{"id":167519,"date":"2026-04-21T16:00:51","date_gmt":"2026-04-21T08:00:51","guid":{"rendered":"https:\/\/facfox.com\/docs\/?post_type=kb&p=167519"},"modified":"2026-04-21T16:05:44","modified_gmt":"2026-04-21T08:05:44","slug":"metal-part-performance-3d-printing-vs-cnc-machining-vs-casting-vs-die-casting","status":"publish","type":"kb","link":"https:\/\/facfox.com\/docs\/kb\/metal-part-performance-3d-printing-vs-cnc-machining-vs-casting-vs-die-casting","title":{"rendered":"Metal Part Performance: 3D Printing vs. CNC Machining vs. Casting vs. Die Casting"},"content":{"rendered":"

Selecting the right metal manufacturing process is not just about cost or lead time \u2014 it fundamentally determines the mechanical performance, surface quality, and long-term reliability of your parts. At FacFox, we offer four core metal manufacturing processes:\u00a0Metal 3D Printing (DMLS\/SLM)<\/strong>,\u00a0CNC Machining<\/strong>,\u00a0Investment\/Sand Casting<\/strong>, and\u00a0Die Casting<\/strong>. Each delivers distinct material properties, even when using nominally the same alloy.<\/p>\n

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Left to right: CNC, 3D printing, casting, die casting products.<\/figcaption><\/figure>\n

This article provides a head-to-head comparison of material performance across these processes to help you make informed sourcing decisions.<\/p>\n

Microstructure and Grain Characteristics<\/h2>\n

The internal grain structure of a metal part is the single biggest factor driving its mechanical behavior. Different processes produce fundamentally different microstructures.<\/p>\n\n\n\n\n\n\n\n\n
Process<\/th>\nGrain Structure<\/th>\nKey Characteristics<\/th>\n<\/tr>\n<\/thead>\n
Metal 3D Printing<\/strong><\/td>\nFine, columnar grains aligned with build direction<\/td>\nRapid solidification (10^3\u201310^6 K\/s) creates very fine dendrites. Grain orientation is anisotropic \u2014 properties differ between XY-plane and Z-axis. Post-process HIP (Hot Isostatic Pressing) can reduce anisotropy and close internal porosity.<\/td>\n<\/tr>\n
CNC Machining<\/strong><\/td>\nInherited from wrought stock (rolled, forged, extruded)<\/td>\nUniform, equiaxed grains from thermomechanical processing. Highly consistent and isotropic. The benchmark for structural reliability.<\/td>\n<\/tr>\n
Investment\/Sand Casting<\/strong><\/td>\nCoarse, equiaxed or columnar depending on cooling rate<\/td>\nSlower cooling produces larger grains. Solidification defects (shrinkage porosity, micro-segregation) are common without careful process control.<\/td>\n<\/tr>\n
Die Casting<\/strong><\/td>\nFine-grained skin, coarser interior<\/td>\nRapid mold contact creates a fine “chill zone” at the surface with a coarser core. Trapped gas porosity is an inherent limitation of high-pressure die casting.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Takeaway:<\/strong>\u00a0CNC parts from wrought stock have the most uniform, predictable microstructure. 3D printed parts are fine-grained but directional. Cast and die-cast parts vary significantly with section thickness and cooling conditions.<\/p>\n

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Tensile Strength and Yield Strength<\/h2>\n

Below is a representative comparison using common alloys in each process. Values reflect typical as-produced or standard heat-treated conditions.<\/p>\n

Stainless Steel 316L<\/h3>\n\n\n\n\n\n\n\n
Property<\/th>\n3D Printing (SLM)<\/th>\nCNC (Wrought)<\/th>\nInvestment Casting<\/th>\nDie Casting<\/th>\n<\/tr>\n<\/thead>\n
Ultimate Tensile Strength (MPa)<\/td>\n640\u2013700<\/td>\n515\u2013620<\/td>\n450\u2013520<\/td>\nN\/A (rarely die-cast)<\/td>\n<\/tr>\n
Yield Strength (MPa)<\/td>\n500\u2013550<\/td>\n205\u2013290<\/td>\n170\u2013250<\/td>\nN\/A<\/td>\n<\/tr>\n
Elongation at Break (%)<\/td>\n30\u201340<\/td>\n40\u201360<\/td>\n30\u201350<\/td>\nN\/A<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Note: SLM 316L often exceeds wrought UTS due to fine grain strengthening (Hall-Petch effect), though ductility may be slightly lower in the as-built condition.<\/em><\/p>\n

