Photo Above: Shown to the left is a Model HZ-220 Centrifugal Barrel machine suitable for deburring and finishing large parts or large volumes of parts in industrial settings. These machines are noted for their high-speed processing, often ten times (10 X) faster than standard barrel or vibratory finishing methods. These machines are also capable of producing low micro-inch finished surfaces and highly attractive polished surfaces. The machine shown to the right a Model HZ-12, is a laboratory machine used widely in the dental and jewelry industry for producing ultra-refined surface finishes.
Free Sample Processing | Contract Finishing Services | Turn-Key Finishing Systems
by Dave Davidson | SME Tech Advisor | firstname.lastname@example.org | 509.230.6821
Shown to the left is an HZ-160 Model Centrifugal Barrel Machine shown with a divider insert to separate the barrel space into separate compartments. This is a useful feature for segregating parts from each other when there is a need to avoid part-on-part contact. Photo by Dave Davidson
Although not nearly as universal in application as vibratory finishing,many important centrifugal barrel finishing applications have been developed in recent years. It is similar in some respects to barrel finishing, in that a drum-type container is partially filled with media and set in motion to create a sliding action of the contents. However CBF is different from other finishing methods in some significant ways. Among these are the high pressures developed in terms of media contact with parts, the unique sliding action induced by rotational and centrifugal forces, and accelerated abrading or finishing action. As is true with other high-energy processes, because time cycles are much abbreviated, surface finishes can be developed in minutes, which might tie up conventional equipment for many hours.
Some operational and case study videos are shown below:
The principle behind CBF is relatively straightforward. Opposing barrels or drums are positioned circumferentially on a turret. (Most systems have either two or four barrels mounted on the turret; some manufacturers favor a vertical setup, and others a horizontal orientation for the turret.) As the turret rotates at high speed, the barrels are counter-rotated, creating very high G-forces or pressures, as well as considerable media sliding action within the drums. Pressures as high as 50 Gs have been claimed for some equipment. The more standard equipment types range in size from one cubic foot (30 L) to 10 cubic feet, although much larger equipment has been built for some applications. Media used in these types of processes tend to be a great deal smaller than the common sizes chosen for barrel and vibratory processes. The smaller media, in such a high-pressure environment, are capable of performing much more work than would be the case in lower-energy equipment. They also enhance access to all areas of the part and contribute to the ability of the equipment to develop very fine finishes. In addition to the ability to produce meaningful surface finish effects rapidly, and to produce fine finishes, CBF has the ability to impart compressive stress into critical parts that require extended metal fatigue resistance. Small and more delicate parts can also be processed with confidence, as the unique sliding action of the process seems to hold parts in position relative to each other, and there is generally little difficulty experienced with part impingement with proper media and part loading. Dry process media can be used in certain types of equipment and is useful for light deburring, polishing, and producing very refined isotropic super-finishes.