CA2619525A1 - Method for mounting ceramic cooktops in appliance - Google Patents

Abstract

A process for mounting a ceramic cooktop in a stove, comprising: a) supplying a frame (5) having an opening therein for receiving a ceramic cooktop (2) , the opening having a periphery and a support surface extending inwardly from the periphery of the opening; b) providing a dam (10) on the support surface extending continuously around the support surface and having a height such that a cooktop will have a spaced relationship between the bottom surface of the cooktop and at least a portion of support surface; c) positioning a cooktop within the opening in the frame, the edge of the cooktop being spaced apart from the side walls of the frame; d) applying a flowable, curable silicone (11) between the side walls of the frame and the edges of the cooktop and allowing the silicone to level to provide a visible seal between the frame and the cooktop.

Description

METHOD FOR MOUNTING CERAMIC COOKTOPS IN APPLIANCE
The present invention is directed to the manufacture of stoves,cooktops, and ranges (hereinafter, collectively, "stoves") which carry a ceramic cooktop surface within a metal frame.

Stoves intended for home use frequently have a glass-ceramic ("ceramic) cooking surface. Below the surface may be mounted ceramic hobs which are heated with resistance wire such as nickel-chromium wire, or quartz halogen lamps. The cooktop surface is often colored and/or textured, and is in general considered an aesthetic improvement over conventional electric cooktops with exposed heating coils. The cooktops are commonly termed "ceramic" although they are sometimes also termed "glass ceramicas well.

In freestanding stoves, in ranges, and in drop-in cooktop units, the "stove" 1 (Figure 1) has a top surface 5 which is a steel stamping, and contains an opening into which the ceramic cooktop 2 is positioned, the opening further characterized by edges or side walls 8 (Figure 3) and ceramic cooktop support surface 5a. For aesthetic reasons, it is often desirable to position the ceramic cooktop in its recess without the use of external clamps or rings. As shown in Figure 2, a sealing compound 6, generally a silicone, fills the gap between the metal frame and the ceramic cooktop.

Conventionally, the method employed to mount the cooktop is both labor intensive and messy. First, (Figures 3, 4) double sided adhesive spacer pads 7 are hand applied from a roll supplying the adhesive pads 7 an release paper. The ceramic cooktop is then centered in the opening and pressed onto the pads. The pads keep the cooktop from contacting the metal frame 5 and provide a space between the ceramic cooktop 2 and the support surface 5a which can be filled with sealant 6. It is desirable not only to fill the gap between the edge of the ceramic cooktop and its receiving hole, but also to force sealant below the cooktop along 5a. When the sealant cures, its adhesive properties are largely responsible for holding the cooktop in place.

Applying the sealant is a hand operation, and the sealant must be difficultly flowable and preferably thixotropic, since otherwise it will flow past the adhesive pads 7 and drip into the space below the cooktop, as shown at 6c in Figure 3.
Applying too much sealant can independently cause exuding of sealant as well. Due to the stiff nature of the sealant, the sealant must be forced into the space between the cooktop and frame with some difficulty, and hand tooling must be used immediately following its application in order to provide a smooth, uniform surface. Often, several "passes" must be made in order to provide the desired aesthetics, with final cleaning up often involving removal of cured sealant with a razor blade. It is not uncommon for a portion of the stoves to be reworked by removing the ceramic top, cleaning it and the frame of silicone, and remounting. As the silicone is, in general, not water soluble, and is also thick and tacky, the overall operation can be quite messy.

It would be desirable to be able to seal and adhesively bond ceramic cooktops within metal frames in a rapid and uniform manner, while avoiding at least some, and preferably most or all of the manual steps of assembly and finishing. It would be further desirable to form a uniform width of adhesive sealant below the cooktop and present an aesthetic sealant surface with little or no hand tooling or cleanup.

