3D printing for IoT prototypes -Best Practices and Thumb rules
I am honored and privileged to have this article co-authored by Vivek , a passionate and extremely talented Industrial engineer and product designer at Techolution. I have collaborated with him during my stint at Techolution for various key initiatives. Through this article, we would like to cover how we leverage 3D printing for various IoT prototype activities. What are some best practices, pit falls, limitations, etc.
Below are the following use cases or requirements for which we have leveraged 3D printing for IoT
- Enclosures for small our home grown, purpose built edge devices
- Custom components for our proprietary hardware products
- Purpose built accessories for our hardware products
- Micro manufacturing of smart sensors
Why (in-house) 3D Printing
The application areas that we have mentioned above are nothing new and possibly many have used for the same purpose. However, below are a few reasons why we have adopted 3D printing to achieve the same and too with an in-house 3D printing setup.
Unleash creativity: We could test out various versions and types of objects being printed. For e.g one use case we have mentioned was enclosures. While there are a lot of custom enclosures, if you are creating a unique solution or want your product to stand out from competition or impress the audience and customers at the first look, it is very imperative that following conditions are met.
- Enclosures should not look very generic. Subconsciously, users (especially technically naïve audiences)will relate it to a random off the shelf product.
- Enclosures should be of correct size and serve the purpose well. Generally off the shelf enclosures follow standard dimensions. At a prototype level, we should have an enclosure which just has the correct dimensions and appropriate provisions. At Techolution we developed an edge device for Industries. It has numerous interfaces and outputs. Since the demo kit will be used by sales folks, we need to have it correctly sized so that it can be carried easily, has appropriate vents for air circulation and heat management, enables us to position components (both input and output) and sensors in a most optimum way, hide the interfaces which are generally used by support team(E.g USB ports etc) from users , but can be accessed by support team when needed, provide holes of appropriate dimensions (sub 10mm diameter) for antenna etc. In such requirements, using an off the shelf enclosure might end up spoiling the aesthetics and visual appeal.
- Components can be made for use cases which are way ahead of time or for unconventional use cases. Assume that you are hacking a robot vacuum cleaner for a function which it is not intended to perform. You need a few extra components to achieve its purpose. As you innovate, and do different trials and improve it, 3D printing helps you significantly.
- Purpose built accessories: Though if you are buying an existing component in the market, if a specific accessory needs to serve a different purpose as well, how would you achieve it?3D printing definitely helps here.
With 3D printing, you can opt for in-house 3D printers or you can outsource to a vendor. If your enterprise or company is planning to continuously invest in hardware or components or venture into a hardware which is positioned to be unique either in function or in look and feel and expected to fetch good margin, it is advisable to go for an in-house 3D printer setup. While we will talk about the setup we have in the Techolution office in later sections, please be aware that you need talent who can understand and operate the machine, work with machine providers in case of issues etc. You might also need expertise to design the object to be printed in software like CAD.So procuring a machine alone is not sufficient. When you start scouting for the machines, it is essential to look at missing skill sets to leverage it and plan for them as well( the missing skills could be a freelancer as well if needed).
While outsourcing to a vendor is advisable for one-off or not so frequent needs, please remember to have your intellectual property safe guarded by NDA (as with any outsourcing agreements). Also it is advisable to have a lot of vendor contacts so that even if one specific vendor has an order backlog, you can go to other vendors. There are different types of 3D printers based on technology they use, features etc. Sometimes the machine you have in-house might not serve the need. So outsourcing to a vendor is still an option even if you have in-house setup. In outsourcing to vendors also there are different types. While a few have expertise to design based on your needs, few might expect you to provide the design files and they will just print it.
Decisions to take before printing
In many ways, 3D printing is similar to constructing a house. There are a lot of questions to ask and decisions to make before going to the design itself.
- End goal: What is the end goal of the object being printed? What are the stated end goals (e.g. Vents for air circulation), functional requirements (explicitly to be told to the designer), and implicit goals (aesthetic standards, logo positioning, colour theme etc) which are organisational standards etc that the product team might not be aware, but designers should be aware of.
- Where it is being used: Is the printed object going to be used or be placed(either in transit or usage) in extreme conditions? How it will be positioned. For e.g in our industrial edge use cases, sensing elements should be exposed to the sensing object. In case if the device is to be fitted on the ceiling, it does not make sense for the sensing element to be facing the ceiling. So the engineering team of the product should brief the designers about the end use and goal of the object being printed, where it will be used, how it will be used etc. Are the components being printed withstand the deployment conditions. For e.g, if you are printing a device which will be used in a steel plant, it should be able to withstand high temperatures etc.
- Scope for future enhancement: Should you need to design the object considering future goals.
- Hide and Seek : As mentioned earlier, in some cases you might need to expose only a minimum things (E.g only power input etc), but few other ports (e.g USB, HDMI) to be available for troubleshooting, So designer should design it so that installation team or engineering team can access them without removing the entire casing or enclosure etc.
Note that these points above are in-addition to the basic principles like heat management, compact circuitry, wiring design, safe mounting etc. If you have read it carefully, you must have realized that clear communication and discussion between product engineering team and design team which is responsible for CAD designs required for printing and printing is required.
Manufacturer : Raise3D
Raise3D are a top tier global company who manufacture industry grade high performance 3D-printers which can be utilized from a broad range of spectrum, right from learning to end product manufacturing.
Model(s) currently used at the lab : Raise 3D Pro2 Plus
This is a top line model FDM 3D-printer from Raise3D. We have 2 numbers of this model at our lab for our internal R&D and in-house manufacturing.
