Abstract: A cylinder liner for a cylinder bore of a cylinder of an internal combustion engine. The cylinder liner includes a cylindrical casing having an outer surface and an inner surface, wherein each surface has a respective surface area. The liner includes a liner seat positioned on the outer surface wherein the liner seat engages with the cylinder bore to position the cylindrical casing in the cylinder bore. The liner includes a relief feature positioned on the outer surface either adjacent the liner seat or above a mid-stop wherein the relief feature resists distortion of the cylindrical casing from the cylinder bore. The liner can include a stiffening feature positioned above the relief feature on the outer surface. The relief feature forms a depressed surface on the outer surface and the stiffening feature forms a raised surface on the outer surface of the cylindrical casing.

Abstract: A method of making a die cast part having high wear resistance is provided. The method comprises providing a mold and an insert pin. The mold comprises an interior surface defining a cavity. The mold comprises a bore formed through the interior surface. The insert pin has a magnetic core having a magnetic field and a barrier disposed about the magnetic core. The insert pin is disposed in the bore and extends into the cavity. The method comprises filling the mold with metallic material such that the metallic material is in contact with the insert pin to define a contact layer. The method comprises modifying iron content within the contact layer with the magnetic field to define an outer layer and an inner layer formed between the outer layer and the insert pin. The inner layer has 3-5 wt % Fe and the outer layer has 0.01-0.5 wt % Fe.

Abstract: An internal combustion engine 100 comprising a cylinder head 102, a cylinder head cover 104, an intermediate flange 106 arranged between the head 102 and the head cover 104. A first opening extending from the head cover 104, through the intermediate flange, into the head 102, the first opening includes first internal threads lying inside the cylinder head area, a second opening having an integrated first threaded bolt provided at an end of the intermediate flange touching the cylinder head 102. A plurality of fasteners comprising a screw having a head, and a shaft fastening the head cover 104 and intermediate flange to the head such that the head of the screw rests directly on top of the cylinder head cover 104 when the screw is tightened.

Abstract: Provided is a method for preventing the accumulation of cylinder oil at scavenging ports of low-speed marine engines. An oil passage is provided on a cylinder wall inside a cylinder. The oil passage includes multiple oil storage grooves processed in a circumferential direction of the cylinder wall. The oil passage is formed by obliquely extending from the inner side of the cylinder wall to the outside of the cylinder in a radial direction of the cylinder. The scavenging ports are uniformly distributed in a circumferential direction of the cylinder wall, and each of the oil storage grooves is correspondingly processed at an upper portion of the scavenging port upper edge of the scavenging port. Each of the oil storage grooves has a shape matching the curved surface of the scavenging port upper edge.

Abstract: A method for purifying powdered silicon carbide is in the form of a starting material to form a silicon carbide having a purity of at least 99.9%. This method has the following method steps: providing a starting material having a grain size of less than 100 ?m and a silicon carbide content with at least 98% purity; and heating the starting material in a vacuum or oxygen-free atmosphere to a temperature above 1700° C. over a period of at least 8 minutes.

Abstract: An engine block includes one or more cylinder bores wherein each cylinder bore is surrounded by a cylinder bore wall. The cylinder bore wall includes a liner stop mechanism to locate a liner in the cylinder bore. The cylinder bore includes a mid-portion that spans between an upper end and a lower end, wherein the liner stop mechanism can be located near the upper end, near the lower end, or the mid-portion. The engine block has an outer cylinder block wall that is exterior to the cylinder bore wall. The outer cylinder block wall includes a first rib positioned above the liner stop mechanism and a second rib positioned below the liner stop mechanism relative to a cylindrical axis of the cylinder bore. The first and second ribs straddle the liner stop mechanism to reduce rotation and buckling of the liner during operation of the engine.

Abstract: A cylindrical sleeve for an internal combustion engine is disclosed. The cylindrical sleeve includes a hollow cylindrical sleeve body, extending along an axial direction, with an inner peripheral side that has, along the axial direction, a first axial portion and a second axial portion. The inner peripheral side in the first axial portion is either cylindrical or opens at a first opening angle towards the second axial portion. The second axial portion opens at a second opening angle away from the first axial portion that is greater than the first opening angle. A first surface roughness of the inner peripheral side in the first axial portion is greater than a second surface roughness in the second axial portion.

