What Is Vibratory Finishing & Why Do You Need It?
Vibratory Finishing is a process that automates the mechanical and chemical finishing of various shaped parts. In this stage a combination of media, parts and compound are placed in a vibrating machine. The vibrations cause the contents to move in a circular motions and the media to grind against the part to get the desired finish.
Vibratory finishing processes can be configured as: Batch system: parts are loaded into the machine, processed and unloaded before the next batch is ready. Continuous system: a process where the parts are loaded at one end and come out at the other end in the finished condition.
Vibratory finishing benefits
Reduced processing times in comparison with manual finishing. Produces a consistent finish in comparison with manual finish, hence there is no need to carry out rework and you avoid high part rejects rates. It is a cost effective finishing solution Vibratory finishing systems can be easily custom built to suit different applications There is a low probability of damaging delicate or large parts due to the circular motion of components and media. Parts of different shapes and materials can be processed in vibratory finishing machines. Vibratory finishing allows processing components with corners, holes, cavities and slots. Vibratory finishing machines can be easily loaded and unloaded.
7 Steps To Identify The Vibratory Finishing Process Suitable For You To identify the right finishing process for your part it implies running finishing trials.This will determine the correct media,compound,vibratory finishing machine and other process parameters which will ensure repeat ability in results. For the trial to be successful we recommend going through 7 steps:
STEP 1: Gather information regarding your part:
The recipe to achieve the required surface finish involves using the correct machinery, media and compound. These parameters can be determined once you know the part details:
- Surface Roughness
- Manufacturing Volumes (per day/ month/ batch quantities)
- Current Process Issues (costs/ poor finish/ long process times/ high scrap rate/ need to carry out rework/ etc.)
- Process Requirement (deburring/ descaling/ radiusing/ polishing/ edge-breaking/ etc.)
The above component details are factors that will also help you to determine:
the amount of parts that can be processed in a batch determine current issues you face when processing the parts so you can improve the finishing process and most important you will know what is the part finishing requirement
Some of the most known and used vibratory finishing machines are the vibratory troughs, bowls, dryers and duals. Below you will find some facts regarding each vibratory machine that will help you to decide which machine works best for you
Vibratory Trough Finishing Machine
- The trough machine is perfect for larger, longer and irregular shaped components.
- This is a versatile machine as it comes in various standard sizes and a choice of combination of lengths and widths.
- Vibratory trough machines suit various customer applications from deburring, descaling, radiusing and cleaning to polishing and surface improvement.
- These machines include a single speed motor as a standard feature with adjustable flyweights set to transfer the optimum amount of energy to produce a finish in the most efficient manner.
- The polyurethane lined chamber is designed in a “U” shape and can be sub-divided using divider plates to provide separate compartments for precision or delicate components.
- Separation of parts and media is done manually for the standard trough machines. However if required parts can be separated from media at the end of the finishing process if an accessory such as the Vibratory Separation System is included.
- For delicate small batch works a trough machine such as the HT Series can be used. This machine runs on a standard 16A socket, 1 phase, 240V AC supply and it is a very user friendly kit for deburring or burnishing operations
Step 3: Calculate the amount of parts you can process/ batch
The amount of parts to be processed per batch also known as workload can be determined through media to part ratio. To do so you would need to calculate the part volume and know the usable volume of the finishing machine work chamber (approx. 90% for vibratory machine). The guidelines below will help you in determining the right media to part ratio for your process: Equal parts of media and components; for a rough surface finish on castings, forgings or stampings.
- Part on part finishing (no media)
- A lower ratio of media to part, which can be used for very small parts; will still produce a rough finish on castings, forgings or stampings.
- Minimised part to part interaction; great for moderate deburring and surface finishing on ferrous metals.
