vibratory finishing process

Vibratory Finishing Guide for Beginner – Get Start within 30 minutes

Vibratory Finishing Guide for Beginner – Get Start within 30 minutes

 

Vibratory finishing is now the most popular type of mass finishing process. In some case, people will think vibratory finishing equals mass finishing. There are still other processes use centrifugal barrel machines, centrifugal disc finishing machines, and rotary barrel machines.

The process vibratory finishing is made in a vibratory bowl or a vibratory tub for parts surface deburring, polishing, smoothing, cleaning, descaling, rust removal, edge rounding and so on.

The first vibratory finishing machine is tub-type which introduced in 1957. Five years later, in 1962, the bowl-type vibratory finishing machine is invented and commercialized.

In 2006, Mr. John Kittredge, a leader in surface finishing fields, publish the book: mass finishing handbook. He listed many experiments and concluded simple rules help to understand the process. Bellow, we make the brief introduction of John’s idea. You can also contact me to get electric copy mass finishing handbook.

1. The major process of vibratory finishing:

Bellow is the major process application for the vibratory finishing process. You will find one or several of your application requirement. The material suitable for the process covers most metal and plastic materials, especially for small and media size parts.

 1.1 Deburring:

Vibratory finishing deburring

Deburring of aluminum machining parts with plastic media

Deburring has the widest application in the vibratory finishing process. Usually, people use a mild compound with the PH around 7.0 and a general performance ceramic media to deburr. Mild steel stamping parts deburr with ceramic media in 30-60 min. And Aluminum die casting parts deburr with plastic media in 1-2 hours.

In the deburring process, compound cleans off machining oil or lubricant in the same time cycle. This leaves a neat surface for assembling and handling.

1.2 Burnishing:

vibratory finishing BALL burnishing

Ball burnishing of copper joints with stainless steel ball in vibratory tumbling machine

The burnishing process usually done with steel ball but also can be done with zirconia ball. Steel media including ball shape and ball-cone shape are most popular. When ball shape steel media can offer better polishing performance, ball-cone shape steel media never remove burrs but hammer down the burrs and leave a dull edge.

In burnishing process, cleaning media before the process is critical to performance. A dull media always results in dull metal finishing. As a result, keep tumbling media shining and glossy is essential.

Compound selection is another important factor to determine ball burnishing quality. There are several different burnishing compounds which formulate according to the different material: stainless steel, aluminum, zinc, and copper.

The ball burnishing process carried out usually in curved wall vibratory finishing machine or tub vibratory machine. In curved wall design machine, tumbling media rotate in cross-section area. This achieves maximum surface contact between parts and media and acquires optimal tumbling performance. The ball burnishing process time usually takes 20-30 minutes to get a brilliant surface.

1.3 Smoothing:

vibratory finishing surface smoothing

Surface smoothing of blade with vibratory finishing machine

Parts surface properties change with different media processing. Cutting marks from machining and wheel grinding process almost every components manufacturers come up with. Ceramic media offer an economical way to give the metal surface a pre-painting finishing.

For soft metal materials like aluminum, copper, and zamak3, plastic media uses to get a superior pre-plating finish.

In some application, you can matt finish surface with ceramic media with increased surface roughness. This property is required in friction pad in the automotive industry.

1.4 Cleaning & Degreasing:

vibratory cleaning and degreasing

Vibratory cleaning of bearing components with degreasing chemicals

When cleaning an oily and greasy parts, vibratory finishing machine is a good choice. In the cleaning process, we want to run it in a pass-through mode. So we save time and give more output.

The larger machine diameter, longer time parts stay in the machine and better cleaning parts there will be.

The best media for cleaning process is porcelain media and steel tumbling media because they have almost no wearing. The media do not leave wear debris which contaminates and leave on parts surface. Besides, media will not reduce in size (which is costly for you) and risk lodging in parts.

However, cleaning compound is the main contributor. Compound type selection, dosing rate, and concentration are the key factors related to performance. This process requires strong acidic compound to clear off fatty and oily substance from the metal surface.

Even though the hot solution can reduce degreasing and cleaning time, we will use cold water. A hot solution will soften PU lining and result in premature wear.

1.5 Rust removal

vibratory rust removal

When Iron components stay in the open air for a long time, rust or corrosion is inevitable. Besides, parts process in high temperature (laser cutting/plasma cutting/welding) leave oxidation layer on the surface. However, the oxides and corrodes adhere to metal surface always result in paint chips and poor plating quality.

