Vacuum Impregnation

Anaerobic Vacuum Impregnation is the most effective method of sealing porous substrates such as die castings and powdered metal components that:

1. Are designed for use under pressure.

2. Require precision machining characteristics.

3. Require high detail post finish operations especially those requiring heat (eliminate out-  gassing on die- castings) such as Powder Coating or a Heat Treatment.

Parts requiring impregnation include parts manufactured to contain gases or liquids and parts that will be plated or coated with additional surface finish. Parts can be impregnated in the as-cast or in the machined state.

Porosity (voids of trapped air) is common in nearly all casted metals and powdered metal applications. Over time, these voids can provide a corrosion path which will likely leads to part failure.

PowderTech provides batch processing for these type of parts. Parts are racked, placed into a vacuum chamber, and immersed in a sealing compound. This chamber then evacuates almost all air in the chamber and with it all air in the microscopic voids within the casting wall. When the vacuum is released, the casting voids fill with impregnation sealant (resin).

After the vacuum impregnation cycle is complete, polymerization of the resin occurs in the absence of air (anaerobic cure). All resin on exterior surfaces is unaffected because of its exposure to air and is removed by a series of subsequent rinses.

The vacuum impregnation process fills and permanently seals the porosity networks of the part. Because of the impregnation process, surface applications like metal plating and painting are enhanced. Future blistering, out-gassing, and discolorations are eliminated with impregnation.

The use of vacuum impregnation aids in two distinct areas. First it's a financial savings for the metal caster by reducing the labor costs in sorting and rework and saving an otherwise rejected part. Second is a financial savings from parts that would otherwise blister, pin hole, or leak as a result of additional finishing operations.

Some of the die-cast components that typically receive impregnation at PowderTech include

Transfer Cases - Fluid Regulators - Transmission Cases - Pressure Plates - Regulator Housings - Engine Blocks - Gas Valves - Water Pump Housings - Pump Housings - Fuel System Components - Pressure Manifolds - Aluminum Wheels - Rack and Pinion Housings - Axle Housings - Crank cases - Torque Converter Housings - Oil Pans - Powdered Metal Parts

Properties of the Cured Resin:

• When cured, the resin maintains flexibility 
• The cured resin has characteristics of a firm, but flexible plastic 
• Hardness Shore D (ASTM D2240) 70 
• Temperature capability, 375 F (170 C) continuous service - perfect for powder coating 
• Dielectric Constant (ASTMD-150) @100 Hz 3.85, @1KHz 3.60, @1MHz 3.2 
• Resistant to common solvents, including oil, glycol, chlorinated and fluorinated solvents, mild caustics and acid solutions 
• Cured resin contains a UV dye that will allow detection with a black light 

This process provides the following advantages:

1. No dimensional changes 2. Reduced finishing rejects 3. Reduced casting rejects 4. Ideal electrical properties