Abstract: A method and a manufacturing line allow for the manufacture of piston blanks of dimensions close to the final dimensions, which in the course of subsequent finish-machining need only be machined with removal of material to a small degree. A piston shaft of the piston blank is produced by backward extrusion. At least one hollow throat element is already produced at the piston blank by an upset-forging operation. For this purpose, a special forging tool is provided, which, after the manufacture of the piston shaft, takes effect on the piston blank in such a way that at least one hollow throat element is formed at the latest at subsequent forming of the piston base. In this way, a perceptible reduction is achieved in the weight of a piston in relation to conventionally manufactured forging pistons.

Abstract: A piston made of a nitride-forming base alloy for a reciprocating internal combustion engine is disclosed. The piston includes a piston upper part having a plurality of peripheral piston ring grooves, each piston ring groove having two groove flanks, one of the piston ring grooves being closest to a combustion chamber of the internal combustion engine than the remaining piston ring grooves, the groove flanks of at least the one of the piston ring grooves being hardened using a boundary layer, the piston upper part including an external surface which includes the hardened groove flanks, and a wear and correction protection layer coating at least the external surface, the wear and correction protection layer includes a nitration layer. The nitration layer is generated by converting the nitride-forming base alloy by one of plasma nitration and plasma nitro-carburization in at least one of a nitrogen atmosphere and a nitrogen-carbon atmosphere.

Abstract: A three-piece oil ring and a combination of the three-piece oil ring and a piston, those capable of realizing improved sealing property and reduction in lubrication oil consumption with avoiding generation of sticking even at low tension and thin width of the ring. The three-piece oil ring includes a spacer expander 10 and two side rails. The spacer expander has a radially inner end portion provided with seating tabs 13 protruding in an axial direction and having radially outer inclined surfaces for urging inner peripheral surfaces of the first and second side rails. The spacer expander has a radially outer end portion provided with side rail support portions 14 projecting in the axial direction for supporting axial end faces of the first and second side rails. A seating tab angle of the outer inclined surface relative to an axis is in a range of 10 to 20 degrees, and a ratio of 2X/Y is in a range of from 0.04 to 0.

Abstract: A robotic workstation includes apparatus for actuating one or more syringes. Each syringe has a cylinder and a plunger movable in the cylinder. A programmable robot has at least one syringe actuating device. The actuating device has a holder for holding and releasing a syringe cylinder and an actuator movable relative to the holder. A coupling couples the actuator to the plunger of the syringe such that, when the cylinder is held by the holder, movement of the actuator relative to the holder causes the plunger to move in the cylinder. A method of dispensing a material into a container includes robotically moving at least one syringe to a position for dispensing into a container. The plunger is robotically moved in the cylinder to dispense material from the syringe into the container. The workstation suitably includes a mixing apparatus for mixing materials in an array of containers at the workstation.

Abstract: A pump for fluid, comprising a pump body defining a bore, a pumping plunger having an end region which is slidably received within the bore, a spill port defined by the pump body in a wall of the bore which port is coverable by the end region of the pumping plunger as the plunger is driven on a pumping stroke, in use, so as to initiate fluid pressurization within a pumping chamber; and a spill feature defined by the pumping plunger being arranged to uncover the spill port during a pumping stroke so as to cause depressurization of the pumping chamber. The pumping plunger further defines a speed sensitive feature configured to permit a controlled leak of fluid from the pumping chamber to the spill port towards the end of a pumping stoke. The invention also encompasses a pumping plunger particularly suited for use in the above described pump.

Abstract: A power piston sealing assembly in conjunction with a Stirling engine is disclosed. The power piston sealing assembly consists of one or several sealing retainers with threads alternatively using fasteners within the power piston. Said power piston sealing assembly comprises of a power piston, displacer rod seal(s), displacer seal spring(s) and sealing retainer(s) all concentrically mounted within the power piston.

Abstract: A motorcycle shock system has a shock body formed at least partially of aluminum and an air compressor that provides pressurized air to the shock body when necessary. A piston held within the shock body defines a rear air chamber and a forward air chamber on the opposite side of the piston. Four electrically controlled air valves include a first air valve that when actuated opens a passage to allow air to flow into the forward chamber, a second air valve that when actuated opens a passage to allow air to flow out of the forward chamber to the atmosphere, a third air valve that when actuated opens a passage to allow air to flow out of the rear air chamber, and a fourth air valve that when actuated opens a passage to allow air to flow into the rear air chamber.

