Linetec's Anodize Process


Linetec utilizes advanced equipment and techniques in all of our facilities: paint, powder coating and anodize. This overview describes the finishing lines available to meet your quality and service requirements. Our facilities have a thorough tracking system that allows us to monitor the progress of your individual order through every step of order entry, receiving, processing and packaging, assuring that every order receives high visibility and individualized attention.

Linetec provides the highest quality anodic finishes. Three completely automated anodizing lines, each containing up to twenty-nine (29) process stations, accept loads as large as 30’-6 long. We provide durable and attractive clear anodize finishes, traditional bronze tones including champagne, black as well as copper colored anodize. A sophisticated computer controlled hoist system guides the material through our process eliminating any chance of manual variations in pre-cleaning, etching, anodizing, coloring or sealing. This ensures a consistent and durable finish on every load.
Dimension Standard Custom
Length 28'6" 30'6"
Height 78" 78"
Width 13" 36"
Weight 1,800 1,800

     * Copper anodize maximum length is 24'2"
Linetec Auotmated Anodize Lines

Automation of Anodizing Line

The use of automation and system controls is imperative when anodizing and even more so with secondary billet extrusion. Linetec employs a computer-controlled hoist system to guide material through the anodize process eliminating any chance of manual variations in pre-cleaning, etching, anodizing, coloring or sealing. This ensures a consistent and durable finish on every load.

This computer-controlled system tracks all aspects of the process including tank sequencing, time, temperature, voltage, current, etc. It ensures all material with the same job and process specification is moved through the same solutions for the same amount of time.
Anodize rack welding method

Material Racking

Racking for anodizing presents a unique challenge because of the amount and consistency of electrical current required. Our standard racking method for lineal extrusions is rack welding which utilizes a tack weld to connect your products to be anodized to the electrical bussing. This system not only holds your product firmly in place, but also provides a continuous electrical contact that minimizes the electrical resistance between all parts being anodized. This type of racking system produces the most uniform anodizing and color consistency available while keeping all rack marks within one inch of the end of the extrusion.

Linetec also has the flexibility to bolt rack and clamp rack for handling prefabricated, cut-to-size, cast, formed or specialty parts. For more detailed information on Linetec's racking methods visit our Racking Method web page.

Linetec anodize process

The Anodizing Process

Cleaning.  The anodize process begins with the material being cleaned in a non-etching alkaline chemical cleaner to remove all shop dirt, water, soluble oils and other unwanted surface contaminates which may have accumulated on the material during handling and / or manufacturing.

Rinse.  After cleaning, the material is rinsed and is then ready for etching.

Etching.  Etching is an important step during the anodize process. It is designed to dissolve a thin layer on the surface of the aluminum to develop a smooth uniform finish. Linetec changed its etch chemistry, from conventional caustic etch to a more eco-friendly acid etch process.

The eco-friendly acid etch creates an aesthetically appealing, “frostier” appearance that helps hide small defects, such as die lines, flow lines, minor corrosion and scratches, that may occur on the aluminum surface. Although neither conventional or acid etch removes irregularities in the aluminum, acid etch does a better job of concealing them. This gives the material a better aesthetic finish on both primary aluminum and secondary (recycled) billet.

Desmut.  Material is then moved to deoxidzing and desmutting process, which further prepares the aluminum surface for subsequent finishing. This step removes surface oxides, removes smut - which is a combination of intermetallics, metal and metal oxides remaining on the surface after cleaning and etching and it actives the surface for the electrochemical anodizing.

Anodizing.  In the anodizing tank the electrochemical oxidation of an aluminum surface takes place to produce a stable film of oxide. In this process a porous, insulative layer composed of aluminum and oxygen is produced by passing electricity through the aluminum in a conductive medium. The basic structure of an anodic coating is based on a series of hexagonal cells, each with a central pore and a thin barrier layer separating the electrolyte in the base of the pores from the underlying metal.

Electrolytic Coloring.  The coloring of an anodic film is designed to enhance the appearance of the material and widen the application for anodized aluminum. In electrolytic coloring, or “2 step”, anodizing is followed by the electro-deposition of a metal. AC power is used to deposit tin metal. Deposition takes place at the bottom of the pore. The intensity of the color is dependent on the amount of tin deposited and the packing density.

Sealing.   After anodizing and coloring, the material is sealed in a mid-temperature hydrothermal seal and then given a final hot water rinse. This last, important step assures that the high-quality anodized finishes will maintain their beauty and durability for many years.