By Industrial Print Staff
Part 2 of 3
Manufacturers leverage relationships with service bureaus when it comes to creating smaller parts used in bigger builds. Putting the pieces together involves a certain trust between customer and provider, which is what happened in this case study provided by 3DEO. It is a design, engineering, and manufacturing service provider specializing in complex metal three-dimensional (3D) printed components produced at scale.
Solving the Problem
3DEO works with many customers to replace investment cast and machined components and assemblies. For example, it produced a ball return tube—part of a linear ball screw—for a U.S.-based Tier 3 aerospace supplier in the aerospace and aviation industry using 3DEO metal 3D printing technology instead of conventional practices.
A linear ball screw is a mechanical actuator that creates high-performance, low friction, linear motion at high speeds and duty loads. Essentially, it is a high-efficiency method of converting rotary motion to linear motion by using a recirculating ball bearing between a screw shaft and a nut. Compared with a conventional sliding screw, the ball screw requires far less driving torque, typically one-third or less for comparable loads. This makes it ideal for reducing the required drive motor power for a given application—according to 3DEO.
The ball bearings must be recirculated to provide continuous rolling contact. Recirculation requires a small, precision bent tube. Fabrication of the tube is challenging, because of the tight tolerances required on the inner diameter of the tube and the very small bearing size.
3DEO’s customer’s design recirculates 0.080-inch ball bearings. The ball return tube was less than 0.65 inches in its longest dimension.
Before the Tier 3 aerospace supplier found 3DEO, only a few suppliers would even attempt to manufacture part. Conventional practices involved bending the tubing, but that would result in crimping and flattening at the elbows of the tube, preventing ball circulation.
3DEO’s applications engineering team spent many hours with the customer to review the design of the ball nut assembly and understand the requirements of the application. “3DEO partnered with us to deeply understand the application and help us solve the problem, and this collaboration was essential to our success,” notes the president of tier 3 aerospace supplier.
During consultations, further value was achieved. A creative solution was reached that leveraged the geometric freedom of 3DEO’s printers to eliminate an expensive post-machining step.
Printed using 17-4PH steel alloy for the material because of its durability, the ball return tubes were refined through multiple interactions and then confirmed for testing.
The the minimum number of cycles of one ball return tube needed to be 12,000. Legacy ball return tubes were failing between 10,000 and 12,000 cycles. The 3DEO parts ran to 20,000 cycles without a single issue. When testing was complete and the assembly analyzed, 3DEO’s ball return tube showed less wear than the ball bearings.
3DEO’s know-how was instrumental in achieving success with the ball return tubes. It continues to exhibit this with other customers.
The final article in this three-part series shares more about 3D metal printing with another real-world example.
May2023, Industrial Print Magazine