Abstract: A linear electromagnetic machine includes a stator, a translator, and a bearing system. The bearing system maintains alignment against lateral displacement of the translator relative to the stator, as the translator reciprocates axially. More particularly, the bearing system maintains a motor air gap between the stator and a magnetic section of the translator. The stator includes a plurality of stator teeth and windings, which form a plurality of phases. The stator teeth and windings are arranged using a hoop stack with spines to form a stator bore and define the motor air gap. The bearing system can include bearing housings that are configured to form a bearing interface with a surface of the translator. The bearing interface can include a contact bearing or a non-contact bearing, such as a gas bearing. Current is controlled in the phases to convert between electrical energy and kinetic energy of the translator.

Abstract: High pressure presses, components for high pressure presses and related methods are provided herein. In one embodiment of the invention, a press base may include a piston cavity formed in the press base and a piston cavity sleeve positioned in the piston cavity. The piston cavity sleeve may include a wall having an outer surface and an inner surface opposite the outer surface. The piston cavity sleeve may further include a floor having an upper surface and a lower surface opposite the upper surface. An outer radius may be formed at a juncture of the outer surface of the wall and lower surface of the floor and an inner radius may be formed at a juncture of the inner surface of the wall and upper surface of the floor. The inner radius may exhibit a radius of curvature that is greater than a radius of curvature of the outer radius.

Abstract: A method and apparatus for casing recovery for well abandonment. A string is run-in, the string including a hydraulic jack (18), an anchor (28), a casing spear (20), a downhole flow pulsing device (22) and a pressure drop sub (24). The casing spear grips an upper end of the length of casing to be pulled. The anchor is set in casing of a greater diameter above the length of cut casing. Fluid pumped through the string and through the pressure drop sub will increase fluid pressure at the hydraulic jack to a first fluid pressure (78). Fluid pumped through the downhole flow pulsing device will vary the fluid flow superimposing a cyclic pressure (82) on the first pressure (78), causing oscillation of an inner mandrel (30) of the hydraulic jack. The jack moves the oscillating inner mandrel upwards relative to the anchor to pull the length of casing.

Abstract: The invention relates to a roller burnishing tool 10 with a base body 12 extending along a longitudinal center axis 11, at least one roller holder 14 arranged radially adjustably on the base body 12, which holds a roller 15 rotatably, and an adjusting device 16 arranged in the base body 12 for adjusting the roller holder 14 cooperates in the radial direction with the roller holder 14. According to the invention, the roller holder 14 has a holder arm 18b holding the roller 15, which can be pivoted out in a radial direction by the adjusting device 16 relative to the base body 12 in a radial direction.

Abstract: Cylinder arrangement (1) and method for cooling the cylinder arrangement (1) addresses a solution with which the heat transfer from a combustion chamber (6) of an internal combustion engine located in a cylinder liner (2) of the cylinder arrangement (1) into a region (7) surrounding the cylinder liner (2), such as a cylinder block or crankcase, is controlled in a temperature-dependent manner. Arrangement solves said problem by providing a jacket (9), the expansion of which changes depending on temperature, arranged between the cylinder liner (2) and the region (7) surrounding the cylinder liner (2). The method uses the cylinder liner (2) with a jacket (9), expands depending on temperature and surrounds the cylinder liner (2); jacket (9) forms a gap (10) between jacket (9) and region (7) in a first temperature range; jacket (9) forms no gap (10) between jacket (9) and region (7) in a second temperature range.

Abstract: The present invention provides an aluminum hybrid metal matrix composite including cerium and graphite. The aluminum-cerium intermetallic is stable at temperatures up to a melting point of aluminum and graphite provides in situ lubrication. This stability is advantageous in applications such as cylinder liners and other applications where strength and stiffness at elevated temperatures are required.

Abstract: A piston ring includes an annular body, a wear-resistant layer that is applied to the annular body by thermal spraying, and a strain-hardened run-in layer, made of an AlCuFe alloy, that is applied to the wear-resistant layer by thermal spraying.

Abstract: A piston for an internal combustion engine includes a piston crown having a crown outer surface forming piston lands alternating axially with piston ring grooves together with the piston lands defining a deposit-sensitive zone. The crown outer surface is smoothed to inhibit deposit formation and/or adhesion within at least a portion of the deposit-sensitive zone to a roughness average (Ra) of 0.0002 millimeters or less, and in a refinement to a mirror finish Ra of 0.000125 or less.