Ceramic cooktops are mounted within metal frames having a support surface by supplying a dam around the inner periphery of the support surface, positioning a ceramic cooktop onto the dam, and injecting a measured quantity of low viscosity, self-leveling, curable silicone between the cooktop and the metal frame, the curable silicone being prevented from leaving the inner periphery of the support surface by the dam, and extending upwards to uniformly fill the gap between the ceramic cooktop edge and the metal frame.

Therefore, the subject of the invention is a process for mounting a ceramic cooktop in a stove,comprising:

a) supplying a frame having an opening therein dimensioned to receive a ceramic cooktop, the opening having a periphery, and having a support surface extending inwardly from the periphery of the opening, the support surface and opening periphery connected by side walls extending therebetween, the ceramic cooktop having a bottom surface, a top surface, and an edge connecting the top surface and bottom surface;

b) providing a dam an the support surface extending continuously around the support surface and having a height such that a ceramic cooktop, when positioned within the opening in the frame and resting on the dam, will have a spaced relationship between the bottom surface of the ceramic cooktop and at least a portion of support surface;

c) positioning a ceramic cooktop within the opening in the frame, the ceramic cooktop bottom surface resting on the dam, and the edge of the ceramic cooktop spaced apart from the side walls of the frame;

d) applying a flowable, curable silicone between the side walls of the frame and the edges of the ceramic cooktop and allowing the silicone to level to provide a visible seal between the frame and the ceramic cooktop.
FIGURE 1 illustrates a free standing range having a ceramic cooktop.

FIGURE 2 illustrates a close-up of the top of a range, showing the sealant between the cooktop and the frame.
FIGURES 3 and 4 illustrate prior art processes of mounting ceramic cooktops.

FIGURES 5, 6, and 7 illustrate embodiments of the present invention process of mounting ceramic cooktops.

FIGURE 8 illustrates a further embodiment of a support surface and dam in accordance with the present invention.

The metal frame per se of the range may be made in any conventional marnner. In general, as shown in Figures 3 - 8, the range has an opening to receive the ceramic cooktop, a depressed ledge or "support surface" 5a of a depth such that the thickness of the ceramic cooktop and a dam (as later described) may be accommodated, while presenting a substantially flush surface with respect to the top 5 of the metal frame and the top of the ceramic cooktop 2. In some designs, it may be desirable that the surfaces not be flush.
The key to the present invention is the ability to use a low viscosity silicone sealant with self leveling capability, in particular, at a known volume. In the prior art process, such a silicone could not be used, since it would merely flow past the adhesive pads and trickle down into the space below the cooktop.
Moreover, the volume of sealant used would vary with the depth of penetration into the space between the cooktop 2 and the support surface 5a, and would vary also with the shape, size, and positioning of the adhesive pads.

By forming a"dam" which is preferably proximate the inner edge or "periphery" of the support surface, or alternatively, spaced apart from and preferably parallel to the periphery of the ceramic cooktop, liquid silicone is prevented from flowing into the range interior. Such a dam is shown at 10 in Figures 5, 6, and 7. Moreover, because the dam is of uniform height and placement, the required volume of silicone may be measured or calculated with reasonable accuracy, such that robotic dispensing tools may be employed. By injecting just the right amount of silicone, which is also self-leveling, the cooktop may simply be left alone following injection, and the silicone will form a smooth, uniform, and aesthetic seal between the frame and the ceramic cooktop. In most cases, no hand tooling or clean-up will be required.

The dam may be supplied by three distinct methods, each of which are embodiments of the present invention. In the first, and most preferred embodiment, the dam is supplied as a rapidly solidifying bead of elastomer and/or adhesive, preferably applied by robotic means in order to provide uniform application. In this embodiment, the rapidly solidifying adhesive may be a hot melt adhesive of any chemical type, preferably one which is heat and oxidation resistant, such as a silicone hot melt adhesive. Most preferably, however, the dam is composed of a very viscous and/or thixotropic, curable adhesive which rapidly cures to a rubbery state. In either case, the bead thus produced should preferably have the characteristics of a tacky, rubbery elastomer.

