Forch 4916 2 Mode D'emploi page 9

Plastic Repair Set /
Welding Procedure
Operation Instruction
Identification of the plastic type
The colour itself does not give any
information about different plastics
because the manufacturer can dye the
parts of his own choice. By and by you will
gain the experience in this field. Search for
an ISO-code in the inside of the part (e. g.
PC for polycarbonate) or do a test welding
as described below. Weldings only retain if
a welding addition of the same kind will be
used. Many plastic types recur at certain
parts such as (nonbinding):
Modelling: aeroplane, car, building PS
Truck and tractor, mudguard, air-induction pipe
Trailer mudhuard PE
Boats if they are not made of GRP (glass reinforced plastic): Canadian, kayaks,
pedal boat PE PP
Rainwater tanks PE, PP
Hoover housing PE
Mower PP
Mobiles ABS/PC
Ski coverings PE
At automotives:
Bumpers, made in Japan or Europe PP
Bumpers Ford PC
Bumpers made in USA PUR
Body parts, instrument panels PUR or PP (body Smart PA)
Mudguard, louvre, new one often ABS
Washing water reservoir PE; Door Seal, if not made of rubber TPE
Testing of the material type:
Normally plastics can only be combined thermally with the same kind of material.
In case of doubt a welding test can immediately be done to find out the material type:
The following table also helps you to identify the plastic types in the range of automotives
and motorcycles and the use of the common mass plastics:
Table about the application of common plastics at automotives and motorcycles
Louvre
Alfa Romeo PP, PUR
Audi
BMW
Cadillac
Chevrolet ABS
Chrysler ABS
Citroen
Daihatsu
Fiat
Ford ABS
Honda ABS
Hyundai
Jeep
Lancia
Landrover
Lexus ABS
Mazda ABS
Mercedes
Mitsubishi
Nissan ABS
Opel
Peugeot
Pontiac
Renault
Rover
Seat
Skoda
Subaru
Toyota ABS
Volvo
VW
Motorcycles PC, ABS
(non-binding):
Cut off a thin particle from the part to be repaired at a hidden position and use it as a "wel-
ding wire", is also possible:
But act with caution at unknown plastics: Fire and toxication danger!
Overview about some plastic types and max. working temperatures
Short Description Name max.
PC Polycarbonate
PE Polyethylene
ABS Acro-Nitrile Butadiene Styrene
ABS/PC (Mix-Polymer)
PP Polypropylene
PP-flex Polypropylene soft
TPE Thermoplastic Elastomer
PS Polystyrene
Art. No. 4916
Bumper Outside Parts
PP
PP
PC PC
PA,PC
PP
PP
PP
PP, PC
PP, PC ABS, PC
PP, PC
PP
PC
PP, PC ABS, PC
PP, PC ABS, PC
PP, PC
PP
PP ABS, PA
PP, PC
PP
PP
PP, PC
PP
PP
PP
PUR, PP ABS, PC
PP
PP
ABS
Working temperature
290 °C
275 °C
265°C
280 °C
275 °C
270 °C
270 °C
265 °C
Danger of health at too high temperatures: In case of smoke emission stop the work
and try to carry on with lower temperature. Only work in ventilated areas and do not
breath in steams! The work with plastics demands patience. The parts have to be warmed
up, fused and processed at low temperature. At too high temperature the
molecules of the plastics will be damaged. They change their colour and the durability will
be shortened. Other than the processing of hardened materials such as filler or filling com-
pounds out of tubes you do not have pressure of time like the process within the "potlife".
Normally you can fuse and reapply thermaplastic plastics long enough. Always practise
the welding technique on a wastage or inconspicuous part before processing at the real
welding part.
