How Do I Choose?

What You Need to Know About Tumbling Media

Tumbling media is available in (4) major types: ceramic, plastic, synthetic plastic, and steel. Each one has specific advantages over the other, whether it be size, shape, cut-rate, bulk density (lbs. per cu. ft.), compatibility with wastewater treatments systems, availability in the supply chain, or suitability to downstream processes such as plating operations, welding, painting, etc. The goal of choosing tumble media is to eliminate or minimize lodging potential while providing an ideal surface for downstream processes in the quickest and most cost-efficient manner possible. The equipment type the media will be run in should be taken into consideration as well. Lesser known media types, such as walnut shell (treated and untreated), corn cob, and urethane media can also be considered for the right applications.

The Value of Compound

Equally important as the tumbling media itself is the compound, or soap, used in the process. There are literally 100’s of different compounds available for mass finishing. Many customers understand the importance of compound as a means to keep the parts clean and free-rinsing during the process but underestimate its importance relative to keeping the media clean and free-cutting. Tumble media is designed to wear, as this is how new abrasive within the media is exposed to impart the necessary work to the surfaces of the parts. If a compound isn’t used, the media can develop a condition called “glazing”, where the pores of the media “load up” with metallic, abrasive, and ceramic fines and wear of the media stops. It is evident when this happens as time cycles become extended or deburring and edge-breaking cease altogether. Compounds also have many other functions as well, including but not limited to rust inhibition and corrosion protection, additional lubricity for burnishing operations, water hardeners and softeners, scale removal, REM-style accelerants for quick time cycles and low Ra finishes, defoamers, and biocides to inhibit bacterial growth in recirculated systems. Depending on water quality in your plant, concentrated versions are also available to mix with water upon arrival and save you shipping costs.

Selecting Abrasives

Abrasive types for blast cleaning are numerous, both in types and sizes available, and should be chosen carefully depending on the desired finish while keeping overall process cost in mind. Abrasive types include Aluminum Oxide (both Brown and White), Glass Beads, Steel Shot, Steel Grit, Stainless Steel Shot, Stainless Steel Grit, Ceramic Beads, Silicon Carbide, Crushed Glass, Plastics, Garnet, Olivine Sands (Oli Mag), Coal Slag (Black Beauty), Baking Soda, and Corn Cob among others. Surface finish requirements are the primary driver of which abrasive type to use. Angular abrasives are the most aggressive in terms of putting profile or anchor patterns on parts for coating adhesion, rust and scale removal, and can provide matte finishes. Round particle abrasives tend to provide more desirable finishes on aluminum and softer metals, produce surfaces that reflect light differently, are used in shot peening applications, and are easier on the equipment they are used in from a wear standpoint. Some applications may be suitable for more than one type of abrasive, so factors such as the type of equipment it will be used in, recyclability of the abrasive, required CFM to achieve certain profiles (compressed air is expensive, so less is better!!), effect on downstream processes (such as iron/ferrous contamination or weld suitability), and product availability should be considered.

Don’t Neglect Spare Parts

In general, anything that is exposed to the abrasive itself, or that is “actuated” (i.e. has moving parts) will eventually wear out. These parts could be nozzles, nozzle holders, dust collector filter cartridges, hoses, couplings, gaskets, gun bodies, abrasive metering valves, check valves, pneumatic valves, foot pedals, window glass, window covers and tear-offs. Knowing which parts are most likely to wear out is key to proper preventative maintenance (PM) schedule that will minimize downtime. Fortune Metal has an extensive inventory of OEM and aftermarket parts and can help you determine which ones are ideal for your application. Cost savings can also be realized, particularly as it relates to nozzle types and sizes vs. compressed air consumption, and with aftermarket dust collector filter cartridges vs. OEM. When was the last time you replaced your high wear parts? Are you using the ideal parts in your application? This is where we can help.