Page 1 of 13
`
`ABOUT ROLL COATERS
`
`- How roll coaters work
`
`— Coating thickness control
`- Feedroller configurations
`-
`Selecting a roll coater
`
`HOW ROLL COATERS WORK
`
`Roll coating machines are commonly used for the application of a liquid to the surface of a part.
`Rollcoaters can be used to apply liquid adhesives, paints, oils, and coatings such as varnish or clear finish
`coats. Rollcoaters can take many forms, from simple paint rollers to sophisticated Coating machines with
`multiple rollers. A roll coating machine works by transferring a layer of coating from the surface of a roller to
`the surface of a part. When this happens, a phenomenon know as “film splitting” occurs. The layer of coating
`on the surface of the roll splits — part of it stays on the roller, and part sticks to the surface of the part. The
`percentage of coating that sticks to the part (the substrate) depends on the surface characteristics of both the
`roller and the substrate.
`
`COATING THICKNESS CONTROL
`
`With most rollcoaters, there is some means of controlling the thickness of the coating on the surface of the
`roller before it contacts the substrate. The three most common approaches to controlling the coating thickness
`are metering blade, metering roller, and transfer from another roll.
`METERING BLADE
`
`A typical arrangement for a metering blade is shown in Figure #1. Coating is picked up from a reservoir by
`the application roller. As the coating clings to the roller and is carried up by the rotation of the roller, only a
`certain amount can pass through the gap between the metering blade and the roll surface. The excess flows
`back to the tank. Metering blades are usually made with some means of adjustment, so coating thickness
`changes are made by moving the blade to open or close the gap.
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`http ://www.schaeferco.com/about_rollcoaters.html
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`9/27/2013
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`Textron Exhibit 2002 pg. 1
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`

`

`Page 2 of 13 .
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`In some cases the metering blade may be moved forward and back on its mount plate, It can also be rotated
`to change the gap between the metering blade and the roller. The advantages of a metering blade over other
`means of coating thickness control are low cost, simplicity of design, and the fact that the metering blade
`system does not require much space. Two disadvantages are the potential for clogging and potential for roller
`damage. Clogging can occur if debris or foreign matter in the liquid gets caught in the gap between the
`coating roller and the metering blade. This can block a portion of the coating from passing through the gap,
`which can cause streaks or inconsistent coating results. In cases where the debris is abrasive, it can cause
`damage to the surface of the roller.
`
`Some types of coatings also tend to congeal or clump if subjected to situations where there are shear forces
`on the liquid. This situation occurs between a metering blade and a coating roller. For this reason materials
`such as latex adhesives do not run well in machines having metering blades. This type of adhesive would
`form clumps which would clog the metering blade to roller interface.
`
`METERING ROLLS
`
`Typical metering roll arrangements are shown in figure #2. In a meterng roll system, the thickness of the
`coating is controlled by adjusting the gap between two rollers. In a typical bottom coating application the
`coating is picked up from a reservoir and carried up to a nip point by one roll, then the excess is metered off by
`a second roll which also serves as an application roller. A similar concept is used when coating must be
`applied to the top surface of a part. Coating is held in the valley formed between the metering roller and
`coating roller, and the gap between the rollers is adjusted to change the coating thickness.
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`Metering roller systems are more expensive to build than metering blade systems, but have several
`advantages. They are more tolerant of debris or foreign matter in the liquid, since it can often pass through the
`
`http ://www.schaeferco.com/about_rollcoaters .html
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`9/27/2013
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`Textron Exhibit 2002 pg. 2
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`

