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Benefits and Costs of Various Mechanical Finishes

This paper continues our series in showing some of the advantages of using the aluminum extrusion process as illustrated by the Alex-Cube business card holder. This paper will outline some of the benefits and costs of using various mechanical finishes for your new project designs.

For many applications where profiles are used in a mill-finish state, aluminum extrusions will not need a protective coating applied to either the interior or exterior surfaces. Aluminum develops a thin, transparent oxide film that naturally protects the surface when it is exposed to the air. If your product designs require extra protection or decoration, aluminum is receptive to many types of finishes, making it a very versatile metal. Mechanical finish methods can give aluminum several different types of surface texture – from rough or patterned to a mirror finish. If your product design requires a final surface finish, improved surface quality, or to prepare for various final cosmetic finishes, please consider the following types of mechanical finishes.

Buffing

Buffing is a very attractive cosmetically appealing finish that replicates polished chrome. It can be functionally necessary for guiding delicate material where imperfections could cause problems. Buffing is a secondary operation and can be a great solution for parts with a generally higher number of rejects, as it can clear up many imperfections that would have resulted in a higher piece part cost.

Brushing

A brushed finish is cosmetically appealing and looks like stainless steel. Brushing is beneficial for blending extruded die lines and covering some imperfections. It is available in a wide range of textures. Brushing is a secondary operation where careful handling of the part is not as necessary which can reduce some of the piece part costs.

Bead Blasting

Bead blasting produces a unique granular appearance that can hide a lot of imperfections with a wide range of textures. This type of mechanical finish is an outside operation with associated lead-time costs. Some of these costs can be offset as bead blasting can cover up defects thus resulting in higher yields for each applied part.

Tumbling

A tumbled finish has a galvanized appearance with the degree dependent on the media and time involved. There is currently a wide variety of tumbling media available. The entire part is tumbled which eliminates the swirl marks resulting from normal end brush deburring machines. Tumbling also eliminates flow lines from the extrusion process. This type of mechanical finishing can serve multiple purposes such as deburring, washing, and polishing. Cost may be prohibitive depending on the part size and length. Tumbling is generally a low cost way of deburring a part.

Aluminum extrusions allow you to design in surface contours and with finishing features that improve the cosmetic appearance of your product while breaking up extruded surface imperfections. Buffing, brushing, bead blasting and tumbling are four very popular and well received alternatives of mechanical finishes, which can replace more expensive chemical finishing operations such as anodizing, powder and liquid paint.

Alexandria Industries offers an in-depth aluminum extrusion seminar at your site where we can educate designers and engineers about aluminum extrusion designing options, cost drivers, and benefits of aluminum extrusions. If you would like to discuss your designing needs or to learn more about our aluminum extrusion seminar, please contact your sales specialist.