What is Impregnation?
Sealant impregnation fills the voids and microporosity in a wide variety of materials. A micropore is a tiny defect in the component, which has the potential to turn into a large and expensive problem. By cleaning and then sealing the surface of the component in a vacuum, these small defects can be filled, prolonging the lifespan of the treated piece.
There are many reasons to use surface impregnation:
- To prevent leaks
- To reduce moisture entrapment
- To improve integrity of welds on cast iron and aluminium substrates
- To reclaim expensive castings and fabrications that would fail due to leakage
- To prevent "blow-out" of entrapped gases during plating or painting processes
What is the process?
During the impregnation process, components are packed carefully into designated baskets. The baskets are then lowered into a vacuum chamber containing Ultraseal resin sealant. The chamber has its pressure lowered to a vacuum greater than 10 mbar. This draws air out of any porosity that has a leak path to the surface of the component. After a suitable vacuum is achieved and held for a specified time, the air is allowed back into the chamber forcing resin sealant into the previously evacuated pores. The components are drained thoroughly and then excess sealant on the external surfaces and in holes is washed off with cold water. The basket is then immersed in hot water to cure the sealant and prevent porosity.
The impregnation process involves five key stages:
- Part preparation
- Cold wash
- Hot cure
Before impregnation, porosity within the component must be completely clean and dry. While this is achievable through a separate pre-process, Ultraseal offers modules for aqueous washing and vacuum drying that can be integrated into the system.
What does impregnation achieve?
- Outstanding void filling capacity due to low shrinkage during polymerisation
- Optimised viscosity and capillary action for fast deep penetration of micro porosity
- Tough and flexible attributes to provide resistance to chemical, temperature and vibration
- Excellent adhesion to cavity walls ensuring a permanent seal
- Stability at operating temperatures between -50°C and +220°C (-58°F and +428°F)
The Ultraseal impregnation process will treat any size of component using sealant formulations designed to ensure full compatibility with various substrates. These include: Aluminium, Magnesium, Cast Iron & Steel, Carbon Fibre Composites, GRP Mouldings, Plastics and Wood, however can work with customer's materials to diversify a sealant to help them cope with porosity in their components.
When the impregnation process is complete, the component can be put to use without further treatment. The process does not damage or distort the impregnated component. Treated parts are resistant to coolants, lubricants, solvents and most corrosive acids. It will continue to function in a wide range of continuous temperatures.