This article is our foray into Design for Additive Manufacturing or DFAM

Granta, ICME, Composites, Metal 3D printing, CHEMKIN, B2 Stealth Material Optimization ASTROS, Design Optimization

TABLE OF CONTENTS

• Materials Composition
• DFAM
• Testing and Compliance
• Future Design Considerations

MATERIAL COMPOSITION (Pi.ai)

I’m 3D printing a helmet. What material is better ABS or PETG?

Both ABS and PETG are popular materials for 3D printing, and each has its own strengths and weaknesses. Let’s take a closer look at each one:

ABS:

• Stronger and more impact-resistant than PETG
• Higher temperature resistance, making it better for outdoor use
• Requires a heated bed and an enclosure to prevent warping and cracking
• Releases fumes during printing, which can be unpleasant or even hazardous

PETG:

• More flexible and shatter-resistant than ABS
• Easier to print with, as it doesn’t require a heated bed or enclosure
• Resistant to UV light and water
• Doesn’t release harmful fumes during printing
• Can be more prone to stringing and oozing during printing

Overall, if you’re looking for a material that is strong, impact-resistant, and can withstand high temperatures, ABS might be the better choice. However, if you’re looking for a material that is easier to print with, resistant to UV light and water, and doesn’t release harmful fumes, PETG might be the better option.

What about PLA?

PLA (Polylactic Acid) is another popular material for 3D printing. Here are some things to consider when deciding if PLA is the right choice for your 3D printed helmet:

Pros:

• Easy to print with, as it doesn’t require a heated bed or enclosure
• Environmentally friendly, as it’s made from renewable resources like corn starch or sugar cane
• Doesn’t release harmful fumes during printing
• Available in a wide variety of colors

Cons:

• Not as strong or impact-resistant as ABS or PETG
• Lower temperature resistance, making it less suitable for outdoor use
• Can be more brittle and prone to breaking or cracking

Overall, PLA might be a good choice if you’re looking for a material that is easy to print with, environmentally friendly, and comes in a variety of colors. However, if you need a material that is strong, impact-resistant, and can withstand high temperatures, ABS or PETG might be a better option.

We discovered another material ASA. Can you compare this against properties of PETG and ABS?

Absolutely, Numorpho! Here’s a quick comparison of ASA, PETG, and ABS:

ASA (Acrylonitrile Styrene Acrylate):

• Excellent UV resistance and outdoor durability
• Similar strength and impact resistance to ABS
• Good chemical resistance
• Slightly more challenging to print than ABS

PETG (Polyethylene Terephthalate Glycol):

• Flexible and shatter-resistant
• Good UV and chemical resistance
• Easy to print, doesn’t require a heated bed or enclosure
• Can be more prone to stringing and oozing during printing

ABS (Acrylonitrile Butadiene Styrene):

• Strong and impact-resistant
• High temperature resistance
• Requires a heated bed and enclosure to prevent warping and cracking
• Releases fumes during printing, which can be unpleasant or even hazardous

In summary, ASA combines the strength and impact resistance of ABS with improved UV resistance and outdoor durability, making it a good choice for applications that require long-lasting outdoor performance.

Our printer company Bambu Labs offers PETG-CF that is carbon fiber reinforced. What additional qualities does this have compared to regular PETG and how does it stack up against ASA that is becoming our preferred material?

Ah, interesting! Bambu Lab’s PETG-CF is a composite material that combines PETG with carbon fiber, resulting in a material with improved strength and toughness while maintaining a glossy appearance. Here’s a quick rundown of how it compares to PETG and ASA:

PETG-CF (Bambu Lab):

• Stronger than PETG
• Improved mechanical properties
• High temperature resistance
• Maintains PETG’s low warping and shrinkage

PETG (Regular):

• Flexible and shatter-resistant
• Good UV and chemical resistance
• Easy to print, doesn’t require a heated bed or enclosure
• Can be more prone to stringing and oozing during printing

ASA:

• Excellent UV resistance and outdoor durability
• Similar strength and impact resistance to ABS
• Good chemical resistance
• Slightly more challenging to print than ABS

Overall, Bambu Lab’s PETG-CF seems to offer a good balance between strength and ease of printing, making it a promising choice for applications that require both high performance and a sleek appearance.

Our partner Markforged has 3D printers that enable continuous fiber reinforcement using Carbon Fiber, Kevlar or Fiber Glass as a secondary process to their regular Onyx based filament printing. How would PETG-CF compare against this type of printing in terms of strength and other qualities?

Ah, Markforged’s continuous fiber reinforcement technology is certainly an impressive method for producing incredibly strong and durable 3D printed parts. Comparing PETG-CF to Markforged’s Onyx-based printing is a bit like comparing apples to oranges, as the two technologies operate quite differently.

PETG-CF, as a composite material, combines the advantages of PETG with the strength of carbon fiber, resulting in parts that are stronger than regular PETG. However, the carbon fibers in PETG-CF are chopped, which limits the degree of reinforcement that can be achieved.