Abstract: An engine includes an output shaft, a cylinder block, a cylinder head, a cap portion, and head bolts. The cylinder block, the cylinder head, and the cap portion are fastened together with the head bolts. The cylinder block includes a cylinder portion and a plurality of output shaft supporting portions. When an outer wall face of at least one of the plurality of output shaft supporting portions is viewed along an output shaft axial direction, the outer wall face includes a first rib diagonally extending from a supporting portion of the output shaft toward one of two head bolt holes.

Abstract: An engine includes a cylinder liner and a piston movable within the cylinder liner, a crevice formed between a top land of the piston and the cylinder liner, and an oil entry clearance formed between a top ring of the piston and the cylinder liner. The engine also includes an abnormal combustion inhibitor having an oil recapture surface exposed to the crevice and oriented to limit migration of oil from the crevice toward a combustion chamber in the engine. The abnormal combustion inhibitor includes a groove structure having as a substrate at least one of the cylinder liner or the piston. Related methodology is also disclosed.

Abstract: A cooling structure of an internal combustion engine includes a thermostat provided to switch circulation between a radiator passage and a bypass passage in an engine body, to thereby enable acceleration of early warming up via the bypass passage without impairing the external appearance or increasing the size of the internal combustion engine. The cooling structure also includes an in-cylinder-block fluid passage partitioned up and down in an axial direction of a cylinder axis into an in-cylinder-block upper fluid passage and an in-cylinder-block lower fluid passage by a partition wall. The bypass passage is partially composed of the in-cylinder-bock lower fluid passage.

Abstract: A cylinder housing for a reciprocating-piston internal combustion engine, in particular of a motor vehicle, includes a first cylinder which is delimited by a first cylinder barrel and a second cylinder which is delimited by a second cylinder barrel. The cylinders differ from one another with respect to their respective inner contour formed by the respective cylinder barrels.

Abstract: In a sliding structure for an internal combustion, a cylinder has recesses in a stroke center region. Piston rings have inclined surfaces on an outer circumferential surface, and a lubricating oil flows between the inner wall surface and the outer circumferential surface that relatively move via the inclined surfaces. At any RPM equal to or greater than at idle, a center friction coefficient at the stroke center region through which the piston rings pass at the highest speed is less than a center friction coefficient when no recesses are formed in the stroke center region. Contrarily, at the RPM, an outside friction coefficient when the piston rings pass through a region outside the stroke center region is less than an outside friction coefficient when the recesses are formed in the outside region. As a result, further improved low fuel efficiency is achieved for the dimple liner technique.

Abstract: Plunger pump includes cylinder having inside cylinder chamber; plunger disposed in cylinder to be relatively movable forward and backward to cylinder chamber so outer plunger's circumferential face is in slide contact with cylinder's inner circumferential face, and having cut face on distal end's outer periphery; and suction and discharge ports provided to cylinder to communicate with cylinder chamber, plunger pump transferring fluid by reciprocating plunger in axial direction while rotating plunger relative to cylinder chamber to let suction and discharges ports alternately communicate with cylinder chamber, wherein cylinder includes cylinder main body and spacer section being disposed in cylinder main body's inner portion of proximal end side, and sliding against plunger's portion closer to proximal end side than portion of plunger advancing and retracting into cylinder chamber, and plunger pump further includes seal section provided on cylinder's proximal end side for sealing cylinder main body, plunger an

Abstract: Systems and methods are provided for a cylinder liner for an engine including a catcher feature on a side surface to provide radial support and improved coolant sealing. In one example, the catcher feature may include a continuous stepped catcher extending from the cylinder liner body and a stepped tab of the engine block, the stepped catcher resting on the stepped tab. Also, a radial flange in the upper portion of the cylinder liner may be coupled to the engine block, the coupling sealed via an O-ring nestled in a groove formed in the radial flange.

Abstract: Provided is a cylinder liner having a first portion with a first thermal conductivity and a second portion with a second thermal conductivity. The first portion having the first thermal conductivity can include as-cast projections or a coating of a material, as desired. The first thermal conductivity can be greater than the second thermal conductivity. In this manner, the cylinder liner can exhibit a thermal conductivity gradient.