`

`Page 3 of13
`
`gap between the rolls and go back into circulation. If the coating roll and metering roll are run at similar
`surface speeds, shear sensitive materials such as latex can be applied without problems. In some situations,
`the coating roll and pickup roll are run at different surface speeds. This can be done to minimize the formation
`of foam in the tank, or to help smooth out the layer of coating on the coating roller.
`
`REVERSE ROLL COATING
`
`In reverse roll coating, the surface of the part is fed across the coating roller in the opposite direction to the
`surface travel of the coating roller. This causes the coating 'roll to serve both as an application roller and a
`wiper roller. A small puddle of coating can form at the interface of roller and substrate, and this flows onto
`the part as it passes under the coating roll. A reverse roll coating arrangement is shown in Fig 3.
`
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`
`Reverse roll coating is used to apply heavier coatings than might be possible with forward roll coating. It is
`also possible to apply a very smooth coating by using the reverse roll technique. Since the coating is heavier,
`it tends to flow out better, and the flow from the puddle at the roller to part interface tends to smooth out the
`coating. The result of these two effects working together can provide coatings that are very flat and smooth.
`
`The difficulties in reverse roll coating are in driving the part and in dealing with any coating build—up on
`the leading or trailing edges of the part. In order to travel in the opposite direction from the coating roller, the
`part must be driven in a positive manner so that it does not slip. This can be done with pressure rolls having
`high friction coverings, with vacuum conveyer systems, or with drive belts having cogs or raised bosses to
`push the parts through.
`
`If a very heavy coating is being applied, it can drip over the lead edge or trailing edge of the part. With
`some types of parts this does not pose a problem, but with others it can cause coating to transfer to the pressure
`rolls or feed conveyer and require cleanup. This problem can usually be controlled by finding the optimum
`settings for coating weight, roller speed, and the speed of part travel.
`TRANSFER ROLLS
`
`Transfer roll systems (Fig 4) are actually a variation of the metering roll system, and utilize additional
`rollers to transfer the coating from the reservoir to the final point of application. Because additional rollers are
`involved, these systems are more expensive than designs using only a metering roller and application roller,
`but there are several reasons why transfer rollers are used in some types of equipment. These reasons are
`coating thickness, roller space limitations, and special roller surface material requirements.
`
`http ://Www.schaeferco.com/about_rollcoaters .html
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 3
`
`

`

`
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`*Traaafer Rel; Systems
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`Page 4 of 13
`
`In
`
`general
`transfer
`roll
`
`systems are
`capable of
`depositing
`a thinner
`
`coating
`than two
`roll
`
`systems.
`This is
`because a
`
`film split
`occurs at every roller interface, so the film of coating will be thinner on each consecutive roller in the roller
`train.
`
`Roller space limitations also may dictate the use of transfer rolls. In some types of equipment, there is not
`enough space to place large diameter metering rollers close to the application point, and transfer rolls can be
`used to carry the coating from the initial metering point to the application point.
`
`Transfer rolls can also be used in situations where the application roller must be made of a material that is
`not well suited to use as a metering roll (such as a soft rubber). .In these cases, metering of the coating is done
`with metal rolls or hard surfaced rolls, and the coating is transferred to the application roll. This configuration
`can also be useful in situations where rolls are used to transfer a pattern, suchas certain types of printing
`presses. The coating is metered out to the surface of one roller, and the application roll picks up the coating on
`a printing plate wrapped around the application roll. The plate transfers the coating to the part.
`
`Besides cost, one disadvantage of transfer roll systems is that they are more difficult to adjust and calibrate
`than metering blade or two roll metering systems. In some situations additional rolls or wiper blades must be
`added to prevent an accumulation of coating on rolls when parts are not being coated.
`
`POST APPLICATION METERING
`
`In many applications roll coating machines are used to apply an adhesive or finish coating to a part, but the
`thickness or finish of the layer being applied does not meet the requirements of the end product. In these cases
`a secondary metering method can be used after the coating is applied to either thin out the coating, smooth it,
`or texture it to meet the final requirements.
`
`Almost all post application-metering situations are used when the material being coated is in the form of a
`continuous web. One method that is very popular is the use of a mayer rod or mayer bar. This is a rod wound
`with a layer of round wire. This device can be used to both meter and smooth out a layer of coating. The bar
`is used as a scraper bar to wipe off excess coating, and the spaces that exist between the round wires serve to
`meter out a uniform layer of coating. In most cases the material being metered off will form a series of peaks
`and valleys that will flow out to form a smooth uniform layer. Mayer bars may be used in sequence to do
`rough metering then fine metering/smoothing, and are used on many production lines that produce pressure
`sensitive films, tapes, and other materials that require a thin, smooth finish coating. A configuration using a
`mayer rod is shown in FIG 5.
`
`http ://www.schaeferco.com/about_rollcoaters.html
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 4
`
`

