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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TIPS WITH TONY: Flame-Retardant Thermoplastics and UL Classifications

UL 94 is a plastics flammability standard released by the Underwriters Laboratories (USA). The standard classifies plastics according to how they burn in various orientations and part thicknesses from the lowest flame-retardant to most flame-retardant in six different classifications.

UL 94 Rating

Definition of Rating

HB

                                          Slow burning on a horizontal part.

V-2

                                          Burning stops within 30 seconds on a vertical                                             part allowing for drops of flammable plastic.

V-1

                                          Burning stops within 30 seconds on a vertical                                             part allowing for drops of plastic that are not                                               inflames.

V-0

                                          Burning stops within 10 seconds on a vertical                                             part allowing for drops of plastic that are not                                               inflames.

5VB

                                          Burning stops within 60 seconds on a vertical                                             part with no drops of plastic allowed but may                                               burn through the part.

5VA

                                          Burning stops within 60 seconds on a vertical                                             part with no drops of plastic allowed and                                                     cannot burn through the part.

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TIPS WITH TONY: 3D Printing Living Hinges

Did you know that living hinges are possible with 3D printing? Here are a few things areas to keep in mind when designing hinge functions so your part’s functionality and integrity remain intact.

Process
We offer two processes for 3D printing thermoplastic or thermoplastic-like materials: selective laser sintering (SLS) and stereolithography (SL). But only SLS will produce parts with the functionality required for a living hinge.

An SLS part with living hinge functionality.

Material
Anytime we see the potential for a living hinge in a 3D-printed part, we will strongly guide you to SLS. SLS uses nylon thermoplastic, primarily PA 850 Black, which is a nylon 11 material. PA 850 has an increased EB of 14-51% followed by ALM PA 650 with an EB of 24%.

However, you can’t take a part that was produced in PA 850 or ALM PA 650 and expect it to function as a living hinge without a secondary process first. When you have a living hinge, we need to know what direction or the range of motion in which the hinge may function. This is critical as we anneal the part by heating it to 250-275°F and flex the hinge in the intended range of motion. This extends the life of the living hinge by stretching the material instead of fracturing the links of resin.

SL offers thermoplastic-like materials, but they are not be recommended for living hinge applications. Somos 9120 is our most flexible material of all SL resins with an elongation at break (EB) of 15-25%.

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TIPS WITH TONY: Replace Metal with Plastic to Save Weight, Cost

To decrease weight and potentially cost, you can replace metal with plastic on certain parts through 3D printing and injection molding. At Proto Labs, we use industrial 3D printing process stereolithography (SL) to produce thermoplastic-like parts that have a nickel coating on the surface. This offers the increased strength of aluminum die-cast components, without the weight. With injection molding, the introduction of thermally conductive plastics has broken new ground when looking for heat dissipation of expensive heat sinks.

Stereolithography parts built with SLArmor have a metal coating applied over a thermoplastic-like base.

SLArmor involves a ceramic-filled DSM Somos material, which has a metal coating applied to achieve the look, feel and, most importantly, comparable strength of aluminum without added weight. SL is a cost-effective prototyping method for initial parts that mimic metal before moving to higher volumes of die-casted parts.

The material properties of SLArmor are greatly improved in regards to heat deflection, tensile strength, elongation at break and elasticity. The chart below shows exactly how the material relates to die-cast aluminum in three different thicknesses that can be applied based on geometry of SL parts. Note that the thickness of the nickel plating may vary on each part due to the ability to apply the coatings.

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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.