The bead is preferably tacky in order that the cooktop, once positioned, will not move, even if the stove is jostled or inadvertently (or purposefully) tilted during manufacture, or during the cure period of the later applied self-leveling silicone. However, rather than being tacky, the bead may have characteristics known in the elastomer industry as "froggy hand", which provides the elastomer with a tendency to grip smooth surfaces without itself being tacky. However, if tilting and jostling of the stove following positioning of the cooktop is prevented, the bead must only provide a modest locating capability together with the ability to prevent flow of liquid silicone past the bead (its "dam" function). In such cases, a non-tacky and only modestly deformable elastomer or polymer may be used.

The rapidly solidifying adhesive is preferably a silicone adhesive, since organopolysiloxanes (silicones) have very advantageous characteristics. In particular, silicones are thermally resistant to relatively high temperatures, and can thus readily survive the temperatures expected near the cooktop periphery, even under conditions where all burners are used for extended periods. Second, silicones are oxidatively stable, and thus long life and continued elasticity can be expected,even after long periods of use.

When a silicone bead is used for the dam, it may be of any rapidly curing type, if not a hot-melt type. Suitable silicones are, for example, peroxide curing, condensation curing, and addition curing. Addition curing silicones are preferable. Since it is most desirable that the curing rate be quite rapid, two-component addition curing systems are preferred. Such systems are commercially available and also can be easily formulated. The organopolysiloxanes employed may contain any organic groups in addition to the reactive groups, for example but not by limitation, methyl, ethyl, propyl, phenyl, chlorophenyl, etc. Halogenated and in particular, fluorinated alkyl groups such as hexafluoropropyl and heptafluoropropyl groups may be present as well. For reasons of economy, in particular, methyl and phenyl groups are preferred, most preferably methyl groups. Thus, the preferred elastomers are substantially polydimethylsiloxanes.
The reactive groups in addition-curable silicone elastomers which cure by hydrosilylation are Si-bonded hydrogen and Si-C
bonded ethylenic or ethylynic unsaturation. Both, a-, w-terminated silicones as well as silicones containing pendent reactive groups may be used. The cured hardness is generally influenced by the crosslink density, with higher crosslink densities providing harder elastomers. The uncured viscosity is largely determined, in the absence of fillers and thixotropes, by the chain length and hence molecular weight of the individual organopolysiloxanes. Addition of fillers, in particular fine particle size fillers, increases the viscosity and may render the composition thixotropic, as may also viscosity and/or flow regulators.

Further examples of materials which may be used for a rapidly setting dam are epoxy resin-based elastomers, particularly those which incorporate fluorinated compounds for heat resistance, and polyurethanes. Other curable polymer systems such as cyanate resins, bismaleimide resins, and the like can also be used, often at higher cost. Hot melt adhesives based on polyesters, polyamides, polyimides, mixtures thereof, and the like may also be used. However, it is preferred that the raised polymer bead or dam be constructed of a silicone elastomer. When hot melt adhesives are employed, it is preferable that these be the type which crosslink to a thermoset polymer following application, or be thermally stable at elevated temperatures, for example the aliphatic polyamides such as polyamide 6, polyamide 6,6, polyamide 6,12, and the like.

For minimum usage of silicone or other dam material, and hence the highest economy, it is desirable that the bead of material laid down assume a roughly half-circular shape in cross-section following application, with the flattened side of the half-circle abutting the surface of the frame. In practice, however, a somewhat vertically flattened or elliptical shape is obtained, and in principle, a quite broad (quite flattened) cross-section may be used, so long as the height is satisfactory for maintaining the ceramic cooktop at the design height. A suitable silicone elastomer formulation is ELASTOSIL RT 722, a two component, RTV-2 elastomer available from Wacker Chemical Corporation, Adrian, Michigan, and Wacker Chemie AG, Muenchen, Germany. This elastomer composition exhibits a curing time of about 10 minutes at 150 C. The curing time is only critical to the extent that longer curing compositions may slow down the production cycle, or may, in some compositions allow for such flow that only a broad bead can be created. An initial cure which provides a dimensionally stable bead followed by a more complete cure is perfectly acceptable also. The curing time is preferably between 5 and 20 minutes, short curing times being limited by the application speed, i.e. the elastomer should not cure while still in the "gun".

