GRC Spraying off a Boom arm
GRC face coat
Adding Fibers to the Gun
Directional spraying
Spraying into a closed mold
Spraying with a lower 7 kg per Minuit output
Spray up GRC is a process of Spraying a composite of fiber and cement simultaneously onto the mold surface in a single operation. In this way it is possible to build up a matrix that contains above 5% fiber, a fiber ratio not possible by any other method. (Spraying of a Pre-mix, of slurry and fiber through a pumping device and spluttering it onto a surface is not spray up GRC . Spray up GRC has over 5% fiber; the fiber length and orientation are controlled by the spray gun parameters. This requires specific equipment, knowledge and skill as well as a discipline to procedures.
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Sprayed GRC composites are actually formed by a spray and roll process. The rolling is done with a special roller that compacts the composite against the mold surface after it is sprayed. The composite is usually built up by spraying and rolling several layers
How is your equipment any different ?
Answer: Spray up GRC is not so complicated . you mix a slurry of sand and cement and water and you transfer it to a pump that can deliver it at a controlled rate to a spray gun. The spray gun pulls into it a continuous roving of glass fiber and chops the fiber delivering the fiber into the cement stream. the gun needs to be supported by electronics and pneumatics control system
The Commercial GRC equipment on the market follows the format of the original commercial GRC equipment designed to produce large Architectural components usually on semi industrial scale .
18 years ago I bought a very expensive commercial GRC machine, it was of the exact type that is still for sale on the market today . I did not buy it so i could make commercial GRC, I wanted to produce Decorative Urns and fountains ! the equipments was simply not designed by some one who understood much about spraying GRC into smaller highly detailed molds ! it was designed to spray up large panels for which it was probably fine ! but for decorative GRC it was to cumbersome .
As innovators of this decorative industry we had no choice to but Build our own equipment that gave us control of our application . and after 20 years of constant development and evolution we have developed GRC equipment that is in use today in a dozen factories in Asia producing decorative GRC .
Mixing smaller 50 kg batches faster was better than mixing 200 kg less often so the mixing equipment was rethought .
Not only did we need lower spray rates but we needed more control of the spray pattern at these lower spray rates and so we evolved the Inline Gun as apposed to the concentric gun as inline gave us this control.
We needed lighter spray guns. having large heavy spray guns bounden with large cement supply hoses and Air lines was fine with a counter weight coil helping the spray operator hold up the heavy gun was fine on very large flat molds where the spray operator only has to point and shoot but when spraying a complex surface the spray gun must follow horizontal to the changing surface at all the times this meant a spray operator needed a gun light enough to hold in one hand unburdened by inflexible feed lines .
often the spray gun is spraying in confined spaces and spraying at close distances to the mold surface so the gun had to produce a good fiber cement lay-down both close up and back at a distance a broader range of operation that existing guns have
the Equipment had to be simplified down as it has to be easy and fast to clean , strip and maintain
And that is what we offer today . the equipment is Simple KISS as it had to work year in year out in Asian hands . the mixer and spray machine can be single phase where three phase is a problem . having a spray gun that could produce good spray pattern with lower Air demand means smaller air compressors can run this equipment .
This is not equipment limited to small operations it is equipment that works extremely well at small and medium ends of GRC manufacturing
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Many people entering the process industries have no experience or training in the “art” of mixing. Most of what they need to know is not taught in trade schools or in traditional college classes. This knowledge is typically acquired over many years of hands-on experience. Learning, and applying the basics, is a key element in producing successful products.
The High-Speed Disperser (HSD) is the basic tool used by all paint, ink, chemical, plastic and adhesive manufacturers. Although a very simple device, the HSD is often misused or misapplied.
The use of High speed high energy mixers for cement is not new it is however not at all common in cement industry and little understood .
The primary purpose of the HSD is to incorporate and break down dry agglomerates into a liquid vehicle and effectively “wet” the dry particles to produce a uniform, stable dispersion with the finest particle size possible. To produce the desired dispersion results, the method used to make the batch can be as important as proper design specification and proper formulation.
For Cement Mortars a special blade designs are used . A high shear high energy mixer will do to a batch of sand and cement in two minuets what a low shear mixer can not do in one hour
This GRC/GFRC spray equipment I have developed over the last 20 years based on hands on experience and it is operating in Australia , New Zealand the Philippines , Vietnam, Indonesia and China and has driven the development of this decorative GRC industry .
The importance of High shear mixing for spray up GRC
Commercial spray set up wall mounted spraying off a boom arm
Studio based spray set up
The IN LINE SPRAY GUN is the lowest profile lightest and most maneuverable spray gun you will find that can handle low spray rates under 5kg per minute up to full commercial output of 20 kg per minute , the average spray rate for decorative GRC is between 7 and 10 kg per minute . An advance for decorative spray operation over the Concentric spray guns supplied with industrial GRC / GFRC machines . This Gun design was driven by the needs of decorative GRC manufacturing , once the first prototype was put in the hands of a spray operator I never got it back and no one wanted the old concentric gun again !
The Spray Gun
I asked Aren to spray moving further away each panel to show that the Inline gun has a large operating range .
Hundreds of cement slurry partials per sq inch rather than 10s of larger cement slurry particles generated buy this spray system mean there is no chance that the converging stream of fiber will not be captured and form a single stream of cement and cement coated fibers in mid stream.
This finer stream with inflight whetted fiber. give the light weight high surface area fibers higher mass now pre-whetted in mid stream , this means fibers maintain the kinetic energy absorbed from the cement particle stream. the velocity of the two streams now match rather than higher velocity larger droplets of cement leaving the gun and lower velocity high surface area lighter fibers traveling independently toward the mold where fibers potentially get blown out of the spray stream buy the turbulence of the air stream pushing out the fibers and the cement. In this inline set up two independent streams of fibers and cement particles form a single stream where fibers are captured and coated midstream giving the fibers/ cement stream a single velocity and direction .