Material selection is one of the most important decisions in any part design. Engineers have to balance many different factors, including performance and cost. In traditional machining, that often leads customers to choose familiar materials like stainless steel or aluminum because higher-performance metals such as Inconel or titanium seem too expensive.

In metal additive manufacturing, that calculation changes. Higher-performance materials may still cost more per pound, but they do not always lead to a higher quote at i3D MFG.

Learn why assumptions around material price and part cost change in additive manufacturing. 

Cost Assumptions May Mislead You in 3D Printing

Many customers come to us with a specific material in mind, but it’s often based on their past experience. For instance, they may request stainless steel because they created a similar component from stainless with traditional machining. 

They know stainless will have the necessary strength and corrosion resistance; a nickel superalloy may offer additional performance advantages, but they assume the parts would simply be too expensive.

What Drives Cost in Traditional Machining

That assumption makes sense in traditional machining. Per pound of raw material, Inconel is significantly more expensive than stainless steel. Materials like Inconel are also more difficult to cut, and that can increase tool wear and slow down machining speeds. 

Ultimately, that leads to longer machine times, driving up costs. Aluminum is widely used in traditional machining partly because the raw material is relatively affordable, but also because it is generally easier and faster to cut than many higher-performance alloys.

Material removal also plays a big role in the cost equation. In traditional machining, the finished part is cut from a larger piece of stock. Depending on the part design, a significant amount of that starting material may be removed, often well over 50%. For high-value materials, that can mean you’re paying quite a bit for material you don’t actually use.

How Cost Drivers Change in Metal Additive Manufacturing

In Direct Metal Laser Sintering (DMLS), the part is built layer by layer from metal powder. Unused powder can often be recovered and reused, which means material utilization is typically much higher than in traditional subtractive manufacturing.

But the process itself also alters the cost structure. In 3D printing, machine time is one of the most important cost drivers. The machine must spread powder, melt each layer with a laser, lower the build platform, and repeat the process many times.

But different metals do not behave the same. In Inconel 3D printing, for instance, the material can be spread in thicker layers than stainless steel on our equipment, reducing machine time and its associated costs. In other cases, certain metals may melt more efficiently, or require more post-processing.

Because of these factors, low-cost materials do not automatically lead to the lowest-cost finished part.

Considering the Math on Material Utilization

Material utilization is only one of many factors that changes between additive and traditional machining, but a simple example can demonstrate how the cost behind your quote changes. Note that this is only a very rough, back-of-the-envelope calculation meant as a general illustration of one specific cost factor; these are not exact numbers taken from real-world quotes.

In this example, consider the material required to produce 5 lbs of finished nickel superalloy components. In a traditional machining process with roughly 60% material waste, the job may require roughly 12.5 lbs of starting material. In an additive process with approximately 8% material loss, those same finished components may consume closer to 5.4 lbs of material.

If the material costs $100/lb, the subtractive process could require $1,250 in starting material. The additive process may consume closer to $540 of material. The subtractive process could require more than twice the material cost in this scenario.

Again, this does not represent a past real-world quote, and it excludes machine time, setup, heat treatment, finishing, inspection, and many other requirements. But it shows why material price alone can be misleading if you’re basing your design choices on assumptions from a machining background.

New Materials Can Open the Door to Better Design Options

The option to consider a wider range of materials without major cost increases can be especially important for demanding industries like aerospace, defense, space, and energy.

In our shop, for instance, the majority of our current projects involve titanium 3D printing. And for many of these projects, customers initially requested aluminum partly because they recognized its affordability in traditional machining. But in 3D printing, titanium may offer a better combination of characteristics like strength, weight, and corrosion resistance without dramatic cost increases.

The same can be true for nickel superalloys such as Inconel 718, Inconel 625, Haynes 282, and Haynes 242. Ultimately, additive manufacturing can allow customers to evaluate more materials based on performance instead of eliminating design options too early due to cost concerns.

Let’s Discuss the Material Options for Your Application

Before choosing a familiar material from traditional machining, it’s worth discussing the full range of options that could be cost-effective for your project. Advanced or high-performance metals may be more practical than you expect.

Contact our team today to discuss your next part!