CNC Machining for Complex Bracket Design Case Study
Learn how WayKen uses CNC machining processes to produce complex bracket designs with high accuracy and ensure assembly.
At a Glance of the Project
| Information | |
|---|---|
| Industry | Automotive & Transportation |
| Product | Car Headlight Bracket |
| Challenges | Sharp corners with assembly requirements, multiple machining directions |
| Technology | CNC machining, EDM |
| Material | Aluminum 6061-T6 |
| Surface finish | Sand blasting, black anodizing |
| Quantity | 1 Set |
| Lead Time | 7 Business days |
About the Product
A headlight usually includes a low beam, a high beam, a daytime running light, etc. In detail, there are many components including LEDs, reflectors, PCBs, lenses, heatsinks, wires, and so on. To achieve a reasonable distribution, these parts will be mounted to the bracket which will be fixed on the housing.
Jamie is an engineer in the headlight R&D department of a well-known automotive product. He designed a bracket with a multi-faceted structure for the headlight. Due to the complexity of the headlight bracket, he tried to make the bracket by 3D printing, but the accuracy was poor. So he wanted to find a suitable process to produce this bracket.
Determine Processes and Materials
This shaped bracket has a complex structure including deep cavities, pins, and undercuts on multiple surfaces. So no matter considering cost or accuracy, the CNC machining process is always the best choice when only 1 set is made.
In addition, consider the complex structure, if choose PC or PA+GF to make the bracket, it’s easier to deform while CNC machining. What’s more, certain structures of this multi-faceted car bracket need to be processed through EDM, which needs the material to be conductive. Therefore, WayKen recommended AL6061 as the workpiece material.
Machining Keypoints Analysis
As we can see, this shaped bracket has complex structures on each side which challenge it to manufacture. Here are key points of analysis and machining solutions from WayKen’s engineer.
Using EDM to Manufacture Sharp Corners
EDM is a process in which a specific shape is burned out by discharging an electrode with the corresponding geometry. As additional cost is needed to manufacture the specific electrode, EDM will bring higher costs. So in general, only when the structure can’t be machined by CNC machining, EDM will be chosen.
Let’s check the structure of the bracket, you can see deep cavities, pins, and undercuts from the front and back sides, but there are still some detailed structures on the lateral side. Therefore, not all these structures can be produced while CNC milling.
Like the emptied pocket structure of the bracket, 1-2cm away from it, there’s a wing structure up to 9cm. While machining, the CNC spindle will be blocked by the wing to reach the bottom of the pocket, consequently the pocket cannot be emptied out internally. Moreover, while machining the undercut (in the green frame), as the cutting tool will be obstructed no matter from which side, there’s always part of the structure that can’t be machined out.
Even without the undercuts, EDM is also necessary. Due to the limitation of CNC machining, fillets will be left at sharp corners, influencing the assembly relationship of this shaped bracket. Similarly, the other slot in the following picture is also required to be processed by EDM.
Consider Fillet Size and Tool Diameter
After analyzing the CAD model of the shaped bracket, WayKen proposed DFMs and discussed with Jamie over assembly requirements.
In general, the front side of this shaped bracket is flat and wide, most structures are designed with large fillets, excluding some ribs. So it’s a key point to determine the fillet size of ribs, which allows a larger cutting tool to reduce material quickly. In addition, these ribs have no assembly need and deep depth, so we suggest Jamie relax the fillet size to R5. In this way, ribs can still perform their function and reduce machine working hours.
While manufacturing the lateral side of the car-shaped bracket, there’s a long wing structure with a deep cavity. Therefore, choosing a cutting tool with an appropriate diameter is crucial. As the picture shows, the small machining area of the wing structure limits the diameter of the tool. However, the cutting tool can not be too small, for it’s easier to break while manufacturing the deep cavity. After careful consideration, the diameter of 2.5mm is selected, leaving fillets of 2.5mm.
Ensure Precision By Set up Fixtures
During the machining process, the machinists will use methods to position workpieces accurately after changing the machining direction. But it’s time-consuming, so programmers will design the sequence of each side, reducing set-up times.
For this shaped bracket, WayKen chose to manufacture the lateral side first to mill the cavity out. Then when machining structures on the front and back side, no plaster is needed to fill the plane. So it can avoid inaccuracy brought by uneven surfaces. In addition, in each set up, we posit the workpiece in the six degrees of accuracy using tools like percent guage. Then, the workpiece will be fixed by fixtures to ensure its stable position and accuracy during machining.
Feedback
When Jason received this shaped bracket, he said “It was amazing that you can do such a complex structure with a high precision. It really helps a lot.” With comprehensive manufacturing capabilities and a dedicated team, WayKen is your trusted CNC machining supplier, offering one-stop services from prototype to production. We are also constantly optimizing our production and inspection capabilities. If you would like to learn more about our CNC machining projects, please contact us and learn more detail.
