Lead foil tapes for chemical milling info graphic

A Guide to Using Lead Foil Tapes for Chemical Milling

Chemical milling, or chemical etching, is the process of using a corrosive chemical called an etchant to selectively remove parts of a metal surface. It is derived from armor decorating practices developed during the Renaissance, as a substitute for hand-carving metal with tools. The corrosive chemical is often an acid mixture, allowing the metal to be eroded in a selective pattern without harming its physical properties. Chemical etching is a precise process, giving it diverse applications from electronics to aerospace.  

This post discusses the chemical milling process, maskants, and the role of lead foil tape.

The Chemical Milling Process

First, the process begins with a surface cleansing to remove impurities and foreign objects. This is typically done with pressurized water, alcohol, and hydrochloric acid. If the surface is not cleaned thoroughly, the maskant may not adhere well or the metal may not dissolve predictably.

After drying the material, every part that is not meant to be etched is covered with a maskant. Finally, the material is dipped into a chemical tank filled with the corrosive substance, and the longer the material sits in the substance, the deeper it erodes the unmasked sections. Once the surface is etched to its desired depth, the material is removed, washed again to remove any remaining corrosive chemicals, and then dried.

Maskants for Chemical Milling

As is likely implied from above, selecting the right maskant is essential to successful chemical milling. Common maskant materials are polymer or rubber-based substances, and these maskants can be brushed, sprayed, dipped, or rolled on. A good maskant has the following properties: chemical resistance to the corrosive substance, strong adherence to the substrate, toughness during handling, ability to withstand the heat etching generates, and ease of removal. Lead foil adhesive tapes meet these standards, and that is why they are a good option for a maskant.

Chemical milling info graphic

Lead Foil Tapes in Masking

Why are lead foil tapes conducive maskants? Chemically, lead is highly durable and resistant to corrosion, making it a prime candidate for chemical milling. Lamart’s lead foil tapes resist chemicals, conform to curved surfaces, and remain durable. Our pressure-sensitive acrylic or rubber adhesives maintain a strong steal against corrosive chemicals– protecting the masked section of metal.

Aerospace Chemical Milling

Chemical milling is essential in the aerospace industry. To reduce weight to enhance plane performance, certain areas—the engine nacelles, cowlings, and fairings—are chemically milled. This reduces the amount of material in those areas. In addition, milling is used to create pockets and channels in the aircraft. The aircraft’s heat transfer plates are also constructed with chemical etching. Chemical milling is popular for constructing aircraft parts because it is one of the only ways to modify metal without leaving behind tool scarring or thermal distortion. The high-quality standards that etching can meet are ideal for an aircraft’s narrow safety margins and performance needs.

Lamart’s 249-L lead foil tape Reliably protects essential parts, like the plane’s fuselage skin, from corrosion. Its quick stick makes for convenient application, and the aggressive acrylic pressure-sensitive adhesive ensures no corrosive material sneaks underneath.

Automotive Chemical Milling

Chemical milling is becoming increasingly popular in the automotive industry. It is used to manufacture parts such as gaskets, shims, washers, electronics, high-end speaker grilles, and more. When etching automotive parts, lead foil tape acts as an excellent moisture barrier and chemical etching barrier.

Conclusion

Chemical milling hosts an array of benefits where precision is needed to create high-performance parts. Without the proper maskant, the integrity of your milling tasks is compromised. Contact Lamart’s team of experts to see if our Lead Foil Tapes are the best maskant for your chemical milling process.

Craig Hirsh

chirsh@lamartcorp.com
Craig is a third-generation owner of Lamart Corporation with over ten years of experience developing custom-designed products to meet customer specifications and expectations.