Preparatory Workings
The total repair technique is applied from the outside which means that the part to be
treated has not to be demounted and cracking edges have not to be drilled. Clean the part
to be treated intensively and lubricate it with grease if necessary. At coated parts remove
(grind) the colour coating mechanically and spaciously until the real plastic
surface is given. In case of deformation of the repairing part heat up the defect position
carefully (hot-air gun, infrared radiator) and press it to the original form with the support of
a teflon or wooden block. Let the part cool down. Choose the plastic type according to the
assortment of the welding wires. Many parts have a manufacturer-stamp on which the
used plastic is performed. Should there still be any doubt concerning the plastic type, do a
welding test: Weld on a material graft at an inconspicuous part next to the position to be
treated (see below). Make sure to heat up the underground sufficiently and that the wel-
ding wire has the beginning melting temperature before you press on the welding wire
through the lead.
Repair of scratchings
Set up the melting temperature according to the applied plastic type at the controller.
As soon as the welding piston achieves the adjusted temperature (blinking of the control
lamp), smooth the surface bit by bit with the holohedral piston foot. Hold the welding
piston like a pen in the hand. Slightly press it on.
Too much power damages the welding piston and is unnecessary: the material has to be
heated up sufficiently to fuse. Insert the welding wire and wait for a short time until it is
fused. Afterwards continuously insert the welding wire through the lead without lifting off
the piston foot. Please note that the fresh material will be put onto a fused surface to
achieve a melting effect. If the surface is too cold (tight) there will not be achieved a
melting. It is necessary to bring meltings to meltings! Carry on with the process until
enough material is fused. The total repair surface has to be filled up at least 1 – 2 mm hig-
her than the finishing surface (shrinkage when cooling down). Afterwards roughly smooth
the surface without material addition and let the part cool down.
1. Hold the welding piston like a pen in the hand.
2. Only apply low pressure.
3. Heat up the material with the welding top and let it fuse.
Inside Parts
4. Insert the welding wire, let it fuse. Attention: hot welding piston.
5. Push out the residues with the repressing piston.
The repaired position will be ground back as usual. For further treatment of the surface
at uncoated parts: see corresponding section. After grinding the coated parts (depending
on the material type (as necessary after flame treatment or treatment with the a
corresponding primer) can be coated. At uncoated parts the structure can be recreated
with a structure spray or colouring can be adjusted matt with a plastic paint.
Repair of crack formations and holes
If the treated part is cracked then first fix the short spot-welding with the front side of the
welding top with distances from approx. 2-5 mm (such as sewing: prick+smooth-prick
ABS
+smooth etc. If the working process of the assembly part can be done from both sides
a relatively solid compound can already be achieved due to this simple procedure.
If the working process can be done only from one side a solid compound would not be
achieved but a further anti-skid treatment of the parts is given. For further treatment cut
off a suitable piece of the armour net by using the scissors and put it on the crack. The
ABS
armour net should stand over at least 7 mm at all sides. Partly fix (attach) the armour net
ABS
on the surface with flat tipped welding top. Therafter start to counterbore the armour net
at one spot into the material with the welding top (without pressure).
If the armour net visibly counterbores due to fusing of the assembly part on the surface
ABS
pull back the foot 2-3 mm and repeat the process once more. Push the creeping out
material with the welding top into the still hot pre-treated spot so that the first
counterbored armour net is now covered. Repeat this process as long as fabric is
counterbored holohedral and sufficiently under the subsequent surface to be treated. Fix
the edges with the welding top with distances from approx. 2-5 mm. Repeat the
counterboring and smoothing over the length of the crack. Cut the armour net into a
standing over of approx. 7 mm. Counterbore the armour net with the top into the material.
PP
The fabric has to counterbored under the surface. This requires patience. The plastic
needs a certain time to fuse. Do not work with pressure or violence!
ABS
1. Hold the welding piston like a pen.
2. Only apply with low pressure. Patience!
3. Work the fabric into the surface of the assembly part. The centrical you work in the
armour net the higher will be the strength of the repair spot.
There can also be fused several plies of armour nets if necessary. The armour net must
not be visible in working condition. Especially the edges of the armour net have to be
embedded in the material of the assembly part. Afterwards insert the welding wire and
proceed working such as the scratching repair. When processing holes the armour net
has to be put on centrical on the hole as described above and has to be worked into the
assembly part and be covered with fresh material from both sides.