A typical example of this is automotive development, where small initial quantities are required for validation processes. This critical demand undoubtedly represents a major challenge for parts manufacturers. When customers order a few dozen parts, it is often difficult to respond, which is why automotive suppliers often have to resort to customized solutions. Traditional, long-lasting, off-the-shelf tools are expensive and generally not practical for small-batch production where only small quantities are needed. Professional rapid prototyping companies are usually the quickest to understand designers' needs and provide custom aluminum machining services to meet the need for small quantities or even a single part.
Among all the rapid prototyping projects I know in the lighting field, the aluminum reflector is one of the most demanding jobs that only the most experienced prototyper can satisfy the optical designer. It goes without saying that the reflector is an optical element of a headlight that not only plays an optical role, but also has a decisive influence on the appearance of the lamp. We were impressed by the enchanting light from the BMW and Audi headlights and the light from the taillights. The reflective part is the reflector. An aluminum reflector used primarily in high-tech automobile prototyping. Product designers particularly expect prototype manufacturers to be able to fully understand every detail that concerns them.
1. What is the best process for making an aluminum reflector prototype?
For automotive parts, rapid prototyping manufacturers often offer different processing options to meet different needs, such as 3D printing (additive manufacturing), urethane casting (silicone molds), RIM, and rapid tooling.
A good surface roughness is often required, generally below Ra0.2 μm and must be of high gloss. Normal SLS and other rapid prototyping processes cannot meet surface quality requirements. Furthermore, as an important optical component, the accuracy must be limited to 0.05mm or less. Therefore, CNC milling is the best option for machining aluminum reflectors. The advantage lies in the high precision machining of the parts and the high surface quality of the CNC milled parts.
However, due to the complex structure of the reflector, 5-axis CNC machining is required to complete production. Some rear mount structures also require additional processing, such as EDM, to clean up the corners.
2. Material selection
In the production of prototypes of automotive lighting parts, the most used aluminum alloys are 2024, 5052, 6061 and 7075.
For parts like heat sinks, we can simply choose Al-6061-T6 because the material is easy to machine. However, for reflectors that need to have a high gloss finish, we usually use Al 7075-T6, which is widely used in the automotive and aviation industries, such as wing and headlight reflectors. The hardness of the material is higher, which means it takes longer to process. The advantage is that the final surface can be high gloss.
3. Editing process
3.1 CNC milling
3.2 Electroerosion
Due to the complicated structure of the lamp, there are many details that even a high-precision 5-axis CNC cannot process completely at one time. CNC programming engineers with extensive experience producing lamp prototypes need to analyze machining feasibility after receiving lamp design drawings. For reflectors, the critical optical surfaces are CNC milled, but there are important mounting structures on the back that are difficult to machine with CNC milling because large radii are created at the corners. Therefore, technicians need to fabricate copper electrodes and use EDM as an additional machining process to clean the corners. This process usually takes a long time.
3.3 After completion
In the later phase of prototype production, hand-made deburring, polishing, plating and other post-processing work are particularly important as they directly determine the final appearance.
Normally the reflector must be of high brightness. This can be achieved in two ways. One method is manual polishing. After polishing, the surface may have a high shine. However, great care must be taken when polishing optical surfaces, as some optics require sharp edges and the polishing process can leave rounded edges.
Another method is plating. Before plating, a beautiful milling surface and the absence of impurities are very important. The final finishes can be very bright and beautiful.