Abstract: A piston has a piston body made of a material selected from any one of aluminum, an aluminum alloy, magnesium, and a magnesium alloy. An entire surface or a predetermined portion of the surface of the piston body is covered with a plasma oxide film.

Abstract: A method of producing a piston that involves providing a piston body formed of a first material, the piston body having a cylindrical portion having a diameter, a rounded end, and a neck connecting the rounded end to the cylindrical portion and having a diameter less than the diameter of the piston body, cladding a portion of the cylindrical portion with a first tool steel layer, cladding a portion of the rounded end with a second tool steel layer spaced from the first tool steel layer, heat treating the piston body and nitriding the first and second tool steel layers. Also a piston (10) having first (18) and second (22) nitrided, tool steel clad portions.

Abstract: A piston has a body with a first circumferentially disposed groove. A first ring is movably disposed within the first groove. The first ring defines an inner circumferential groove. A blocking ring is at least partially located in the groove of the first ring and the groove of the piston. One or more vent passages may connect a first volume in the piston to a second volume outside the piston.

Abstract: Disclosed is a piston (1) for a combustion engine, comprising hub bores (3) that are provided with plain bearing surfaces (5) and are used for accommodating a piston pin. In order to very effectively and inexpensively prevent the piston pin and the hub bores from jamming and wearing off, a self-lubricating coating (6) made of a thermally cured resin which contains embedded solid lubricant particles is applied directly to at least one subarea (Tb) of the plain bearing surfaces by means of rotary atomization.

Abstract: A piston-cylinder assembly includes a working cylinder, and a one-piece stamped and formed piston body which is attached to a piston rod, the piston body being axially movable in the cylinder and dividing the cylinder into two working spaces. The piston body has at least one fist opening provided with a first valve for passing fluid when the piston moves in a pull direction, and at least one second opening provided with a second valve for passing fluid when the piston moves in a push direction. A circumferential surface of the piston body is formed with a shallow groove which holds a seal between the circumferential surface and the working cylinder.

Abstract: A high velocity actuator, which may be used as a blast simulator, is provided with an actuator cylinder tube having an opening at first and second cylinder ends, and an actuator piston rod slidably mounted within the actuator cylinder tube and extending through the opening in the first cylinder end. A control valve concentric to the actuator cylinder tube is configured to be coupled to a source of pressurized fluid and controls admittance of the fluid under pressure to the actuator cylinder at the second cylinder end to act on the actuator piston rod to extend the actuator piston rod towards the first cylinder end.

Abstract: A piston formed from an Al—Si alloy having an average Si composition includes a high wear region having a surface that is Si-rich with respect to the average Si composition of the Al—Si alloy. The surface of the predetermined high wear region is treated, as by etching, to selectively remove Al from the surface to produce the Si-rich region. The Si-rich region has improved resistance to wear. The piston may be treated to produce one or more high wear regions which are Si-rich with respect to the average Si composition of the alloy. High wear regions may include the annular grooves for receiving a piston ring, the piston skirt and the pin bore.

Abstract: A metallic sliding member which is improved in initial compatibility and significantly reduced in frictional resistance: and a process for producing the member. The process comprises causing fine particles of molybdenum disulfide to collide against the surface of a base to form a layer containing molybdenum disulfide, serving as a solid lubricant, as a surface layer having a depth not larger than 20 ?m from the surface.

Abstract: Disclosed is a piston having a top chamfer functioning as an oil reservoir, the top chamfer designed to reduce piston noise and friction. The top chamfer partially defines a tapered volume or cavity configured to enhance oil flow to the middle portions of the piston skirt so as to increase lubrication during piston up stroke and thereby reduce piston noise and friction.

Abstract: A piston includes a cylindrical body having a neck formed on an outer periphery of the cylindrical body so as to form a first annular disk and a second annular connecting to the first annular disk via the neck, multiple through holes defined through the second annular disk to communicate with a first space among the second annular disk, the neck and the first annular disk, an annular recess defined in an outer periphery of the second annular disk and multiple slits defined through a bottom face defining the annular recess to communicate with a second space below the first annular disk after passing through the neck.

