SynChem – Resins & Varnishes WEVOSIL 26040 FL

Material Preparation:

• Pay attention to the FIRST IN - FIRST OUT principle when taking goods from the warehouse.
• The mixing ratio should be checked and documented daily before starting production. It may also be advisable to check the mixing ratio after short breaks in production. The density (dosing of the components via the mixing head) should also be checked.
• The mixing ratio must be exactly as specified in the data sheet. The deviation for silicone potting compounds must not exceed ±1 % in relation to both components (example: with a mixing ratio of 100:100, the “tolerable” deviation is 101:99 to 99:101). Excess crosslinker can react with the moisture in the air, which can lead to the formation of bubbles. Excess polymer component, on the other hand, acts as a plasticizer. A deviation from the ideal mixing ratio with the aim of changing the properties of the molding material is not permitted.
• Bring the goods from the warehouse to the production area in a timely manner so that the product's temperature can adjust - cold material is more viscous, flows poorly = changes in pressure on the system, potential mixing problems.
• Store goods correctly in the production area (not on cold floors or in draughty areas, but on drip trays / pallets)
• Clean the lid before opening the original container (impurities such as wood splinters can otherwise get into the A component and cause blockages in the system)!
• The filler in both components can sediment. The components must therefore be homogenized (stirred) before use. Stirring is carried out with a special stirring unit (e.g. cup or helix stirrer), a drill with stirring attachment or manually with a stick or spatula (no rough wood, splinters could get into the casting compound). Avoid stirring in too much air and thus humidity. The deposited filler must be completely homogenized (especially sediment). Without sufficient homogenization, there will be too much polymer (reactive component) in the upper half of the container and too much filler in the lower half. In this case, over- or under-crosslinking may occur during processing and the resulting cured material will have different mechanical, thermal and electrical properties than those specified in the technical data sheet..
• Even filler-free potting compounds contain small amounts of solids (pigments) that can sediment. Therefore, all potting compounds must be listed before use
• Homogenization should always be carried out before dispensing the casting compound if the last dispensing was not carried out on the same day. Barrel goods must be stirred at intervals in a special barrel stirring and pumping station.
• Both components must always be protected from moisture. Frequent opening of the can/container and repeated homogenization leads to moisture absorption of the components. This moisture damage to the components cannot be detected immediately, but only during or after curing (bubble formation / non-crosslinked areas).
• If necessary, air that has been stirred in after homogenization can be removed in a vacuum. To do this, the components are placed in the storage containers and degassed under vacuum (50 - 100 mbar is sufficient for most casting resins) for approx. 10-20 minutes.

The following also applies to manual processing:

• If the material is to be processed in partial quantities, it is advisable to divide the casting compound into several small dry containers after homogenizing it once.
• After homogenization, the stirred-in air should be removed for 3 - 5 min in a vacuum (50 - 100 mbar). This is particularly recommended for potting compounds with a viscosity above 3000 mPas.

Component Preparation:

• If components are cast, it is advisable to dry them before casting. Drying for 1 - 2 hours at 60 - 80 °C in an oven is sufficient. Every metal or plastic surface has surface moisture at room temperature. This can lead to the formation of bubbles or curing problems during the hardening of the casting resin. For this reason, please carry out preliminary tests to determine the necessary pre-drying of the component.
• The sensitivity of casting compounds and hardeners to moisture and the moisture content of various plastic surfaces varies greatly. Please consult SynFlex for specific cases.
• Preheating the components has a positive effect on the flow behavior of the potting compound and thus also on the wetting of the substrate surface
• The warm component heats the potting compound, which reduces the viscosity. The potting compound flows faster into the component and displaced air can rise more quickly. Component temperatures of up to 100 °C are not harmful to the not yet cured potting compound.
• A preheated component also accelerates the curing of the casting compound. The preheating temperature must be determined by means of preliminary tests, as some systems have a processing time of over 90 minutes at room temperature and only a few minutes at 100 °C.