Abstract: To provide a cast iron cylindrical member capable of improving the bonding strength when metal on the outer peripheral side and the cast iron cylindrical member are integrated. For this objective, in a cast iron cylindrical member including a plurality of projections including constricted projections on the outer peripheral surface, the anchor portion index (I) represented by {(Aav2?Bav2)×?/4×Pn×Pr/100}×0.35H/2 is set in a specific range.

Abstract: Aspects of the present disclosure are directed to a cylinder housing of an internal combustion engine. In one embodiment of the present disclosure, the cylinder housing includes at least two adjacently arranged cylinders, each of which includes a wet cylinder liner, a support structure, and a coolant jacket arranged between the support structure and the cylinder liner. The cylinder housing further including at least one screw receptacle for a cylinder head screw, and is positioned between at least two adjacently arranged cylinders in a region of at least one engine transverse plane.

Abstract: Provided are a method of manufacturing an engine, an engine, and a connected cylinder. The method of manufacturing an engine includes at least a fitting step of fitting a connected cylinder to a hollow portion of a cylinder block main body. The connected cylinder is (1) a first connected cylinder including two or more cylinder liners and a connecting portion configured to connect the two or more cylinder liners to each other or (2) a second connected cylinder including a connected cylinder main body portion having two or more cylinder bores and a coating configured to cover an inner peripheral surface of the connected cylinder main body portion in which the cylinder bores are formed. The cylinder block main body has one end side, another end side, and the hollow portion passing through the cylinder block main body from the one end side to the another end side.

Abstract: Methods and systems are provided for coatings of a portion of an engine block shaping a combustion chamber. In one example, the engine block includes a first coating with a thermal conductivity higher than a conductivity of the engine block arranged in an upper region of the combustion chamber and a second coating with a thermal conductivity lower than the conductivity of the engine block arranged in a lower region of the combustion chamber, and where the second coating touches the first coating.

Abstract: A member having a sliding contact surface that exerts a reduced frictional force when making sliding contact with a prescribed member and retains the lubricating oil more uniformly is provided. The sliding contact surface is a honed surface having flat plateau parts and groove parts. As calculated in regard to the sliding contact surface by using a mean line derived from a cross-sectional curve of the sliding contact surface in accordance with ISO 13565-1, a ten-point average roughness is 0.6-7.0 ?m, a load length ratio at a cut level of 20% is 60-98%, an effective load roughness is 0-1 ?m, and a mean value of intervals between the groove parts having a depth of 0.2 ?m or greater from the mean line is 79-280 ?m.

Abstract: A hardfacing metal composition and method of restoring worn work string tubing by application of a hardfacing metal to the worn regions of the work string tubing.

Abstract: A plunger pump includes a cylinder section having a cylinder chamber and a spacer section sliding against a portion of the plunger closer to a proximal end side than a portion of a plunger advancing and retracting into the cylinder chamber. The cylinder section is made of a material having first hardness, and the spacer section being made of a resin material having second hardness softer than the first hardness. A length in an axial direction from a proximal end of a sliding portion of the spacer section sliding against the plunger to a distal end of the spacer section is larger than a maximum stroke length of reciprocation of the plunger.

Abstract: Provided is a cylinder liner having a first portion with a first thermal conductivity and a second portion with a second thermal conductivity. The first portion having the first thermal conductivity can include as-cast projections or a coating of a material, as desired. The first thermal conductivity can be greater than the second thermal conductivity. In this manner, the cylinder liner can exhibit a thermal conductivity gradient.

Abstract: A component for an engine is provided. The component includes a thermal barrier coating applied to a body portion formed of metal, such as steel or another ferrous or iron-based material. According to one embodiment, a bond layer of a metal is applied to the body portion, followed by a mixed layer of metal and ceramic with a gradient structure, and then optionally a top layer of metal. The thermal barrier coating can also include a ceramic layer between the mixed layer and top layer, or as the outermost layer. The ceramic includes at least one of ceria, ceria stabilized zirconia, yttria, yttria stabilized zirconia, calcia stabilized zirconia, magnesia stabilized zirconia, and zirconia stabilized by another oxide. The thermal barrier coating can be applied by thermal spray. The thermal barrier coating preferably has a thickness less than 200 microns and a surface roughness Ra of not greater than 3 microns.

