Powder metallurgy (PM) is increasing in popularity for both magnetic and structural applications. But no matter how many design proposals come across the desk of a PM manufacturer, there’s always a unique challenge.
So, what are your powder metallurgy design considerations?
Early engagement and exchange of information with your powder metallurgy company of choice should always happen before you get deep into development. By engaging powder metallurgy suppliers early, you're more quickly able to determine the most cost-effective way to make a powder metal part -- or whether your part is even a fit for PM.
Here's a look at what you should discuss with your PM partner at the onset of each project.
5 Things to Tell Your Powder Metallurgy Supplier Now
A powder metallurgy vendor needs to know these five parameters of your project as soon as possible:
- Size and shape
- Magnetic and mechanical properties, including strength, fatigue, and hardness requirements
- Price point
- Order volume
1. Size & Shape
A big advantage of the powder metallurgy process is that it can create shapes that are expensive or impossible to fabricate via conventional machining or other competing processes. Depending on the specific features, or lack thereof, PM may not always be the most cost-effective option unless the order volume is high. (More on that in a bit.)
Size is also a key consideration, as most powder metal parts only comprise about 12-14” of surface area. In other words, if a part is too big, PM might not be the answer. (For example, engine blocks would be far too big for a powder compaction machine.)
Even if you don’t know the exact shape of your design yet, take the general concept to your manufacturer -- how does your part need to work within your assembly? An advanced PM parts supplier may actually come up with a solution that’s more compact and requires less material (and less money).
2. Mechanical & Magnetic Property Performance
What are the mechanical and magnetic characteristics that your part needs? This will determine the type of metal your manufacturer uses, not to mention the sintering process.
- Strength is an ability to endure an applied load without deformation or failure. Strength often includes the ability to withstand cyclic stresses, aka fatigue.
- Wear resistance is a part’s ability to withstand surface abrasion and is often measured by the hardness of a part. This can also imply keeping the surface integrity of surface features. Alloys that are more wear-resistant tend to be harder.
- You'll also want to discuss corrosion resistance with your powder metallurgy partner so you can ensure the end product is able to stand up to its end-use environment.
- Magnetic performance is a broad term that often begins with whether your application is AC or DC. In DC applications, your main concerns may be magnetic saturation or permeability. In AC applications, you need to look at losses and induction.
Your needs may limit your pool of potential partners. Not all manufacturers use advanced material alloys, and not all sintering furnaces are capable of ultra-high temperatures.
This is just a 101-level description of how to begin a design conversation with your supplier.
Yes, one of the biggest advantages of powder metallurgy is its ability to create unique shapes. That doesn’t mean you should abuse this powder -- er, power.
While PM can produce tighter tolerances than many think, most powder metallurgy manufacturers will be able to discuss process capability specifically to features. Your manufacturer should guide you in establishing reasonable tolerances and make your design more manufacturable. This could reduce overall cost.
In some cases, secondary machining operations will still be necessary. These may include sizing, machining, grinding, and more. In most cases, these secondary processes add to the total cost of powder metallurgy.
By communicating tolerance and precision requirements with your PM partner early on in the process, you'll get a more accurate quote and avoid surprises later.
4. Price Point
As is the case with any manufacturing technology, there’s a fine balance between cost and functionality. Cost is usually a fluid factor when it comes to powder metallurgy.
Here’s an example of what goes into your price considerations for a structural PM component:
- Level of mechanical/magnetic performance
- Size and weight
- Shape complexity
- Order volume
5. Order Volume
Powder metallurgy is generally a high-volume part-making process that requires an investment in part-specific tooling. That investment is a key component in weighing cost vs. volume of PM (and competing processes).
As such, a run of 10 parts is likely best off going through a traditional machining line. Where powder metallurgy is truly able to shine is when it comes to large part runs of several thousand or more. On large part runs, you’ll receive enough parts to more than make up for the tooling investment.
Engage early with your PM partner to relay how much you’ll need, when you’ll need it, and how frequently you’ll need it.
Checking Your Boxes
Whether you’re looking to improve a current powder metal part or upgrade from a competing process like die casting, communication is key. Make a checklist of what’s most important for the supplier to know, and both sides will be happier.
To learn more about what a powder metallurgy supplier can and can’t handle, download the free handbook below: