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Prodding the button on the left should give you a site map. I'd be interested in knowing how well it works and what you think of it.
This is the home for all the bits that don't fit elsewhere.
Heatshrink Sleeving
This material has been common in aerospace and commercial use for many years. It is an irradiated Polyolefin (or Kynar for
hight temperature applications) which shrinks in one plane only (its diameter) when heated. Its main use is in providing both mechanical and environmental protection for joints and connectors. The most common material is
irradiated polyolefin and this is available in a variety of temperature ratings and with or without an adhesive lining. The adhesive lined version has an inner coating of polyethylene which melts at a slightly lower
temperature than the shrink temperatutre and flows as the sleeve contracts to encapsulate the joint and form a flexible warteproof seal.
The conventional sleeving simple shrinks onto the cable and the joint is not guaranteed to be water resistant. For normal connections where strain relief or physical protection is needed the standard heatshrink is fine. If
a joint is to be used outdoors in all weathers the adhesive lined should be used. If a material is required which withstands higher temperatures and aggresive chemicals then Polyvinylidene (Kevlar) can be used although its
shrink ratio isn't normally quite as good as polyolefin and it requires a higher shrink temperature.
Polyolefin heatshrink with a shrink ratio of 3:1. The left hand side has been shrunk and the decrease in diameter and increase in wall thickness can be seen.
Shrink Temperature 150°C |
The same material as in the picture above used to provide weather protection and strain relief on a crimped FME connector. |
Adhesive lined heatshrink - the polyethylene adhesive lining can be seen clearly on the shrunken section on the right and the enlarged section below it. |
Heatshrink is great for most assembly applications but there are occasions in the field where it can't be used or where an existing complex shape must be
environmentally protected. Examples include mast head fittings to antennae where the plug and socket must be shielded from the elements. In such situations standard PVC sticky tape rarely works well and degrades rapidly in
sunshine and extremes of temperature. Self amalgamating tape is a polyisobutylene tape which has no adhesive but over a period of hours adheres to itself and forms a single amalgamated rubber moulding conforming to the shape
of the items it is covering. It is essential that it is completely dry when used but beyond that is safe on any material. It does not adhere to the substarte so can be cut away with a sharp knife if access is required
later. Once in place for more than about 30 minutes it cannot be unwrapped but must be cut away.
On the left you wiil find a stunning illustration of a reel of tape. Below it a connector before and after wrapping. The ability of the tape to
conform to complex shapes is obvious and far better than PVC tape. Once left for a few hours the tape bonds to itself to form a shaped rubber moulding resistant to water and most solvents. It remains
stable over a wide temperature range and degrades only very slowly (several years) in sunlight. |
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