A Guide to Chemical Processing for the Aerospace and Defense Industry
Aerospace and defense parts often face harsh environmental conditions and may require chemical processing to ensure their long-term functionality.
At Alard Engineering, we handle chemical processing for many of our customers and are here to guide you toward receiving high-quality parts that meet all your specifications.
Common Types of Chemical Processing at Heinz Engineering
There are numerous methods of chemical processing, but we typically employ one or more of these three methods for aerospace and American defense manufacturing parts:
1. Chemical conversion coating
Chemical conversion coating is a surface treatment that provides increased protection from corrosion. It involves creating a chemical reaction to form a protective coating on the part's surface.
This level is cadmium plated, which offers an exceptional bonding surface for adhesives and resists mold or bacteria growth.
The protective coating can add a buffer to the part ranging from 0.010”-0.050.” It’s critical to anticipate this buffer during precision machining to ensure completed parts are in tolerance.
A chemical conversion coating is necessary to prime parts for liquid coating/wet paint or powder coating:
Liquid coating/wet paint. A popular choice among aerospace and American defense manufacturing customers, liquid coating protects parts from exposure and mitigates wear and tear. However, it’s not an environmentally friendly option.
Powder coating. Powder coating, which is gradually becoming more common in the aerospace industry, produces a thick coating without sagging or running. It’s an environmentally friendly alternative to liquid coating that provides a strong, durable finish.
2. Passivation
Passivation is widely used to inhibit corrosion and rust in stainless steel parts. Nitric or citric acids remove free iron particles from the part’s surface, leaving a protective oxide layer that’s less likely to react upon exposure to air.
This process adds minimal thickness to the part, so we don’t typically have to make significant adjustments during precision machining to keep parts in tolerance.
3. Anodizing
Anodizing—which increases corrosion resistance and enhances the aesthetic appearance of a part’s surface—is often used for aluminum parts but can also be used for nonferrous metals like titanium and magnesium.
Anodization occurs via a highly controlled oxidation method that involves submerging the part in an acid electrolyte bath and passing an electric current through it. Like chemical conversion coating, anodizing adds a buffer to the part that we must account for during precision machining.
Quick Tips for Better Chemical Processing Outcomes
We manage chemical processing at our precision machine shop, which includes helping customers determine which method is optimal for their part. These quick tips can ensure the process goes smoothly and results in top-quality parts:
Clarify if tolerance requirements are before or after chemical processes. Our standard is to assume that all dimensions apply after chemical processing, which means we'll make precision machining adjustments as necessary to ensure that final parts are in tolerance. If your noted tolerances apply before chemical processing, just let us know. We’re always happy to talk through how different processes affect final part dimensions.
Call out your desired color for anodizing. Color options for anodizing vary from one anodizing house to the next, so it’s important to specify color preferences if you have them. Most vendors follow a military specification for anodizing, and Alard Engineering defaults to clear anodize unless otherwise noted. Keep in mind that lighting conditions in different environments can affect color appearance, so be sure to consider this factor when indicating the color you prefer.
Choose powder coating over liquid coating. At Alard Engineering, we prefer powder coating and always encourage our customers to select this option when possible. Though less common than liquid coating in aerospace machining, powder coating is more environmentally friendly and produces a stronger finish.
When your part needs chemical processing, bring it to Alard Engineering. We’ll ensure that the processing method yields high-quality parts well-suited for their applications. Request a quote today!