Model : Raise 3D E2
This printer is one of the best in the game and below are the few deal breaking features which makes it stand-out
Large Build Volume
A build volume of 305mm x 305mm x 605mm gives the user the flexibility to print long & large prints for their prototyping.
Supports Variety of Different Materials
The printer supports a variety of plastics & composites which gives the user the flexibility of exploring into the domain of material science.
Intuitive User Experience
Visual interface / Rapid reviewing / Visual print progress / Full adjustment control.
Power Loss Resuming
The printer in the scenario of a power shutdown, it stored the print status in its memory & we can resume the task once the power is back.
High Performance Motion Controller
400 MHz ARM Cortex- M7 32 bit RISC FPU and a 256 micro-steps driver system
User Interface : Remote administration capabilities
The printer comes with a Raise3D cloud solution, where-in the controlling, monitoring & the complete additive manufacturing project management can be executed by the user through an electronic device with an OS [ Windows, Linux & iOS ]. It also provides a browser based interface
Time to Print
These are three factors which affect the time required to print a 3D component. They are
- Layer height
- Size of the components
- Part placement orientation
- In-fill density
- Support structures generation
- Print speed settings
The Raise3D’s original slicing software IDEAMAKER, gives the user the following data features which gives a great insight on the complete manufacturing process.
- Material usage required
- Cost of material usage
- Virtual simulation of the complete 3D-printing process
- Time taken for the printc
- Since time taken for 3D printing is influenced by a lot of factors, plan ahead accordingly. Once you run a sample run, you can guess some reasonable time for the machines you are using. There are a lot of open source models for you to print.
- 3D printing is not suited for mass manufacturing. It may at best serve orders for small quantities. Have a road map from prototyping to mass manufacturing
- If your printer cannot support multiple materials and if having multiple materials is mandatory for the prototype, think of alternatives ahead of time.
- The 3D printers cannot give high IP rated objects. So if you are using it for deployment in extreme conditions, work with your product engineering and design team to achieve it.
- While choosing a 3D printer, choose a machine which helps you to monitor the job and its status remotely. This will help the team to be more productive.
- Have more than one unit of 3D printer if you are using it heavily. We have experienced unplanned downtimes due to filament issues, filament jam etc. Having an extra machine helps to mitigate single point of failure
- Have enough stock of accessories, tools for maintenance & back-up of parts like nozzles, heat sinks / hot end assembly like filaments etc handy
- Spare parts / replaceable parts for a product deployed can be 3D-printed by the OEM or even at the end customer due to which the serviceability / maintenance can be carried out in a more efficient way.
Design rules for 3D printing
Factors affecting the quality
Let’s take a single layer into consideration. The crucial factor is the layer’s thickness. This determinant is not only connected to slicer settings (that you use to obtain your gcode) but also to the 3D printer you are using. The rule is simple — the smaller layer thickness, the better the quality of a 3D print. Although thin layers will make your print’s walls smoother, you have to bear in mind that it will take a 3D printer much more time to accomplish printing.
Not every 3D printer will be able to print really small layers. Common RepRaps can go up to 100 microns tops. Professional machines will go beyond that and give a maker the ability to deposit layers of 90 microns and less.
This factor may be obvious to some users, but I would like to dig deeper into the subject. Mechanical properties of a material are reflected in a 3D print’s features. There are no illusions — poor material properties will affect the quality of a 3D printed object, especially in a field of impact strength and hardness. Moreover, if a low-grade filament is contaminated, the risk of the extruder jamming is rising.
Now let’s consider some other facts. The material quality can be measured by its diameter deviation. If a filament’s diameter alters rapidly on a small linear distance, you will probably observe some inconsistencies on a 3D printed wall, such as small bulges and cavities. This can happen because a 3D printer extrudes more material (feeding filament of larger diameter) in one moment and deposits less material in another moment, when the filament of a smaller diameter is inserted into the printhead. In extreme cases, when the material’s diameter is too big, it may not fit in the extruder entrance.
Diameter deviation can be examined in a workshop environment during spool unwinding. The only needed tool for this test is a caliper. Just write down the values every 10 or 15 meters of material usage. If diameter deviation is higher than 3–4%, I would recommend changing the material provider or informing them about the existing issue.
This factor is strictly related to the slicer set up that is — most commonly — easily accessible by the user. The temperature of plastic extrusion must be configured differently for every type of material. On the other hand, Zortrax materials can be automatically recognized by the 3D printer — Zortrax M200 will apply the best 3D printing settings as soons as you hook a spool on a holder.
To achieve great 3D printing quality using ABS, remember to set high extrusion temperatures of 240- 250 degrees Celsius, and be sure to pump up your building platform temperature to around 100 degrees Celsius. Set your fan speed to around 10% to avoid extensive thermal shrinkage and close the build chamber, if your 3D printer has one.
To be successful with PLA plastic, be sure to set the nozzle temperature to around 200 degrees Celsius and your fan speed to 100% after initial layers are deposited. You can heat your build plate to around 50–60 degrees Celsius for the PLA to stick better.
Retraction settings of the Extruder
This feature can be configured in your slicing software. Configuration of material retraction is very important when the extruder needs to travel some distances without actual extrusion. For example, when you are printing fishnet objects and the printhead jumps to perimeters.
In this case, the best way to maintain good surface quality is to set a high speed for material retraction. This will prevent the forming small clods of material on the perimeters.
Sparse- or Solid-Fill
If you have an enclosed part, like a cube for example, it can be filled solid or Stereolithography and Fused Deposition Modeling allow you to build with a custom interior density using air gaps between the exterior walls. This build technique, called ID-Light, uses less material and is faster, resulting in a lower price compared to a solid-fill, however it can slightly affect overall part strength. We recommend working with a project engineer on these applications.