Abstract: A five-sided open top forming mold for material such as snow having peripheral walls with in-turned flanges at a bottom thereof, a mold bottom adapted to rest against the in-turned flanges, inter-engaging edge portions of the bottom and configurations on the walls retaining the bottom in place until application of a force sufficient to overcome the retention whereby the bottom can push the molded material out of the mold, and the bottom can be re-snapped into position at the bottom before another material molding.

Abstract: A vent assembly (453) for a high pressure die casting system including a pair of opposed chill blocks (450, 452) having corresponding chill surfaces defining a continuous vent chamber therebetween, each of the chill surfaces comprising a plurality of adjoining chill faces (62, 136, 162, 163, 170) extending the length of the vent chamber, each chill face having a corresponding chill face on the paired chill block defining a section of the vent chamber, the plane of each chill face being oriented at an angle to an adjoining chill face on the corresponding block. Preferably the chill face on a chill block is substantially equidistant from the chill face of the corresponding chill block defining the respective section of the vent chamber.

Abstract: This invention relates to a process for making toothbrushes, in particular an injection moulding process.

Abstract: A microcontact printing tool having a print unit including a stamp head with a stamp and a wafer chuck for retaining a substrate. The stamp contained by the stamped head movable relative to the substrate by an actuator and a stage. A plurality of sensors detect the position of the stamp relative to substrate. A method of using the printing tool that includes a real-time feedback for consistent and accurate application of force during the printing of the substrate. The stamp head includes a pressure chamber carrying the stamp. The stamp backing is deflected prior to contact of the stamp with the substrate to form a minimum point and the stamp backing and the stamp is returned to a plane to create a printing propagation contact. An apparatus has a master backing and a stamping backing in close proximity and the stamp material drawn in through a vacuum. The stamp is separated from the master by use of a parting fluid.

Abstract: To provide a vent piece capable of being attached to and detached from a mold easily. A vent piece body 4 and a connection sleeve 5 are connected to each other to form a cylindrical shape. The vent piece body 4 and the connection sleeve 5 are inserted in an insertion hole 3 penetrating the wall surface of a mold 2 to connect the inside of the mold 2 to the outside thereof. One end portion 9 of the vent piece body 4 is beforehand formed into a countersunk head screw shape. A cone-shaped concave portion 10 is beforehand formed around the inside opening of the insertion hole 3 in the mold 2. The countersunk head screw shaped end portion 9 is fitted in the cone-shaped concave portion 10. Thereby, the movement of a vent piece 1 to the other side is restrained. A nut 8 is threadedly mounted in the other end portion 14 of the connection sleeve 5 from the outside of the mold 2. By mounting and demounting the nut 8, the vent piece 1 can be attached to and detached from the mold 2 easily.

Abstract: Vent valve for venting bores of vulcanization moulds, especially for the tread profile area, consisting of a valve sleeve, in which a valve insert and a wound spring are movably located, wherein the valve insert consists of a valve shank, which is at one end equipped with a disk and at the other end with a conical surface changing into backwards oriented conical end, and the movement of the valve insert is controlled by a delimiter of opening the valve. Inner surface of the valve sleeve is in its part located further away from disk provided with conical surface, oriented away from the disk, and the delimiter of opening the valve is formed by two mutually cooperating conical surfaces or parts of conical surfaces, wherein the conical surface formed at the end of the valve shank of the valve insert is oriented against the conical surface or part of conical surface of the valve sleeve.

Abstract: A gas purging block for use with injection molding and die casting systems comprises a stationary-side block for connecting to a stationary mold or die half, and a movable-side block for connecting to a movable mold or die half. The stationary-side block comprises a recessed cooling face having a first smooth contour extending between a first side and a second side of the stationary-side block to increase the surface area of the recessed cooling face. The movable-side block comprises a protruding cooling face having a second smooth contour extending between a first side and a second side of the movable-side block to increase the surface area of the protruding cooling face.

Abstract: A method for forming a composite structure. The method comprises providing a first injection port on a first metal plate, spacing the first metal plate from a second metal plate such that the first metal plate and the second metal plate define a core cavity therebetween, casting a core of cementitious material into the core cavity, and injecting a bonding agent through the first injection port into an interfacial space between the core and the first metal plate.