`

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`Page 5 of 13
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`In certain cases,
`application rolls can be
`built with surface textures
`
`that provide the type of
`surface finish desired
`
`without post-application
`metering. The ability to do
`this will often depend on
`the characteristics of the
`
`coating being applied, as
`well as the characteristics
`of the substrate. With the
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`right combination of
`characteristics, a simple
`machine may be able to produce results that normally would be produced by a more complex machine. Some
`' machines are built with application rollers having grooves, knurled surfaces, or engraved surfaces designed to
`carry more coating than can be carried by a smooth roller. The surface texture can be used as a method of
`controlling the amount of coating deposited by a roller.
`
`W
`
`The majority of coating applications are ones where a continuous strip (web) of material is coated, then
`dried (or chilled), and rewound into a roll. Web coating lends itself to high production rates, and can be used
`with almost all types of adhesives and coatings. Many web coating applications utilize roll coaters to apply
`the adhesive or coating, and most utilize some form of post—application metering. In general, web coating is
`done at much higher speeds than sheet coating, and considerable attention must be given to factors such as
`proper web tracking, web tension control, web flutter, and stretching. Since the web is a continuous strip, it
`can pass over a number of rollers as it is being coated or treated, and some web coating configurations can be
`very complex. An engraved roller (gravure roll) is used in many web—coating applications. This is used to
`transfer a very precise amount of adhesive to the web. Two typical web coating configurations are shown in
`Fig 6, both of them utilizing a gravure roller.
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`PRESSURE ROLL CONFIGURATIONS
`
`With any roll coater, the substrate to be coated must be brought into contact with the application roller to
`pick up coating. In some situations the part can be directly pressed against the coating roller by a pressure roll,
`and in others the substrate must be guided over the surface of the coating roller so that it just kisses the roller
`with enough contact to pick up the liquid. Pressure rolls are sometimes called feedrolls, backup rolls, or guide
`
`http ://www. schaeferco.com/about_rollcoaters.htm1
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`9/27/2013
`
`Textron Exhibit 2002 pg. 5
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`

`

`Page 6 of 13
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`rolls.
`
`The configuration of the pressure roll relative to the coating application roll is usually determined by the
`thickness and flexibility of the substrate to be coated. If the pressure roll is too close to the coating roller there
`is a possibility that it can pick up excess coating that flows off of the substrate, and then transfer this coating
`on the opposite side of the substrate. In some cases a droplet of coating can travel around on the surface of the
`pressure roll. This can allow it to pick up a bit of coating on each revolution until the roll becomes almost
`totally covered, requiring that the equipment be stopped for cleanup.
`
`When coating thin substrates the pressure rolls must be a sufficient distance from the coating roller to avoid
`contamination, but still ensure that the substrate can be driven through the machine and pick up a coating.
`This can be accomplished by locating the pressure rolls in such a way that the substrate is forced to bend over
`the coating roller, or by pressing the part directly against the coating roller with the pressure roll and removing
`any excess that transfers to the pressure roll with a wiper or cleaning roll. A third technique is to coat only a
`portion of the substrate and leave the edges uncoated to avoid any transfer of coating.
`
`If the substrate to be coated is sufficiently thick there is less chance of coating transfer and the pressure roll
`can be located so that it presses the part directly against the coating roller.
`
`Different configurations of pressure rolls relative to coating rolls have been used for various types of
`equipment. Some typical configurations are shown here:
`
`http://www.schaeferco.com/about_rollcoatershtml
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 6
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`

