CASE STUDY: Brain-Machine Robotics System May Help Paraplegics Walk Again

Proto Labs is helping researchers at the University of Houston move a science fiction concept to a real-world application that may help paraplegics walk again.

A University of Houston research lab is developing a powered exoskeleton that will be part of a futuristic brain-machine robotics system. Proto Labs is helping by providing custom-machined aluminum-joint housings.

Photo Courtesy: University of Houston

A multidisciplinary research team that includes engineers, neuroscientists, health professionals, and students is working to create, from scratch, a powered wearable robotic device that allows those with lower-limb paralysis from spinal injury, disease, or stroke to regain mobility without a walker or canes.

A sci-fi element lives on in the project, which is taking place at the university’s Laboratory for Noninvasive Brain-Machine Interface Systems. As the lab’s futuristic name suggests, the ultimate goal is to allow users to control the exoskeleton—commanding it to go forward or backward, to turn, sit, or stand—using their thoughts instead of a joystick, switches, or external operator typical of other devices.

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TIPS WITH TONY: Machining Capabilities for High Performance Parts

Do you know how machining a part from titanium can improve its functionality and performance? How about using key inserts for improved durability to your part. Here are few capabilities and design options to keep in mind for your next machined part.

Titanium machined parts.

Titanium
Let’s start off with some big news. Previously, we only offered titanium for 3D-printed parts, but it’s now available to customers for machined parts. And, if that wasn’t enough to catch your attention, how does titanium machined parts in as fast as three days sound?

Titanium is extremely strong and boasts a high strength-to-weight ratio. It also has excellent corrosion resistance, high operating temperatures (up to 1,000°F) and is nontoxic.

Titanium has range of applications due to its advanced material properties. Frequently, you’ll find titanium parts in the aerospace, medical, military and marine industries. More specifically, it’s used for parts like rotors, compressor blades, hydraulic systems, surgical equipment, dental and orthopedic implants as well as in military aircrafts due to excellent ballistic characteristics.

The only drawback is the cost of the raw material. It’s more expensive than steel. For this reason, most manufacturers don’t hold a lot of inventory, but that isn’t the case at Proto Labs. We maintain a level of inventory that allows for on-demand milling and turning of titanium parts

Visit our machining materials page for more information.

Key insert for added durability.

Key Inserts
Key inserts are steel threaded inserts commonly used in aluminum parts for added durability. Note that these are different from standard coil inserts as they have an added keyway with a tab inserted to prevent twisting under extreme load.

Key inserts are primarily used by the aerospace and military industries following the military standard of MS51835B. We offer eight thread sizes ranging from #8-32 to ½-13. For a full list, visit our threading page and click the key inserts tab.

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WEBINAR: Improving Manufacturability with ProtoQuote

Join us for a webinar on improving part manufacturability. Our technical specialist Tony Holtz will demonstrate how to navigate ProtoQuote to optimize your design for 3D printing, CNC machining or injection molding. 

tonyholtz

In case you’re unfamiliar with ProtoQuote, it’s our fully automated quoting and design analysis software. Simply put – it makes your life a whole lot easier. It allows you to know exactly how much a part will cost and provides an analysis of your design within hours.

Sign up and learn how to tap into the full potential of ProtoQuote and its design for manufacturability analysis:

TITLE: Improving Manufacturability with ProtoQuote
DATE:  Thursday, May 26 at 1 p.m. CDT
LINK: Click here to register!

At the end of the presentation, there will be time for a Q&A session.  Have a colleague who might be interested? We’d love to have them join as well. And if you can’t make it at the specified time, you can still register and we’ll send you a recording afterward.

TIPS WITH TONY: High-Temperature Thermoplastics

We offer two high-temperature thermoplastics: PEEK and PEI. Both high-performance materials can be machined and injection molded, and produce parts that can withstand extreme temperatures.

PEEK
PEEK parts contain excellent mechanical and chemical resistance during high-temperature applications. Its mechanical properties consist of tensile modulus strengths of 90-200 MPa and a melting temperature of 662˚F (343˚C). Some grades of PEEK have operating temperatures around 482˚F (250˚C).

Because of its robustness, PEEK is commonly used in applications for mechanical and medical instruments. PEEK is also used widely in the aerospace, automotive and chemical industries due to the insulating properties and creep resistance of any dimensional changes in high-temperature applications.

PEI
Like PEEK, PEI (often called by its trade name Ultem) offers outstanding elevated thermal resistance, high strength, stiffness and chemical resistance. PEI consists of tensile modulus strengths of 96-190 MPa and with a melting temperature above 420˚F.

PEI is available in transparent and opaque colors including glass additives for improved mechanical properties. Unlike other thermoplastics, PEI provides optimal strength and resists stress cracking when the material is exposed to hydrocarbons, alcohols and acids that makes them ideal for automotive and aerospace applications.

Which Manufacturing Process is Best?
If you’re in need of small quantities (up to 200) of PEEK and PEI parts, we can machined them in less than 3 days. For increased quantities in the thousands, rapid injection molding can produce parts in 15 days or less.

The physical properties vary little between processes, so please test out one sample using machining before moving to injection molding if you are unsure if your parts design is complete or not.

Contact us if you have any further questions about high-temp plastics and specific questions regarding PEEK or PEI. We have a full staff of customer service engineers who can be reached at customerservice@protolabs.com or 877-479-3680.

TIPS WITH TONY: The Material Properties of Machined Plastic

If your ultimate product development plan involves a move to injection molding, CNC machining offers a material selection conducive to a transition into increased molded quantities. Proto Labs has more than 30 engineering-grade thermoplastic materials with various benefits.

To illustrate the material properties better (Figure 1), we took four frequently used thermoplastics — ABS, polycarbonate (PC), polypropylene (PP) and nylon polyamide (PA) — and compared the maximum heat deflection, tensile strength and elongation at break that occurs within injection molding, machining and 3D printing.

ABS Molded

ABS Machined

ABS-like SL

Heat Deflection

215°F

214°F

138°F

Tensile Strength

6,091 psi

6,100 psi

7,800 psi

Elongation at Break

30%

40%

6-20%

PC Molded

PC Machined

PC-like SL

Heat Deflection

280°F

280°F

482°F

Tensile Strength

10,442psi

8,000 psi

11,300 psi

Elongation at Break

100%

50%

1.0-13%

PP Molded

PP Machined

PP-like SL

Heat Deflection

203°F

210°F

142°F

Tensile Strength

5,801 psi

4,800 psi

7,250 psi

Elongation at Break

100%

14%

7-25%

PA Molded

PA Machined

PA SLS

Heat Deflection

410°F

370°F

370°F

Tensile Strength

16,500 psi

10,000 psi

6,946 psi

Elongation at Break

60%

25%

14-51%

Figure 1: Thermoplastic material properties compared between different manufacturing processes. Properties are dependent on actual material selected, part thickness and geometry. Please review each material data sheet individually as these are estimates.

Translation: CNC machining is ideal for functional prototyping and end-use production parts, and readies your design for an eventual move to injection molding. We have a full staff of technical experts that can answer any machining questions you have at customerservice@protolabs.com or 877-479-3680. For more information on 3D printing, CNC machining or injection molding at Proto Labs, head over to protolabs.com.