This technology can be separated into
several categories.
1. Material Preperation: Uniform melt blending
of plastic and cellulostics is a difficult and exacting process.
The cellulosic is a porous powder which will absorb the plastic.
This absorption is the characteristic which binds the materials
together and gives the finish product greater strength,
however it also increases molten viscosity and restricts ability
to flow in the extrusion prosess. Cellulostics also usually
contain moisture and are more sensitive to processing heat than
plastic polymers. The Cierra system addresses these problems by
careful use of additives such as curing, coupling agents,
lubricants and processing aids. The end product can then
become sufficiently strong to be used as construction material.
2. Extruder Design: A standard extruder is
not properly designed to blend and compound composites. Proper
gear boxes, thrust bearings, length to diameter ratio, all must
be engineered into the design in order to insure adequate mixing
and drying of the cellulosic material. Cierra remanufactured
machines incorporate all these features into the design.
3. Screw Design:
The screw design is configured to uniformly mix and control
temperature of recycled plastic and cellulosic material while
compressing sufficently to obtain uniform strength.
4. Cooling Technology: Standard
cooling tanks limit production rate. Cierra designs speed the
cooling rate by use of proprietary techniques and enable higher
speed production.
5. Die technology: It has long been
known that pressure forming increases strength. Cierra's
dies apply uniformly controlled die pressure to assist in
forming the part as it is being extruded. The pressure is
monitored and is increased or decreased to main constant within
a predetermined varient. This permits a higher loading of non
plastic material without loss of strength and it also produces a
precise board by eliminating
product surging.