Abstract: An insert for a tire mold is provided. In one embodiment, the insert has an elongated cylindrical body. The insert includes at least one channel portion with a plurality of channels disposed in a non-axial direction along the surface of the insert. The at least one channel portion extends from a first end of the insert. The insert may further include a reduced diameter portion with at least one axial groove disposed thereon.

Abstract: An insert for a tire mold is provided. In one embodiment, the insert has an elongated cylindrical body. The insert includes at least one channel portion with a plurality of channels disposed in a non-axial direction along the surface of the insert. The at least one channel portion extends from a first end of the insert. The insert may further include a reduced diameter portion with at least one axial groove disposed thereon.

Abstract: A paper making apparatus includes a mould having a mesh screen and a deckle of comparable size. The deckle includes a shaped inner edge for directing pulp onto the screen. The mould and deckle are held together and dipped in a vat having a pulp and water slurry to form a sheet of paper. The mould and deckle are constructed of materials that will not warp, crack, twist, or otherwise deform from repeated use in water. The mould also includes structural ribs to hold its shape. An alternative embodiment of the invention includes a mould having a mesh screen and structural support ribs and a deckle box having a shaped inner lip and a sealing means attached to the lip. The combination of mould and deckle box may be dipped in water and does not require the presence of a vat having a pulp stock. Pulp may be poured into the mould and deckle box assembly. The mould and deckle box are constructed of materials that will not warp, crack, twist, or otherwise deform under normal use in water.

Abstract: [Object] To provide a vent piece capable of being attached to and detached from a mold easily. [Solution] A vent piece body 4 and a connection sleeve 5 are connected to each other to form a cylindrical shape. The vent piece body 4 and the connection sleeve 5 are inserted in an insertion hole 3 penetrating the wall surface of a mold 2 to connect the inside of the mold 2 to the outside thereof. One end portion 9 of the vent piece body 4 is beforehand formed into a countersunk head screw shape. A cone-shaped concave portion 10 is beforehand formed around the inside opening of the insertion hole 3 in the mold 2. The countersunk head screw shaped end portion 9 is fitted in the cone-shaped concave portion 10. Thereby, the movement of a vent piece 1 to the other side is restrained. A nut 8 is threadedly mounted in the other end portion 14 of the connection sleeve 5 from the outside of the mold 2. By mounting and demounting the nut 8, the vent piece 1 can be attached to and detached from the mold 2 easily.

Abstract: Semi-circular cover members 17 and 17 having a spring function for opening and closing the openings of pores 15S are provided on the cavity inner wall side of a porous air vent 15 in order to close the openings of the above pores 15S while a small space remains between the above cover members 17 and 17 and the openings of the pores 15S of the porous air vent during vulcanization, whereby the occurrence of the occlusion of the above pores 15S is reduced and stains adhered to the cavity inner wall side of the mold 10 are removed by physical means such as a blast treatment while the above cover members 17 and 17 are closed at the time of cleaning to remove the stains of the above mold 10. Further, the above openings are opened as required to allow a cleaning liquid 24 go into the above pores 15S to clean the above mold 10 and remove stains in the pores 15S.

Abstract: A method and an apparatus 10 for selectively venting air 98 from the internal cavity 94 of a mold 90. Particularly, the apparatus 90 includes a body 12 having a selectively movable member 30 whose position within the body 12 determines whether the air 98 is vented from the mold 98. After the air 98 is vented,. The member 30 returns to a normal position in which communication between the internal cavity 94 of the mold 90 and the ambient environment 100 is foreclosed.

Abstract: A resin mold material includes one-dimensional communicating holes extending substantially linearly from a mold surface and having diameters from 1 nm to less than 10 ?m; a surface layer including the mold surface and the one-dimensional communicating holes; a support layer covering a back of the surface layer; and three-dimensional communicating holes communicating with the one-dimensional communicating holes in the support layer and having diameters larger than those of the one-dimensional communicating holes. Accordingly, a liquid resin is unlikely to enter the one-dimensional communicating holes, thereby reducing a contact area of the mold surface and the liquid resin, i.e., the mold surface is repellant to the liquid resin. Gas in a mold cavity bounded by the mold surface is discharged through the one-dimensional and three-dimensional communicating holes sequentially. Consequently, a release property of a molded product from the mold surface is improved and generation of voids is suppressed.

Abstract: A mold used to form a rubber or resin article which includes a shaping surface for shaping a surface of an object to be molded, and a vent structure for releasing air between the shaping surface and the surface, wherein the vent structure includes EDM vents each having a gap of not more than 0.1 mm at the shaping surface.

