Automatisms

Evolution
The impact treatment is linked to some very varied industries and is subjected to their various influences (aerospace science, navy, railway, car industry, nuclear technology, arms, petroleum, chemistry, electronics, etc..). Under the pressure of the economic and technological conditions, the products, the equipments, their implementation, their control and their association with modern means of manufacturing management and quality control, lead to the conception of advanced production means which can be associated with the "C.A.M".(Computer Aided Manufacturing)

Economic factor
The execution time of a treatment is essential, because any excess will lead to an excessive treatment that will damage the quality of the part and will generate an additional cost that cannot be compensated. Likewise, the variation of roughness before treatments such as painting, plating, plasma, electrolysis or sticking can ruin the final result of the treatment. The control of the different variables and in particular the production time factor and the eventual drift of a parameter is thus essential.

Consequences
In order to improve the reliability and the reproductibility of the treatments, it is necessary to reduce as much as possible the influence of the human factor by automating the operations (see charts below). As a consequence, there are numerous optimization works of the known processes, based on mechanisms which move the parts or the jets, and even the combination of the two movements.
The "machine" executes a repetitive cycle. It is possible to control the variables through appropriated sensors that will stop the machine in the case of an anomaly. It is adjustable and it is thus possible to adapt it to various products in a margin of very limited dimensional variations.
The main automatisms of a machine are:
- the programmable automatons,
- the numerical controls,
- the robots.

Programmable automaton

Definition
This is an electronic system which masters the sequences of the different functions of the machines. These automatisms can apply as well to handling as to the parts movements, or the ones of the nozzles or the projection guns.

Uses
This system is well adapted to big series with little variations or frequencies. It is much more flexible than the traditional relieving which it replaced favourably, as well for the first adjustments as for the eventual changes of the running cycle. It requires a programming unit with a specialized language.

Numerical control

Definition
It is similar to the one used with the machine tool and is essential when two movements or more have to be combined, (2 axis or more interpolated) in order to manage the interconnection of the different axis.

Precautions
Even if the numerical control is perfectly adapted to the impact treatment, it requires:
- mechanics with more precise tolerances than the ones usually necessary,
- an operator with a training superior to the one usually met in the workshops,
- a quite long programming made by a specialist.
These factors generate an important total cost, included the interfaces and the manual controls required.

Mechanized rotating hub

Horizontal scanning nozzles

Vertical scanning nozzles

Robots

Definition
It is used when the parts to treat have a very complex configuration requiring the coordination of a variable movement of jet presentation with a shifting movement not linear.

Precautions
The mechanical parts of the robot are bad adapted to the aggressive atmosphere of the projection enclosures.
A specific and necessary protection has to be brought to the robot in order to avoid any quick damaging.
The robots are programmed:
- either through calculations, for works such as shot-peening for which the homogeneity of the treatment is essential,
- or through learning which is particularly adapted to the usual works of surfaces preparation.
The employees using and cleaning the machine have to be very competent.