Abstract: A method of producing a piston that involves providing a piston body formed of a first material, the piston body having a cylindrical portion having a diameter, a rounded end, and a neck connecting the rounded end to the cylindrical portion and having a diameter less than the diameter of the piston body, cladding a portion of the cylindrical portion with a first tool steel layer, cladding a portion of the rounded end with a second tool steel layer spaced from the first tool steel layer, heat treating the piston body and nitriding the first and second tool steel layers. Also a piston (10) having first (18) and second (22) nitrided, tool steel clad portions.

Abstract: A device, method, and system for a piston assembly are disclosed herein. A piston may have an outer circumferential groove. A semi-rigid ring seal may be sized and shaped to fit within the circumferential groove. The semi-rigid ring seal may provide a seal between the piston and a bore of the piston. The semi-rigid ring may be positioned during assembly within the outer circumferential groove without stretching the semi-rigid ring.

Abstract: The invention relates to a lightweight piston comprising heat pipes. The aim of the invention is to simplify the structure of such a piston while at the same time allowing for an improved heat dissipation from the piston areas subject to heat load while avoiding thermal stress. For this purpose, a plurality of liquid-filled heat pipes each having an evaporator and a condenser end is used, whereby the evaporator end is configured by short pipe sections that are oriented in the thickness at bottom towards the focal point and that are interlinked by means of a composite heat pipe extending in parallel to the piston head. At least two pipe sections functioning as the condenser end are coupled with the composite heat pipe in such a manner as to configure, by way of a pipe connection arranged on the condenser ends, a closed coolant cycle between the evaporator end, composite heat pipe and condenser end of the heat pipe.

Abstract: A piston cartridge having a piston chamber, an inlet port, an outlet port, and a piston moveable between a first position and a second position. Also, the cartridge includes a first barrier positioned between the piston and the inlet port and a first sealing member moveable between the first barrier and the inlet port, wherein the first sealing member seals the inlet port when positioned adjacent to the inlet port but allows the fluid into the chamber when positioned adjacent to the first barrier. In addition, the cartridge also includes a second barrier positioned adjacent to the outlet port and a second sealing member moveable between the piston and the second barrier, wherein the second sealing member seals the outlet port when positioned adjacent thereto but allows the fluid to pass through the outlet port when positioned adjacent to the second barrier.

Abstract: A fluid cylinder for high temperature applications is disclosed. The fluid cylinder includes an extensible member that moves between a retracted position and an extended position by forcing a fluid, such as a pneumatic fluid or a hydraulic fluid, into the cylinder. In order to seal the extensible member against an internal surface of the cylindrical housing, the extensible member includes a sealing member defining a plurality of grooves. A corresponding plurality of metallic sealing rings are placed in each of the grooves. The sealing rings include a gap that allow for thermal expansion. The sealing rings are positioned in the grooves so that the gaps on the rings are in a staggered arrangement in the axial direction. Further, a metal alloy coating may be applied to at least certain parts of the fluid cylinder. Through the above configuration, the fluid cylinder can be made without any polymeric sealing rings, composite bearings, or lubricants that may degrade during high temperature applications.

Abstract: A piston assembly includes a cross-head piston and a cylindrical cross pin. The cross-head piston includes a piston head having a cylindrical wall, a lateral surface and an opposite inward surface. Two spaced-apart connection ears, each having a proximal end and an opposite distal end, extend outwardly from the inward surface. Each proximal end is affixed to the inward surface and each distal end defines a pin bore passing therethrough. A piston well is defined by the inward surface and the connection ears. The cylindrical cross pin is disposed coaxially with a central axis so as to be engaged with both pin bores. The cross pin defines a central cross pin oil passage passing transversely to the central axis. The cross pin is placed in relation to the piston head so that the second end of the cross pin oil passage is directed to the piston well.

Abstract: A pumping system including a pump is disclosed. The pump includes a replacement piston and a replacement cylinder associated with the replacement piston. The replacement piston has a cross sectional area smaller than a cross sectional area of an original piston of the pump.

Abstract: A reciprocating piston compressor for a gaseous medium is provided having a reduced structural height. The compressor is especially for a level control system in a motor vehicle. The maximum pivot angle of the piston ring longitudinal axis relative to the longitudinal axis of the cylinder running path is smaller during the upward movement of the piston than for the downward movement of the piston. The longitudinal axis of the cylinder running path is offset relative to the first spatial axis.