As a result, the vibratory finishing process is necessary to remove oxide layer and make the metal surface smooth before the next procedure.

The rust layer usually is thick. Also corrosion surface sticks tightly to the metal base material. To remove these materials, we use ceramic media with strong cutting power. In some case, we also strong cutting compound to reduce processing time. Hydrochloric acid and sulfuric acid or their mixtures are used in some special applications for oxide removal.

1.6 Radiusing

vibratory radiusing edge rounding

Radiusing also called edge rounding or edge breaking. It is the process to make parts edge round and smooth. This property required for most metal components with direct contact with users.

The round edge can protect user and operator from likely injuries. Besides, it also makes easier for labors to handles and smoother parts on parts workflow.

In the vibratory finishing process, edge rounding process usually comes together with deburring and surface material removal.

2. Key elements in vibratory finishing

There are four elements in vibratory finishing system: parts to finish, vibratory tumbling media, vibratory finishing machines and compound. These elements interdepend with one another. They all have a significant influence on the final finishing result. If one of the element fails, the whole process will fail.

parts media compound equipment interaction

parts media compound equipment interaction

2.1 Parts

The parts size decides the type of vibratory finishing machine that can be used. Small parts like pins and tabs usually made with huge production volume every day. You don’t want to pick 10,000 pieces of parts one by one out of machine once they are ready. As a result, vibratory bowl finishing machine is preferred in the situation.

Various parts to finish from different industries

Various parts to finish from different industries

Larger parts like transmission gear parts would be faster to take out by hand.

If the parts size is even larger like the ceramic coated exhaust pipe, most vibratory bowl channel cannot accommodate. Then you need to consider a vibratory tub.

2.2 Equipment

When you make the decision that you need a vibratory finishing machine, you need also check out different type and size available. Choose the one best suitable for your task is very important.

2.2.1 Vibratory finishing machine with curved wall design

circular vibratory finishing machine_VB(A)

circular vibratory finishing machine VB(A)

The curved wall design vibratory finishing machine is popular for an excellent cascade of media and parts flow. This makes shorter cycle time of the process and saves cost in the high polishing process.

One of the major applications for the curved wall vibratory machine is the ball burnishing process. When burnishing with stainless steel tumbling media, vibrator motor power updated to support increase loading weight.

Some small parts or lightweight parts (for example aluminum die casting parts) tend to float at the outer surface with standard vibratory machines. With the increased tumbling performance, these parts have excellent movement with media mass.

2.2.2 Vibratory finishing machine with straight wall and wide opening

Circular vibratory finishing machine VB(B)

Circular vibratory finishing machine VB(B)

The standard vibratory finishing machine without internal separation deck is simplest machine type. If you have no special requirement on parts, you can use this economic model to get started.

Straight wall vibratory finishing machines widely suit for most medium size parts deburring and cleaning.

vibratory finishing machine vertical wall

vibratory finishing machine vertical wall

Vibratory finishing machine vertical wall is one of our standard design. So this design provides efficient finishing of all part sizes. However, it is especially well suitable for larger parts as the straight outer wall allows unrestricted turnover of the work

vibratory finishing machine curved wall

vibratory finishing machine curved wall

The curved outer wall of vibratory finishing machine chamber aids in the roll-to-center action of the mass. Then it improves parts and media circulation and prevents small, light parts from remaining against the outer wall. Therefore it is especially effective in steel ball-burnishing, as well as ceramic and plastic media finishing.

2.2.3 Straight wall vibratory finishing machine with internal separation deck

Circular vibratory finishing machine with separation VBS(B)

Circular vibratory finishing machine VBS(B)

When you process hundreds or even thousands of parts each load, taking out parts piece by piece with the hand is time-consuming. Then you need a vibratory machine with separation deck integrated with the machine. When parts are ready, the lever at the right side of machine pulled down then the mass moves onto separation screen.

Media with smaller size go through the screen and parts with larger size keep up over the screen. After the final parts come out, you can close the level shutter and continue with next batch processing. For machine details, please check model VBS(B) vibratory machine.

2.2.4 Curved wall vibratory finishing machine with internal separation deck

Circular vibratory finishing machine VB(A)

Circular vibratory finishing machine VBS(A)

Curved wall design vibratory finishing machines are an excellent improvement based on straight wall design. They offer better tumbling performance with shorter processing time.