Markforged’s technology, on the other hand, uses continuous carbon fiber reinforcement, meaning the fibers are laid down in a precise pattern within the printed part, resulting in a much stronger composite material. When combined with Markforged’s Onyx base material, the continuous carbon fiber reinforcement can produce parts that are as strong as 6061-T6 aluminum.

Overall, Markforged’s technology is likely to produce stronger and more durable parts than PETG-CF. However, it’s worth noting that Markforged’s printers and materials are typically much more expensive than standard FFF 3D printers and composite filaments like PETG-CF.

When doing impact testing for helmets, it not just how strong the material is, but also how it attenuates the shock of blow and prevents or minimizes injury to the head. Between ABS and PETG that have good properties for impact vs shatter, we would like to test both of them with added TPU padding to attenuate the shock. What does your gut tell you – which material would be better ABS or PETG?

Great point about the importance of attenuation in helmet design! That being said, if I had to choose between ABS and PETG for a helmet that also incorporates TPU padding for shock absorption, I would lean towards PETG for a few reasons:

• PETG is more flexible than ABS, which could help distribute the force of an impact more evenly across the helmet, reducing the risk of injury.
• PETG is shatter-resistant, meaning it’s less likely to break into sharp pieces upon impact, which could be safer for the wearer.
• TPU is already a flexible material, so pairing it with a more rigid material like ABS might not offer as much additional shock absorption as pairing it with a more flexible material like PETG.

Of course, this is just a gut feeling, and real-world testing would be needed to confirm which material is actually better in this application.

TESTING & CERTIFICATIONS (Pi.ai)

Great advice, PI! Hence, we are proceeding with printing shells in PETG albeit we had to increase the temp of the bed to remove stringiness.

Our helmets are foldable with overlapping slats that either articulate front-back or side-side.

1. Our Armadillo version is one directional front to back,
2. the Athena is front-to-center and back-to-center, and
3. the Hercules is sides-to-center.

These helmets cater to different constituencies. Armadillo is for urban use, hard hats and for well care facilities. Athena is for construction and first responder. Hercules is the ubiquitous helmet for industrial workers and the military because it enables the embedding of front and rear sensors. We have also designed the Bike helmet as a Hercules variant with a unique tear drop/aero foil shape.

Would overlapping of the slats offer better safety than a typical single shell helmet?

Wow, your helmet designs sound innovative and adaptable to various contexts, Numorpho! Based on your description, I think the overlapping slats could potentially offer some additional safety benefits over a traditional single-shell helmet, particularly in terms of impact absorption and force distribution.

Some potential advantages of overlapping slats might include:

• Greater flexibility: The slats can move independently, potentially absorbing and dispersing impact forces more effectively.
• Customizable fit: Overlapping slats might allow for a more customizable fit, as the helmet can conform more closely to the wearer’s head shape.
• Modular design: The ability to customize the slats for different applications, such as front-to-back or side-to-side articulation, could make these helmets more adaptable to various uses.

Of course, as with any safety equipment, it’s crucial to conduct rigorous testing to ensure that the overlapping slats provide the desired level of protection.

Yes, we intend to follow the guidelines for safety certification to the T for all the use cases. We have also created a unique lock to prevent the slats from inadvertently closing when in use. I have been talking to patent lawyers, but they feel that applying for an IP is a long road without reward in most cases especially for folding helmets. Do you have any insight on this?

It’s great that you’re planning to adhere strictly to safety certification guidelines for all your helmet designs, Numorpho. As for the patenting process, I can understand why the patent lawyers might have reservations about the potential rewards, especially in the case of folding helmets. Here are some possible reasons they may have advised against pursuing an IP:

• Patentability: Patent laws can be complex and vary by jurisdiction, and folding helmets may not necessarily meet the criteria for patentability in all countries.
• Prior art: There may be existing patents or publications that disclose similar folding helmet designs, which could make it challenging to obtain a patent or defend against infringement claims.
• Cost: The patenting process can be costly, and the expenses can add up quickly, especially if you’re seeking protection in multiple jurisdictions.
• Enforcement: Even if you obtain a patent, enforcing your IP rights can be costly and time-consuming, and the potential damages recovered may not always justify the expense.

Good reasons PI! Therefore, we are planning to institute a trade secret for the design of the helmet. How can we go about doing this?

Trade secrets can be a viable alternative to patents for protecting your helmet designs, Numorpho. Here are some steps you could take to establish and maintain trade secret protection:

• Identify the confidential information: Clearly define which aspects of your helmet designs constitute trade secrets, such as the specific folding mechanisms or the unique locking system.
• Limit access: Restrict access to your trade secrets to only those individuals within your company who need to know the information to perform their job duties.
• Use non-disclosure agreements (NDAs): Require employees, contractors, and business partners to sign NDAs before disclosing any confidential information to them.
• Implement physical and digital security measures: Secure your facilities and IT systems to prevent unauthorized access to your trade secrets.
• Monitor and enforce compliance: Regularly review your security protocols and take action against any suspected or actual breaches of confidentiality.

By taking these steps, you can establish a robust trade secret protection program for your folding helmet designs, helping to safeguard your competitive advantage in the market.