Sandblasting Aluminum: A Comprehensive Guide

Mostly people have no idea what sand blasting Aluminum (Al) is, unless you are professional or previously you have done any project related to this. But we are here with this article to provide an ultimate guide to this article. The other name of this method is abrasive blasting. a generic term is used to smooth, shape, and clean the hard surface. Solid particles are applied with force at high speed, same as by utilizing sandpaper but the component has better and smooth finishing at corner by sandblasting. More information about this method is mentioned in this piece of writing explained with the procedure, types of blasting media and common issues occur in this process.

What Is Aluminum Sandblasting?

A method of applying abrasive material forcefully to an Aluminum component is Aluminum sandblasting. The abrasive material is normally sand or glass bead blasting aluminum. It helps in smoothing or roughening the component or used for removing paints and changing the surface finishing. The purpose of this method is to take off the pains or primers from the part, for cleaning the rust, can be applied as a pretreatment for new paints or powder coating, for removing damaged surface finishing, for adding decorative element, to clean the surface by fire damages, or for smoothing or roughening the part.

Can you sandblast aluminum?

Conventional process of sandblasting Al surfaces is by dry blasting. After that, the surface was polished, and it is then able to paint or coat. This procedure is suitable for automotive applications or for boat hulls. The sandblasting Al for openair application is normally carried out by pressurized pot sandblasting.

Best Media for Blasting Aluminum

The best medias for sandblasting al are crushed glasses,

Crushed Glass

Normally consisted of using recycled glass that can be used for removing powder coatings and which sharpness profile can be identified easily. Surface The polishing results are better than that obtained with sandpaper or slag. Crushed glass method is toxic free and non-recyclable. The polishing surface has an angular shaped feature, and it is a relatively fast process than can be done with water.

Aluminum Oxide abrasive

Aluminum oxide abrasive is a cost-effective option for sandblasting. Normally carried out for removing, deburring, and etching the paints. Various size of abrasive material is available for smoothing the corners in polishing. It is a reusable process and a fast process providing angular shaped polishing features of the final product.

Staurolite

Staurolite is a combination of iron silicates obtained from metamorphic rock. A relatively efficient media used for powder coating, paints, corrosion, and scale removal. Generally, produces less dust and has a sub-angular shape that is suitable for reducing surface profile.

Plastics

Polycarbonate and polystyrenes are normally used as abrasive materials. A suitable option for removing paints and molds on delicate parts. This material is toxic free, provides anchor free patterns on surface with having angular shape. It is relatively fast abrasive process.

Walnut Shells

Utilized for relatively sensitive operations such as for polishing or cleansing. The reason is the organic nature and less rigidity of walnut than plastic or metal. general applications are for polishing jewelry, antique parts, motor, aircrafts engine, and for die and mold cleaning. It does not form anchor pattern, sub angular shape and relatively a slower process. It is a non-recyclable material unlike others.

Silica Sand

A common abrasive material but has limited application due to high toxicity. It is a round shape abrasive with high hardness and a low-cost process. It causes respiratory issues and moisture present in sand cause parts ageing.

Garnet

A silica derivate occurs naturally with outstanding abrasive features. The best coating preparations and qualities make it suitable for dry and wet blasting. a good option for outdoor applications with high stripping rates. Produces relatively less dust, is cost effective and is a fast-polishing material. also, a recyclable material allowing feathering controls.

Glass Beads

Normally used for propeller and turbine blade. It produces smooth and bright surface by sphered particles rather than having angular abrasive. They can be used for cleaning, polishing the auto components, and removing paints. It is a recyclable material with cost effective features.

Soda

Soda bicarbonate is used as abrasive material for paint removal and cleaning the surfaces. Metals can easily be sandblasting with soda without being deformed. It has angular shape particles and a non-recyclable media.

Surface Type and Condition

Sandblasting is used for cleaning the surface. The surface and finish and textures are dependent on the blast media type, densities, shapes, sizes, hardness. It also depends on media accelerations, volume, distance, and angle of the processing. Sharped and hardened particles can result in unwanted damage. Therefore, recommended materials for aluminum sandblasting are glass bead blasting aluminum, stainless steel and ceramics shots, soda, plastic and walnut shell.

Blasting angle

The required sandblasting angle is 60-45ᵒ for gun. When it is at 90ᵒ, it can cause peeing by the collision of particles, and they can start bouncing off the surfaces and media wear can be resulted at higher rates.

Pressure control

Recommended pressure is 50-60psi to avoid warping and indents to occur. Aluminum panels are thin and are prone to warping during blasting. Therefore, it is recommended to use low pressure initially and then increase gradually.

Sandblasting Aluminum Wheels

The best abrasive medias for sandblasting Al wheel are plastics and glass bead blasting aluminum. Walnut shell and corn cob are also good choices for wheels. The recommended grit must be 200 for initial stages then it can increase up to 300 grits for fair sandblasting. Conventional method for aluminum is dry blast method which is followed by polishing and powder coating.

Sandblasting Aluminum Cost

Normally, sandblasting aluminum can cost you $2-5/square ft. It is a relatively expensive method which charges $45-75/hr. A professional sandblaster can cost up to $1.5-3/square ft.

Common issues with sandblasting aluminum surfaces

During sandblasting, different issues are related to each abrasive material. It is therefore important to follow guidelines.

1. Abrasive properties are important to consider. Sharp corners can cut the surface and soft material can cause pitted surfaces.
2. Steel grits must be avoided for aluminum sandblasting because it can cause corrosion.
3. Aluminum oxide abrasive and crushed glass are the best choices for aluminum painting and powder coating because it makes adhesion easier.
4. Glass bead blasting aluminum has a good finish and leave a cleaner aluminum surface after polishing.
5. Fines sandblasting media ease in surface preparation.
6. Low pressure is recommended for thin surfaces to avoid warping.
7. The small section is recommended to test first before applying to whole surface to avoid any undesired results.
8. Size and shape of products has great effect on the hardness, size, and shape of abrasive media. It affects the surface finish.
9. Wet abrasives have less velocity and efficiency than dry abrasives.
10. It is important to consider that Lifetime of nozzle assembly decreases in the wet abrasives.

FAQs

Sandblasting Aluminum Surface roughness or unevenness

Sandblasting can decrease surface roughness. But different rotational speed during the process can result in poor surface roughness.

How to polish sandblasted aluminum

Fine grit sandpapers are used to polish sandblasted aluminum. The grit is normally 400 size and can be buffed for mirror-like polishing.

120 grit aluminum oxide sandblasting media

Aluminum oxide abrasive glassis a hard-wearing sandblasting medium and has a long lifetime. It is a fast process and removes impurities rapidly and quick surface texture preparations.

Soda blasting aluminum

Delicate parts are sandblasted by soda. It is a nondestructive method and leaves a smooth surface with a non-anchor profile.