Crunchies

Product=20 Knowledge=20
Crunchies

Ten-thousand years from now = when=20 anthropologists from another culture sift through the rubble = of our=20 civilization, they might discover a slab of solid surface = and ponder=20 its significance to our ignorant and backward civilization. = Most=20 likely, as more samples of the product are discovered, they = will=20 divine that solid surface only began receiving widespread = acceptance=20 in our culture once granite-like particles were added to the = mix.=20 They will then probably correctly assume that the = introduction of=20 these crunchies was pivotal in the early development of = solid=20 surface.

Who knows? They might even = unearth a=20 well-preserved skeleton from our generation, and call it = "Crunchy=20 Man."

The Manufacturing=20 Process

"There are two different ways = that solid=20 surface granite particles, sometimes called granules, chips, = or=20 crunchies, are produced," explains Lou Giovannini, Vice = President of=20 Sales and Marketing for ACS International, Inc., a producer = of=20 granite-look fillers for solid surface. "The methods = include, (1)=20 casting ingot, flat sheet stock, or finish cast solid = surface and=20 then impact grinding the material, or (2) combining the = essential=20 ingredients within an extruder, cooling the product and then = attrition grinding the particles."

Sheet or Ingot = Casting

The same process of combining = resin, ATH=20 filler, pigments and catalyst is used when casting sheets or = ingots=20 for grinding into particulate, as when making regular solid = color=20 solid surface sheets. After the material has cured, it is = reduced to=20 a mixture of fine and coarse particles by feeding it into = machines=20 that grind, nibble or pulverize the material, depending on = the=20 desired result. These particles are then separated and = graded=20 according to size before being blended into a new sheet of = solid=20 surface.

One might think that less = care is needed=20 when making crunchies than when casting sheets. According to = Doug=20 Turner of American Granule Corporation, a sister company to = solid=20 surface producer Karadon Technologies, just the opposite is = true.=20 "It is actually more difficult than making solid surface," = he=20 explains. "The material you produce for granules has to be = the same=20 quality as what you want your finished product to be. = Grinding the=20 sheets and making a granule that stays the same size while = your=20 machines wear out, dull, and are constantly changing can be = quite=20 tricky."

Some manufacturers process = granules with=20 hammer mills driven by 100 horsepower or larger motors, = which=20 effectively pulverize the material with heavy steel fingers = rotating=20 inside a steel drum. A steel screen at the bottom of the = drum allows=20 only those particles small enough to fit through holes = drilled to a=20 certain size to escape.

Other companies employ roller = mills for=20 sizing their particles, which consist of two spinning steel = rollers=20 spaced closely together, through which the material is fed. = As the=20 solid surface pieces enter the mill they are crushed to a = width=20 equal to, or less than, the distance between the two=20 rollers.

The resulting particulate is = sorted into=20 its various sizes by sifting it through graded screens. Both = roller=20 mills and hammer mills generate a quantity of very fine = particles=20 and dust as a by-product of crunchies production, a = condition which=20 some manufacturers consider too inefficient for their=20 purposes.

"We use two different types of = machines in=20 various combinations," says Avonite=EF=BF=BDs Frank Scott. = Avonite is the=20 company that introduced granite-look solid surface to the = world in=20 the 1980=EF=BF=BDs, and holds the original patent for the = process of=20 combining particulate into solid surface sheets. "For some = of our=20 grinding we use a classic grinder, which works with a set of = rotating knives and a set of stationary knives that slices = the=20 material into smaller pieces. We also use centrifugal pin = mills.=20 Particulate that has been divided into a variety of sizes = shoots out=20 of a rotating dispersion head, and collides with a set of = stationary=20 knives to achieve a further reduction in size. It tends to = reduce=20 the size of the bigger particles, where the smaller ones = just fire=20 on through. It has been a classic development for=20 Avonite."

Doug Turner says that = American Granule=20 uses a similar process for reducing the size of its = particles, with=20 a slight variation. "It=EF=BF=BDs almost more of a punching = effect," he=20 says. "We call it cracking. What we have done in our process = is=20 develop systems where we cut the material to the size we = need with=20 very little left over. So we really don=EF=BF=BDt need to = create a market=20 for these fine dusts."

According to Turner, = pulverizing solid=20 surface into smaller particles creates tiny cracks in some = of the=20 crunchies, which could act as stress risers in the finished = product.=20 "You will find that you get a very low thermal shock when = you test a=20 solid surface sheet using a low quality granule," he = explains. "Part=20 of that quality is related to the way it is broken down from = a sheet=20 or an ingot to the finished size."

Turner also indicates that = breaking up=20 crunchies in a hammer mill or similar machine can mar the = physical=20 appearance of the particle. "You will notice that when some = dark=20 granules are cast into a sheet, the granule will have a nice = dark,=20 rich color in the center," he says. "But on the outside = perimeter=20 there is what we call a halo, which is a lightening effect = all the=20 way around that granule. If you see that, you know the = granule has=20 been abused before it got put into the sheet. Just the fact = that you=20 see that whitening all around the edge means that the resin = has=20 bonded to an area that has been subjected to impact, and = therefore=20 is a very weak bond."

