Sheet Metal Shaping Department – Press Shop
The production process begins in the Sheet Metal Shaping Department. Sheet metal arrives at the plant in coils. On the cutting line, it is cut into plates of various sizes which are given their final shape on presses by using different dies for each type of component and by performing different operations such as pulling, trimming and piercing. Between individual operations, the plates are moved manually, automatically by mechanical hands and by transport conveyor, or by robots.
A new line of extra large presses, entirely robotised, is an important technological improvement. It produces the most demanding external parts of the car body (body sides, bonnet, doors etc), die change is completely automatic and it takes only 6 to 8 minutes. Pressings are produced in pairs (left and right part) by one stroke.
There are also two lines for injection of plastic wings which are made of a granulated substance heated to 300°C and injected into a special mould at 350 bar.
Assembly and Welding Department – Body Shop
The pressings are transferred to the Assembly and Welding Department – the Body Shop, where geometry and the initial shape of the vehicle are determined. The latest technological acquisition is a new robotised measuring of body geometry by means of laser scanners. In a sequence of several automated operations of assembly and welding, the pressings are first assembled to sub-assemblies (front unit, central and rear unit, body sides). All components are inserted into assembling jigs pneumatically and then welded together manually or automatically by resistance welding, arc spot welding and laser welding. Between assembly stations, sub-assemblies and assemblies are moved manually, by manipulators and by ground and hanging conveyors. Sub-assemblies are welded together and the body of the vehicle is then transferred to robotized welding of the body and the roof. Laser brazing of the roof of the new Twingo is realized by two lasers in a robotized cell. Opening elements (doors, bonnet) and wings are set in. The bodies are then equipped with spacers and hangers and sent for paint shop pre-treatment by means of hanging conveyors.
Paint Shop Department
The procedure is carried out in three stages:
metal sheet preparation and cataphoresis, mastic application and varnishing.
The investment into the new line of surface pre-treatment provided Revoz with a 12-year anti-corrosion warranty, unleaded cataphoresis, increased capacity and environment indicators' improvement, especially releases into the air. Pre-treatment in 8 steps, composed of pre-degreasing, degreasing 1 and 2, cold water rinsing with industrial water, activation, phosphatation, cold water rinsing and bathing in demineralised water, represents basic anti-corrosion protection. After the sheet metal is cleaned in baths, application of crystallization cores on the sheet metal is performed which allows a homogeneous formation of a phosphate layer.
Then the body is dipped into a 120 m3 bath where cataphoresis varnish composed of pigmented paint, bonding and solvent, is applied by means of electric current. The body is then dried at 180°C.
Follows application of mastic in six steps: masking the underbody, application of mastic to the joints of the underbody by pressing and jetting, protection of the underbody with anti-gritting paste, demasking, application of mastic to particular joints in the interior, soundproofing and application of mastic to all exterior joints.
The body is then sent to the surface treatment workshop. Several coats of basecoat are necessary to obtain the right colour, gloss and permanence. The bodies are first cleaned with resinous cloth and blow dried. Next comes the electrostatic application of sealer by automatic machine. Sealer in three different shades is dried for 15 minutes at 150° C.
The interior is varnished manually, the exterior is varnished in two coats by automatic machines. The first coat of basecoat is applied by an automatic electrostatic machine. The second coat of metallic shades is applied by robots. The transparent top coat is applied manually in the interior and by means of an automatic electrostatic machine on the outside of the body. Then follows automatic varnishing of the side sills with black varnish. The bodies are then dried for 15 minutes at 140° C. Next comes checking and polishing and finally protection of hollow parts of the vehicle by waxing.
The Assembly Shop starts at the exit of the painted body shell depot – here the car interior is decorated and the steering and the driving systems are installed. Some elements of the brake system are manufactured in the Mechanic Treatment Workshop where front and rear axles are assembled as well. The body shells are placed on the conveyor belt, followed by the installation of the wiring on the trunk lid. The side doors are taken off in order to facilitate access to the interior. Hangers shift the doors to a sideline where all the fittings are attached. Next comes vehicle numbering, ceiling assembly, installations, sound insulation, etc. The dashboard is assembled on the sideline and then fitted into the car as a whole. Then the carpets, cabin lights, handles, sun visors and other parts are put in. The application of mastic on the windscreen and rear window is carried out by a robot. Body shells are put on hangers and continue on a hanging conveyor. Gearboxes and engines are completely assembled on a side line and then installed as a whole. Then follows the assembly of the exhaust systems, axles, lights, safety belts, bumpers, seats, side windows, side doors, wheels, steering wheel, grille screens etc. The vehicles are then positioned on the ground conveyor where radios are installed, brake fluid is added and cooling systems are filled. After that, the engine is started, wheels are aligned, headlights are adjusted, roller testing is performed and protection is applied to the body understructure. A new testing lane built for testing the new Twingo is designed for road-testing of vehicles, while waterproofing tests are performed in a special cabin.