How to Decide Between 3DPrinting vs Machining for Your Prototype Needs

Once you own a 3D Printer it can be easy to get carried away with all the cool things you can print. But is it always the best option? Let's compare machining (turning) four parts vs. 3D printing the same parts.

These spools are for a new product that removes Zeus FluoroPEELZ®​ heat shrink after reflowing catheters. They are 1" OD and feature a knurled grip and threaded holes. They are well suited to either machining or 3D printing. We'll consider these prototype components for this study.

Time to Make This is how long it took to machine or print the parts once the parts were designed. The machine parts beat the printed parts in this category by 30 minutes.

Material Cost The raw material cost. The printed parts pictured here were made with generic PLA and cost $0.58. But if your printer uses proprietary material, this can be as high as $3.84 for the set.

Additional Modeling Time These parts needed to be knurled so extra time was required to "cut" the knurls in SolidWorks. The machined part doesn't require the knurl to be modeled.

Labor Cost This is where the magic of leaving the printer unattended comes into play. This figure represents labor to model the extra features in CAD, and a quick printer setup. The machined part requires a machinist to spend the full 2 hours on the parts.

Total Cost The machined parts are over 3X more expensive when taking into account labor. This can vary, but 3D printing is a much more hands-off process and will usually be cheaper than machining for prototyping.

​Robustness of Part Here is where the machined aluminum parts shine. They are of course much more robust. They are also a user touch-point and feel much better to the touch.

In this case, machining is the better option for these parts. The parts are stronger and feel better in the hands of the user. The decision to machine these parts was made with the user needs in mind. There is no single answer to the print vs. machine question. Each part must be evaluated on a case by case basis.

3D Printing End-Use Parts for a Wire Feeder

Most of us think of 3D printing as a great way to build prototype parts quickly. We then think of conventional manufacturing methods like molding or machining for final parts. But what if you could skip that step altogether?

Using 3D printing for end-use parts requires us to think of 3D printing as a manufacturing process. And like all manufacturing process it has its strengths and limitations. But once these strengths and limitations are understood, parts can be designed for 3D printing. Just like a part that is well designed for machining may not be easily injection molded, such a part won't be ideal for 3D printing. So we need to understand the process when designing.

There are two ways of designing parts for 3D printing. One is to start with parts that are already designed to be machined or molded, and convert the design for 3D printing. This can allow for reliably printed parts that are able to meet the requirements of the originals. But this approach does not take full advantage of one of the key strengths of 3D printing which is that complex parts can be made. The second way to design parts for 3D printing is to conceive of the design from the beginning with 3D printing in mind. This allows for a high integration of features onto a low part count. This allows us to simplify the overall design by adding complexity to the components.

For this wire feeder, a gear needed to be added to a timing pulley. With a conventional machining approach, two or more parts would have been made and put together as an assembly. But by printing the parts as one piece, the gear, pulley, and flanges can be integrated into a single part. This saves cost, complexity, and assembly steps.

This feeder will be used in a ISO class 6 clean room, and will be used on a medical device manufacturing line. For this reason, carbon fiber-filled nylon was chosen. It can be run without lubrication and is stiff enough to withstand the loads needed. In future posts, print orientation, material selection, other 3D printing specifics will be explored.

You may want to consider 3D printing for your next design. Or maybe you're already a 3D printing design hero. Let us know in the comments if you've made end-use parts that are printed.