Abstract: The present disclosure relates to an internal combustion engine, in particular a reciprocating internal combustion engine, having at least one cylinder, wherein a cylinder wall of the cylinder is formed at least at a wall region forming a cylinder barrel by a coating of a crankcase or of a cylinder liner of the internal combustion engine by means of a coating material. According to the present disclosure, the coating material is formed of a high-alloy, steel alloy including, as alloying elements, chromium, nickel, copper and niobium.

Abstract: A cylinder liner for internal combustion engines has an outer roughened surface that has particularly good adherence properties. The surface has is covered with protrusions or spines of varying shapes and sizes, which are created by spraying the mold with a coating and then casting the cylinder liner in the mold. The spines are generally worm-shaped, with a length greater than a width, and a large spacing between the spines.

Abstract: An arrangement may include one of a cylinder liner or a cylinder bore formed in a crankcase of an internal combustion engine, a piston having a peripheral top land and being accommodated in the cylinder liner or cylinder bore, and an annular insert accommodated in the cylinder liner or cylinder bore and extending axially parallel to the piston top land. The cylinder liner or cylinder bore may have a radially inwardly-directed shoulder at an upper free end of the cylinder liner or cylinder bore. The annular insert may have along an upper peripheral free edge of the annular insert, distributed around a circumference of the annular insert, at least two beads or embossments located opposite one another and resting on the radially inwardly-directed shoulder.

Abstract: A cylinder block of an internal combustion engine includes a cylinder bore wall that holds a piston so as to allow the piston to reciprocate. In at least one part of the cylinder bore wall in a cylinder axial direction, the density of a layer located farther from a cylinder head is lower than the density of a layer located closer to the cylinder head in the cylinder axial direction.

Abstract: A method and system for processing an engine block that includes a cylinder liner. The engine block having a first material with different coefficient of thermal expansion than a second material forming the cylinder liner. The method includes providing an insulating barrier to the cylinder liner, and quenching the engine block. The insulating barrier provides a lower cooling rate to the second material forming the cylinder liner than a cooling rate for the first material forming the engine block during the quenching.

Abstract: An alloy composite material comprising an aluminum alloy layer and a thermal spray alloy layer of 20 to 40% Mn and 47 to 76% Fe by weight in overlaying contact with the aluminum alloy layer. An alloy composite material comprising an aluminum alloy layer or base layer and a thermal spray alloy layer of 20 to 40% Mn and 47 to 76% Fe by weight in overlaying contact with the aluminum alloy layer or base layer. The aluminum alloy layer or base layer and the thermal spray alloy layer have a mechanical compatibility to each other of 20-60 MPa as determined using tests specified by ASTM-C633 test. A process of thermal spraying comprising providing a base layer and a feed stock alloy of 20 to 40% Mn and 47 to 76% Fe and thermally spraying the feed stock alloy onto the base layer to form an alloy composite material.

Abstract: A bearing interface of an apparatus, the apparatus having a first element and a second element configured to move relative to each other during operation of the apparatus, the first element comprising a first bearing surface configured to engage at least a portion of a second bearing surface of the second element thereby defining a contact zone between the first bearing surface and the second bearing surface, the first bearing surface having at least one recess indented into the first bearing surface, wherein the dimension of the recess in the direction of movement of the second element relative to the first element is less than the dimension of the contact zone in the direction of movement of the second element.

Abstract: A high strength cast iron material for application in heavy duty diesel engines with Pa peak cylinder pressure greater than 240 bar is disclosed, the material a ductile material austempered to get a ausferrite matrix structure with higher mechanical properties than conventional cast iron materials available by using a designed low cost alloying cast material with heat treatment. Furthermore, the cylinder liner may be formed using novel heat treatment and/or fine honing processes to improve the properties thereof.

Abstract: A cylinder of an internal combustion engine, in which cylinder liner an oscillating piston is guided on a running surface wherein the cylinder line is fixed vertically by means of a collar between a cylinder housing and a cylinder head. The wet cylinder includes an outer side which deviates from a circular shape and/or a rotationally asymmetrical outer contour of the collar. The cylinder liner is fitted in a positionally oriented manner in a corresponding receptable of the cylinder housing.

