Aluminum Fabrication Prototypes: CNC Machining, Sheet Metal, and Die Casting
Aluminum parts can be seen everywhere. It might be a robot arm, a medical device housing, or engineering components. Or a new consumer product. People like aluminum because it is strong, light, , stable, and affordable. It is also good for machine processing, and looks pretty after finishing.
Aluminum fabrication is not just one process, it has a wide range of methods. The best option depends on your part shapes, quantity, the lead time etc.
In the Xinprototype factory, we focus on 3 ways for aluminum prototypes:
- CNC machining for solid aluminum material with precision features.
- Sheet metal for covers, enclosures, and bracket-style parts via laser cutting, or bending aluminum.
- Die casting is the next step when the design is stable and the start volume.
Aluminum CNC Machining for Prototypes and Small Batch
CNC machining can mill accurate aluminum prototype parts in a fast delivery time. Especially when you need testing for urgently project. CNC milling a solid raw material to get the final shape as per the CAD design. This is a good choose for aluminum prototypes, which require parts have accurate holes, high tolerance, and precision size.
Many R&D companies use CNC aluminum parts as bridge production components in the early stages. For example, volume is still low, and design may still change.
CNC cost is closely tied to machining time. Such as deep narrow pockets, tiny internal corners, thin walls, and designs that require multiple setups. These are affect price and lead time. Adjustments a small detail without changing function, often also can reduce machining time. For example, changing the internal radii is bigger, without deep pockets design, and designing for straightforward tool access, etc. These factors will usually reduce CNC milling time and costs. Besides, quantity is very important for price. 1 piece prototype also needs to set up all programs, that make the labor price high. If for a small batch quantity, only need to set up one-time cost, avearage unit piece is very low.
For most custom aluminum parts, the 6061 series is the default aluminum choice because it machines well and takes anodizing surface finished is good. If you need higher strength for structural testing, 7075 series can be a good option, although it often costs more. If you’re unsure what is the specific series number aluminum in the start, 6061 is a safe baseline. Also you can swtich to other series material after testing.
Aluminum Sheet Metal Fabrication for Enclosures, Covers, and Electronic Parts
When a part is thin (0.5-5mm) and of the same thickness, or primarily defined by cutting and bends. Sheet metal fabrication makes sense. Sheet metal parts begin as a flat sheet, then they’re laser cut into a flat pattern. And then maybe bent on a press machine. Hardware part such as inserts, standoffs, and studs, can be added, and multiple pieces can be joined using screws, rivets, or welding, depending on design needs. More information, please read another article of ours about the application of fasteners in sheet metal.
Sheet metal fabrication is ideal for enclosures, covers, panels, guards, and electronic parts. A well-designed bent part can be surprisingly stiff, even at relatively thin thickness. That makes the parts have strong performance. It also creates a clean industrial appearance. Many manufacturing company, such as robotics, automation use sheet metal processing production of their aluminum prototypes.
For an aluminum sheet metal prototype, 5052 is commonly used because it bends well and resists cracking. For other grades may work as well, but 5052 is a safe starting point, as it has a good bending performance.
Aluminum Die Casting Parts for Mass Volume
In the early stages, aluminum prototypes may be made from CNC machining or sheet metal. Along mature of the test, the company will expand the markets. In this case, Die casting is primarily a production process for mass production. Product the aluminum part via a steel tool with singificantly fast speed. The unit cost is low along with volume. That’s why die casting becomes attractive when you need thousands or ten thousands of pieces.
Using CNC first to check the design, and then die casting for stable volume production. This is most of companies do like that. Because the tool is expensive. If a need for modification of tool design is take lot of time and costs.
Some factories are use a common hybrid approach for CNC milling and die casting both. Use the tool to die cast the main shape of the part. Including overall geometry, ribs, and bosses, etc. Then CNC milling the positions which requirements high tolerance, or need more details. Such as bearing seats, sealing faces, and tight hole patterns. Casting gives the part of the shape efficiently, while CNC provides the precision where it matters. If you are considering that your part will be produced by die casting, the design must include draft angles, stable wall thickness, and good flow paths.
Case Study: One Aluminum Prototype, Two Processes
One of our customers is from Europe. They’re an automation company that needed a new sensor housing for a compact conveyor system. The housing should be lightweight, strong, and easy to maintain. Also requirement fits in a tight space near moving belts.
At the start, they chose these aluminum parts made from a CNC-machined 6061. Because the first goal was to test assembly fit, to see if the design if reasonable, alignment, and real mounting behavior. The finished aluminum prototypes precision threaded holes, a pocket for the sensor, and a through hole as a cable channel.
During the testing stage, Two issues have been found. One is that the cable bend radius was too tight, which may stress the wire over time. Another is that the housing was heavier than expected, it will increase the load on the mounting arm.
To solve these two issues, our customer re-designs. They changed the cable path to a smoother curve. Change the thickness of the housing from 5mm to 1mm, the weight most of close to reduce 4 x times.
Based on the new version’s drawings, our engineers reviews of the details carefully. Our team recommends that we use CNC machining combined with sheet metal to cut the production costs for batch production in the future. The customer is very happy and accepted of our advices. Second aluminum prototypes passed the fit test and performed is perfect.
How to Choose Between CNC, Sheet Metal, and Die Casting for Your Design
Keep one thing in mind is the process you choose should match what you’re trying to know. If you need the part to be accurate, with precise threads and holes. The idea of CNC machining is typically the best option. If you need a part has lightweight feature. Such a PCB board, or an enclosure with laser cutting and bending. Sheet metal is often fast and more cost-effective. If your design is already tested samples, and you’d like to go into mass production, die casting makes sense.
In our experience, one part mix of two or three process methods is common. CNC-machined with sheet metal fabrication is a practical combination. CNC milling a groove, and then laser bending. Or CNC milling combined with die casting for complex structure parts. Casting the shape of the part, and CNC focuses on the details. The best choice is not one, it is according to different stages to switch as the product matures.
