Advantage 1: AluSPATZ+ makes RSW a capable and reliable process for joining aluminium sheets
Reproducible joining quality of 2- and 3-sheet combinations of e.g. aluminium material class AA 5xxx and AA 6xxx with single sheet thicknesses from 0.8 mm to 3.0 mm realized by
- AluMASTER: particularly for RSW of aluminium developed adaptive weld control mode for compensation of the following process variations:
- Shunt effects
Due to the higher electrical conductivity of aluminium compared to steel the disturbing influence of current shunts is even severer.
- Gaps between sheets
- Surface quality of the aluminium sheets
(lubricants, surface scratches! distribution and thickness of aluminium oxide etc.)
- Variations in application thicknesses of adhesives and sealers
- Wrong weld gun equalization, wrong position of electrodes to the sheets when welding
- NuggetIndex and GUNIndex spot and weld gun supervision for RSW of aluminium. Well known from RSW steel adapted to the needs of aluminium.
- CapClean "Electrode management system"
For the demands of aluminium spot welding optimized electrode treatment: cleaning and reshaping of the electrode surface
Advantage 2: Speed
- Application of weld schedules containing short weld times, depending on total gauge of the sheet stackups: 60 ms - 300 ms
- Combined control of weld current and gun & electrode movement in one device allows the utilization of hard- and software that can be optimized for
The result is short cycle times combined with optimum spot quality.
- combined control of weld electrode (main actuator) and fix electrode (gun equalization actuator) movement offering fast gun closing paired with soft touch of electrodes on sheet
- fast buildup of weld force
- real time force control during weld
Time needed for a complete welding operation of a 2-sheet combination 2x 2.5 mm AC600 including electrode travel from/to 80 mm opening stroke = approx. 1.1 seconds.
Advantage 3: Flexibility of RSW
2- and 3-sheet combinations of e.g. material classes AA 5xxx and AA 6xxx with single sheet thicknesses from 0.8 mm to 3.0 mm can be reliably spot welded in automated serial production with one weld gun equipped with one electrode cap geometry only, independent from
- sheet sequence in the sheet stack up
- orientation of the stack up to the moving electrode (weld current direction)!
This flexibility results in a significant reduction of needed equipment for the joining process and floor space in comparison to the application of mechanical joining methods. Thus, for the same output less equipment and floor space is needed.
Advantage 4: High availability
Due to the fact that the AluSPATZ+ spot weld equipment is just a "simple" spot welding system as known from spot welding steel it is principally characterized by a higher grade of availability compared to mechanical joining methods or spot welding equipment using additional material and hardware, e.g. for prevention of direct contact between copper electrodes and aluminium sheets.
The availability of AluSPATZ+ when spot welding aluminium is the same as for spot welding of steel, just providing higher electrode life times.
No additional feeding or other guiding equipment is needed on the weld gun. For the same output less equipment and floor space is needed!
Advantage 5: Low cost joining method
The costs for a welded joint connection of aluminium sheets are basically the costs for the weld energy! The energy needed for joining e.g. the 2-sheet combination of 3.0 mm AA 5754 + 2.5 mm AA 6082 is about 30 KWs per weld joint. Provided a rate of 0.08 € per KWh this corresponds to a cost of 0.0008 € per weld spot.
Secondary costs are the costs for the consumables only, which are the electrodes and the cleaning wheels. The life time of a pair of electrodes when applying AluSPATZ+ equipment is about 10,000 weld spots. Life time of a cleaning wheel is > 250,000 weld spots.
The energy costs for the spot welded joints in an aluminium body of a car model with a production volume of 200,000 cars per year and 4,000 spot welded joints per car are 640,000 € per year.
Whereas in case riveting would be selected as joining method instead of spot welding the costs for the rivets only for the same car model would be 20,000,000 € per year, based on a price of 0.025 € per rivet. That is about 30 times higher costs compared to RSW.
Summary: The AluSPATZ+ equipment ensures reliably good joining quality in serial production paired with short cycle times and very low production costs!