Vetus Poly-wood Instructions D'installation page 10

1.7 Expansion and contraction
Poly-wood differ from wood because it react more to tempera-
ture change. Poly-wood contracts and expands at the rate of
2 . 10
-4 m/m/˚C. This interprets into changing approximately
3 mm in size for every linear meter of length or width over a
15˚C temperature range.
Drilling oversized holes for screws or fasteners prevents pro-
blems. If oversized holes are not used, Poly-wood installed in
low temperature may bow when it warms. Poly-wood installed
at warm temperatures may crack when cooled and fasteners
may bend or sheer.
1.8 Structural capabilities
Poly-wood is not a structural material. When using Poly-wood, it
must be supported by a load bearing framework or rigid shell
such as a fiberglass hull.
Poly-wood is a plastic, and like all plastics, it will cold flow
(change shape as a result of gravity, over time).
Using Poly-wood means less waste because there is no grain
like wood. Parts can be cut from any part of the sheet, in any
position, getting the most out of every sheet.
1.9 Finishing
Poly-wood textured finish (on both sides) resists scuffing and
scratching.
1.9.1 Protecting the finish
Poly-wood is shipped with a protective masking on one side to
protect its finish during shipping, cutting and machining. It is
suggested that it remain on the product for as long as possible
during fabrication. To further protect your sheets we encourage
you to mask the other side when you receive them.
1.9.2 Stains
Poly-wood is resistant to most stains. However, Poly-wood can
be stained by some materials.
The most common problem is with teak oil. Teak oil can cause
permanent stains when it comes in contact with Poly-wood.
When marking the Poly-wood, use China markers or wax pen-
sils that wipe off easily. Do not use pencils, pens or magic mark-
ers which can leave a permanent discoloration.
1.9.3 Marking the masking
If you should find it necessary to write on the masking, for
identification purposes, you may use a grease pencil or certain
felt tip markers.
1.9.4 Storing the material
The product should be stored flat or if necessary inclined (fully
supported) at no more than a 10˚ angle.
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11.0705
2 Machining methods
2.1 General instructions
Thermoplastics can be given a machine finish with all known
tools used in wood and metal processing.
The normal machining operation becomes one of friction and
deformation, with most of the energy finally converted into heat.
Metals are generally good thermoconductors. Thermoplastics
are approx. 100 to 1000 times less thermoconductive than steel.
Where there is a large amount of machining to be done, it is
advisable to work at high cutting speeds and law depth.
Parameters such as tool size, feed, cut and input speed shall be
selected to remove heat produced with the chip.
Deeper cuts should be tooled so that the materiaI does not
smear or melt. Cooling can be provided by means of com-
pressed air or emulsions. Exceptionally smooth surfaces and
finished parts with high tolerance specifications must be cooled
during machining.
2.2 Stresses in semi-finished products
Semi-finished plastic products produced by extrusion or press-
ing have varying levels of internaI stress. Such stresses are usu-
ally caused by the process, not external forces. Semi-finished
products which are straight, flat and within tolerance will bal-
ance stress. Mechanical processing disturbs this equilibrium
and can distort the part concerned.
2.3 Machining technology
Nearly all high speed tools used in the timber and metal indus-
tries are able to machine our materials. Efficient removel of
swarf is essential to prevent build up of heat in the machining
zone. Any heat produced should be removed together with the
swarf. Swarf removaI is possible by rinsing with coolant, vacu-
uming or both. Using a coolant has a positive effectt on the sur-
face quality achieved. Coolants can be used freely with Poly-
wood, as there is no moisture absorption.
Poly-wood