The rapidly solidifying polymer bead may be laid down by hand, particularly if pneumatic guns are employed to exude a constant amount of material. However, the use of manual techniques should be avoided, and it is highly preferable that a conventional robot be employed. Such robots generally contain an articulated arm which directs the nozzle or "gun"
through which rapidly settable polymer flows. In addition to eliminating manual steps during manufacture, the robotic application has the distinct advantage of far greater consistency. The bead should be applied so as to produce at least one substantially continuous dam which will prevent the flow of later applied flowable silicone past the dam. Small "vacancies" in the continuous dam can be tolerated so long as these do not allow for substantial leakage past the dam. The end of the continuous bead may abut the beginning of the bead, may overlap its flanks, or have any other termination such that substantial leakage of low viscosity silicone past the dam and into the stovetop interior is prevented.

In a second, less preferred embodiment, a continuous dam of already solid elastomer is applied, either by hand or by machine (i.e. a robot). In one such embodiment, a continuous roll of double sided adhesive tape of suitable thickness is hand applied, or preferably applied by robotic means. For hand application, for example, continuous linear strips which abut at their corners to provide a continuous dam may be used, or a lengthy strip which is bent around the corners may be used. In such applications, it is preferable that the width of the strip not be excessive, in order that bending around corners may be facilitated. The same modes of applications may be made robotically, which is to be preferred over manual methods. For manual methods in particular, the support surface from which the ceramic cooktop will be spaced apart may be manufactured with a groove, step, or other locating device to assist with proper location and positioning of the dam. As with the rapidly settable dam, any "vacancies"
in the continuous dam should be small enough so as to avoid leakage of low viscosity silicone past the dam.

In a third embodiment, the support surface itself is provided with a raised dam as shown in Figure 8 at 5b, for example by stamping the dam at the same time as the stamping of the frame. In this embodiment, the dam will have no positioning restraining ability an its own. For example, the ceramic cooktop, once positioned, may slide if the stove is tilted, or may be easily jostled out of position, However, it is possible to spray the dam with an adhesive or tacky substance to provide this restraining feature. In this case, manual application of spray adhesive or tacky substance may be used, since the dam is already positioned, and application of the adhesive spray can be done very quickly.

Thus, by the term "dam" is broadly meant a raised area above the level of the support surface located between the inner periphery of the support surface and tbe sidewalls of the opening in the frame, which is capable of eliminating or substantially eliminating the flow of flowable silicone past the dam after the ceramic cooktop has been positioned in the opening, resting on the dam. By " substantially eliminatingis meant preventing the flow of flowable silicone into the interior of the stovetop to the extent that the commercial viability of the process is not defeated. Small amounts of leakage may be tolerated, however the amount should be small enough so as not to require any substantial cleanup, preferably not more than 10 mL over the entire periphery between the dam and the bottom surface of the ceramic cooktop or through small vacancies in the dam, more preferably less than 5 mL and most preferably less than 1 mL. Most preferably, only isolated droplets or no flowable silicone at all passes by the dam. By "dam" is also meant a continuous structure, i.e. in the form of a loop, such that such leakage is prevented. A discontinuous structure with discontinuities of sufficient size such that considerable flowable silicone can flow through or past the discontinuities is not a dam within the scope of the invention. It should be noted, however, that a dam is not necessarily a single, unitary, closed structure.
For example, a raised spiral, where the pathway between the entrance, through which flowable silicone can flow, to the exit is so long that either the viscosity and surface tension of the flowable silicone or its cure rate prevent flow out of the spiral into the stove interior is within the scope of the invention, as are a plurality of concentric rings having openings in adjoining rings, such that a labyrinthal path is presented to the flowable silicone. The principle consideration is the function of the dam, prevention of substantial leakage of flowable silicone, and maintenance of proper spacing between the support surface and the ceramic cooktop, and not its exact configuration.

