Before diving deep into the what, why, and how of vibratory deburring, let’s understand what the word “burr” means. Oxford Dictionaries defines it crisply as “A rough edge or ridge left on an object (especially of metal) by the action of a tool or machine.” Burrs are usually produced by machining operations such as grinding, drilling, milling, engraving, or turning.
Burrs can significantly affect the part’s functionality, efficiency, and life-span. In essence, they can potentially:
- Reduce resistance to fractures (due to increased stress in specific areas)
- Increase unwanted friction and heat
- Cause issues with lubrication
- Shorten fatigue life (stress cycles a material can withstand before failure)
- Cause material failure due to cracks
- Increase the risk of corrosion
- Concentrate electrical charge and cause a risk of static discharge
- Cause issues with lubrication due to increased wear at interfaces
- Render the part unsafe for handling
Clearly, burring is a menace. So, the purpose of “deburring” is to smoothen the rough edges or ridges of such objects.
What is Vibratory Deburring?
Basically, in the vibratory deburring process, a container consisting of the workpieces and tumbling media is subjected to a controlled gyratory vibration. The vibration prompts the workpieces and tumbling media to rub against each other, producing a lustrous look.
While it may seem that vibratory deburring is a very niche specific activity, it is anything but that. An enormous range of mass-produced metal, plastic, and even wooden components require this type of deburring. It is not unusual to find a vibratory deburring machine next to CNC milling, laser cut, or waterjet cut type operations.
As a matter of fact, the medical, motorsport, and aerospace industries have relied on vibratory deburring processes for decades.
Benefits of Vibratory Deburring
While there are many other techniques you can use to perform the deburring process ― manual, electrochemical, thermal, and so on ― vibratory deburring stands out due to some notable benefits, as it:
- Can be used with delicate or fragile components
- Helps complete large projects quickly
- Is very cost-effective because it requires little-to-no labor
- Reduces imperfections and thus improves the cosmetic appeal of the components
Vibratory deburring machines seldom breakdown and the uniform results are easy to reproduce over and over again. Modern machines come complete with “sealed for life” bearings and require a minimal amount of maintenance.
How Vibratory Deburring works
Vibratory deburring is actually a part of a larger process called vibratory finishing.
The vibratory deburring machine comprises a process chamber (ordinarily lined with polyurethane or a rubber guard) which is installed on a base with springs. The process chamber is usually circular in shape and has a center plate on which the motor is mounted.
The motor is fitted with top and bottom weight segments that are offset by 90 degrees. The normal running rotational speed of the motor is 1500 RPM at which point the process chamber vibrates.
Vibratory deburr employs abrasive media to eliminate excess sharp edges and burrs from stampings or other machined parts. The parts are placed into a vibratory machine that tumbles/vibrates and rotates the product in abrasive media.
The vibration causes the media (abrasive/polishing chips) in the process chamber to move in a toroidal (corkscrew) action. This movement lets the media to alter the surface of the components. It polishes rough surfaces and expunges all sharp corners on the product. The deburring process can be either wet or dry, depending on the application.
The deburring operation is determined by the media and compound being used. The operations performed on die castings are usually polishing or refining, both of which utilize a combination of plastic media and a mild alkaline compound. Because of the soft, lightweight nature of the media used, die-cast parts are unlikely to be scratched or gouged.
Different Types of Abrasive Media
We discussed above that an abrasive media is used to perform the deburring process. There are different types of abrasive media, each with a different purpose:
- Ceramic Media: This type of media is useful for both, light and heavy deburring processes. It is recommended for all general purpose polishing and aggressive metal removal. It is best for hard metals and heavy cutting.
- Steel Media: This type of media is produced from hardened carbon and stainless steel, and its general application is to apply pressure to deburr steel parts. It is also used for polishing of stainless steel (and occasionally aluminum) and ball burnishing.
- Plastic Media: This type of media is recommended for general metal deburring, pre-painted finishing, and fast and heavy cutting. Also, it is often used for precision deburring, polishing, and burnishing. It produces a very smooth finish, but very little shine. Plastic media is very suitable for preparing parts for anodizing, and for parts with threads.
- Organic Media: This type of media is chiefly used to dry parts after vibratory finishing. It can also be used to provide a highly glossy finish on aluminum, stainless steel, and other metals when blended with a polishing paste. Employing organic media is favorable because they are natural, biodegradable, reusable, and durable.
Size matters when choosing abrasive media for deburring. Smaller media has more area in contact with the parts’ surface than larger materials and thus, creates a smoother, more attractive surface. In general, the smaller the media, the better the finish. However, because smaller finishing material requires gentler processing, it takes longer.
Conversely, the larger the media, the quicker it will deburr. Choosing the right media is key to successful deburring.
Applications of Vibratory Deburring
Vibratory deburr is very suitable for parts that require safe handling, such as camshafts, telescoping magnesium steering columns, and stainless steel IV stands for the medical industry.
Provided the correct media, chemical additives, water levels, and time this process will yield results ranging from edge breaking/light deburring to burnishing, degreasing, descaling, radiusing, super-finishing, and corrosion inhibition. Other applications include creating a cosmetic surface of specified depth and cleaning.
Circular bowl vibratory deburring machines were first introduced over four decades ago. Today, they represent the vast majority of sales as the design makes sure that part damage is circumvented; not to mention, their overall cost-effectiveness, reliability, and rapid speed of operation.