Hybrid Machine Design
Posted by nnfuller
|
Hybrid Machine Design January 27, 2015 03:18PM |
Combined Additive and Subtractive Machine
Additive manufacturing has come a long way in the past decade, specifically in the areas of FDM (Fused Deposition Modeling). We have seen astounding growth in methods, precision, materials, and speed. Still, certain instances occur where the desired combination of traits for a specific application aren't attainable in a single step. Here post processing such as vapor finishing, sanding, or even post machining have been used to help create parts that more fully satisfy the demands of industry. Post machining shows perhaps the most promise for creating engineering grade parts, due to the high level of controlled precision compared to the previously mentioned methods. It also it the only process which can increase the precision of a 3D print. Up till now post machining required a second highly sophisticated machine, with additional work holding and tooling. This is the issue which this project will attempt to address. Below are my comments on Pros and Cons of Hybrid Manufacturing.
Pros
Increased precision
Because the printed object isn't repositioned, there is no uncertainty as to its location. The standard practice of touching off reference points can cause problems when using a 3d printed part is uncertain dimensions.
Increased Throughput by Decreased Print resolution
Parts designed to be post machined can be printed faster at lower resolution, then have critical areas machined to tolerance. These parts could be thought of much like a casting, where non critical areas remain rough while other precision areas are honed within the desired tolerance.
Machined Internal Cavities
At a high level of functionality, this machine could be capable of more than a 2 step process, machining geometry after any number of layers had been printed, accessing areas that would later be covered by additional material,
Cons
Increased Machine Cost, Weight, and Complexity
Because the system must have the all the traits needed of both a 3D printer as well as a mill, there will be certain trade offs required which will likely result in greater weight and cost, while a head that can alternate between additive and subtractive processes will be more complex than a single purpose head.
It is my opinion that the benefits mentioned above outweigh the potential detriments and obstacles presented by combing these to processes into one machine.
Current State of Project
In order to pursue this project, I first needed a reliable set of axes that promised to be both rigid enough for machining, and quick enough for printing. The ShopBot Desktop was the perfect tool, and Autodesk was able to supply one that could be hacked in order to function as both a machine tool and a 3D printer. Below is the shopbot with the bed removed for maintenance after shipping.
The next step was to create a CAD model of the system to allow the additive head to be retracted to allow for machining or lowered to print. This was all done in Autodesk Fusion 360. Preliminary renderings can be seen below.
These parts have been printed and I am waiting on hardware and Aluminum plate before the parts can be mounted. Example of printed hotend carriage can be seen below.
Additive manufacturing has come a long way in the past decade, specifically in the areas of FDM (Fused Deposition Modeling). We have seen astounding growth in methods, precision, materials, and speed. Still, certain instances occur where the desired combination of traits for a specific application aren't attainable in a single step. Here post processing such as vapor finishing, sanding, or even post machining have been used to help create parts that more fully satisfy the demands of industry. Post machining shows perhaps the most promise for creating engineering grade parts, due to the high level of controlled precision compared to the previously mentioned methods. It also it the only process which can increase the precision of a 3D print. Up till now post machining required a second highly sophisticated machine, with additional work holding and tooling. This is the issue which this project will attempt to address. Below are my comments on Pros and Cons of Hybrid Manufacturing.
Pros
Increased precision
Because the printed object isn't repositioned, there is no uncertainty as to its location. The standard practice of touching off reference points can cause problems when using a 3d printed part is uncertain dimensions.
Increased Throughput by Decreased Print resolution
Parts designed to be post machined can be printed faster at lower resolution, then have critical areas machined to tolerance. These parts could be thought of much like a casting, where non critical areas remain rough while other precision areas are honed within the desired tolerance.
Machined Internal Cavities
At a high level of functionality, this machine could be capable of more than a 2 step process, machining geometry after any number of layers had been printed, accessing areas that would later be covered by additional material,
Cons
Increased Machine Cost, Weight, and Complexity
Because the system must have the all the traits needed of both a 3D printer as well as a mill, there will be certain trade offs required which will likely result in greater weight and cost, while a head that can alternate between additive and subtractive processes will be more complex than a single purpose head.
It is my opinion that the benefits mentioned above outweigh the potential detriments and obstacles presented by combing these to processes into one machine.
Current State of Project
In order to pursue this project, I first needed a reliable set of axes that promised to be both rigid enough for machining, and quick enough for printing. The ShopBot Desktop was the perfect tool, and Autodesk was able to supply one that could be hacked in order to function as both a machine tool and a 3D printer. Below is the shopbot with the bed removed for maintenance after shipping.
The next step was to create a CAD model of the system to allow the additive head to be retracted to allow for machining or lowered to print. This was all done in Autodesk Fusion 360. Preliminary renderings can be seen below.
These parts have been printed and I am waiting on hardware and Aluminum plate before the parts can be mounted. Example of printed hotend carriage can be seen below.
Sorry, only registered users may post in this forum.