However, machine chamber width is narrower compared with straight wall design. Bigger components not easy to make the complete turnover. In addition, fewer media and parts mass can be put in the machine. For machine details, please check VBS(A) vibratory machine.

parts and media unloading in vibratory deburring machine

parts and media unloading in vibratory deburring machine

During processing, media move together with parts. At the same time, the weight of the motor is in an optimum processing motion. Meanwhile, separation deck inside the machine have no media and parts. So flap or deck will not affect media/parts mass tumbling.

parts and media processing in vibratory deburring machine

parts and media processing in vibratory deburring machine

The curved outer wall of vibratory finishing machine chamber aids in the roll-to-center action of the mass. Then it improves parts and media circulation and prevents small, light parts from remaining against the outer wall. Therefore it is especially effective in steel ball-burnishing, as well as ceramic and plastic media finishing.

2.2.5 Vibratory dryer machine with corn cob as media

Vibratory dryer VD200A

Vibratory dryer VD200A

Vibratory dryers have mostly the same design as vibratory finishing machines. Practically there are two types of vibratory dryers: one with PU lining and another without.

The one without PU design is most popular among workshops for simple design and maintenance free. There are 6 sets of heating elements installed beneath the vibratory bowl.

Usually, parts come out of vibratory finishing machine fall straightway into the vibratory dryer. Then parts run one circle in vibratory dryer tunnel and come out.

Corn cob is lightweight material, especially for the small size and grounded corn cob. A PVC cover is necessary to prevent corn cob dust flying.

However, if parts have blind holes, vibratory dryers not recommend. Because corn cob stuck into parts slots or holes is hard to take it out.

2.3 Media

2.3.1 Media type

For general deburring of hard metal material, ceramic media with brown aluminum oxide abrasive (corundum) is frequently used.

An experienced engineer selects case hardened stainless steel tumbling media for ball burnishing process. Plastic media usually choose for aluminum and zinc die casting parts smoothing and deburring. Please refer to article: vibratory tumbling media selection guide

2.3.2 Media shape and size

After you select the right media type, the next step is to choose right media size and shape. Right media size and shape is important to prevent parts lodging and easy for separation.

Firstly we choose the shape of media, the media shape not easy to lodge on parts even after a long time of running. Secondly, we choose the size of media. Media size should be significantly smaller than parts. As a result, vibratory finishing machines can easily make the separation on the screen. If parts are much smaller than media then you can make an inverse separation.

different media shape for mass finishing

Different media shape for mass finishing

Compared with small size media, big size media is cheaper, longer life, and cut faster. However, big size media leave rougher surface compared with small media. So you can choose the bigger media that not affect your surface quality.

2.3.3 Media to parts ratio

The final step is to decide media to parts mixture ratio. The media to parts ratio help to take control of media and parts surface contact. If media and parts surface contact insufficient, parts surface will scratch. The media act as a cushion to prevent parts-on-parts imprigement. For forgings, parts surface contact is not a key factor. However, preplating parts or polishing parts this is important factors to control

parts to media volumetric ratio

To maximize your output, you always want to put extra pieces in your vibratory bowl. However, too many parts in a vibratory bowl result in parts on parts impingement. So here we make some idea regarding media to parts ratio:

1:1 ratio: Media and parts are mixed in equal capacity. A small amount of media will make parts on parts hit and scratch a lot. This can work out when the surface mark is not a problem.

media to part ratio 1 by 1

The 1:1 ratio for parts have general deburring requirement, no special surface required

4:1 ratio: The average ratio use in the vibratory finishing process. However, with vibratory finishing machine with internal separation, you need to have higher ratio

media to part ratio 4 by 1

4:1 mixing ratio for most application, usually use for general smoothing and degreasing

8:1 ratio: 8 times and higher media to parts ratio suggest for delicate parts. This mixing ratio also used in vibratory polishing and burnishing process.

media to part ratio 8 by 1

8:1 mixing ratio for burnishing and polishing, as well as delicate parts process

2.4 Compound and water

The correct choice of the compound is very important to get optimal finishing result. Today most compounds are formulated in liquid form.

The most grinding compound can give a good deburring performance. Ball burnishing process requires specific compound formulation. Degreasing and cleaning of heavy dirt and oil need a strong acidic compound recipe.