Abstract: In an injection molding machine 1 for supplying clean air 10 to a die 8 in a direction perpendicular to a direction that opens/closes the die 8, in order to effectively pass the clean air 10 through an opened space in the die 8 so as to prevent dust from depositing on a die cavity surface or a molded product when the die 8 is opened and a ventilating hole 12 is provided in a safety door 11 provided so as to be in parallel with the die opening/closing direction.

Abstract: Thermoplastic polymers, rubbery polymeric components and reinforcing fillers are mixed and heated to a range of 380° F. to 440° F. The resulting mixture is then fed into a BANBURY mixer, with the resulting mixture fed into a diverter feeding two molds. The velocity of the piston of each mold being filled is controlled to thereby control the density of the molded product along its length (BANBURY is a registered trademark of Farrel Corporation). As each mold is filled, it is deposited in a cool water bath (50° F.–60° F.) while the next mold is being filled. The molds are sequentially transferred to an air cooling rack to complete the process. A texture, generally comprising indentations perpendicular to the longitudinal axis on the molded object, provides a frictional surface between the railway crosstie and the ballast beneath the crosstie.

Abstract: A resin molding die includes: a cavity; a resin inlet through which a liquid resin to be cured is injected into the cavity; and an air vent through which air is released to an exterior space of the resin molding die during injection of the resin, the air vent being provided on an opposite side from the resin inlet with respect to the cavity.

Abstract: The present invention relates to a gas purging block for use with injection molding and die casting systems, which includes a stationary-side block adapted to be removably mounted to a stationary-side mold half of the injection molding or die casting system, and an ejector-side block adapted to be removably mounted to an ejector-side mold half of the injection molding or die casting system. At least one of the stationary-side block and the ejector-side block includes a pair of channels extending through the block adapted to selectively function as conduits for cooling fluid and as mounting bores for mounting the block to the respective mold half.

Abstract: A loudspeaker diaphragm manufacturing apparatus of the present invention comprises; a paper tank, a pulp dispersion reservoir tank connected to the paper tank, a stirring means provided in the paper tank, a water inlet unit connected to the paper tank, a drain unit disposed under the paper tank, and a paper mold disposed at the bottom of the paper tank or in the drain unit, wherein a sectional area of the drain unit is larger than the plane area of the paper mold. The drain unit may be further provided with a water flow control plate in a draining direction of the paper mold. According to the manufacturing apparatus and the manufacturing method of the present invention, diaphragms with very uniform internal composition and diaphragms with intentionally varied internal composition in accordance with required sound characteristics can be mass-produced with good reproducibility.

Abstract: A method of venting a rotational mold at a predetermined condition by actuating an actuating venting assembly pierces the shell of the molded article and introduces a passageway to relieve pressure during the molding cycle. The actuating venting assembly enables a tactical methodology for venting such molds.

Abstract: The element has at least one porous permeable impression surface, on which the clay slip is deposited. A drainage system for the slip fluid is provided having a relatively thin, empty or porous chamber in the form of a slab which is incorporated into the body of the mould element itself, is disposed within the range of drainage action of the impression surface, and has a degree of porosity greater than the front part of the body delimited between said thin chamber and the impression surface, evacuation means connected to said thin chamber being provided to evacuate the drained fluid collected by the chamber. In particular, said thin chamber is disposed substantially parallel to the impression surface at a relatively short distance therefrom.

Abstract: A tire mold including a molding face for shaping the outside of a tire and a vent structure, wherein the vent structure contains a hole having an opening in the molding face, an inserted piece disposed in the hole so that the surface of the inserted piece defines a part of a molding face, and a micro-gap of not more than 100 micrometers formed between the inserted piece and the hole for the purpose of vent.

Abstract: A high strength lightweight product formed from particulate inorganic materials such as a masonry building block is formed in a mould (1) from a flowable slurry of inorganic particularly materials and water. The interior of the mould is lined with perforate walls (2a, 3a, 4a, 3) fluidically coupled to a vacuum source (9). The fluid slurry contains entrained air and when pumped into the mound under superatmospheric pressure the gas bubbles contract in size. The fluidic mass is then subjected to subatmospheric pressure which enables the gas bubbles to expand the expel excess moisture from the mass.

