Aluminum is one of the most widely-used materials in the industrial field. It is used to make products almost in every industry. Aluminum CNC (Computer Numerical Control) machining is one of the processes of manufacturing aluminum parts from aluminum plates. Besides mass production, CNC machining is also for one-off aluminum prototype production and low-volume manufacturing. Making aluminum prototypes through CNC machining plays a vital role in the R&D processes. That is why you must know how to maximize the advantages of CNC-machined aluminum prototypes. 

1. Advantages of aluminum material in CNC machining

Low density:

Aluminum has low density but relatively high strength, which is close to or more than that of high-quality steel. The CNC machining tool has low resistance when cutting aluminum material, so the machining process is faster and consumes less energy. Therefore, high-speed machining can be used to machine aluminum parts, while also obtaining better surface smoothness. In many cases, just having the aluminum parts as machined without any finishing is enough for prototyping. For as-machined aluminum parts, you will see obvious tooling marks but the surfaces are smooth.

Good figurability:

With good figurability, aluminum can be processed into a variety of shapes, even with complex structures. So there are possibilities to realize your fancy designs.

Excellent thermal conductivity:

Aluminum has excellent thermal conductivity and can dissipate heat faster than most materials during machining. During CNC machining, the tool cuts the material at high speed and generates a lot of heat. In the event that the heat is not dissipated in time, it may lead to high spindle temperatures and damage to the motor and other equipment.


Aluminum is harmless in waste disposal. Its melting is 660 ℃. So it is also easy to regenerate.

Wide applications:

A combination of excellent electrical, thermal, and corrosion resistance, aluminum is widely used in industry, second only to steel, as a structural material for airplanes, trains, trams, and automobiles, as well as industrial machinery and tools, electrical equipment, and thermal installation parts.

Aluminum materials used in prototyping are usually the 6061, 6063, 5052, and 7075 series. Aluminum 6061-T6 is the cheapest aluminum alloy, thus enjoying the broadest application in CNC-machined aluminum prototypes. If you do not have a strict requirement for the specific aluminum, AL 6061-T6 is enough for prototyping. In other cases, ask your manufacturer to help you decide the material type based on the material properties you need. Be careful to choose good quality raw materials. Otherwise, there is a good chance of blowholes after oxidation.

2. Choices of aluminum prototype machining methods

CNC machining is not the only way of aluminum prototype machining. SLM 3D metal printing, sheet metal fabrication, and aluminum extrusion can also manufacture aluminum prototypes. Then how can you decide the specific process when needing aluminum machining services? Generally speaking, CNC machining is the best option. 


SLM, Selective Laser Melting, is a crucial technology in the additive manufacturing of metal materials. It uses a laser as the energy source to scan the metal powder bed layer by layer according to the path planning in the 3D CAD slice model. The scanned metal powder is melted and solidified to achieve the metallurgical bonding effect and obtain the metal parts as designed. 

During the processing of SLM, it is likely that there is spheroidization and warpage deformation. It also has pores, and its mechanical properties are not as good as those of CNC-machined aluminum prototypes.

Sheet metal fabrication:

Sheet metal fabrication is a manufacturing process for thin sheet metal parts that can be processed through stamping, bending, stretching, etc. The thickness of the sheet metal remains unchanged during processing.

For sheet metal fabrication of aluminum parts, the thickness is very limited. The thickness must be within 6mm.

Aluminum extrusion:

Aluminum extrusion is the process of extruding aluminum profiles, commonly known as "aluminum pulling" or "aluminum extrusion". Aluminum bars are heated to about 480 degrees in a furnace, and the die is heated simultaneously to 480 degrees. Then, the heated aluminum bar is extruded by mechanical pressure through the mold installed in advance. 

As mold is involved, there is often a MOQ requirement for aluminum extrusion. So it is relatively rare in prototyping.

CNC machining:

The engineer writes the processing program according to the 3D drawing provided by the customer. Based on the program, the CNC machine removes part of the materials leaving the rest the same as the 3D drawing.