There are mainly 3 compound dosing systems mostly used in industry. Bellow, I want to share the general idea with you:

2.4.1 Compound batch system

Vibratory finishing compound batch process

Vibratory finishing compound batch process

The batch methods refer to the addition of concentrated compounds to the mass of water, media, and parts. Usually, the drain is kept closed until the cycle is complete. After process finishing, the drain is open and the mass flushed with clean water.

2.4.2 Compound flow-through system

Flow-through compounding flows a controlled quantity of solution through the mass and out to drain. It is by far the most common method used today because it provides continuously clean media and parts.

compound flow through system vibratory finishing

vibratory finishing compound flow-through system

Flow through compounding is the most cost-effective way when in a correct control. To keep costs under control, flow-through compounding requires an accurate and automatic mixing the compounds, a controlled flow rate, and the introduction of the solution to the process in a correct location.

In compound flow-through system, liquid pump in and run away constantly

2.4.3 Compound Close-loop Recirculation system

Recirculation reduces or eliminates the effluent from the vibratory process. Recirculation includes compound discharge, filtering system, and compound dosing system to recharge effluent. So you can use the compound again and again.

compound close-loose system vibratory finishing

Compound in recycled in closed loop system in vibratory finishing machine

3. A step by step guide for vibratory finishing

3.1 Check your parts and decide machine volume

Make the estimation how many parts you need to run every day, how much time to finish them, the parts to media ratio. With the information above you will know the right size and model of vibratory finishing machine for your job.

how to select vibratory finishing machine size

How to select vibratory finishing machines size

For example:

You have 2000 pieces of the zamak3 belt buckle to deliver to your customer every day.

Each day you have 10 working hours in your workshop.

From sample testing you know vibratory smoothing process takes 1.5 hours with plastic media.

It will take 30 minutes for parts loading and unloading.

Now we can calculate we need a machine can hold up to 400 zamak3 buckles a batch.

To prevent parts scratch and hit, media to parts volume ratio is 3:1

After that, you measure 400 pieces belt buck stacking volume as 50L

The real volume for machine is 200L

However, in vibratory finishing machines, we only use about 70% of total capacity. This means machine total capacity 200÷70%=285L

You know you need a 300L (or 10 cubic feet) vibratory finishing machine

3.2 Find a suitable but not expensive machine

The most expensive machines not always the best choice. Keep machine simple as possible. The more complicated the machine, more likely it will go malfunction somewhere, especially for electronic structure.

Please check my article: 8 things you need to consider before buying mass finishing machines.

Sometimes, you already have the amount of money you want to invest in the project. Please read my article: how to make a budget plan for vibratory finishing machine in 60 minutes and how to order a vibratory finishing machine

We don’t install automatic oil lubrication system in the vibratory motor. This adds to cost and complexity of the machine. We would rather prefer a manual gun which lubricates once a month with 2-3 strokes. However, there are some accessories that we would recommend. Please read the articles: top 5 vibratory finishing accessories every workshop owner must have

If you can do with vibratory finishing machines without internal separation, then buy a machine without it.

The machine installation is important before you start to use the machine. Vibratory finishing machines structure is simple and ready to go. If you have experience for the job, you can do it by yourself following our vibratory finishing machine installation guide.

If you are first time user of vibratory finishing machines, better to find an electrician close to your location.

3.3 Make installation and run

Once you have vibratory finishing machine in your room, you cannot wait to run. However, check machine condition before running is necessary. Please refer to my article: vibratory machines checklist before running.

If you can choose electricity, go with 3 phase electricity, for example, 380V, 460 V or 480 V. A single-phase voltage 220V will greatly increase your amperage flow. Besides, 3 phase electricity is safer because it usually grounded.

After confirming with compound performance, you need also take a look at compound concentration. Because it is one of the important factors for your operational cost. A compound with high concentration and mixing ratio will save you lots of money; even their price is higher with the same package.

3.4 Make good maintenance to extend machine life

However, if the machine not works in the right condition, just call to the man where your machine purchase from. You can call your media supplier, your compound supplier. However, if you want to make maintenance of your machine with your own stuff, here is the guide: how to make maintenance of your vibratory finishing machine.

Also, read the articles: the 9 common mistakes you need to avoid to get most out of your machine.

And the article: A Definitive Guide to Reducing Cost of Operating a Vibratory Finishing Machine