Abstract: An adjustable piston pump for displacement and extraction of remnant from soft sand and or soft soil includes a pump casing cylinder that is capped at one end and opens at the other end. It includes a handle fixed to the pump casing cylinder, a shaft rod, a shaft rod handle and a piston that includes a flexible ball. The shaft rod is retractable through the center of the capped end of the pump casing cylinder and is connected to a shaft rod handle. The portion of the shaft rod that always remains embodied in the pump casing cylinder is connected to a piston. The flexible ball mounted inside the piston construction is compressed or decompressed by the clockwise or counter clockwise rotation of the handle located at the other end of the shaft rod. Pressure is controlled in this manner. Upward and downward strokes of the piston initiate displacement and extraction of remnant.

Abstract: Cooled two-part piston for internal combustion engines having an upper piston part containing the piston ring grooves and piston pin bosses, and a piston skirt connected with the former exclusively by way of a piston pin. The upper piston part has a cooling oil annular channel that is open towards the piston skirt, into which channel the cooling oil is introduced, and discharged. There are collecting pockets attached at the upper end of the piston skirt, which faces the upper piston part. The pockets at least partially cover the cooling oil annular channel. When the engine and piston are arranged horizontally, a tub-shaped recess is provided in an interior bottom region of the piston skirt for accommodating cooling oil. The circumferential wall limitation of the recess is formed exclusively by a wall of the inside piston skirt.

Abstract: The invention relates to a cup-shaped hydraulic piston (10) made from rolled sheet metal, which comprises an open end (12), a side wall (16) with a cylindrical outer surface (18) and an inner surface (22), as well as a piston head (14). The side wall (16) at its outer surface (18) is provided with an annular groove (20) in a portion adjoining the open end (12). To ensure a lightweight style of construction combining high stability with ease of manufacture, the part of the inner surface (22) adjoining the open end (12) and extending axially over the annular groove (20) has a cylindrical shape, and the thickness of the side wall (16) decreases monotonically from the portion (24) of the inner surface (22) up to the piston head (14).

Abstract: In a piston for a compressor, the piston comprises a stem by which the piston may be guided in the housing in an axially displaceable manner, and a force introducing section where an outer drive force can be introduced into the piston. The piston head, the piston skirt and the force introducing section are successively arranged in the direction of the piston axis. The piston head, the piston skirt and the force introducing section are produced as a single element of graphite or a synthetic material, and the piston skirt comprises a solid strut structure and a guide section, the cross-sectional area of the strut structure being smaller than the surface of the piston head. The piston consists of a non-organic, non-metallic material having an average thermal expansion of less than 7×106/° C. in the temperature range of 0° C. to 200° C.

Abstract: To provide the pistons of internal combustion engines with profiled ring grooves in a simple manner. To this end, the profile is produced by laser beams.

Abstract: In a piston for a compressor, the piston comprises a stem by which the piston may be guided in the housing in an axially displaceable manner, and a force introducing section where an outer drive force can be introduced into the piston. The piston head, the piston skirt and the force introducing section are successively arranged in the direction of the piston axis. The piston head, the piston skirt and the force introducing section are produced as a single element of graphite or a synthetic material, and the piston skirt comprises a solid strut structure and a guide section, the cross-sectional area of the strut structure being smaller than the surface of the piston head. The piston consists of a non-organic, non-metallic material having an average thermal expansion of less than 7×106/° C. in the temperature range of 0° C. to 200° C.

Abstract: A system for preventing scuffing of a cylinder wall by a piston ring includes a piston ring, the piston ring including a surface, wherein the surface of the piston ring is coated with tungsten disulfide. The coating provides lubrication during the piston and piston ring break-in period and prevents localized high pressure and high temperature areas that produce scuffing.

Abstract: A piston unit (10) comprises a piston (10a) and a connecting element (5). The piston comprises a piston head (1) comprising a compression surface (1a1) and a skirt portion. The skirt portion comprises a first and second ring (2, 3) apart form each other in the axial direction. The first and second rings (2, 3) are jointed to each other by jointing members (4a) at angularly-spaced positions with widows being left between the first and the second rings (2, 3). The piston head (1) is made of resin and is fixedly mounted at an axial end of the first ring and the connecting element (5) is fixed to the opposite axial end of the second ring (3). The connecting element (5) comprises four plates (5b, 5c) combined to form a cross in cross section. The four plates (5b, 5c) connect the axial end of the second ring (3) at angularly-spaced positions.

