Elastomer bearings

The following statements refer to pure rubber products and to rubber products that are combined with other materials. These are

• natural rubber and/or synthetic rubber
• as well as adhesives and solutions

The guidelines refer to storage that is required for longer than 6 months. For storage of less than 6 months, the requirements for the storage room can be applied analogously, as long as the function and appearance are not impaired. However, the general requirements for the storage room must be observed. If the rubber products are stored and treated correctly, their properties remain almost unchanged over a long period of time (several years) .

change in physical properties

If the storage conditions are unfavorable, most rubber products change their physical properties. The consequences can be serious and can even lead to damage that renders the product unusable. Examples of this are:

• excessive hardening,
• softening,
• permanent deformation and
• by peeling,
• cracks or
• other surface damage

Influencing factors are:

• oxygen and ozone,
• Warmth,
• Light,
• Moisture,
• solvent
• storage under tension

Requirements

• storage room

The storage room should be cool, dry, dust-free and moderately ventilated.

• temperature

The storage temperature should be +15°C and must not exceed +25°C. Failure to comply can lead to a change in the physical properties or shorten the service life. The storage temperature should also not be below -10°C . Lower temperatures are generally not harmful to rubber products, but they can become very stiff at lower temperatures. Highly cooled products should be brought to a temperature of over +20°C for a longer period of time before being put into operation. Products made of chloroprene rubber types should not be stored at temperatures below +12°C.
Rubber products should remain in storage for as short a time as possible. For long-term storage, care must be taken to ensure that new products are stored separately from those already in stock. At this point we refer to DIN 9088 (aerospace guidelines for the permissible storage times of elastomer products).

• Heating

If the storage room is heated, radiators and pipes must be shielded. The temperature of the stored items should not exceed +25 °C. The distance between the radiator and the stored goods must be at least 1 m.

• moisture

Rubber products are not suitable for storage in damp rooms. Condensation should not occur. The most favorable relative humidity is below 65%.

• lighting

The influence of light should be avoided. This applies in particular to direct sunlight and intense artificial light with a high UV content. For this reason, the windows of the storage rooms should be given a red or orange (not blue) protective coating. All light sources that emit ultraviolet rays, such as openly installed fluorescent tubes, have a damaging effect. The reason for this is the associated formation of ozone. Room lighting with normal light bulbs is preferable.

• oxygen and ozone

Rubber products should be protected from air changes, especially draughts. This can be done by wrapping them, storing them in airtight containers or other measures. The instructions apply in particular to articles with a large surface area in relation to their volume, for example rubberized materials or cellular articles.

Ozone is particularly harmful. For this reason, the storage rooms must not contain any ozone-generating devices, such as fluorescent light sources, mercury vapor lamps, electric motors or other devices that can generate sparks or other electrical discharges. Please remove combustion gases and vapors that can lead to the formation of ozone through photochemical processes.

Solvents, fuels, lubricants, chemicals, acids, disinfectants, etc. must not be stored in the storage room. Rubber solutions must be stored in a special room. Official regulations on the storage and transport of flammable liquids must be observed.

• deformations

Rubber products must be stored without tension, ie without pulling, pressure or other deformations. Otherwise, tensions can encourage permanent deformation and the formation of cracks. Certain metals, particularly copper and manganese, have a damaging effect on rubber products. Rubber products must therefore not be stored in contact with these metals, but must be protected by packaging or by covering them with a layer, eg paper or polyethylene.

The materials used for containers, packaging and covering must not contain any components that are harmful to rubber products, such as copper or copper-containing alloys, petrol, oil and the like.

No films containing plasticizers may be used in the packaging. If rubber products are powdered, the powder must not contain any components that could damage rubber products. Talcum powder, whiting, fine-grained mica powder and rice starch are suitable for powdering.

Contact between products made of rubber of different compositions should be avoided. This applies in particular to products made of rubber of different colours.

• cleaning and maintenance

Rubber products can be cleaned with soap and warm water. The cleaned items should be dried at room temperature. Products cleaned with water must be dried completely immediately. We recommend using a dry, soft cloth or storing them for a short time in a dry environment at around +23 °C. Drying with a radiator, hair dryer or other heat sources will damage the sealing and guide elements.

After a longer period of storage (6 to 8 months), the products can be cleaned with a 1.5% sodium carbonate solution. The residue of the cleaning liquid must be rinsed off with water. The manufacturer recommends effective and particularly gentle cleaning agents.

Solvents such as trichloroethylene, carbon tetrachloride and hydrocarbons must not be used for cleaning. Sharp-edged objects, wire brushes, sandpaper, etc. must also not be used.

• Packaging

All materials for containers, covering and wrapping must be free from substances that have a degrading effect on elastomers.

Coated kraft paper, aluminum foil or opaque PE film (min. 0.075 mm thick) can be used as packaging materials.

storage conditions

• The storage temperature must be below 25°C;
• the parts must be stored away from direct heat sources and
• must not be exposed to direct sunlight,
• the relative humidity must be such that no condensation occurs when the temperature in the storage room changes,
• The effects of ozone and ionizing radiation must be fundamentally excluded.

Further extensions may be possible, but only after consultation with the supplier. The supplier carries out appropriate tests and decides whether the products can continue to be used or whether they must be discarded.

Source: German Standards Committee. The most recent edition of the standard sheet in standard A4 format is authoritative.

Synonyms: Elastomeric Storage, Storage Elastomeric Products