Extrusion

In contrast to casting = sheets, ingots or=20 blocks and grinding them to size, ACS International uses its = own=20 patented process, which mixes raw ATH and pigments together = with a=20 thermoplastic polyester resin and sends that mixture through = an=20 extruder. Coming out the other side of the extruder are long = ribbons=20 of very hot material, which must be cooled to room = temperature in a=20 water bath.

"After air drying, the = material is broken=20 up into =EF=BF=BD" nuggets using a Fitch mill," Giovannini = says. "Fitch=20 mills are commonly known as flake breakers or cutters, and = are able=20 to quickly break up small spaghetti type strings into = pellets. These=20 chips are then ready to be ground into various sizes, = including=20 large, medium, and small particles in attrition grinders. = This=20 process is fast, accurate, and able to reproduce consistent = particle=20 sizes and shapes with a minimum of fine = particles."

Giovannini claims that the = unique shape=20 of thermoplastic particles provide better physical = properties than=20 do those made from acrylic or polyester thermoset resins. = "Under=20 magnification thermoplastic particles look like lava rock," = he=20 explains. "Acrylic or thermoset polyester particles look = like pea=20 gravel. When you put them in a resin matrix there is no = chemical=20 infusion into the particle by the resin, which means it is = more of=20 mechanical than a chemical bond. Whereas, with a = thermoplastic=20 particle, the monomer actually infiltrates the particle, and = that=20 causes the molecules to cross-link. So when you catalyze it = in a=20 resin system you get cross-linking through the particle. = Thus, your=20 tensile strength, flexural strength and even elongation are = actually=20 higher."

Multicolor, And Other Types = of=20 Crunchies

Having perfected the process = of adding=20 particulate to a solid surface sheet, it wasn=EF=BF=BDt long = before=20 manufacturers improved their methods to produce crunchies = within=20 crunchies. This random dispersion of two or more colors of = tiny=20 particles embedded within larger solid surface chunks = creates a=20 randomness akin to that found in nature. Thus, when several=20 varieties of multi-colored chunkies in different sizes are = dispersed=20 throughout a sheet, the appearance is so close to natural = granite=20 that even experts sometimes have trouble telling the two = materials=20 apart.

Avonite=EF=BF=BDs Frank Scott = says that even=20 though making multi-colored particulate adds several = additional=20 steps to the overall manufacturing process, it is a = technology that=20 is well understood. "It is analogous to making a typical = filled=20 sheet," he explains. "You are combining several different = colored=20 particulate into a composite, which is then ground again and = added=20 to a new sheet."

Yet, for ACS International, = which uses=20 the extrusion process exclusively, making composite = crunchies is,=20 indeed, a difficult proposition. "There is a disadvantage to = that,"=20 says Giovannini. "I think it can be done, but we = don=EF=BF=BDt do it, and I=20 am not aware of anybody else doing it with the extrusion = process. We=20 are working on some things like that now."

Today, solid surface = manufacturers are=20 devoting considerable resources towards increasing their = existing=20 filler repertoires to include new materials and = technologies.=20 Fountainhead=EF=BF=BDs Artifacts Collection was one of the = first materials=20 to challenge the notion of a strictly granite look for solid = surface=20 with a "directional" particulate, that actually changes its=20 appearance when viewed from different angles. Clear = particulate,=20 mica, specially coated metal shavings and synthetic fibers = have all=20 been successfully introduced as solid surface fillers, each = with its=20 own unique look.

Possibly signaling the next = generation of=20 multi-colored crunchies, Avonite has recently introduced a = layered=20 particle, called Nougat, which exhibits a zebra-like = appearance.=20 "Rather than a random composite, you have a layered = composite,"=20 explains Scott. "The process is analogous to making buttons. = It is=20 not anything that we necessarily invented, but if you look = at=20 several buttons you will find that there are some = interesting=20 patterns. They might be like mother of pearl and have that=20 opalescence, or any variety of patterns."

Also on the horizon for = Avonite is=20 particulate that takes on recognizable geometric forms. = "What=20 everyone is limited to now is that crunched up look -- = either small,=20 or large, or black, or blue," says Commercial Devlopment = Manager,=20 Wayne Rutledge, "There is only so far you can go with that = to create=20 something interesting. To really push it you need special=20 shapes."

According to Rutledge, the = time is not=20 too far distant when designers could have, in addition to a = variety=20 of colors, a full palette of solid surface themes to choose = from=20 when specifying the product. "You might say it=EF=BF=BDs a = seashell or you=20 might say it is a sphere," he says. "It could be almost = anything.=20 The point is, you are going to have a totally new = look."=20