Shotpeening installations
The shot peening process is based on the effect of introducing compressive stresses in the surface of a metal part by controlled impinging with spherical particles. By this the resistance against fatigue will be increased and therefore also the life of a part.
In the space and aircraft-industries the advantages of the shot peening process are already known: the increase of the fatigue-life of critical parts without weight increase. The designers who used shot peening in applications where the effects of fatigue were caused by grinding, electrical discharge- and electrochemical-machining (EDM and ECM), electroplating, anodising, thermal spraying and welding. It also can help increase resistance to fretting, galling, caviation erosion, stress-corrosion cracking, intergranulair corrosion and hydrogen-embrittlement.
In the Netherlands Straaltechniek International was spezialised in the general blast technologies for cleaning, roughening and activating surfaces. This way, Straaltechniek International was able to encounter demands of the industry in the early 80's for the shot peening process.
To control the shoot peening process, one needs the very precision of the shot peening parameters. Straaltechniek International started with the development of precise controlled parameters:
- shotsize
- shot material and shot shape
- shot velocity and shot flowrate
- aiming of the nozzles (distance and angle)
- shot peening time
These parameters determine the intensity (indication for compressive stress) and the coverage (indication for effectively impinging the complete surface).
Straaltechniek International shows its capability to precisely control, monitor and record the critical shot peening parameters.
- shotsize - by changing the shot-particle size (at the same velocity) the energy-content of the particles changes, so keeping the shotsize constant is essential for the result. Straaltechniek International controls the size of the shot by: variation-sieves, air-curtains and centrifugal exhaust systems (cyclones).
- shot material and shot-shape -Straaltechniek International provides 5 types of shot: cast--steel-shot, glass-bead, ceramic - bead, cut-wire-steel-shot and stainless-steel-cut-wire-shot. The spherical shape of the shot has to be controlled and maintained (broken shot, hollow shot, shot with sharp edges and two particles connected to each are not allowed). Double spiral separators can be used in combination with sieves.
Straaltechniek International is exclusive retailer of shot media manufacturers which means that special contracts can be made for stock and deliveries of shotmedia.
- shot velocity and shot flowrate - the impact-energy depends greatly of the shot-velocity. The shot-velocity is being controlled by the air - pressure, which is controlled and monitored continuously. The shot flowrate determines the coverage in a certain time-frame.
- aiming of the nozzles - the distance and the angle of the nozzle to the part-surface is very important, because variation of both parameters give variation in shot-spreading and therefore different coverages, which decrease the reliability of the Saturation-curve. STRAALTECHNIEK INTERNATIONAL supplies control aiming the nozzles by using PLC or CNC controlled robots, which guarantee distances and angles whereby it also is possible the shot peen parts according a programme stored in memory.
- shot peening time - controlled in order to determine the saturation point. In PLC and CNC-systems time-devices are part of the system.