Abstract: A linear compressor is provided that may include a shell including a suction inlet, a cylinder provided in the shell to define a compression space for a refrigerant, a piston reciprocated in an axial direction within the cylinder, a discharge valve provided at a first side of the cylinder to selectively discharge the refrigerant compressed in the compression space, at least one nozzle, through which at least a portion of the refrigerant discharged through the discharge valve flows, the at least one nozzle being disposed in the cylinder, and at least one expansion portion that extends from the at least one nozzle to an inner circumferential surface of the cylinder, the at least one expansion portion having a flow cross-section area greater than a flow cross-section area of the at least one nozzle.

Abstract: A sliding combination for use in an internal combustion engine may include at least one cylinder liner defining an internal sliding surface and a ring having an external lateral sliding surface. The external sliding surface of the ring may slide in relation to the internal sliding surface of the liner. The external sliding surface of the ring may include a first coating of a physical vapor deposited metal nitride in sliding contact with a second coating of a diamond-like carbon (DLC) material disposed on the internal sliding surface of the liner.

Abstract: A hydraulic piston pump includes a reciprocal piston disposed in a blind housing bore of a piston housing to generate a pumping action. To accommodate the piston, a piston cartridge is installed in each of the housing bores. The piston cartridge includes a piston sleeve having an inner sleeve periphery, a first outer sleeve periphery, and a second outer sleeve periphery. The inner sleeve periphery is configured to establish sliding contact with the piston. The first outer sleeve periphery has a first outer sleeve diameter that is larger than a second outer sleeve diameter of the second outer sleeve periphery. To seal against the blind housing bore, a liner cap having a cylindrical liner wall and an axial liner cover is disposed over the first outer sleeve periphery. The axial liner cover abuts a housing bore ceiling of the blind housing bore and can receive hydraulic fluid there through.

Abstract: A cylinder liner for an engine block includes a first engine block bonding surface, and a second engine block bonding surface that provides a lower heat transfer coefficient between the cylinder liner and an adjacent engine block material than the first engine block bonding surface. The second engine block bonding surface extends a substantial portion of the axial length of the cylinder liner.

Abstract: A wet cylinder liner for internal combustion engines may include a cylindrical body composed of a ferrous alloy having a circumferential outer surface. The cylindrical body may include a first layer and a second layer disposed sequentially on the outer surface. The first layer may include at least one of at least one silicon and at least one two-component epoxy adhesive. The second layer may include a silane-elastomer compound. The silane-elastomer compound may include nanoparticles of silicon oxide and an adhesion modifier additive. The second layer may be configured as an interface between a cooling fluid and the first layer, as well as to resist erosion by cavitation. The first layer may facilitate an interface for resistance at high temperatures.

Abstract: A cylinder liner for an engine block that includes an inter-bore saw cut includes a first engine block bonding surface, and a second engine block bonding surface that has a lower level of bonding between the cylinder liner and an engine block than the first engine block bonding surface. The second engine block bonding surface extending from an axial end portion of the liner a distance greater than a depth of the saw cut in inter-bore section of the engine block.

Abstract: To provide a piston ring of low-alloy steel having excellent nitridability, namely, a piston ring of low-alloy steel having excellent thermal conductivity and capable of being provided with a sufficient nitrided layer, steel comprising by mass 0.45-0.65% of C, 0.15-0.35% of Si, 0.65-1.00% of Mn and 0.60-1.10% of Cr as indispensable alloy elements, and less than 0.35% of Mo, less than 0.25% of V and less than 0.001% of B as optional alloy elements, the total amount of the indispensable alloy elements and the optional alloy elements being less than 3.0% by mass, is formed into a piston ring; and the nitrided layer is formed on its surface.

Abstract: A cylinder bore including an inner surface including an axial travel area and an axial non-travel area including two discontinuous axial widths of the cylindrical bore and the axial travel area extending therebetween. A nominal diameter of the axial travel area is greater than that of the axial non-travel area. A plurality of annular grooves is formed in the two discontinuous axial widths of the cylindrical bore.

Abstract: A cylinder liner for internal combustion engines has an outer roughened surface that has particularly good adherence properties. The surface is covered with protrusions or spines of varying shapes and sizes, which are created by spraying the mold with a coating and then casting the cylinder liner in the mold. The spines are generally conical or needle-shaped, with the bases being larger than the tips. The spines have an aggregate cross-sectional surface area measured at 0.2 mm from a ground cylindrical surface that is between 50-90% of the total ground cylindrical surface area, and an aggregate cross-sectional surface area measured at 0.4 mm from the ground cylindrical surface that is between 20-45% of the total ground cylindrical surface area.