insulating fluid can be air where the electrolyte is a membrane between layers of air above and below the membrane, or a body of a liquid insulator below the electrolyte layer where the insulator and the electrolyte form a bath.

Abstract: A method for electrochemical machining a work piece using an electrochemical machining device including a tool electrode opposing the workpiece across a predetermined machining gap and a device for supplying a pulse current to the machining gap via electrolyte provided in the machining gap includes the steps of determining a predetermined pulse current having a predetermined pulse width, selecting a plurality of partial pulse currents each having a predetermined partial pulse period, calculating a plurality of rest periods based on said partial pulse widths and applying the partial pulse currents, each of the partial pulse periods separated by at least one of the rest periods. According to the method of the present invention, the predetermined pulse width is in the range of about 10-50 msec.

Abstract: An apparatus for electropolishing surfaces includes an inner housing having an open side with a rim facing toward a surface to be electropolished and being otherwise closed. A guide apparatus moves the inner housing along the surface to be electropolished. An inner seal is disposed between the rim of the inner housing and the surface to be electropolished. An electrode is retained in the inner housing. An outer housing has an interior in which the inner housing and the electrode are disposed. The outer housing has an open side with a rim facing toward the surface to be electropolished and is otherwise closed. An outer seal is disposed on the rim of the outer housing. Connections are associated with the outer housing for supplying and removing a rinsing fluid to and from the inner housing. Ducts are associated with the outer housing for supplying and removing electrolyte fluid to and from the inner housing.

Abstract: An apparatus for electrical processing according to the present invention comprises a machine tool, a power supply means and a working fluid system. A tool is rotatably mounted on the machine tool. A workpiece and the tool are connected to the output terminals of the power supply means. In course of the processing, the tool is rotated through a motor, and working fluid is applied to the tool and the workpiece by the working fluid system. The operation voltage and current rnage from 25V to 28V and 1600A to 3000A respectively for a rough processing, and 1V to 9V and 1A to 90A for a fine processing.

Abstract: There is provided an apparatus and a process for using same for etching a metallic object (22), suitably a plate to prepare a metallic printing plate. The object is partially covered by a resist surface (14) wherein the exposed portions (16) of said metal, will be exposed to the action of an electrolytic etchant force. The apparatus comprises a bath (10) for an aqueous electrolyte (12), an electrode (23), suitably but not critically metallic, immersible in said electrolyte, which will serve as the cathode, a source of direct current voltage (32), which may further be associated with adjustment means (38) for controlling the applied voltage.

Abstract: Semiconductor wafers, in particular, silicon wafers, with differently poled front and rear sides and high geometrical quality can be fabricated by double-sided polishing if the wafer surfaces are differently polarized during the polishing process. This can be achieved in a simple fashion, in that during polishing, an electric field is set up between the upper and lower polishing plates. This can be accomplished by providing the upper polishing plate between the plate surface and the polishing cloth with a thin conductive layer insulated with respect thereto, on which a voltage can be impressed, while both polishing plates are grounded to the frame.

Abstract: There is provided an apparatus and a process for using same for etching a metallic object, suitably a plate to prepare a metallic printing plate. The object is partially covered by a resist surface wherein the exposed portions of said metal, will be exposed to the action of an electrolytic etchant force. The apparatus comprises a bath for an aqueous electrolyte, an electrode, suitably but not critically metallic, immersible in said electrolyte, which will serve as the cathode, a source of direct current voltage, which may be adjustable for controlling the applied voltage. The voltage should be adjustable to operate accurately within a rather narrow voltage range, such that the minimum voltage shall be at least that of the ionization potential of the metal of the metal object in the electrolyte chosen and the maximum shall not substantially exceed the sum of the decomposition voltage of the aqueous electrolyte and the over-voltage of the cathode selected.

Abstract: An apparatus and a method of machining optical components such as lens is disclosed. The apparatus comprises an optical raw stock or material, a rotatable holding shaft for holding the optical raw stock, a machining tool having a machining surface thereof held by a rotatable machining shaft and arranged opposite to a surface to be machined of the optical raw stock, an electrically conductive tool as the machining tool, an electrode arranged at a certain distance from the machining surface of the conductive tool, an electrolytic power supply source for applying a positive voltage to the conductive tool and a negative voltage therefrom to the electrode, respectively, and a coolant supplying unit having a nozzle and for spraying weakly conductive coolant between the conductive tool and the electrode, thereby performing the machining of the optical raw stock or material.

Abstract: A method of grinding a lens and an apparatus therefor during dependent machining in which an electrically conductive grinding tool which rotates and a workpiece slide in close contact with each other on the work surface of the electrically conductive grinding tool. An anode is applied to the electrically conductive grinding tool, whereas a cathode is applied to an electrode which does not move together with the workpiece, while a fixed distance is maintained between the work surface of the electrically conductive grinding tool and the electrode. Grinding is thus performed with the aid of a weakly charged coolant fed between the electrically conductive grinding tool and the cathode.

