Vibration Isolation Overview

1. Vibration Isolation Overview • Session 1

2. What is Isolation? • A discussion of the terminology of isolation

3. Terminology Often the key to success in a business interaction is to understand the language of the customer. This presentation is intended to provide a basic understanding of the terminology of vibrations, and vibration isolation.

4. Isolation • Keeping the MOVEMENT of one object from affecting another. In this case the movement of the vibrating screen is necessary for its function, but we don’t want that movement to cause damage or long term deterioration to the supporting structure or foundation of the machinery.

5. Isolation Keeping the MOVEMENT of one object from affecting another. In the case of the “optical table”, the purpose is to reduce the effect of floor vibrations on the equipment mounted to the surface of the table. It is the floor that is moving and the table that we want to keep still.

6. A device joining two entities, intended to allow each to remain in its natural state WITHOUT influence from each other NO ISOLATOR IS PERFECT We will discuss the concept of isolation effectiveness later on, but nothing can isolate 100% Isolator

7. Isolation System Representation A system consisting of a mass suspended on an elastic member • An oscillating suspended mass • A suspended static mass to be isolated from a vibrating support structure

8. The force required to deflect a spring a given distance. It is normally expressed as the force needed to deflect a spring one unit length from its equilibrium position. In metricunits that is normallyNewtonsper millimeter. Spring Rate

9. Spring Rate Coil Springs are LINEAR - They have a CONSTANT Spring Rate - calculated by a formula: Air Springs are NONLINEAR - They have a VARIABLE Spring Rate - calculated by a formula: MarshMellows are NONLINEAR - They have a variable Spring Rate determined by test data

10. Spring Rate

11. No Load (0 kg) Height = 57 cm

12. 22,5 tons Height = 38 cm

13. 45 tons Height = 33 cm Load increases by 100% Deflection increases by 13%

14. Active Isolation One that supports and isolates an object by providing motion that counteracts the disturbing motion This requires extremely fast acting actuators, and high gain feedback devices to sense the motion and control the actuators Passive Isolation One that supports and isolates an object without the contribution of any outside energy source Firestone products, and most machinery supporting systems are passive isolators Isolation System types

15. Number of vibrations in a unit of time Usually expressed in Cycles per Minute (CPM) or Cycles per Second (Hz) Frequency

16. Amplitude - The distance from the null (or neutral) point to peak of the motion of an oscillation or vibration Excursion - The peak to peak distance of the oscillation Amplitude & Excursion

17. Amplitude & Excursion The movement of the suspended mass can be an important factor for the customer. It is possible to get very high isolation performance, but the suspended mass would be moving at very high excursions. This can be not only dangerous, but also difficult for the customer to incorporate into his process. The movement is proportional to the ratio of the moving mass to the static mass.

18. Frequency of an oscillating spring-mass system without outside influence A function of spring rate and load Natural Frequency

19. Incoming frequency of disturbing motion Frequency that needs to be isolated Also called excitation or disturbing frequency Forced Frequency

20. Measure of ENERGY passing through an isolator from the vibrating surface to the isolated surface Inverse of ISOLATION Transmissibility & Isolation OK, here we start to talk about isolation effectiveness.

21. When comparing the isolation effectiveness of two isolators, remember to think in terms of transmissibility (don’t get caught thinking about isolation percentage). For example Isolator #1: 95% Isolation (5% Trans.) Isolator #2: 98% Isolation (2% Trans.) Isolator #1 transmits 2 ½ times more energy than #2 Transmissibility Times more transmission

22. Exists when the forced frequency EQUALS the natural frequency ALL of the energy is transmitted into the isolated object TRANSMISSIBILITY approaches infinity ISOLATION approaches 0% Resonance

23. Resonance – Tacoma Narrows Bridge

24. Resonance

25. Resonance Open video from folder

26. NOT THE SAME AS ISOLATION Damping is what SLOWS an oscillating system over time until it comes to rest ISOLATOR: like the springs on your car to reduce amount of vibration energy transmitted to passengers DAMPER: like the shock absorbers on your car to keep it from bouncing after a bump Damping (Not Dampening!)

27. A damping force inherent to a deflected solid object. When a solid is deflected, some of the energy necessary to deflect it becomes heat, which is then not returned in the form of return force, but dissipated into the environment Hysteresis

28. Hysteresis

29. Spring-Mass System A system consisting of a mass suspended on an elastic member • An oscillating suspended mass • A suspended static mass to be isolated from a vibrating support structure

30. High Tech Vibration Isolation Demo

31. A function of spring rate A system becomes UNSTABLE when the lateral forces are greater than the ability of the isolator to return the system to equilibrium Lateral Stability

32. Lateral Stability • When you deflect the bellows laterally at a low height it causes the tension vectors on the side wall to shift as in figure F = instable • When you deflect the bellows laterally at a high height it causes the tension vectors on the side wall to shift as in figure G = stable

33. Always use Airmounts at the Recommended Design Height Triple Convoluted and 1T Style parts are less laterally stable than Single and Double Convoluted parts - please contact Firestone Lateral Stability

34. Tag Line - Firestone Product that provides lateral stability Pages 57-58 MMDM Lateral Stability

35. The End(of this presentation)