Abstract: This invention relates generally to opthalmic molds and methods useful for casting opthalmic moldings. In one aspect, the invention relates to a mold for casting an opthalmic molding formed from a first mold half detachably affixed to a second mold half, whereby the mold has a top and a bottom; and a cavity formed by the first and second mold halves, wherein the cavity receives a lens forming material through an opening at the bottom of the mold and vents gas and excess lens forming material from an opening at the top of the mold. In another aspect, this invention relates to methods for casting opthalmic moldings, particularly intraocular lenses.

Abstract: A vent for a mold having a mold cavity comprises a valve member housed within a main body sleeve and reciprocally moveable therein in an axial direction between open and closed positions. The sleeve is mounted within a mold wall and contains an expansion agent such as silicon. An increase in mold temperature causes the expansion agent to expand and move the valve member from the closed position into the open position. An external annular groove is provided within the sleeve to receive displaced mold wall material as the sleeve is press inserted into the mold wall. A tight fit of the sleeve within the mold wall results. The sleeve and valve are configured to allow air to escape in the open position. The valve member is moved to the closed position by material within the mold cavity pressing against the valve member.

Abstract: A panel for forming a masonry wall on a building surface, comprising a back face for covering the building surface, opposite edges and a front face with a predetermined pattern of first and second depressions. The first depressions are shaped and sized for receiving masonry pieces as a whole whereas the second depressions, which intersect the opposite edges, are shaped and sized for receiving parts of masonry pieces, so that, when the panel is mounted side by side with a complementary panel, some masonry pieces bridge both panels by means of the second depressions. The panel makes it possible for an unskilled worker to build relatively rapidly a masonry work having a complex predetermined pattern of masonry pieces. Thanks to the second depressions that make it possible for some pieces of masonry to bridge panels mounted side by side, the general arrangement of pieces, when completed does not look like a series of individual panels but rather look continuous.

Abstract: A mold (1) includes an upper mold half (U) and a lower mold half (L). The mold (1) includes a gate (G), a pole vent pin (P), a support pin (S) and an intermediate vent pin (M). The support pin (S) has a latitude (&thgr;s) of 45 degrees to 85 degrees. Each of the upper mold half (U) and the lower mold half (L) has at least three support pins (S). The intermediate vent pin (M) has a latitude (&thgr;m) of 45 degrees to 85 degrees. Each of the upper mold half (U) and the lower mold half (L) has at least three intermediate vent pins (M). A difference between the latitude (&thgr;m) of the intermediate vent pin (M) and the latitude (&thgr;s) of the support pin (S) is equal to or smaller than 15 degrees. A clearance between the intermediate vent pin (M) and a pin hole (13) is 5 &mgr;m to 50 &mgr;m. By the mold (1), a cover having a thickness of 1.4 mm or less is formed.

Abstract: A plug for sealing and resealing the passages for heating and cooling liquid in a casting mold. The plug includes a stainless steel socket head NPT plug which is screwed into the passage to seal it. Inboard of the plug there is mounted a resilient expandable silicone tubular element that is expanded by squeezing it to further seal the passage.

Abstract: A mold for molding a tire is provided, including at least two sub-molds that form a predetermined form as a whole when used for molding a tire. Each of the sub-molds has a venthole for discharging air from blockades formed between the surface of a green tire and that of the sub-mold when the green tire is pressed on the surface of the sub-mold, and a ventlid made of a flexible member and having a lid mechanism capable of discharging air from the blockades while preventing the green tire from flowing out therefrom.

Abstract: A vulcanization mold is described for the manufacture of technical rubber products comprising a plurality of vent bores in which a blocking member is mounted which consists of a central body and a sealing part coupled to it which together form at least one angled flow path for air to be dissipated, with the central body being fixed in the vent bores, on the one hand, by clamping ribs provided at the central body and, on the other hand, by blocking elements which are formed at spring limbs of the sealing part.

Abstract: A pneumatic tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core and a bead apex therein, each sidewall portion provided on the outer face with means of escaping air between the tire and a mold for vulcanizing the tire, wherein the air escape means comprises a circumferentially extending vent emboss line disposed adjacently to a radially outer end of the bead apex and a circumferentially extending vent groove adjoining the radially outside of the vent emboss line and having a depth of at least 0.15 mm. Preferably, the vent groove has a width of from 5 to 10 mm and a depth of from 0.2 to 0.5 mm, and the vent emboss line and vent groove are disposed in a lower sidewall region having a substantially straight profile. The bottom of the vent groove may be substantially parallel to the straight profile of the lower sidewall region and the bottom may be provided with emboss marks.

