A couple of weeks ago, I posted a video of a heat exchanger which was redesigned for Direct Metal Printing and printed on a 3D Systems DMP Flex 100. That video received more than 26,000 views and was shared widely.
Here are some pictures of a scaled down version of the heat exchanger.
I took this picture on my iPhone which had a hard time focusing. So instead of using the camera directly I used the magnifier tool and took a screenshot instead.
This camera angle gives you a better idea of how the cooling fins are positioned and just how fine they are.
Here is a cut out showing what the inside of the duct looks like. Needless to say it would be impossible to manufacture this using any traditional manufacturing technique.
The reason the DMP Flex 100 is able to print in such fine detail is due to the manner the metal powder is laid down and spread out on the platform. Unlike other metal printers in the market, the DMP Flex 100 uses a counter rotating roller instead of a wiper blade. This makes a world of a difference. Let me explain how.
When a wiper blade is used, a layer of metal powder is spread across the platform and leveled to the desired layer thickness. However, when a counter rotating roller is used the powder is not only spread across the platform, but is also compacted. This is similar to the action of the wheel of a car rolling over a road. But unlike the wheel of a car, the direction of rotation of the roller is opposite, also known as counter rotating. This compacts the powder to an even greater degree. Imagine the wheel of a car moving in reverse gear while the car is moving forward. Due to this layering technique, we are able to use powders of much finer grain size as well as greatly vary the distribution of the grain size. The result is a much more dense layer of powder, which has a direct impact on the accuracy and level of detail.
A high level of accuracy is critical in applications like this intricate heat exchanger or where the metal part needs to match something else exactly. A dental prosthesis is an excellent example of this. The common trick in printing mating surfaces is to add stock to the part in the 3D model, print the extra metal and then machine it off later to get a perfectly smooth mating surface. You can’t do that with dental prosthesis as the shapes are organic. What you print is what you have to deal with, which is why how you layer metal powder plays a crucial role.