Regardless of which method of dam construction (or combination thereof) is used, the cooktop is then placed atop the support surface in the proper spatial relationships with the edges 8 of the frame. This operation is also preferably robotically performed.

Finally, a low viscosity, curable silicone (11) is applied between the edge 9 of the ceramic cooktop and the edge 8 of the frame. While hand application is possible, and is far less time consuming than the application of conventional, high viscosity silicone, robotic application is far to be preferred. Hand application, while saving some time, still in general would require hand tooling for finishing, since even the most skilled worker will be unable to attain the precision required such that the silicone self levels to a uniform, aesthetic seal between edges 8 and 9. On the other hand, the volumetric output of adhesive, lineal speed, etc., of a robot is easily adjusted within fine limits, such that hand tooling should not be required. Robotic application is thus preferred.
The amount of silicone dispersed can be calculated from the volume encased between the dam and the surface height of the silicone between edges 8 and 9. The delivery rate can be adjusted to supply more silicone at corners if the "dam" does not follow the cooktop periphery at these locations.

The silicone composition is preferably an addition-curable composition with a relatively low viscosity and a moderate gel time. The gel time and viscosity have, essentially, an inverse relationship, since it is desired that the silicone be self leveling, i.e. that it flows to fill any voids, and also forms a smooth and level seal between the ceramic cooktop edge and the stovetop frame. The more viscous the composition, the more flow time prior to gelation will be required. For substantially the same reasons, the amount of particulates in the silicone will, in general, be much less than in a caulk or traditional sealant. The composition will offen be pigmented, i.e. white, gray, or black, by incorporation of pigments such as ground chalk, titania, black transparent iron oxide, or carbon black. As with most pigments, a relatively small amount is generally all that is required. lt may be desirable to leave the composition colorless and translucent or transparent. For such compositions, either no filler of any kind is used, or fillers such as very small particle size silica or titania, preferably the former, i.e. fumed silica, are used. The cure time is preferably between 5 and 30 minutes, more preferably between 5 and 20 minutes. The cure time may also be much longer, and as indicated earlier, full cure may even occur only upon use of the stove, although this is not desired.

The addition-curable silicone composition, like that of the polymer dam previously described, contains both Si-bound ethylenic or ethylynic unsaturation, and Si-bound hydrogen, and a hydrosilylation catalyst. The amount of catalyst is generally lower than that of the rapid-curing bead silicone, since a slower curing composition is desired. The amount can be easily adjusted by one skilled in the art to vary the gel time and cure rate, or even to adjust these rates for changing climatic conditions, i.e. the temperature in the manufacturing facility.

lt is, of course, possible to employ other types of curable liquid silicones, for example those whose cure is facilitated with peroxides, or condensation curing systems, for example those employing silanol-functional organopolysiloxanes and alkoxysilanes or alkoxysiloxanes as crosslinking agents, or those employing silanol-functional organopolysiloxanes and silanes or siloxanes (including polysiloxanes) bearing Si-bonded hydrogen. Such curable RTV-2 and LTV-2 silicone elastomers are well known, and are available from numerous sources. RTV-1 compositions may in principle be used, although they are not preferred, and RTV-1 compositions containing catalysts or initiators which are activated at only modestly elevated temperature may be used, if the stove can be heated, for example in a heat tunnel, etc. However, elastomers which require elevated temperature cure are not desirable.