`

`Page 7 of 13
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`In the configuration shown in Fig 8 the substrate must flex as it hits the coating roll, and the deflection
`creates a slight pressure of the substrate to the roll. Once the substrate is in contact with the roll, the surface
`tension of the adhesive will tend to cause it to stick to the roll and be pulled through the machine. The stripper
`points indicated are small knife like fingers designed to break the leading edge of a flexible substrate free of
`the coating roller and allow the part to feed through without wrapping around the coating roller. This type of
`single pressure roll configuration is typically used with paper.
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`http://www.schaeferco.co1n/about_rollcoaters.html
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 7
`
`

`

`With the roll configuration shown in Fig 9 the two pressure rolls force the part to cup over the coating
`roller and pick up a full coating. The part flexes upward as it passes under the first roller and hits the coating
`application roll, and is forced around the coating roller as it hits the second pressure roll.
`
`Page 8 of 13
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`This roller arrangement can be versatile — it can often be used with a range of substrate thicknesses, since
`moving the pressure rolls relative to the coating roller can allow paper to be coated when the rolls are close to
`the coating roll, and thicker parts coated as the pressure rolls are moved away from the coating roll. By raising
`the dual rollers high enough above the coating roller, it may be possible to also coat rigid and semi—rigid
`substrates with this roll configuration. Stripper fingers are generally used with flexible substrates, but may not
`be required with stiffer materials.
`
`In Figure 10 the part is pressed directly against the coating roll by the pressure roll. If the part has
`sufficient thickness, stripper fingers are not needed since the part will not cling to the coating roll. Pressure
`rolls may or may not be driven, depending on the type of material being coated and the type of adhesive, since
`some types of adhesive generate sufficient driving force to pull the part through the machine.
`
`
`
`The configuration shown in Fig 11 is designed to force a traveling strip of material to come in contact with
`the coating roller and pick up coating. Web guide rolls do not need to be driven, since the web is generally
`pulled by a rewind or take—up roll, and the tension on the web creates the pressure of the substrate against the
`coating roller.
`'
`
`http ://www.schaeferco.com/about_rollcoatershtml
`
`9/27/2013
`
`Textron EthbIt 2002 pg. 8
`
`

`

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`Page 9 of 13
`
`In web coating, it is
`possible to pull the substrate
`over the coating roller at a
`different speed than the
`surface of the roller. This
`
`technique is often used to
`deposit a thinner layer of
`coating than would be
`deposited by the roller
`running at the same speed as
`the web. The traveling action
`of the web can also cause the
`
`coating roller to act as a wiper
`bar, so that the coating is
`smoothed out as it gets
`squeezed between the web
`and the coating roller.
`
`SELECTING A
`
`ROLLCOATER
`
`The selection of the best roll coating machine for any particular type of work depends on a number of
`factors. The key questions that need to be considered are as follows:
`
`A. Type of adhesive
`B. Thickness of substrate
`C. Width of substrate
`
`D. Full coat or partial coat
`’E. Handling after coating
`F. Cleanup
`
`http://www.schaeferco.com/about_rollcoaters.html
`
`Textron Exhibit 2002 pg. 9
`
`9/27/2013
`
`

