Islamic University of Gaza

Faculty of Engineering

Mechanical Engineering Department

Wood-Plastic Manufacturing and Production Line

Requirements.

Prepared by:

Faisal F. Al-Safadi 120101964

Mahmoud N. Murad 120102509

Maisara A. Habeil 120101035

Wood-Plastic Composites (WPCs) are composite materials made of wood fiber/wood

flour and thermoplastic(s) (includes Polyethylene (PE), Polypropylene (PP), Polyvinyl chloride

(PVC) etc.).

Chemical additives seem practically "invisible" (except mineral fillers and pigments, if added) in

the composite structure. They provide for integration of polymer and wood flour (powder) while

facilitating optimal processing conditions.

In addition to wood fiber and plastic, WPCs can also contain other ligno-cellulosic and/or

inorganic filler materials. WPCs are a subset of a larger category of materials called natural fiber

plastic composites (NFPCs), which may contain no cellulose-based fiber fillers such as pulp

fibers, peanut hulls, bamboo, straw, digestate, etc.

Production

Wood Plastic Composites (WPCs) are produced by thoroughly mixing ground wood particles

and heated thermoplastic resin. The most common method of production is to extrude the

material into the desired shape, though injection molding is also used. WPCs may be produced

from either virgin or recycled thermoplastics including PVC, PP. Polyethylene (PE) based WPCs

are by far the most common. Additives such as colorants, coupling agents, UV stabilizers,

blowing agents, foaming agents, and lubricants help tailor the end product to the target area of

application. Extruded WPCs are formed into both solid and hollow profiles. A large variety of

injection molded parts are also produced, from automotive door panels to cell phone covers.

In some manufacturing facilities, the constituents are combined and processed in a pelletizing

extruder, which produces pellets of the new material. The pellets are then re-melted and formed

into the final shape. Other manufacturers complete the finished part in a single step of mixing

and extrusion.

1. Prepare and Mix Ingredients

The wood flour used in WPCs has to contain far less

moisture than one would find in nature, so before going into

the hopper, it gets heated and dried until it's almost free of

water. At the same time, the plastic–which looks like soap

flakes–is heated to a liquid state. (That's why it's typically

called "resin.") Those ingredients are mixed along with

additives until the plastic is considered to have thoroughly

covered (or "encapsulated") the wood flour. If you're making

PVC products, there's no wood flour used, so only plastics

and additives get mixed. Ingredients for a top coat, or capstock, on WPCs are mixed

separately. Capstocks don't have wood flour, but exactly what each company puts in is a

closely guarded secret. Basically, it's a plastic with additives like colorants.

2. Extrude the Mixture

The heated mix is pushed through a die that typically

contains a series of four to eight computer-cut metal

plates. These progressively shape the product into the

desired configuration: a deck, a piece of trim, a railing

component. The capstock mixture gets introduced into

the die near the final plates, after the core's shape has

been formed. WPCs and PVCs get bigger as they

leave the die. This expansion is known as free

foaming. At this point, some manufacturers move the extruded product immediately into a

vacuum chamber. That process keeps the free foam expansion from taking place and instead

yields a hard crust on the surface and softer material inside. This Celuka process is often used

to produce products that have to meet tight standards on size variations.

3. Cool What's Produced

The extruded product has the right shape but is still so hot it's barely stiffer than a licorice

whip. Stiffness comes as the product cools. Most

manufacturers do this by spraying water on the product as

it's pulled down the line, but it's a fine art; a misdirected

spray can cause unreached sections to bulge. At least one

manufacturer cools its decking with air alone, sending the

product on a circuitous trip up and down several adjacent

lanes, like going through an airport security line. Another

applies giant cooling wheels to each side of the product.

By this point, manufacturers have a good idea of how the

end product will look. Often they're unhappy; it's not unusual to reject as much as one-eighth

of the output. The discards are set aside to be reground and put back into the mix.

4. Imprint, Treat, Cut, Stack

By now, the product has cooled to the point where its surface can get imprinted with a faux-

wood finish. Typically this is applied with a big

wheel that contains a grain pattern. Depending

on the manufacturer, this pattern can be set up to

repeat after so many feet or–by moving the

board left or right under a wide wheel–can make

the grain on one board in a pallet nearly unique

from others. Here also is where manufacturers

apply more additives, particularly those designed

to keep the product from fading when it is put

out in the sun. After that, the product is reinspected, cut to desired length, and stacked. Often

it's still warm. Problems have been known to crop up if it hasn't been given time to

completely cool before it's put on a truck and heads out the door to you.

PE/PP WPC Profile Extrusion Line

Product Details

Price: $25000.0 - $300000.0 / Set

ExtrudersThe extruder is the heart of the wpc lumber processing system, and the primary purpose of the extruder is to melt the polymer and mix the polymer, wood and additives in a process referred to as compounding. In addition, the extruder conveys the compounded wood-polymer mixture through the die. There are four primary types of extrusion systems used to process wpc lumber. These are the 1) single screw, 2) corotating twin screw, 3) counter -rotating twin screw, and 4) Woodtruder ™. Cost for an extruder can vary from $150,000 for a simple single screw extruder to over $1 million for a complete wood plastic composite lumber extrusion system

Wood Plastic Composite Profile Extruding Machine

Specification:

Finished Products: