Metal prototypes are prototypes made in metal materials, such as aluminum, stainless steel, copper, zinc, magnesium, etc. The aluminum prototype is one of the most commonly applied metal prototypes. Metal prototypes are usually produced via CNC machining, 3D printing, casting, sheet metal fabrication, extrusion, etc. 

In this case, we would like to show you our previous work of CNC machined aluminum prototypes in gray satin painting with pictures shown at the end of the article.

Why did the client choose metal as the material, not plastic?

Prototype materials are determined by the material of the end-use product, part structures, prototyping methods, and budgets. In most cases, the end-use product material is the top priority. Because the purpose of a prototype is to test the design. It is better to use the same material as the end-use product. As the products were designed to be in aluminum material, our client chose to make aluminum prototypes but not plastic ones. 

Despite considering the end-use material, compared to plastic prototypes, metal prototypes are more accurate, firmer, and usually last for a longer time. Aluminum is often commonly used metal material because it is light, easy to be manufactured, and cheap. Also, CNC machined aluminum prototypes can precisely reflect the engineering design. After surface treatment, aluminum prototypes can even look better than those by mass production.

Why did we CNC machine the aluminum prototypes?

Several methods can be used to manufacture an aluminum prototype. Among them are CNC machining, 3D printing, sheet metal fabrication, die casting, and extrusion. In this case, CNC machining is the best choice because of the following reasons:

1. The costs of 3D metal printing are estimated based on the weight of the metal powder needed. It is relatively expensive. The tolerances are not as high as that of CNC machining. And the surfaces are rough as well.

2. The material thickness for sheet metal fabrication is very limited, usually, it is less than 6 mm. But in this case, the thickness of the aluminum parts is more than 6 mm. Sheet metal fabrication is not possible to make them.

3. Though aluminum prototypes produced by die casting are highly durable, it requires expensive tooling for production. CNC machining is more cost-effective.

4. Aluminum extrusion is usually used to make squared bars or hollow profiles. The part shapes are quite limited. CNC machining embraces greater design flexibility.

Painting Finishing

Painting is the most widely-used finishing treatment, by which you can get glossy, matte, satin, or textured surface. There are two kinds of painting: coating spraying and powder spraying. The processes for plastic and metal prototypes are different.

Before the plastic prototypes are painted, the finishing technician first has to polish them. When it is sanded, it has to be polished smooth, make corners clear, and remove the obvious glue marks. The sanding must be done several times. After grinding the parts for the first time, the technician sprays primer paint and then grinds again. After filling ashes and other processes, the painting is finished with the last time of grinding.

For sheet metal prototypes, after it is prefinished, the technician sprays the coating on the surface with a spray gun. Just waiting for the coating to dry out, and the painting work of the sheet metal prototype to be done. The painting process of sheet metal prototypes is simpler than that of plastic ones.

Before painting aluminum prototypes, the technician needs to polish the surfaces. But don’t take polishing for granted. You must pay attention to precision requirements, and keep the smoothness and clear angles accordingly. The paint for aluminum prototypes is generally metal paint.

However, some materials are difficult to be painted, such as PP, Nylon, and POM. The painting is easy to fade. They are suitable to be high wear-resistant prototypes, mainly as gears and other parts for assembly, rather than appearance prototypes.

Pictures of aluminum prototypes with tapping

aluminum prototypes with tapping

Pictures of other painted metal prototypes in aluminum for the same project

painted metal prototypes in aluminum

painted metal prototypes in aluminum

painted metal prototypes in aluminum

painted metal prototypes in aluminum

FAQs of Metal Prototypes

1. Why should I choose metal prototypes?

Prototypes made of metal are better mechanically, more accurate, and more aesthetically pleasing.

2. In metal prototypes, why the aluminum prototype is a good choice?

Aluminum material is the cheapest metal material for metal prototypes. It is relatively easy to machine and has excellent electrical conductivity, thermal conductivity, and corrosion resistance. 

3. What’s the most commonly-used aluminum material?

Aluminum 6061. It is the cheapest aluminum alloy material. When developing aluminum prototypes, AL 6061 is always the first choice.

4. Instead of painting in this case, what are other finishings for aluminum prototypes?

Other finishings include sandblasting, anodizing, electroplating, e-coating, and thermal transfer printing. With these treatments, you can enhance the surface hardness and wear resistance, expand its application range and prolong the usage life. Anodizing is currently the most commonly applied finishing for aluminum prototypes.