The Mavic Air is DJI's latest addition to the drone market and a combination of its predecessors, the Mavic Pro and the DJI Spark, the smallest DJI drone.
The camera, the gimbal and flight related aspects of the drone are impressive, however, we’re not here to review those features.
Instead, we take a different approach. We break down the design to identify the manufacturing decisions behind this new product and give you better insights into the why's, the what's, and the how's of the Mavic Air manufacturing process.
The body of the drone, the home of all main components, like the camera, gimbal, control unit and battery, is manufactured in several production steps.
Ejector pin marks (injection molding) clearly visible on the frame.
Step 1: Choosing a manufacturing process for the frame
The main structure of the body, the frame, is injection molded. Injection Molding is a cost-efficient technology for manufacturing high volumes of identical parts that need to meet specific design requirements.
To implement this technology, the molds for the injection molding process need to be manufactured in an earlier stage. This is done through CNC machining. CNC Machining offers excellent accuracy and repeatability and can produce parts with very tight tolerances.
The material for the mold? Tool steel H13. It is commonly used for injection molding of aluminum, magnesium and zinc and the ideal choice for molds designed to produce millions of parts at fast cycle times.
This video shows an example of the manufacturing process of a drone frame mold:
Once the molds are manufactured, the injection molding process can begin.
Step 2: Selecting the right materials
For smaller drones like the Mavic Air which weighs in at only 430g, a few additional grams can reduce the battery time dramatically, making weight the number one concern.
To make the Mavic Air as light as possible, the body is injection molded from the same material as previous high-end DJI drones, a magnesium alloy. The alloy used for the Mavic Air is the AZ91D with 90% magnesium, 9% aluminum and 1% zinc. Magnesium AZ91D offers excellent strength and corrosion resistance and better manufacturability than other magnesium alloys.
With a density of only 1.7 g/cm3, it is one of the lightest structural metals in the world. It is 34% lighter by volume than aluminum, 50% lighter than titanium. Due to its mechanical properties, it is a popular choice when manufacturing enclosures and frame components of electronic products.
Step 3: Assembling the body
With the help of a totally automated assembly line the cameras, the gimbal, the control unit and, all other electronic components are screwed onto the frame.
Sequence from the Mavic Air assembly line
To offer a more robust yet light framework, DJI uses the same magnesium alloy for the brackets that reinforce the seven onboard cameras.
To finalize the body, the electronic components are then covered with another injection molded part, a white plastic cover. We are not sure what material exactly was used, but a common material for this step is ABS, a low cost and easy to manufacture polymer. ABS has a high impact resistance and is lightweight. It can also work continuously on a temperature level of up to 60°C, perfect for the high temperatures built up by the electronics of the drone.
Step 4: Attaching the arms
The four foldable arms are injection molded as well, using nylon reinforced with 30% glass fiber ( PA66+30GF). With injection molding, nylon (PA66) is sometimes filled with a certain percentage of glass fibers in order to increase its tensile strength. The percentage of glass is typically between 10% and 40%.
The arms of the Mavic Air are made of a composite with 30% fiberglass, making the arms stronger. The remaining part of nylon keeps the arm flexible. This comes in handy since the arms are usually the first part to make contact with a potential crash object (except for the propellers). The material offers well-balanced yield-resistant characteristics, to avoid early fragmentation and permanent deformation at the same time.
Step 5: Making the drone fly
The final step in the manufacturing process is creating and installing the propellers. They play a crucial role in the overall drone performance. To produce the propellers of the Mavic Air, injection molding is again DJI's manufacturing technology of choice. It is simply the best option to produce the highly uniform shapes of the propellers and is able to keep up with the speed of production needed. It also importantly creates a smooth surface finish of the airfoil that helps to avoid air turbulence.
For the Mavic Air, DJI got their inspiration from the Phantom 4, which has props that are made with glass fiber reinforced composite. This composite has a nylon base and offers the ideal balance between flexible propellers and the more rigid carbon nylon propellers used for the high-end models. The fiberglass makes the propellers stronger and more resistant. Fiberglass is also more flexible than carbon fiber, which ultimately means that the propellers have a higher breaking point than similarly shaped carbon fiber reinforced propellers. Each of the four propellers is powered by a brushless motor.
Ready for takeoff!
All materials utilized on the drone prove their function through their excellent lightweight functional properties. Especially the magnesium alloy, used for several components within the drone, bringing in a lot of potential savings. Also, the PA66+30GF material used for the arms saves weight and helps to increase the battery life by almost 25%.
The use of injection molding offers excellent repeatability and very high productivity for high volumes of identical parts. This keeps the cost for 10.000s of parts low.
Due to these two main factors, the Mavic Air maintains a low price yet doesn’t compromise on key features such as battery life. The manufacturing processes used for the drone didn’t change but the materials did, the versatility of injection molding and the sheer number of materials compatible allowed DJI to find the innovations they needed.