`

`Page 10 of 13
`
`A. Type of adhesive — (or coating)
`
`3)
`
`The type of adhesive or coating will influence the way the liquids are brought to the metering point.
`Although most adhesives will work for short periods of time in any type of rollcoater, problems can occur
`with certain adhesives that would cause the coating results to become inconsistent as the material runs for
`longer periods. Some general guidelines are as follows:
`1) Evaporation of the solvent or water in an adhesive is a major consideration in how well it will run
`in a roll coater. When running solvent based materials, as little surface area as possible should be
`exposed, and material should be in constant agitation to prevent dead areas which can form a skin
`of partially dried adhesive. Machines designed for solvent base adhesives or fast setting water base
`adhesives would have rollers shielded as much as possible, and would include pumps or other
`methods to keep the material in constant circulation.
`2) Machines for latex—based adhesives would be designed to minimize areas where the adhesive
`would be subject to a shearing action which could cause clumps to form.
`It should be easy to add fresh adhesive to any machine. The design of the tank should be a
`compromise between the capacity and the exposed surface area. Too large a tank may cause too
`much surface area to be exposed to evaporation, but too small a tank may require constant
`refilling. Automatic refill systems can be fitted to some machines to alleviate the need to refill
`constantly.
`4) Some types of materials do not flow well, and need to be pumped to the metering point. In some
`cases these materials can be carried up by a pickup roll that rotates slowly enough to be wetted by
`then adhesive, but in other cases pumping systems are required. This is especially true with certain
`high viscosity materials such as epoxies, solvent cements and urethane adhesives.
`5) Certain types of adhesives and coatings have special characteristics that must be taken into account
`when selecting or designing a rollcoater to handle them. An example of this are Ultraviolet cured
`coatings (UV cure). Machines that are used to apply these coatings must have shielding or
`guarding in place to keep the coating shielded from light as much as possible, since light exposure
`can cause UV cure coatings to catalyze earlier than desired or can degrade the characteristics of the
`coating.
`
`The type of adhesive will affect the choice of materials for the rollers and reservoir, the approach to coating
`thickness control, the method of machine cleanup, and the way that coating gets delivered to the metering
`point. Certain types of adhesives (such as hotmelts, waxes and certain high viscosity materials) require that
`the machine or the rollers be heated to melt the material or lower the viscosity to a point where it can be
`applied. Some adhesives or coatings will react with certain metals or other materials, and this can degrade the
`adhesive as the machine runs, or cause damage to the coater. Examples of this are the reactions of copper
`containing alloys with latex cements and UV. cured adhesives. Other examples of incompatible materials
`would be aluminum components used with highly acidic adhesives (such as hot animal glue). In this case the
`metal components would be attacked and damaged by the glue.
`
`Some adhesives are sensitive to a shearing action which occurs with a scraper blade, and can tend to
`congeal when subjected to this type of force. These adhesives and coatings must be run in machines having
`metering rollers.
`
`For adhesives and coatings that must be heated either the rollers must be heated directly or the tank which
`holds the material must be heated, and the heat from the tank and material transferred to the application roller.
`The need for heating can limit the choice of materials for the roller, since any material selected must be
`capable of maintaining critical dimensions when heated to the operating temperature.
`
`With any type of coating machine the type of adhesive or coating will affect the cleanup method. Some
`types of materials can be easily cleaned — others require extensive washing with solvents or water to remove
`any residue. Most machines used for the application of hotmelts do not require cleanup. The adhesive is
`simply allowed to cool and hardens up in the machine. One exception to this are the “reactive” hotmelts or
`
`http ://www.schaeferco.com/about_rollcoaters.html
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 10
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`

`

`Page 11 of13
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`“moisture cure” hotmelts which must be purged from the equipment before it is shut down.
`
`B. Thickness of substrate ——
`
`The thickness of the substrate determines the type of feed roll configuration that will give the best results in
`coating the part. The part must be able to come into full contact with the coating roller to pick up a
`consistent coating, but should not cause the coating to transfer to the feed roller (or feed rolls).
`
`Thin flexible substrates (such as paper), are usually best coated by using an offset pressure roller or dual
`feed roller arrangement, and coating of individual sheets will require the use of stripper fingers. Extremely
`flexible substrates such as fabrics, thin foam, non—woven fabric, thin rubber etc, can be very difficult to
`coat since they will tend to bunch up and fold over themselves as they exit the coating point. In some
`cases, these types of material can only be coated using a backing board of sufficient stiffness, coating them
`in a web form, or by leaving a portion at the leading edge uncoated, and using this part to pull the substrate
`through the coating point. This can be done by loading the part into the coating machine with the feed
`roller open, then bringing the feed roller into a position where it can drive the part while there is some
`tension on the part to keep it from going slack and bunching up.
`
`Thicker or stiffer substrates can be driven with a dual feedroll or single feedroll arrangement. In some
`cases, stiff substrates such as plywood or fiberboard can present problems, since they may have high and
`low spots that will bridge over the coating roll and create voids in the coating. For these types of materials
`a soft faced coating roller may be needed to contact the entire surface and apply coating.
`
`http ://www.schaeferco.com/about_rollcoatershtml
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 11
`
`