Abstract: The invention relates to a cup-shaped hydraulic piston (10) made from rolled sheet metal, which comprises an open end (12), a side wall (16) with a cylindrical outer surface (18) and an inner surface (22), as well as a piston head (14). The side wall (16) at its outer surface (18) is provided with an annular groove (20) in a portion adjoining the open end (12). To ensure a lightweight style of construction combining high stability with ease of manufacture, the part of the inner surface (22) adjoining the open end (12) and extending axially over the annular groove (20) has a cylindrical shape, and the thickness of the side wall (16) decreases monotonically from the portion (24) of the inner surface (22) up to the piston head (14).

Abstract: A simplified piston (14), slidable in a cylinder (16), moved by magnetic coupling to an external magnetic element (20) which moves along the cylinder (16).

Abstract: A piston for use in the cylinder block of a hydraulic power unit. The piston has an elongated cylindrical body with one end configured to connect with a slipper element. The second end of the piston is open with an annular cavity in the piston body defining an elongated stem extending from the head end of the piston and slightly protruding through the open end. The stem is concentrically located within the longitudinal axis of the annular cavity and has an elongated fluid conduit that extends longitudinally through the stem and completely through the piston. The fluid conduit traverses the piston body along the center axis, providing a path for pressurized fluid. The piston is composed of a unitary cast construction.

Abstract: A combination of piston and piston ring comprises a piston having a piston ring groove in which at least the groove portion of the piston is made of steel, a piston ring made of cast iron and fitted into the piston ring groove, and a hard coat film formed to at least an outer peripheral sliding surface of the piston ring.

Abstract: A pad plunger assembly includes a central mandrel having externally-threaded opposite ends, collars defined about the mandrel inwardly adjacent to the opposite ends and having circumferentially spaced recesses formed in the collars, end members having inner ends with internally-threaded bores threadably removably attached to the externally-threaded opposite ends of the mandrel, and inner annular flanges attached to and extending axially from the inner ends of the end members and adapted to receive the collars such that, for locking the end members onto the mandrel, the end members are threadably screwed onto the opposite ends of the mandrel and then the flanges are crimped so as to force circumferentially displaced portions thereof into the collar recesses thereby locking the end members.

Abstract: A method of manufacturing a piston using a swaging tool includes the step of positioning a portion of a first member and a portion of a second member of the piston within a first end of an opening formed through the swaging tool, such that a reduced diameter portion of the second member is substantially aligned with a first ring portion of the first member and an end portion of the second member contacts a second ring portion of the first member to create an annular space adjacent to the first ring portion and the reduced diameter portion. The method also includes the step of subsequently swaging the first ring portion by moving the first ring portion in a direction toward a second end of the swaging tool, such that a portion of the first ring portion is positioned within the annular space to fix the first member to the second member.

Abstract: A closed cavity piston includes an elongated piston body and a separately formed piston cap having an elongated stem and head thereon. The body includes a closed end and an open end with a cavity having a bottom wall adjacent the closed end and an outer wall terminating in a rim at the open end. The stem of the piston cap is friction inertia welded to the bottom wall of the piston body and the head of the piston cap welds to the rim of the piston body so as cover the open end and sealingly enclose the cavity. The piston components can both be formed by conventional and relatively inexpensive cold forming techniques. The stem of the cap is inserted into the cavity of the body until it engages the bottom wall. Then the cap is friction inertia welded to the body at the stem/bottom wall and head/rim interfaces.

Abstract: A single-headed piston for a swash plate type compressor including a head portion having an outer circumferential surface for sliding contact with an inner circumferential surface of a cylinder bore formed in a cylinder block of the compressor, and an engaging portion engaging a swash plate of the compressor, characterized in that; the outer circumferential surface of the head portion includes a cylindrical surface and a curved surface which is formed adjacent to at least one of opposite axial ends of the cylindrical surface, so as to smoothly extend from at least one circumferential part of the cylindrical surface, the curved surface being formed such that a radial distance between a centerline of the cylindrical surface and the curved surface gradually decreases in an axial direction of the cylindrical surface from the corresponding axial end of the cylindrical surface toward the corresponding axial end of the piston, and such that a radius of curvature of a cross sectional shape of the curved surface taken

