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Rust Removal with Vibratory Finishing

1.   The cause of Rusting

A whole lot of interdependence comes into play in having a machine work properly. Without parts, there would be no process, and when parts are worn out or rusty, the entire process would be compromised. In order to have important parts of various components working properly, one must make sure that they are clean and free of rusts.

It is common knowledge that metals containing iron or steel become susceptible to corrosion when exposed to air, bases, salt, oil as well as water and oxygen. Rust is a coating of iron oxide formed by the process of oxidation on iron or steel. This has a lot of undesirable effects on metals and working components of machines. When corroded, metal parts which have been built to rotate become stuck.

It causes weakening of parts, slowly eating away even the biggest chunks of iron. Faced with this challenge, manufacturers have sought out different ways of ensuring manufactured parts last longer while performing better.

2.   Rust removal of with mass finishing

Vibratory finishing processes are largely used in manufacturing industries. These processes are very effective when it comes to rust removal. It improves the quality of parts making them safer to handle. It is a cost-effective mass-finishing process that allows for large quantities of parts to be refined at the same time.

There are various types of mass finishing processes including tumble or barrel finishing, as well as vibratory finishing. However, for the purpose of this article, we’re going to consider rust removal using vibratory tumbler mass removal machines.

This process consists of an operation in which compounds and specially shaped pellets of media are placed into a vibratory rust removal equipment along with the workpieces to be cleaned. As the process begins, the machine and all its contents are then vibrated. The vibratory action inside the compartment causes the media to rub against the workpieces leading to a smoother finish which are unattainable by hand.


3. Recommended Mass Finishing Machine for Rust Removal

There are two most commonly used mass finishing machines when it comes to rust removal from metal parts. They include barrel tumbling rust removal machine and vibratory tumbling machine. The major difference between the both lies in the way they create the friction required for eliminating imperfections from metal parts.


3.1 Barrel tumbling Mass Finishing Machine

The action on this machine can be compared to that of rocks tumbling down a steep hill. The machine consists of a barrel in which parts to be mass finished are placed along with suitable media and its complimenting compounds. Rotating the barrel causes a tumbling action on the workpiece that is placed inside. As the parts tumble down, they rub against themselves and the media producing the friction which leads to abrasion. This action causes the metal parts placed in the tank to be deburred, cleaned or polished.


3.2 Vibratory Mass Finishing Equipment

This machine consists of a vibratory tube or bowl. Metal parts to be cleaned are placed in the tube, and the process is started. The machine produces a vibratory action which is transmitted to the parts causing them to turn and grind against each other. This grinding action is responsible for the deburring or cleaning of the metal parts inside the bowl.


3.3 Comparing and Contrasting the Two Mass Finishing Processes

Vibratory mass finishing has remained the most popular option for mass finishing applications the world over. Reasons include:

  • The process is a lot more compatible with automation
  • Saves time
  • Reduce labor cost
  • Suitable for finishing more delicate parts
  • Causes minimal surface wear, leading to durability and increased lifespan of parts

Regardless of being the most widely accepted, vibratory finishing equipment and finishing systems, on the other hand, are a lot more complex when compared to barrel tumbling finishing systems. These complexities make them expensive to purchase, own as well as operate.

When compared to vibratory mass finishing systems, barrel systems could be seen to have the following disadvantages:

  • Longer finishing cycle
  • More aggressive leading to increased surface abrasion.


4. Case study:

Iron material easy to rust if not protected by an external coating layer. Below we share two cases of iron parts rust removal with ceramic tumbling media in the vibratory finishing machine.


4.1 Case 1 Iron shovel parts:


General comparison of iron shovel before and after rust removal
The general comparison of iron shovel before and after rust removal


Process before and after in details:


Comparison of iron shovel before and after re-rusting in details
Comparison of iron shovel before and after re-rusting in details

Before rust removal, parts surface is dirt and with rust spots. After 2 hours tumbling in the vibratory deburring machine, the surface is clean. Then it exposed the iron natural color on the surface.


Ceramic cylinder media is lodged in the shovel hole.
Ceramic cylinder media is lodged in the shovel hole.


However, we still need to take into account the ceramic media size and shape. The ceramic media size (width) should have 60-70% of holes diameter. So we can get the most use of the media before it has lodging issue. Compared with cylinder shape ceramic media, angle cut triangle cut faster for the same parts.

After deburring and rust removal, the parts need to soak into the rust inhibitor to prevent corrosion. This is an essential procedure before painting.


4.2 Case 2 Iron hollow disc:


Comparison of iron disc parts in general
Comparison of iron disc parts in general


When we get a close look on the part before finishing, we can see the rust is heavy. Also, there is a visible burr on the edge of the hole.


Comparison of iron disc parts before and after vibratory finishing in details
Comparison of iron disc parts before and after vibratory finishing in details


So the de-rusting process takes 3 hours with fast cutting ceramic media. For iron material, we have HM-A cutting compound which facilitates the cutting process. As a result, rust can be removed in a shorter time.

The bigger size ceramic media is proposed. Reason 1 is big size media cut faster. Reason 2 is the iron disc has many small holes. The big size media can use quite a long time before it starts to lodge in.


5. Conclusion

Many considerations come into play when considering which mass finishing method to use. Some of the factors to consider include the weight and geometry of the parts to be finished, time factor or production schedule as well as the cost and availability of resources.

Last, we show two examples of case study for rust removing out of iron parts surface.