`

`Page 12 of 13
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`C. Width of Substrate —
`
`In general, the width of a roll coating machine should be at least 2 inches wider than the widest part to be
`coated. With this extra width, if the part is loaded into the machine slightly crooked, the full surface will
`still get coated.
`'
`
`D. Full coat or partial coat ~—
`
`Roll coating machines are available that can apply coating to only a portion of a sheet or the full surface.
`There are also pattern coaters available that can apply stripes or other types of patterns in the same manner
`as a printing press (see transfer roll systems). In selecting a coating machine, it is important to define the
`area to be coated. Is it full surface, a pattern, or a stripe along one edge?
`
`E. Handling after coating ——
`
`Once a part is coated with adhesive, it can become much more difficult to handle than a dry part, so it is
`important to think about how the part will be handled once it is coated.
`
`The simplest and least inexpensive roll coaters coat the bottom surface of the part. This means that the part
`must be handled immediately as it exits the machine, and must be handled by the coated surface. With
`many types of parts this does not present a problem, but potential problems with wet glue getting on
`operators fingers need to be addressed. If the operators are able to handle and locate parts without
`contaminating the clean surfaces there will be no problem, but in some cases the operators will need to use
`special tools to handle the parts, or wipe their fingers clean of glue at some point in the gluing and
`assembly operation.
`
`With machines designed to apply adhesive or coatings to the top surface of the parts the issue of glue
`contamination is drastically reduced. The top surface of the part is coated, and the bottom side remains
`clean for handling. Parts can be fed directly onto a conveyer— (which is not possible with bottom—coated
`parts). This can be important with large parts which would be awkward to handle by the coated surface.
`Top Coating is essential for parts which are being coated with a finish coat, since the finish coat must have
`time to self—level and flow out into a smooth coating after being applied.
`
`F. Cleanup —
`
`With any rollcoater, any adhesive remaining in the machine after operation is complete must be cleaned
`completely or it can dry on the rollers or other parts of the machine and cause problems. Liquids which do
`not dry (such as oils) can be left in the machine, as can most hotmelt adhesives, but other types of adhesive
`and coatings must be cleaned out of the machine.
`
`Ease of cleanup must be considered when selecting a rollcoater. Most rollcoaters are designed for quick
`cleanup, and may incorporate features in their design to facilitate this aspect of operation. Some design
`features that are used to make cleanup easier are:
`
`a) Washdown systems for rollers and tanks
`b) Removable coating units
`c) Easily removable tanks
`d) Separate wash tanks
`e) Built-in flush systems (often used on printing equipment)
`f) Removable rollers
`
`RoLL COATER SELECTION
`
`http ://www.schaeferco.com/about__rollcoaters.html
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 12
`
`

`

`Page 13 of 13
`
`Once the factors described above are taken into consideration, the choice of a rollcoater suitable for the
`work to be done will often be narrowed down to one or two machines. As each question is answered, only one
`or two machines from any manufacturer may fit the requirements, so by the time the entire list of questions is
`reviewed, the choice of the best machine for the job will usually be obvious. In some cases questions about
`the suitability of a roll—coating machine for a particular application still remains. In these cases the best way to
`answer the questions is to run a test using the rollcoater, the adhesive, and the substrate together to determine
`if they produce the desired results.
`
`http://www.schaeferco.com/about_rollcoaters.html
`
`9/27/2013
`
`Textron Exhibit 2002 pg. 13
`
`