- A good ratio for ferrous metals but average for non-ferrous parts; also minimised part to part interaction
- A minimum part on part interaction; great for non-ferrous and softer materials
- Used when processing non-ferrous and fragile parts for pre-plate and decorative finish
- Recommended for bright burnished finish and high quality pre-plate finish
- Great for finishing parts with irregular shapes and fragile components
For precision or delicate components we recommend finishing these individually, in work chambers sub-divided using divider plates. This will avoid part on part interaction
Step 4: Set up the finishing machine amplitude
The amplitude of a vibratory finishing machine controls the final finish of the component. The amplitude can vary from 1mm to 8mm, with 3mm to 6mm being the normal operating range. The required amplitude can be obtained by adjusting the motor weights. While for finishing delicate parts you can use a lower amplitude, a higher set amplitude is best for heavier cutting, rolling burrs or peening edges. For a polished finish or for deburring parts with slots and wholes consider a small amplitude and a fast speed.
Step 5: Identifying the right media for the finishing process
As we have previously explained in this eBook the recipe to achieve the required surface finish involves using the correct machinery, media and compound. The following factors must be considered when choosing theright media:
On the market there is a wide range of media types such as Ceramic, Plastic, Agro, Pre-Treated, Stainless Steel, Wood Pegs, Aluminium Oxide and many more.
Media transmits the energy generated by the equipment to the parts being processed and are capable of heavy burr removal, edge radiusing to smooth and bright surfaces.
Ceramic Media is recommended for removing burrs, edge radiusing, burnishing and to quickly remove polishing lines on components made from harder materials. Faster cut Medias are designed to be softer, thus allowing the cutting elements to be exposed. Polishing Medias are harder and are used for burnishing. In general, the slower the cut, the harder the media Plastic Media is light-weighted and is manufactured out of soft bonding agents, which allows it to remove burrs without rolling the burr onto the part. Furthermore, we recommend using this media to achieve a very smooth surface finish, or a bright or matte finish on components made from softer materials. Agro Media can be used for surface brightening or final finish refinement. Pre-treated Media is recommended for achieving a high lustre or mirror finish. Applications for Stainless Steel Media include burnishing, cleaning, improving strength and light deburring
When choosing the shape of the media it is important to consider the geometry of the part - hence any lodgement of media can be avoided and the part finish will be consistent.
A flat sided media, such as triangles, tri-stars, wedges and the end side of cones, can generate longer surface contact time on edges for deburring and radiusing. However,
round shaped media, such as balls, cylinders and cones generate a single point contact concentrating energy in one small point, therefore producing more work in that area.
For components which have corners, holes and slots both Tri-Star media and wedge media are recommended, minimising the possibility of media lodgement. For surface improvement of hard to reach areas, an ellipse or cylinder shape can be considered
The component finish is also subject to the size of media chosen. A larger media will generate higher energy; hence it will cut and finish faster with higher wear rates. This is also recommended for processing larger parts.
A smaller media can hold more water and compound resulting in less part-on-part damage. Also, a smaller media has a gentler impact on part, which results in longer processing times, better finishes and less media wear.
Generally, media size has to be of a different size to the part to allow complete separation at the end of the finishing process. If media is larger than parts, then an inverse separation system can be used. For ferrous components, consider magnetic separation.
To avoid damaging the component, it is important to consider the part material and the hardness of the media. Ceramics are harder than plastic; hence it may cause damage to soft materials
Step 6: Identifying the right compound for the finishing process
Compounds are integral to the success of a process. These have many functions such as suspending the dirt, oils and media residues and flushing them from the system, as well as keeping the components and media clean, which brings stability to the process. Other advantages include corrosion inhibition, brightening of different materials and removing scale post heat treatment. As the compound acts as a lubricant, it extends the media life
Here are the 3 considerations when choosing the compound
Process requirement: such as parts that need a compound with corrosion inhibitor; flat parts that can stick to each other in process will require a separating compound; or removal of heavy machine marks and burrs can be accelerated using an abrasive powder compound.
Finish requirement: from removing heat treatment, descaling, cleaning to brightening, polishing, and burnishing you need to chose a compound that has been designed for that particular finishing requirement Component material: compounds are formulated to finish ferrous and non-ferrous parts.
Step 7: Run the vibratory finishing trial
The final step is to run the finishing trial. This will enable you to test, improve and ascertain the finishing process parameters and establish a repeatable solution.
As this is a trial you should consider having a number of part samples to use for testing. Make sure these samples are the exact replica of the component to be finished, to ensure the solution is viable.