The viscosity of the curable, liquid, self leveling silicone composition, as applied, is preferably between 10 mPa=s and 100,000 mPa=s, more preferably between 5,000 and 15,000 and most preferably between 8,000 mPa=s and 10,000 mPa=s. A
composition with a viscosity (25 C) of 9,000 mPa=s has been found very advantageous. As the viscosity which is suitable is dependent an many factors, including the distance of separation between the ceramic cooktop edge and the metal frame, and between the ceramic cooktop bottom surface and the support surface, higher or lower viscosity silicones may also be useful for certain applications. The viscosity should increase at a moderate pace following application, to give the composition time enough to flow and level. Cure should reach a degree of completion after, for example, but not by limitation, 10 - 15 minutes, whereby the stove or stovetop can be manipulated without damage to the sealant, but complete cure may be prolonged, even over days or weeks, or may be effectuated during use of the appliance, when the temperature of the appliance is elevated. The self-leveling silicone may cure at ambient temperature, generally in the range of 15 C to 30 C, or at higher temperatures, for example but not by limitation, up to 150 C.

Preferred flowable, low viscosity is silicones are two component addition curable silicones with viscosities in the range of 6,000 to 9,000 mPa=s, most preferred is ELASTOSIL
RT749, available from Wacker Chemical Corporation and from Wacker Chemie AG. These silicones have a cure time of 10 minutes at 150 C.

Thus, in a preferred process according to the invention, and as illustrated in Figure 6, a stovetop having a frame 5 dimensioned to receive a ceramic cooktop 2, the frame having a support surface 5a, is positioned within reach of a robot which dispenses a rapidly curing, very viscous and/or thixotropic RTV-2 silicone through nozzle or "gun" 12. The robot supplies the RTV-2 silicone 11 through a nozzle to form a raised, substantially semi-circular bead or "dam" 10 of tacky silicone elastomer onto the support surface and at a pre-defined location, such as a bead parallel to the edge of the support surface or parallel to the edge position of the later-applied ceramic cooktop, the positioning of the frame and placement of the dam preferably being such that the bead always occupies the same position with respect to the frame for each stove of the same type. The dam is substantially continuous so as to prevent leakage of later applied flowable silicone past the dam.

A second robot then positions a ceramic cooktop within the opening in the frame, the lower surface of the ceramic cooktop resting on the raised bead (dam) of silicone, defining a "seal" volume extending outwards from the outer periphery of the dam towards the side or edge of the frame, and upwards to the level of the top of the cooktop and frame or the lower of these, should they not be at the same height.

Finally, a further robot (or the same robot with a further silicone supply and/or nozzle) dispenses a flowable silicone 11 around the periphery of the cooktop, between the frame and cooktop, in an amount which is substantially the same as the defined seal volume. The flowable silicone is allowed to fill the defined seal volume and to level itself, forming, as it hardens (cures), a non-tooled seal 13 between the edge of the frame and the edge of the cooktop.

In the preferred embodiment described above, it is of course possible to have but one or two robots perform all the functions described. Moreover, it is possible to transport the stovetop to the robot, or to transport the robot to the stovetop. It is envisioned that the most preferable and economic production method will have the stove or stovetop transported on a conveyor past three robots, pausing at each long enough for the respective robotic functions to be performed. Many variations are clearly possible.

In less preferred embodiments, the preferred embodiment is substantially followed, but with certain deviations. For example, in one embodiment, the dam is applied robotically as is also application of the flowable silicone. However, the cooktop is manually positioned. In another embodiment, the application of a polymer dam is not practiced; rather, a support surface with a raised section which provides the function of a dam is used instead, as illustrated at 5b in Figure 8.

While it is preferable, for the sake of simplicity, to apply the polymer dam in the same manner from stovetop to stovetop of the same model, it is of course possible to vary the position, width, height, etc. of the dam applied by the robot and maintain the data in hardware or software to allow the seal volume to be calculated for each respective unit. However, this embodiment, while clearly within the scope of the invention, is not preferred.

