Hybrid Part Spotlight - Additive Manufacturing and Post Machining

Most client work stays behind closed doors making it difficult to promote capabilities. So, Rennscot MFG developed its own part to showcase its work.  

Design

The component that was selected is an advanced manufacturing hybrid part – utilizing both additive (3D printing) and subtractive (CNC machining) techniques. The design was carefully engineered to capture advanced features relevant across multiple industries across many applications. It fits the aesthetic of avionics enclosures and exhibits the benefits of additive manufacturing by integrating a fluid channel, ports, and fin geometry that would not be achievable with only subtractive methods. The result highlights the ability to take a part from design to printing to post-machining - all under one roof in Woburn, Massachusetts - reducing lead times and eliminating the friction of multi-vendor coordination.    

Printing

Rennscot MFG’s in-house team of additive manufacturing engineers and CNC machinists collaborated during the hybrid part’s design for additive manufacturing (DFAM) process. Together, the team identified critical design features which required material additions necessary for post-print machining. These areas often include tightly dimensioned features, threaded or tapped holes, mating or sealing surfaces, and material additions to enhance part printability. 

This graphic identifies just a handful of the model changes that were made in order to optimize the form for printing while preserving critical features. Read more about how the Rennscot MFG works collaboratively on these efforts below.

Adding material in the right places is critical to ensuring a clean print, optimizing the post-machining process. In the case of this hybrid test part; internal pockets had to be filled, and “ramps” of material placed under features that would protrude laterally in its print orientation. This allowed the part to print without traditional support material, and all material not present in the intended design was precisely machined away in the post-machining process. 

The hybrid test part was printed on an EOS M300-4 Laser Powder Bed Fusion (LPBF) metal 3D printer. The parts were produced in AlSi10Mg aluminum — a material which has become extremely popular for both prototyping and full-scale production of aerospace and thermal management related parts, due to its lightweight, high print speed, low cost, and high thermal conductivity characteristics. Four parts were built in a single run, each assigned to a dedicated laser—an approach optimized for the M300-4 printer’s capabilities. After a 30-hour build, the parts were removed, de-powdered inside and out, cut from the build plate, and finished with secondary cleaning before moving to CNC machining. 

This image displays two parts that have been printed and cleaned, but have not made it to machining yet. You can see the "ramps" of material still present under features that would be overhung, and almost no holes exist in the parts except for the two small ports that give our additive team access to the internal cooling channel for powder removal.

Machining

Traditional alignment methods fail on printed parts due to surface roughness and potential warping. Instead, in-machine probing with custom alignment cycles – designed in-house ensures accuracy across multiple axes; extending tool life and delivering consistent, precise machining. This method allows the tool to take consistent bites rather than increasing and decreasing engagement throughout the cut, which can be a major cost savings in tougher materials (i.e. Inconel and Stainless Steels).  

This photograph shows the part shortly after it has entered the milling machine. It has been clamped into the vice, and a probe is traveling around gathering datapoints to align the actual part and the machines understanding of where the part is.

Once the parts were cut off from the build plate the part was located in the machine and probed, and machining was able to begin. Similar probing strategies were repeated for the subsequent machining operations, and some features from the first operation were located upon to ensure proper alignment as the part advanced through machining operations.   

Here you can see that the majority of internal features have now been cut into the part, removing the rough printed texture with extremely well placed, precise interfacing features.

Collaboration amongst subtractive and additive engineering teams made it very easy to add features to the part that helped speed up the post machining process. This reduced the need for custom “soft jaws” (special vise jaws that are made to match the profile of the part) to hold the part, and decreased turnaround time in the machine shop.  

At Rennscot MFG, our machinists and additive engineers don’t just collaborate - they sit side by side. This proximity accelerates problem-solving, reduces turnaround times, and enables creative design solutions that would stall in a fragmented supply chain. The Hybrid Test Part is more than a demonstration piece; it’s proof of how integrated expertise unlocks new levels of performance. With design feedback, printing, and machining all under one roof, projects move from concept to completion faster, smarter, and without compromise. 

The hope is that this part demonstrates it well, but nothing can substitute experiencing the Rennscot MFG difference yourself. Inquire about your project today!