CNC machining is more flexible for making aluminum parts. The parts are also more stable and aesthetic after finishing. So it is better to turn to an aluminum CNC machining service than all the methods we are talking about.

aluminum CNC machining service by X Rapid Technologies

3. Surface treatments for CNC machined aluminum prototypes

The surface treatments of CNC machined aluminum prototypes are relatively more complex than that of plastic prototypes. Despite painting and silk screening and other finishing that can be done to plastic and aluminum prototypes. Aluminum prototypes via CNC machining can also be oxidized and electroplated in different colors. They can also be polished to gain a mirror surface. Occasionally, you can get aluminum machined without any surface treatment if you only need it to test the structure of your new product, which saves you money.

Via proper post-treatments, the stability of aluminum parts can also be improved:

Anodic oxidation:

Anodizing uses the principle of electrolysis to form a layer of oxide film on the surface of the CNC machined prototype to increase corrosion resistance and get a good-looking surface. Black anodizing is the most widely applied finishing for aluminum parts.

Conductive oxidation: 

After conductive oxidation, aluminum parts via CNC machining obtain a certain degree of corrosion resistance and conductivity. It is often applied for electronic equipment prototypes. Aluminum parts with conductive oxidation can prevent electromagnetic signal interference.


With the aluminum part acting as the cathode and the plating material acting as the anode, a plating solution is used to plate the metal parts. Then a direct current or alternating current is applied to cause the plating material to ionize and run from the plating solution to the surface of the workpiece, firmly attaching to it to form different thicknesses of plating.

CNC machined aluminum prototype

CNC machined aluminum prototype1

4. Costs of aluminum machining services

It is common knowledge that aluminum raw material is more expensive than plastics. The time required for aluminum prototype machining is longer than for plastic prototypes because aluminum sanding can be more complicated and surface treatment can be more complex. Due to these reasons, the cost of aluminum CNC machining service is higher than that of plastics. 

Meanwhile, SLM 3D printing aluminum prototyping, which charges based on weight, is more expensive than CNC aluminum prototype machining in most cases.

In X Rapid Technologies, we select aluminum raw materials of the highest quality and ensure tight tolerances. Our CNC machined prototypes are finished with excellent surface treatments. We pride ourselves on delivering every project on time. Welcome to contact us for free quotes and kickstart your project. We would be honored to witness a new design turning into reality. 

FAQs of Aluminum CNC Machining

1. How can I get a quote for CNC machined prototype from you?

Just send us your 3D files in CAD, STP, STEP, IGS, or X_T format with the quantity and finishing needs. We will quote you within 24 hours. In many cases, the clients send us STL format, which is widely used for 3D printing. But for CNC machining, STL cannot be used for manufacturing, it is only for cost estimation. Only the files mentioned above can be used for production.

2. How do you ensure the secrets of my intellectual property?

Our professional ethics demand that we safeguard the secrets of our customers' intellectual property. We totally understand that keeping the secrets of the intellectual property of new products is vital. We can also sign NDA whenever you need it. Even without one, your intellectual property will be well protected.

3. What is the average lead time?

The lead time depends on the quantity, finishing, and your other requirements. It will be included in our free quotes. The lead time depends on the overall production schedule of our factory. It is usually 3 to 7 days. The production schedule is changing. You will be informed of the actual lead time after the order is placed.

4. How do you ship aluminum prototypes to other countries?

International express is always the first choice for cross-border shipment. If the amount is large, we will help our customers to decide whether to ship the aluminum parts by sea or train together with our shipping agent. The average shipping time is 3 to 7 days. You can also work with your own shipping forwarder. We are very flexible depending on your needs.

5. What are your after-sales policies?

Ideally, we don’t expect any problems after you get the parts. Within 3 days of receiving the components, if you have problems, please contact us to communicate so that we can resolve them in a timely manner.