Soft metals — aluminum, magnesium, brass, copper — are available in different grades at Proto Labs depending on the 3D printing, CNC machining and injection molding service chosen. Quantities range from 1 to 5,000+ parts in 1 to 15 business days.
Aluminum engine bracket 3D printed through DMLS.
At Proto Labs, we use the industrial 3D printing process of direct metal laser sintering (DMLS) to build parts from soft (and hard) materials like aluminum.
DMLS-built aluminum provides parts with excellent strength-to-weight ratios, temperature and corrosion resistance, and provides good tensile, fatigue creep and rupture strength. With a tensile strength of 37.7 ksi (260 MPa) and a hardness of 47.2 HRB, for example, you are able to have parts produced in nearly any part geometry with features like internal channels or complex undercuts that can’t be manufactured through any other method. And, final parts are still up to 98% dense.
You can also get aluminum parts using CNC machining in 6061 and 7075 grades. 6061 can provide you with improved corrosion resistance and can be welded while 7075 provides you a part that has a higher tensile strength and is harder than 6061.
Do you need a prototype of an aluminum die-cast part? We can mimic aluminum die casting using our stereolithography (SL) process and SLArmor technology. SLArmor uses our DSM Somos (NanoTool) material, applying a nickel metal coating that gives the look and feel of metal without the added strength or weight.
Here’s a question that’s often asked: How do materials used in 3D printing compare to injection-molded thermoplastics when the temperature rises? To answer that, I’ll briefly dissect the materials used in stereolithography (SL) and selective laser sintering (SLS) processes as these are commonly compared to injection molding.
SL involves a thermoset resin that is solidified by an ultraviolet laser, followed by a UV post-curing process to completely solidify the resin. As far as material properties, the big takeaway is that SL parts are built from thermoplastic-like resins, so they do break down over time in direct UV light.
SL uses materials that mimic ABS, polypropylene and glass-filled polycarbonate, and they offer an array of material properties still exist. But today we’re concerned with the thermal properties of the materials that are best suited to handle the heat — 3D Systems Acura 5530 and DSM Somos NanoTool. Both are offered in post-cured states and there’s an additional process for thermal post-curing that increases the operating temperatures.
The chart shows optimal heat deflections for SL materials. The other materials offered in SL have a much lower heat deflection ranging from 120˚F to 177˚F.
UV Post-Cure +
|DSM Somos NanoTool
In this week’s tip, we look at best practices for designing text on parts, and answer questions like raised or recessed, which fonts to use and alternative options.
Raised or Recessed?
Features can either be raised up or recessed in to part surfaces, but which way is best? Because molds are machined, we prefer to mill the actual text or logo instead of milling around those features. This allows for faster machining, easier polishing and eliminates very small mold features that may break off.
Please extrude the text/logo features by a minimum of 0.010 in. and a maximum of 0.020 in. This allows your text to be legible and not stick in the features while molding — any deeper and you risk having the text peel off and remain in the mold. So, design raised features on your CAD model to improve moldability during manufacturing and legibility on final parts.
Raised text on part is recommended.
If you must have recessed features on your part, many of the same guidelines still exist, but there is one additional concern that you will need to address in regards to the spacing between characters. Having text recessed on your part now means that the features in the mold are raised and we need to machine between each character. Features with less than 0.125 in. of clearance require spacing between each character at a minimum of 0.020 in. to properly remove all material to ensure the legibility of text.
How do you know if you should use low-volume injection molding or traditional methods? What benefit does soft aluminum tooling provide? These are just a few questions we hear regularly, so we wanted to shed some light on these important molding considerations.
Before Proto Labs began in 1999, prototyping with injection molding was costly and took months to receive the very first sample parts. We took a low-volume approach to injection molding where it was possible to get a handful of parts in a few days rather than the large-scale approach that nearly all other manufacturers used that involved part minimum in the tens of thousands and full-scale production in the millions of parts.
Proto Labs specializes in aluminum molds that use high-speed CNC machines to create a standard single cavity mold in as fast as one business day with the ability to produce up to 10,000 parts or more. Complex parts are also possible by using pin-actuated slides as well as hand-loaded mold inserts. We try to take the difficulty out of injection molding design by simplifying it.
Conventional molding uses a much more complex molds that take weeks to design, where Proto Labs is highly automated. Complex multi-plate mold designs using lifters, collapsible cores and multi-cavities are able to produce much more complex parts at high volumes, and typically, mold creation for these molds take anywhere from four to 12 weeks.
We discovered that there was a much greater need for low-volume manufacturing. Customers were placing additional orders for a few thousand parts that were being used to set-up production lines and even limited short-run production while the conventional tooling was being built.
Conventional tooling is your production mold. It’s difficult to have a bridge tool produced without having your production molder hold off on manufacturing while they create a bridge tool. Using both methods allows you to have two manufacturers producing molds side-by-side to ultimately have parts produced faster.
In my years of working closely with product designers, I’ve seen some really great designs, but on occasion, I’ve encountered part designs by both novice and experienced designers and engineers that have needed some work to improve moldability and reduce cosmetic defects. Let’s look at some common design mistakes that could result in parts with sink, warp and voids.
Why is uniform wall thickness important? Thermoplastics simply don’t like transitioning from thin to thick sections due to the ununiformed cooling. All thermoplastics shrink as they cool but when thin areas cool before thick areas, stress is created. The results may vary depending on material selection and part design, but if you’re not following the proper material guidelines for wall thickness and mold design, you may end up with unsightly voids, sink and possibly even warp within your parts.
How can you reduce the risk of these molding concerns? Provide proper wall thickness through appropriate coring, rib and boss design, which in turn, helps you avoid excessive thick or thin wall sections.