Once you have carried out the finishing trial we recommend recording every stage in a trial report. This will be helpful as you might need to carry out more than one trial and it will help you review and improve the final finishing process.
Once you are happy with the final vibratory finishing process we recommend making a data card. This should contain process parameters, inspection criteria and any other notes to ensure repeatability in results.
Itching to apply all this good stuff? Great. Armed with your newfound knowledge of vibratory finishing, it’s time to dive into the challenge of finding the right vibratory finishing technology for your needs .
Vibratory Bowl Finishing Machine
Built to suit various applications from deburring, descaling, radiusing and cleaning to polishing and surface improvement.
The polyurethane lined work chamber is designed in a manner that the components are subjected to effective tumbling action which ensures shorter process times. Bowl lining ensures the fabrication is protected and reduces the coefficient of friction between the media and bowl, thereby increasing media life expectancy. Both large and small batches of components can be processed in this machine.
Bowl machines can be customized to suit user application and can be designed to include manual or auto functionality.
For processing batches of parts that require a separation of components from the media at the end of the process we recommend using a bowl finishing machine with separation system (check out Series bowl machine).
If you require to process only small batches of parts and you do not have the luxury of space you can consider a Bench Mounted Bowl machine. This machine can be with our without a separation system and it is usually operated via a standard DOL starter.
For heavy duty applications such as ball burnishing we recommend using a bowl finishing machine such as our B series. With a powerful drive system and special springs, this bowl machine has a special rubber lining to assist the movement of the parts during the process.
For processing large circular components such as vane rings there are bowl machines with narrower central section of the working bowl. Our C Series bowl machine can accommodate a part with a bore ID 250 mm and an overall OD not larger than 940 mm.
To avoid implements when processing small, delicate parts divider plates can be installed in the working chamber. In this case parts are manually loaded and unloaded.
For a process where 100% discharge of media and part is required at the end, we recommend a bowl machine with pneumatically operated discharge door. This machine is also great for part-on-part finishing process.
If you need to process, separate and unload magnetic parts, you can use a bowl finishing machine with an over-band electro-magnetic separator. The process of separation and demagnetisation is automated giving the required control of process.
To achieve a highly polished finish on automotive and motor bike wheels, consider a wheel polisher. Both forged and casted wheels can be processed in this machine.
Vibratory Dual Finishing Machine
The Dual Finishing machine design integrates two process chambers: an inner chamber that can be used for wet process application, and the outer chamber for dry process applications. The inner chamber has a hot cured polyurethane lining and can be used from deburring, descaling, radiusing and cleaning to polishing and surface improvement. The heated outer chamber can be used for drying/cleaning the parts after being processed in the inner chamber. Parts can also be polished in the outer chamber using agro media. The Dual finishing machine typically includes a separation system for each chamber to separate media from parts. At the end of finishing process in the inner chamber media is screened through the separation screen and is retained in the bowl, while the parts are discharged to the outer chamber for drying. This operation is repeated once the parts have been processed in the outer chamber and then suitably collected
Choosing the correct dryer depends on the finishing applications and part specification. Hence you can choose between a Conveyorised Electrically Heated Drying Oven, a Vibratory Finishing Dryer, a Rotary Dryer, or a Centrifugal Dryer. The Conveyorised Electrically Heated Drying Oven is best suited for drying a variety of parts, which are large in nature or where the agro media cannot be used due to the risk of lodgement. Parts are loaded on the metal conveyor belt, which travels through the heated drying chamber and collected at the discharge end. The Vibratory Finishing Dryer has an elliptical shaped work chamber which gives an extra drying area, thus minimising the drying time. Both large and small batches of components can be dried, using heated drying media, either as a batch process or a continuous single lap process. The design of the Rotary Dryer includes an inner rotating chamber where the components get dried using appropriate agro media which absorbs the moisture from the components. Some of the advantages of this dryer are: 100% separation of components and media; re-circulation of drying media with continuous output of parts; energy efficient unit with minimum loss of heat. The Centrifugal Drier is best suited for drying large volumes of small components where the agro media cannot be used due to the risk of lodgement. The machine works with the circulation of open loop hot air. The finished parts are stain free and protected against corrosion