Toyota
Ford Kuga
 Service Manual
Body Repairs - General Information » Plastic Repairs
Plastic welding

Splits formed in plastic bumpers are typical possible plastic repairs.

NOTE: Do not carry out plastic welding in the area of fixed foam backing. The foam backing will usually be destroyed and the function of the component is then no longer guaranteed.

If repair using adhesive methods is not possible because of unfavorable conditions at the rear of the repair location, plastic welding is a possible repair process.

There are two methods of welding: hot air draw welding and hot air fanning welding.

Plastic welding set

Plastic welding set

Item Description
1 Various welding rods
2 Scraper (heart-shaped)
3 Hot air blower (approx. 1500 W)
4 Clamps
5 Welding nozzles

In addition to the components listed, plastic welding requires tools already found in the workshop such as scrapers, sanders, face cutters etc.

As with all other welding processes, only certain material combinations can be joined together using plastic welding.

NOTE: Basic and in-depth training is offered on the following topics. You will find an overview of the complete range listed in the Training brochure published by the Ford Service Organization.

NOTE: The manufacturer's data must be taken into account when choosing welding materials and the correct temperature setting of the hot air gun.

Repair sequence during plastic welding:

  • To prepare the location for welding, remove paint residues and sand the weld area.
  • If parts of the material have been pushed in by an impact, the damaged area can be brought back to shape by heating.
  • Drill out the ends of the split to stop it spreading further. Machine the location of the weld into a 90 V-shaped groove, to accept the welding rod.
  • Lay the welding rod in the groove
  • Perform the welding. Hot air draw welding or hot air fanning welding.
  • Rework the weld seam. After cooling, sand the raised weld seam.
  • Clean the sanded repair surface using plastic cleaner. Apply plastic primer thinly to the repair surface and paint it.

Despite good preparation and the correct choice of welding materials, weld faults may occur.

The following points must be noted when welding plastic:

Weld together like with like:

  • With very few exceptions, only the same materials can be welded together, e.g. PP with PP.

Correct temperature:

  • The correct choice of temperature is important for the success of the repair. The plastic must be warmed until it plasticizes (dough-like, soft).

Guideline values for welding temperature:

Brief description Plastic Temperat ure
ABS Acrylonitrile butadiene styrene copolymer 360
PA Polyamide 400
PC Polycarbonate 370
PP Polypropylene 280
PP/EPDM Polypropylene/ethylene propylene diene copolymer 280
PUR Polyurethane 300
Hard PVC Polyvinylchloride 340
Soft PVC Polyvinylchloride 370
  • Even pressure:

When rod welding, the pressure is applied by pressing on the welding rod.

  • Steady speed:

To achieve a good weld, care must be taken that the working speed is steady.

Possible causes of weld faults:

  • Deformation caused by overheating of the repair area or tensions in the material while welding the component.
  • Plastic material too thin.
  • Poor weld joint because the weld temperature was too low or the welding speed was too fast.
  • Welding different materials together.
  • Weld seam dropped because the split gap was too wide or the welding temperature was too high.

A good weld is recognized by a slightly raised, smooth and even weld bead on the surface of the component.

The weld bead must only be worked once it has fully cooled down.

    More about «Plastic Repairs»:

    General

    Plastic identification

    Safety instructions

    Plastic welding

    Plastic adhesive bonding

    GRP repairs

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