Abstract: An apparatus for electrochemical machining has a bath for machining workpieces capable of providing in the zone of treatment an ascending laminar flow of electrolyte occupying the bath. A bath for cleaning the electrolyte communicates with the bath for machining the workpieces by way of a pipe for feeding the electrolyte having a pump and pipe for discharging the electrolyte. The workpieces are conveyed to the bath by workpiece gripping mechanisms.

Abstract: An electrochemical polishing device and method for selective anodic dissolution of the surface of test specimens comprised, for example, of nickel-chromium-iron alloys, which provides for uniform dissolution at the localized sites to remove metal through the use of a coiled wire electrode (cathode) placed in the immediate proximity of the working, surface resulting in a polished and uniform grain boundary.

Abstract: A deformable electrode for electrochemical machining (ECM) of passages, in particular curved passages or passage sections in workpieces, is constructed from a deformable, electrically insulating tube having electrically conductive electrode tip means arranged around the end of the tube to form the working tip of the electrode. Electrical conductor means are connected to the electrode tip means and extend along the tube. During ECM of a passage an electrolyte solution is supplied along the center of the tube, and a voltage is applied between the workpiece the electrode tip means, via the conductor means, so that dissolution of the workpiece occurs near the electrode tip means at the working face of the passage being machined.

Abstract: Apparatus for electrolytic processing of materials, includes an electrolytic processing bath, plural first electrodes, at least one second electrode, and a power supply for supplying time multiplexed power to the electrodes. The power supply may include a pulse width modulator or a pulse position modulator and is operative to control the relative amounts of time that the respective electrodes are energized for electroplating, electropolishing, and the like. Current control and bath composition control are provided. A method for electrolytic processing of materials includes placing plural first electrodes in an electrolytic processing bath, placing at least one second electrode in such bath, and at different times supplying power between at least one of such first electrodes and such at least one second electrode and supplying power between at least another of such first electrodes and such at least one second electrode.

Abstract: A method and apparatus for electrolytically assisting the mechanical shaping of a workpiece is provided which is particularly useful for precision machining. A tool is used comprising an electrically conductive (copper alloy) tool shank, a cutting tool of an electrically insulating material (reinforced ceramic), and means for flooding a gap, between the tool shank and the localized electrically conductive surface layer to be shaped, with a stream of electrolyte. With the electrolyte flowing, and a low voltage, direct current applied across the gap using the localized, electrically conductive surface layer as the anode and the tool shank as the cathode, the structure of the localized, electrically conductive surface layer of the workpiece just ahead of the tool is weakened structurally sufficiently to be removed easily by the cutting tool in discrete form and carried away from the tool by the stream of electrolyte.

Abstract: A control system for flushing fluid flow in an EDM machine provides independent control of flow characteristics at the upper and lower nozzle outlets. The control system operates in a flow control mode and a pressure control mode. In the pressure control mode, pressure transducers are utilized to provide a feed-back signal.

Abstract: Electrodes of an electro-chemical machining tool are in the form of tubes which carry electrolyte to the surface of the article to be machined. The ends of the tubes adjacent the article are gripped between opposed clamping surfaces (13,14) of a block (10). One of those clamping surfaces 14 has a series of facets (15,16,17) with each facet inclined relative to the adjacent facet. The tubes are gripped between those facets (15,16,17) and serrations (18) in the opposed surface (13). This causes the tubes to have different orientations along the line of those tubes due to the relative inclination of the facets (15,16,17). This enables the tubes to conform to the trailing edge of e.g. a turbine blade.

Abstract: Method of electrolytic drilling of a fluid metering orifice through a metal substrate including the step of terminating electrolytic current flow when the volume of the electrolyte stream impinging on the substrate correlates to the desired flow of the fluid through the orifice.

Abstract: An apparatus for the anodic treatment of aluminum alloy pistons used in internal combustion engines. The apparatus comprises at least two members applied symmetrically to the lateral cylindrical surface of the piston which are connected to a source of positive direct current. An electrode connected to a source of negative direct current and having at least one aperture therein is positioned adjacent the head portion of the piston which is to be treated. A deflector of electrically insulating material disposed generally parallel to and spaced from the electrode and having a circumference curved toward the electrode is provided with a central passage therethrough which receives the head portion of the piston, with the head portion being disposed opposite the electrode.

Abstract: A method of electropolishing and grinding the both surfaces of a circular workpiece comprises polishing and grinding the both surfaces of a circular workpiece with a pair of grindingstones which are so arranged as to oppose the polishing/grinding surfaces, the body material of the polishing/grinding surface of the grindingstones being composed of an electric conductive material wherein the grindingstones are connected to the positive pole of a power source and an electrode located in the vicinity of the grindingstones is connected to the negative pole, and a voltage is applied across the positive and negative poles, whereby a dressing operation to the polishing/grinding surfaces is conducted by the electrolysis of the pair of grindingstones during the polishing and grinding operation.

Abstract: The inner end of a spray hole in a fuel injection nozzle for an internal injection engine is electrochemically machined by providing a negative electrode inside a chamber in said body, while applying an electrolyte under pressure to the exterior of the nozzle body, so as to cause the electrolyte to flow through the spray hole inwardly of said body. The electrolyte is preferably an aqueous solution of NaCl.