Abstract: A piston and cylinder unit includes a housing, a piston and a piston rod. The piston rod has an outer surface being designed to be symmetrical with respect to a first axis. The piston rod includes a protrusion and an outer thread being located on the protrusion. The protrusion and the outer thread are designed to be symmetrical to a second axis. The second axis is spaced apart from the first axis to define a first eccentricity of the piston rod. The piston is located in the housing. The piston has an outer surface being designed to be symmetrical with respect to a first axis. The piston includes at least one seal, at least one guiding element, an opening and an inner thread being located in the opening. The opening and the inner thread are designed to be symmetrical to a second axis. The second axis is spaced apart from the first axis to define a second eccentricity of the piston.

Abstract: There is disclosed a high-pressure compressor comprising a compression mechanism for reciprocating/driving a piston with respect to a conventional cylinder by rotation of a motor and compressing an operating fluid sucked by this driving to generate the high-pressure operating fluid according to improvements in a piston shape, positions of a cylinder operation surface and the piston, specifics shapes of the cylinder and piston, and connecting constitution of the piston to a connecting rod, which solves problems such as occurrence of wear on a cylinder inner surface by displacement of the piston, size enlargement by an increase of a removal capacity, difficulty in processing the piston and connecting rod, and a large top clearance.

Abstract: Described is a radial piston pump with a pump housing (3), which has a plurality of cylinder bores (5) arrayed in star shape around a cam (4), for the reception of pistons (6) and possesses inlet (7) and outlet (8) when penetrate to each cylinder inner chamber (9) with a therein compressible working volume. In accord with the invention, each cylinder inner chamber (9) is provided with at least one relief opening, which connects the working volumes during a compression stroke of the piston (6) with a space of lesser pressure for the reduction of the pressure gradient and also thereby reducing the noise of the pump.

Abstract: A compressor piston has protrusions which extend upwardly into discharge ports to minimize clearance at the end of the compression stroke. The protrusions fit into circumferentially isolated discharge ports, and each of the ports are associated with reed valves. Preferably a cutout portion is formed into the piston head to allow clearance for movement of the suction valve. The suction valve is positioned on an inner face of a valve plate and the discharge reed valves are positioned on an outer face. The protrusions are preferably frustro-conical.

Abstract: A master cylinder for use in the power train of a motor vehicle to actuate the brakes or the friction clutch is designed to avoid the generation of screeching noise and/or the transmission of stray movements to the piston rod in response to shifting of the piston relative to the housing and relative to the sealing element(s) between the piston and the housing. This can be accomplished by causing the piston to turn relative to the housing and the sealing element(s) during axial movement in the housing and/or by installing one or more dampers between the piston and the housing and/or between the piston and the piston rod. The dampers can constitute separately produced parts and/or specially configured and/or finished surfaces provided on the piston and contacting the housing and/or the sealing element(s). The invention also relates to improvements in the configuration and/or the material(s) of the piston.

Abstract: The aim of the invention is to provide the pistons of internal combustion engines with profiled ring grooves in a simple manner. To this end, the profile is produced by laser beams.

Abstract: A single headed swash plate type compressor includes a swash plate and pistons reciprocatingly arranged in cylinder bores. Each piston has a body portion and a neck portion. The body portion of the piston has a cavity to reduce the weight of the piston, and the piston has ribs to reinforce the body portion. A first rib is arranged within the cavity near the front end wall of the body portion, and a second rib is arranged outside the cavity near the front end wall of the body portion.

Abstract: A device used for pneumatic control, includes a control piston carried in a cylinder. The control piston is mounted so as to be movable in the direction of a longitudinal piston axis, and a primary flow path that can be closed by the control pressure passes through the cylinder. The control piston is provided with a control surface that faces a control chamber of the cylinder and that is designed to transmit a control force to the control piston. The control piston is made at least partially of a plastic.

Abstract: A metallic sliding member which is improved in initial compatibility and significantly reduced in frictional resistance: and a process for producing the member. The process comprises causing fine particles of molybdenum disulfide to collide against the surface of a base to form a layer containing molybdenum disulfide, serving as a solid lubricant, as a surface layer having a depth not larger than 20 &mgr;m from the surface.