By terms such as "providing a damis meant that a dam is present, regardless of whether it is supplied as a raised portion of metal produced while stamping the frame from sheet metal, or applied as a continuous strip of solid adhesive or a continuous bead of rapidly solidifying adhesive.
By the term "support surface" is meant an inward extension and usually horizontal extension of the frame onto which the ceramic cooktop rests, through the intermediary of the dam.
The support surface is preferably integral with the frame, but may also be separately manufactured and attached to the frame.
Due to the heightened positioning accuracy inherent in the inventive process, the width of the support surface may be made narrower than in prior support shelves, onto which adhesive pads were placed. As indicated previously "stove" is inclusive of stoves, ranges, drop-in cooktops, etc. By "flowable", when not defined by a viscosity limitation, is meant a composition which flows by itself under the influence of gravity.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention.
Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.

Claims (20)

1) A process for mounting a ceramic cooktop in a stove,comprising:

a) supplying a frame having an opening therein dimensioned to receive a ceramic cooktop, the opening having a periphery, and having a support surface extending inwardly from the periphery of the opening, the support surface and opening periphery connected by side walls extending therebetween, the ceramic cooktop having a bottom surface, a top surface, and an edge connecting the top surface and bottom surface;

b) providing a dam an the support surface extending continuously around the support surface and having a height such that a ceramic cooktop, when positioned within the opening in the frame and resting on the dam, will have a spaced relationship between the bottom surface of the ceramic cooktop and at least a portion of support surface;

c) positioning a ceramic cooktop within the opening in the frame, the ceramic cooktop bottom surface resting on the dam, and the edge of the ceramic cooktop spaced apart from the side walls of the frame;

d) applying a flowable, curable silicone between the side walls of the frame and the edges of the ceramic cooktop and allowing the silicone to level to provide a visible seal between the frame and the ceramic cooktop.

2) The process of claim 1, wherein said dam comprises an applied bead of rapidly setting polymer.

3) The process of claim 2, wherein said rapidly setting polymer is an RTV-2 silicone elastomer.

4) The process of claim 3, wherein said RTV-2 silicone elastomer is an addition curable elastomer.

5) The process of claims 2 to 4, wherein said rapidly setting polymer is a viscous and/or thixotropic composition which forms a dam having a semi-circular or flattened semi-circular cross-section.

6) The process of claims 1 to 5, wherein said dam is applied to said support surface by a robot.

7) The process of claims 1 to 6, wherein said ceramic cooktop is positioned within said opening by a robot.

8) The process of claims 1 to 7, wherein said flowable curable silicone is applied by a robot.

9) The process of claims 1 to 8, wherein at least two of steps b), c) and d) are performed by a robot.

10) The process of claims 1 to 9, wherein said dam is applied in such a manner so as to define a seal volume extending from the inner periphery of the dam to the top of the visible seal, and wherein a volume of flowable silicone substantially the same as the seal volume is applied.

11) The process of claim 10, wherein said flowable silicone is supplied by a robot.

12) The process of claims 1 to 11, wherein no hand tooling or cleanup is necessary following step d).

13) The process of claims 1 to 12, wherein said dam is formed from a solid elastomer applied to said support surface.

14) The process of claim 13, wherein said solid elastomer is applied in the form of a continuous strip by a robot.

15) The process of claims 1 to 14, wherein said dam is provided as a raised portion of the support surface.

16) The process of claim 15, wherein said raised portion is provided by a metal stamping operation.

17) The process of claim 15, wherein prior to step c), said raised portion is coated with a tacky substance.

18) The process of claims 1 to 17, wherein said flowable curable silicone is an addition-curable silicone.

19) The process of claims 1 to 18, wherein said flowable curable silicone has an initial viscosity of 6,000 mPa.s to 9,000 mPa.s at 25°C.

20) A stove having a ceramic cooktop within a metal frame and having a silicone seal therebetween, produced by the process of claim 1.