All industrial machines, regardless of their type, must be properly insulated. Insulating a machine means protect all its components from the vibration-emitting element (motor, compressor, pump, etc) and other elements or machines that are located around it. To achieve this, the designer must take into account the location of the elements that will prevent the passage of mechanical waves to the rest of the equipment, thus avoiding possible damage to machines, people and products.
Index
Determining factors in vibration isolation
The factors that determine which element we should install are:
- Machine geometry.
- Number of supports.
- Weight and center of gravity.
- Work performed by the machine (produces radial, axial, shear and torsional forces).
- Working environment; i.e., atmospheric conditions and available space.
In this article we are going to focus on the vibration isolation in machine tools, One of the types of machinery that emits the most vibrations. They operate pneumatically or hydraulically; and each of the actuators, motors, pumps and the tool itself, when forming parts, produce a series of vibrations that must be isolated.
Types of vibration isolation on machine tools
We distinguish between two groups:
Vibration isolation from the machine to the ground
One of the elements that must be taken into account in the contact of the machine with the ground is the machine foot, an element that can be found in various materials. For heavy machinery, the most common and recommended is the steel foot with a vulcanized elastomer element. The steel allows very high loads working in compression and the elastomer, normally NR (natural rubber) or NBR (nitrile rubber), is in charge of avoiding the passage of mechanical waves from the machine to the floor.
Other widely used elements are the “V Lager” and the “Machine Lager. The “V Lager”, or V-shaped supports., The vibration isolators are used to isolate vibrations in very heavy elements (from 50 to 3200 Kg in axial load). They consist of a metal cap protecting the elastomer part and are very easy to install due to their shape. Available rubber hardnesses range from 40 to 65 Shore.
The “Machine Lager” , or rectangular support for machines., isolate heavy weight elements (from 140 to 1600 Kg in axial or compression load). The possibility of resisting the combination of compression loads and shear loads of these supports allows very good performance and provides a long service life to the element under these conditions. The installation of this type of element is very simple since it has holes and threads that allow it to be fixed to the floor and to the machine. Available hardnesses range from 45 to 70 Shore.
Isolation of components within the same machine
For example, it is the case of the isolation of the pump or motor with the other components that make up the machine, whether electronic or mechanical. There is a wide range of vibration isolation elements.
The most common are brackets or “mounts” where, depending on the geometry or the space available to mount them, we can install three types:
- Type A (male/male)
- Type B (male/female)
- Type C (female/female)
Depending on the hardness of the elastomer (normally 45 and 60 Shore), the intensity and direction of the load, we will have maximum admissible loads. In this case the maximum admissible load can be given at axial level.
For the isolation of the vibration generating elements with the instrumentation contained in the machine (electronics, tools, etc.), we can also use “O-shaped brackets” , The rubber ring is connected to plates with fastening screws. This design allows isolation of suspension oscillations in the low-frequency and low-load range. This is often the case in instrumentation and measuring devices.
These mounts have different spring characteristics in the three possible directions of deformation, so it is necessary to study which direction is optimal to isolate vibration correctly. They are available in NR from 40 to 60 Shore.
It is essential to ensure the quality of these elements, which will be decisive for the proper operation of the machine. In addition, they help to avoid possible problems in production, which, if they occur, could result in significant losses for our customers.
In addition to having many other standard solutions for the vibration isolation, at Epidor SRT we have the option to manufacture on request, if you provide us with the appropriate information (application, specifications, stress/deflection diagrams, etc).