Abstract: A compact disc (CD) molding apparatus. The CD molding apparatus comprises a movable mold, a fixed mold, a mold cavity, an outer ring, a gas passage, an outlet and an auxiliary gas channel. The movable mold is disposed adjacent to the fixed mold. The mold cavity is defined between the movable mold and the fixed mold. The outer ring surrounds the mold cavity, and the outlet is defined between the fixed mold and the outer ring. The gas passage is defined between the fixed mold and the outer ring and connects the mold cavity and the outlet. Particularly, the auxiliary gas channel is disposed in the fixed mold and connected to the gas passage to facilitate exhaust of high temperature gas from the mold cavity, wherein a material is injected into the mold cavity and the high temperature gas passes through the gas passage before exiting through the outlet.

Abstract: The invention comprises a printing cylinder precursor comprising a plastics cylinder in which is located an immovable spine. The invention further extends to a moulding apparatus for manufacturing a printing cylinder precursor, comprising a cylindrical moulding vessel comprising an inlet for the ingress of moulding material, the vessel further comprising a removable spine located centrally within the moulding vessel. The invention further extends to methods of manufacturing printing cylinder precursors and gravure printing cylinders.

Abstract: The present invention relates to a gas purging block for use with injection molding and die casting systems, which includes a stationary-side block adapted to be removably mounted to a stationary-side mold half of the injection molding or die casting system, and an ejector-side block adapted to be removably mounted to an ejector-side mold half of the injection molding or die casting system. At least one of the stationary-side block and the ejector-side block includes a pair of channels extending through the block adapted to selectively function as conduits for cooling fluid and as mounting bores for mounting the block to the respective mold half.

Abstract: Solid rollers of a urethane material are formed in closed mold formed by a tube and two end plugs spaced by a shaft, the latter becoming the shaft for the roller. The closed mold avoids rough grinding to a cylindrical shape, as well as avoiding the resulting waste of material and introduction of defects that arise from rough grinding. The formation of bubbles during injection of the urethane material is avoided by filling the closed mold with carbon dioxide gas prior to injection. The formation of gate marks in the urethane material is avoided by repositioning the end caps after injection to separate the injection gate from the cylindrical cavity. The need to trim the ends of the roller is avoided by providing an annular cavity between the top end cap and the tube that receives excess urethane material to be drawn into the cylindrical cavity as the urethane shrinks during curing.

Abstract: A flap ventlid installing assembly comprising a flap ventlid and an anchor member, the top portion of which is connected to the flap ventlid and which has a longer portion not capable of being inserted as it is into the air removing hole through the opening and which has such a shape as capable of being press fitted into the air removing hole through the opening by making the longer portion to have such a size and shape capable of being inserted into the air removing hole with causing elastic deformation by applying an external force to the longer portion, and the flap ventlid can be installed in such a state that at least a part of the flap ventlid contacts with the design surface of the mold by press fitting the anchor member into the air removing hole, and the flap ventlid installing construction therefor.

Abstract: Method and apparatus for molding an IOL comprising first and second mold halves each having an optic forming surface and haptic forming surfaces which together define a mold cavity in the shape of the IOL to be molded therein when the mold halves are assembled together. An injection port is formed and connects to one of said haptic forming surfaces or the optic forming surface wherethrough a polymerizable material is injected into the mold cavity. A venting port is formed and connects to another haptic wherethrough air escapes from the mold cavity as the polymerizable material is injected through the injection port.

Abstract: An impression mold includes a main body and a detachable segment. The main body has an obverse bearing a first intaglioed pattern, and is formed with an opening defined in the obverse thereof. The segment has an obverse bearing a second intaglioed pattern and has a shape complementary to the opening of the main body. Therefore, a complete pattern is formed by the two intaglioed patterns when the segment is fitted in the opening of the main body.

Abstract: Processes and apparatus for blow molding include a mold surfaces having micrograined patterns to improve venting and surface finish. The micrograined patterns are preferably in the form of projections that define between them a network of interconnected channels. The projections are of a sufficient height that they engage the outer surface of a fully-expanded parison and form venting passages with the parison surface to permit trapped air to escape and migrate through vent holes which communicate with the channels. The dimensions and shape of the projections are selected to provide for the formation of venting passages while preventing the formation of patterns in the surface of the molded product.

