A steel part can be made by powder metallurgy (compacting iron powder particles and sintering to produce a solid) or by machining from a solid steel block. Which part is expected to have the higher toughness?
Dear Oshamh,
In powder metallurgy process all the metals are in powder form. In casting the metal is heated above its melting point and poured into a die and allowed to cool. The part is then machined for a accurate part.
Both powder metallurgy and die casting entail filling a die or mold that forms your desired shape. Then they formed part is released. This process influences part and tool design.
In die casting, molten metal is poured into the die, where it freezes. After release, it usually goes through several machining operations and often a heat treatment.
In contrast, the powder metal process involves use of cold powder. (Some variants do involve heating the powder, but not to melting point.) When the die is full, an upper tool comes down to compact the powder. The die then opens, and the part is ejected.
Many powder metal parts then go through sintering, which fuses the mix into a fully hardened piece.
Where Powder Metallurgy and Die Casting Separate (Differences)
Even though the processes share similarities, many of powder metallurgy's advantages and disadvantages are quite different from casting's pros and cons.
Quality
In die casting, a turbulent liquid fills the cavity. Sometimes this will trap air, leading to non-fills (your material doesn’t fully fill the mold). Oxide skin can drop into the liquid to create internal defects, and flow lines and porosity are common. To verify integrity and detect defective parts after casting, sometimes you need leak testing, X-rays and other inspection
One of the advantages of powder metallurgy is consistency. A uniform weight of powder is deposited into the die on each cycle, and compacted to the same density. Providing the powder metal manufacturer follows good housekeeping practices and avoids powder contamination, internal defects are highly unlikely.
A second advantage is control over microstructure. In die casting this is determined by cooling rate, which varies depending on factors like surface area and volume. Powder metallurgy provides much greater control and consistency, plus an ability to form finer microstructures. Why does this matter to the designer? It makes it especially skilled at producing hard, tough components -- think high-speed steel tools.
When order volume exceeds a few dozen, process economics dictate a near-net shape manufacturing process with little after-work necessary. Many engineers and buyers gravitate to die casting, but there are good reasons for considering powder metal especially as new uses, materials, and design possibilities are unlocked better to evolving technology and understanding of powder metallurgy.
To compare powder metallurgy vs. casting specifically, die casting and can be explained the many advantages of powder metallurgy.
Advantages of Powder Metallurgy Vs. Die Casting
When comparing powder metallurgy vs. casting, it's most important to look at these factors:
- Quality
- Material implications
- Mechanical properties
- Cost
- Applications
To generalize, another main advantages of powder metallurgy can be very economical for mass production (100,000 parts). Long term reliability through close control of dimensions and physical properties. Very good material utilization - loss of material very less. minimization or elimination of machining.
Hope it is helpful to you.
Ashish
Dear Osamah, agree with Hamed Mirzadeh, for PM toughness. In addition, the fatigue strength of PM component is usually lower than the forging material in a smooth specimen, but may have low sensitivity to a notch. Some interesting references may be useful: https://www.researchgate.net/post/How_about_the_fatigue_strengths_in_additive_manufacturing_components
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