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How to remove rust

Date: 19 July 2022 | Category: Articles Conseil, How to...

Removing rust from mechanical metal parts and protecting them from rust build-up is a common and very necessary operation across industries. It helps sustain equipment and machinery lifespan, and supports durability and full functionality.

Many solutions exist for de-rusting metal parts, using both chemical and mechanical processes, but they are often time-consuming, risk damage to the surfaces being cleaned of rust, can harm the environment and come with significant health and safety complications. Safetykleen’s parts cleaning services provide safe, effective, efficient ways to remove rust from metal parts.

How does rust form?

Rust forms as a result of a slow chemical process called an oxidation-reduction reaction. When the iron molecule, whether pure iron or an iron-based alloy like steel, is exposed to oxygen and water (both present in air) it reacts to form an orange-brown compound called hydrated iron(III) oxide.

Conditions that increase rusting

  • Proximity to salt water (because salt accelerates the rusting process)
  • High oxygen environments
  • Exposed, untreated surfaces

As soon as oxidation begins, it corrodes the metal, coats its surface with rust and changes its appearance. This process is not limited to rusting iron. Copper turns orange then green during oxidation, lead can turn blue/green, and even aluminium turns white. Left unchecked, oxidation will gradually spread, weakening the metal until it is perforated and crumbles.
 

Why remove rust from metal parts?

The consequences of rust forming on metal parts are significant in all industries.

Mechanical parts that swell or become more brittle due to rust can, under the pressure of production processes, easily reach breaking point and cause stoppages in production lines or breakdowns in vehicles. This can lead to significant intervention costs, as well as production losses and risky situations for the safety of operators.

One consequence of rust for businesses can be overconsumption of iron and steel products: more than 15% of steel production serves only to replace parts damaged by rust, at considerable cost in terms of purchasing and storage.

The consequences on the environment are also considerable in terms of the generation of waste from excessively damaged metal parts that are extremely hard to recycle or repurpose.

Implementing effective methods of rust removal as part of preventive maintenance, along with protective anti-rust coatings and can therefore help to ensure the durability of parts, saving money and saving new replacement purchases for expensive equipment.
 

How do you remove rust from metal effectively?

An effective industrial anti-rust process would ideally include a process for cleaning mechanical parts, components and tools upstream, which are generally covered in grease and dust. Cleaning like this can include special surface treatments to reduce the risk of rusting as the parts dry.

Removing rust from metal parts is a complicated task, especially when the surface of the part is not flat.

Fortunately, there are many current solutions for derusting and degreasing metal parts:

  • Chemical cleaning approaches using baths filled with things like phosphoric or hydrochloric acid
  • Mechanical processes such as sandblasting, shot-blasting or mechanical brushing and polishing
  • Industrial parts washers using specially formulated detergents and/or ultrasound

 

Chemical rust removal

A chemical deoxidation process based on phosphoric acid, hydrochloric acid or caustic soda can remove rust easily, but presents many risks, both for the operators and for the parts.

These products will stop oxidation and remove rust but are highly corrosive and will irritate the skin, eyes, respiratory system and digestive tract. Best practise is to consult the product’s Safety Data Sheets (SDS) before handling or using them. They are also dangerous for the environment, in particular aquatic environments because they increase the pH of waterways and can harm both flora and fauna.

They can even damage the material being cleaned, in particular when the surfaces are finely machined or precisely finished.

Mechanical rust cleaning

Mechanical approaches to rust removal are the most common methods use when dealing with cleaning metal parts and components, but they can be time-consuming and labour-intensive.

Most common among them are sandblasting and shot-blasting. These blast-based parts cleaning methods must be performed manually by a trained operator, require a steady supply of single-use cleaning material (blast media), and expose operators to respiratory risks associated with the dust generated and dispersed in the air.

Damage during cleaning is also a risk. High-pressure abrasive blasting can cause severe pitting to appear on the surface of the metal being cleaned, while techniques using abrasive sandpaper or radial brushes can leave trace grooves in the metal. In addition, these processes often need to be followed by intensive polishing to achieve a satisfactory finish.