Abstract: In one embodiment, a microreplication tool includes gas release features that allow gas to escape from microreplication cavities of the tool. The gas release features can be disposed at the bottoms of the respective cavities to avoid air entrapment within the cavities of the tool during the microreplication process. In this manner, the quality of the microreplicated product can be improved.

Abstract: A mold with integral screen comprising a body of material having a surface, the body has a grid-like pattern of vacuum holes extending through the body of material and opening through said surface and permitting a vacuum to be supplied to said surface, a screen overlying said surface, said screen and said body being formed of the same material as the body and being integral.

Abstract: The invention relates to a vulcanization mold for producing rubber goods, especially vehicle tires. The mold has a number of deairing holes into which blocking mechanisms are introduced. The blocking mechanisms ensure, especially by means of the air duct being bent, that the air can be drained without any disadvantageous flash being produced. In a second embodiment, the blocking mechanisms forms a two-part valve with the central body. In this case, the blocking mechanism has an elastically deformable planar area placed on the inside of the mold which acts at least essentially as a seal in conjunction with the central body when impinged upon by the surface of the blank.

Abstract: Apparatus for integrally molding articles with a foam member, including a charger for supplying raw material beads made of resin to a die cavity containing articles for integral molding with foam, a plurality of work piece nozzles each having a nozzle opening in fluid communication with the cavity. At least one of the workpiece nozzles is located at a position corresponding to an opening located in an article located in the die. A plurality of exhaust nozzles for exhausting air from the cavity, the exhausting air beginning with a group of exhaust nozzles at locations maximally distant from the raw material charging port, and groups of exhaust nozzles located successively closer to the raw material charging port, each group in turn for sequentially exhausting air from the cavity, while the port is charging the cavity with raw material beads.

Abstract: This invention relates generally to opthalmic molds and methods useful for casting opthalmic moldings. In one aspect, the invention relates to a mold for casting an opthalmic molding formed from a first mold half detachably affixed to a second mold half, whereby the mold has a top and a bottom; and a cavity formed by the first and second mold halves, wherein the cavity receives a lens forming material through an opening at the bottom of the mold and vents gas and excess lens forming material from an opening at the top of the mold. In another aspect, this invention relates to methods for casting opthalmic moldings, particularly intraocular lenses.

Abstract: A removable plug for an air vent in a mold includes an annular bushing and an annular insert. The annular bushing includes a central bore preferably of about 0.8 mm. The annular insert includes a central bore preferably of about 0.1 mm to 0.4 mm. The annular insert is snugly fitted into the central bore of the annular bushing. A mold including the plug and a method for making the mold are also described.

Abstract: A three piece full port ball valve for use with a form for producing a cast concrete article is provided wherein the housing of the valve has been modified by creating openings through the valve housing to access the flow opening in the ball member for clearing concrete slurry therefrom after the form has been filled. Additional openings in the housing at other locations can be created for cleaning around the ball member and the inside of the housing.

Abstract: A mold vent and method. The vent has expanding passages. A preferred vent comprises an insert that has a plurality of passages. One insert comprises a grate formed of a plurality of portions that interleave fingers forming vent passages therebetween that preferably are vent slots. Supports can be disposed between fingers. The grate preferably is discharge-machined from a blank cut from stock made material that preferably is non-porous and smooth. The grate can be mounted in a pocket in the mold cavity or carried by a movable pin. The grate can be used in a system that includes valving, a source of fluid, and, if needed, a source of vacuum to help facilitate venting by drawing atmosphere out of the cavity during molding. The grate can also be used to introduce fluid into the mold that can be foaming moldable material or a heat transfer medium.

Abstract: A cast mould for use in the manufacture of a contact lens by the polymerisation of a flowable precursor comprises a female mould part and a male mould part. The female mould part has a concave first surface region adapted to receive the flowable precursor in use, and a second surface region. The male mould part has a convex first surface region and a second surface region. The male mould part is engageable with the female mould part to define a lens-forming recess between the concave and convex surface regions and to define a first overflow cavity between said second surface regions. The first overflow cavity is adapted to receive excess flowable precursor displaced from the lens-forming recess in use, and the first overflow cavity is provided with first retaining means such that, in use, after polymerisation, polymer in the first overflow cavity is mechanically interlocked with a single one of the mould parts after separation of the mould parts.