21 janvier 2020
High power pneumatic grinders are widely used in the metalworking industries such as foundries, shipyards and heavy machinery fabrication. We know that safety is of utmost importance in these industries. The overspeed shut-off function, a feature available in certain high-power pneumatic grinders, greatly reduces the risk of the grinding wheel from accidentally overspeeding. This is vital, since an overspeed incident can result in a burst disc that can injure the operator – potentially fatally.
Powerful pneumatic grinders have a governor that regulates the air inlet as a function of the speed. When speed increases, the inlet gets smaller to limit it to the maximum speed defined for the tool. This mechanism is developed to work at a certain air pressure; if the air pressure increases significantly, the speed will become too high. This is where the overspeed protection comes in. See it in action:
At the correct pressure, air travels from the air inlet through the motor to the exhaust, without any intervention from the shut-off mechanism. The tool can work at its full effect.
Shut-off system not activated – The air flow is continuous.
If pressure increases heavily and the wheel speed significantly exceeds the maximum speed defined for the tool, the centrifugal force will liberate a steel ball that will block the air inlet. This shuts off the air flow and the tool stops. This happens instantly, in a fraction of a second, before the grinding wheel has the time to reach a speed where it could burst and send fragments into the path of the operator or someone else.
Shut-off system activated – The air flow is interrupted.
IMPORTANT: To restart the tool, you need to carry out maintenance; the steel ball has to be removed from the air flow and put back in its initial position. An actioned shut-off typically signals an abnormality with the air flow, so we highly recommend you perform airline diagnostics and investigate the root cause.
The overspeed shut-off is there to protect you as an extra security on powerful grinders. If it goes off, you need to investigate why and correct any malfunctions in your airline
The shut-off function design varies between products and it may be slightly different to the example presented above.
7 décembre 2020
Coin des experts Meuleuses Travail des métaux Coin des experts
Le prix est un élément important lors du choix d'un outil pour les applications de métallurgie, mais il ne devrait pas être le seul facteur de décision. D'autres éléments contribuent également au coût total d'exploitation, aux performances et, en...
24 août 2020
Clés à chocs Outils Sécurité Travail des métaux Coin des experts
Grâce à son coût relativement faible et à sa composition robuste, l'acier continue de rivaliser avec les matériaux alternatifs dans les applications où la rentabilité est plus importante que la réduction maximale du poids. Toutefois, avec une densité...
27 juillet 2020
Outils Sécurité Meuleuses Travail des métaux Accessoires Dispositif d'auto-équilibrage Coin des experts
L'outil que vous utilisez peut jouer un rôle important dans la réussite d'un travail de métallurgie. C'est pour cela que les responsables doivent faire particulièrement attention lors de la spécification des outils pneumatiques, afin de garantir...
Download our free technical guide
Join our mailing list
We love hearing from you! Please send us your questions, feedback or topic suggestions. Your submissions are greatly appreciated.