Rust removal with industrial parts washers

Fast, simple and efficient, industrial parts cleaning machines can remove rust from metal parts as effectively as they clean grease and dust.

Ultrasonic cleaners are the best solution for degreasing and completely eliminating rust while preserving even the most delicate and complicated metal parts. Ultrasound waves create pressure variations when passed through a liquid. These produce millions of tiny microscopic bubbles which burst on contact with the items being cleaned, releasing a lot of energy energy which causes rust particles to detach from the surface, and generating movement in the liquid that helps separate the waste from the cleaned item.

Once loaded with the parts to clean, these machines run automatically on preset programmes that free operators for other important tasks while ensuring consistent cleaning results from load to load.

 

Safetykleen rust cleaning solutions

Regular MRO can help slow the build-up of rust, and so both our high-pressure manual parts washers and our automatic parts washers can act as your first stage of rust removal. Our service solutions include machines suitable for a wide range part sizes. We match these with high-performance cleaning detergents that are specially formulated to prevent flash rusting.

When it comes to removing built-up rust, we offer an electricity-free, immersion approach to removing rust that delivers outstanding results with virtually no operator involvement, and ultrasonic cleaners that add the precision cleaning performance of ultrasound to that immersion approach to tackle even the most intricate component shapes.

Our rust removal products

Our rust cleaning machines combine with special water-based de-rusting detergents that are VOC (Volatile Organic Compound) free to quickly and effectively remove all the rust from your metal parts.

Passive rust-removal

Our Rustkleen immersion tanks allow you to remove rust by immersing the parts in a bath filled with a special water-based cleaning solution. Simply load the parts you want to clean into the bath and leave the detergent to do its work. No electricity needed, minimal manpower and no danger of damaging the underlying material beneath the rust.

Ultrasonic rust cleaners

For higher levels of cleaning performance, our Rustkleen Ultra machines are the ideal solution. Up to 10 times faster than traditional approaches to removing rust, they offer shorter cleaning times and automated cleaning cycles so that your team can turn to tasks elsewhere.

Rust removing fluids

Both our rust cleaning approaches use a custom water-based, non-corrosive, non-toxic and VOC-free chemical solution. This targets the elimination of rust while keeping the fine or painted parts of components intact. It gently breaks apart rust molecules and lifts them away from the surface of the part so that they can be rinsed away easily after cleaning.

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Rust removal FAQs

What is the difference between rust, oxidation and corrosion?

Oxidation is a chemical reaction in which a substance loses one or more electrons from its atoms, molecules or ions. Corrosion is the name given to a range of different chemical reactions that take place on the surface of a range of materials. Rusting is a specific type of oxidation and corrosion of iron (and iron alloys) that results from exposure to oxygen and water.

How do you prevent the reappearance of rust?

Once you have removed rust from a metal component, one of the most effective ways to protect it and prevent future rusting is to treat the surface. The right surface treatment can help reduce maintenance costs and extend the usable lifespan of the part.

Different part materials and uses will require different anti-rust surface treatments.

Temporary storage oil and grease coatings are used to protect parts for a short period of time, usually for transport, and some wax and ceramic coatings can be used as a combination of lubrication and waterproofing. Temporary surface treatment can also involve things like anti-corrosion paint or varnish.

Permanent coatings tend to be more expensive, but can extend the life of metal parts much further. Some common examples include covering the part with a layer of another metal to isolate it from contact with air and water. These fall into two categories:

Non-reactive coatings that use with a so-called passivating oxidation layer. This could be a metal like tin (especially in the food industry), chromium and cadmium, or a ceramic or carbide (for example tungsten carbide)
Reactive coatings, for example galvanising steel with zinc. The zinc oxidizes and forms a barrier layer that protects the steel beneath.

Is rusting always a bad thing?

Mostly yes, but there are examples where it can become a protective coating in its own right, for example weathering, or COR-TEN steel, which was developed to remove the need for painting. In these materials, the reaction with weather and other external factors is controlled by the mix of alloys and the way they are distributed within the material. Over time, this results in the surface developing and sustaining a stable rust-like coating that actually preserves and protects the material as a whole.