The choice of tumbling media used during surface finishing plays a significant role in the finishing effect of parts in any material – including metals, super alloys, polymers, and synthetics.
Typically combined with water and surfactant in centrifugal barrel finishing (CBF) and vibratory surface finishing equipment, media alters the appearance and finish of parts to meet exact standards and requirements.
Tumbling media is the work horse of CBF and vibratory finishing. Media is typically molded, sintered, cut, or extruded into rigid shapes of various sizes containing a bonding agent or abrasives. While there are multiple factors affecting surface finish during processing, the media selected plays a pivotal role in the success of the finished surface.
The most common media types include ceramic, porcelain, plastic, steel and organic compounds – such as corn cob or walnut shell, which may be combined with micro-abrasives or burnishing compound and is available in a variety of shapes and sizes
Ceramic media has a relatively high density, making it ideal for hard and heavy metals such as titanium and stainless steel and can also be used on plastic and aluminum. It is used for general-purpose polishing and rust removal. Porcelain is a type of ceramic media and is commonly used to achieve a higher gloss finish.
Plastic media is typically used for softer or malleable metals, such as aluminum, brass, and zinc. With its relative ease to manufacture, durability and water-resistant properties, plastic media is a cost-effective option used for general deburring, precision deburring, burnishing, and polishing. Common abrasive types such as silica and sand are used to help deburr and deflash softer metals and typically wear down more slowly.
Steel media is made from hardened carbon and stainless steel and is known for its ability to effectively burnish. It is used for shining, polishing and burnishing of materials and applies heavy pressure for deburring steel parts. Steel media offers a longer lifespan due to its reduced lodging properties.
Organic media, including corn and walnut shells have multiple uses. Not only used to dry parts after wet finishing, organic media can be combined with polishing paste, to produce a high gloss finish on materials such as stainless steel, aluminum, and acrylic.
Media is combined with parts, water and surfactant in a CBF barrel or vibratory bowl/tumbler. As energy is created within the barrel or bowl, the parts and media rub against each other, refining the surfaces of both the part and media and uniformly exposing new abrasive material.
There are many factors considered when selecting media – including the part’s material type, size, and shape along with a media’s ability to burnish, clean, color, deburr, deflash, descale, radius, refine, or dry as needed.
The shape of a part plays an important role in the selection of media shape. Spheres, ovals and cylindrical media wear evenly, chip less frequently and are less likely to get lodged in a part. Cones, stars, pyramids and wedges are ideal for complex parts with hard-to-reach geometries, despite wearing and chipping at a higher rate.
The size of a part along with a part’s geometry influences the size of media used. Smaller media size offers a more detailed and smoother finish but takes longer to complete. A larger media size offers a quicker processing cycle but creates a rougher surface.
The team at ISO Finishing is experienced in selecting the right media to achieve the right finish. We have the proven ability to customize surface finishing solutions on any material that is documented and repeatable.
The best way to show you how our finish will be your finish is to process your sample. Let us show you what we can do. LET’S GET IT FINISHED.