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Aluminum AlSi10Mg<\/h3>\n\n\n\n\n\n\n\n
Property<\/th>\n3D Printing (SLM)<\/th>\nCNC (6061-T6)<\/th>\nInvestment Casting (A356-T6)<\/th>\nDie Casting (A380)<\/th>\n<\/tr>\n<\/thead>\n
Ultimate Tensile Strength (MPa)<\/td>\n400\u2013450<\/td>\n290\u2013310<\/td>\n260\u2013290<\/td>\n320\u2013330<\/td>\n<\/tr>\n
Yield Strength (MPa)<\/td>\n230\u2013270<\/td>\n240\u2013275<\/td>\n185\u2013205<\/td>\n160\u2013170<\/td>\n<\/tr>\n
Elongation at Break (%)<\/td>\n6\u201310<\/td>\n10\u201317<\/td>\n3\u20136<\/td>\n3\u20134<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Tool Steel \/ Mold Steel (e.g., Maraging Steel 1.2709 \/ MS1)<\/h3>\n\n\n\n\n\n\n\n
Property<\/th>\n3D Printing (SLM, aged)<\/th>\nCNC (Wrought, aged)<\/th>\nInvestment Casting<\/th>\nDie Casting<\/th>\n<\/tr>\n<\/thead>\n
Ultimate Tensile Strength (MPa)<\/td>\n1900\u20132100<\/td>\n1900\u20132050<\/td>\n1600\u20131800<\/td>\nN\/A<\/td>\n<\/tr>\n
Yield Strength (MPa)<\/td>\n1800\u20132000<\/td>\n1800\u20131950<\/td>\n1400\u20131600<\/td>\nN\/A<\/td>\n<\/tr>\n
Hardness (HRC)<\/td>\n50\u201354<\/td>\n50\u201354<\/td>\n44\u201350<\/td>\nN\/A<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Takeaway:<\/strong>\u00a03D printed metals can match or even exceed wrought strength \u2014 especially in stainless steels and tool steels \u2014 thanks to rapid solidification. However, CNC parts from wrought stock remain the gold standard for consistent ductility and fatigue life. Castings generally show lower strength unless specifically heat-treated.<\/p>\n

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Fatigue Life and Fracture Toughness<\/h2>\n

Fatigue performance is where process differences become critical in load-bearing applications.<\/p>\n\n\n\n\n\n\n\n\n
Process<\/th>\nFatigue Performance<\/th>\nPrimary Limiting Factor<\/th>\n<\/tr>\n<\/thead>\n
CNC (Wrought)<\/strong><\/td>\nExcellent \u2014 highest and most repeatable fatigue life<\/td>\nUniform microstructure with minimal internal defects<\/td>\n<\/tr>\n
Metal 3D Printing<\/strong><\/td>\nGood to Excellent (with HIP + machined surfaces)<\/td>\nInternal porosity and rough as-built surfaces act as crack initiators. HIP can close pores; machining critical surfaces is strongly recommended.<\/td>\n<\/tr>\n
Investment Casting<\/strong><\/td>\nModerate to Good<\/td>\nShrinkage porosity and inclusions reduce fatigue life. HIP is beneficial but adds cost.<\/td>\n<\/tr>\n
Die Casting<\/strong><\/td>\nModerate<\/td>\nTrapped gas porosity is difficult to eliminate. Parts generally unsuitable for fatigue-critical structural applications without additional processing.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Key insight:<\/strong>\u00a0If your application involves cyclic loading (vibration, pressure cycling, rotating components), prioritize CNC machining or 3D printing with HIP + surface finishing. Standard castings and die castings carry higher risk of premature fatigue failure.<\/p>\n

Density and Porosity<\/h2>\n\n\n\n\n\n\n\n\n
Process<\/th>\nTypical Relative Density<\/th>\nPorosity Source<\/th>\n<\/tr>\n<\/thead>\n
CNC (Wrought)<\/strong><\/td>\n>99.9%<\/td>\nEssentially fully dense<\/td>\n<\/tr>\n
Metal 3D Printing<\/strong><\/td>\n99.5\u201399.8% (as-built); >99.9% (after HIP)<\/td>\nLack-of-fusion defects, gas porosity from powder<\/td>\n<\/tr>\n
Investment Casting<\/strong><\/td>\n97\u201399.5%<\/td>\nShrinkage cavities, dissolved gas<\/td>\n<\/tr>\n
Die Casting<\/strong><\/td>\n95\u201398%<\/td>\nEntrapped air from high-speed injection<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Takeaway:<\/strong>\u00a0Porosity is the hidden enemy of mechanical performance. CNC parts are inherently fully dense. 3D printed parts approach full density with HIP. Castings require careful process control, and die castings inherently contain some porosity.<\/p>\n

Surface Finish and Dimensional Accuracy<\/h2>\n\n\n\n\n\n\n\n\n
Process<\/th>\nAs-Produced Surface Roughness (Ra)<\/th>\nTypical Tolerance<\/th>\n<\/tr>\n<\/thead>\n
CNC Machining<\/strong><\/td>\n0.4\u20133.2 um<\/td>\n+\/-0.025 mm achievable<\/td>\n<\/tr>\n
Metal 3D Printing<\/strong><\/td>\n6\u201315 um (as-built)<\/td>\n+\/-0.1\u20130.2 mm (as-built)<\/td>\n<\/tr>\n
Investment Casting<\/strong><\/td>\n3.2\u20136.3 um<\/td>\n+\/-0.1\u20130.5 mm<\/td>\n<\/tr>\n
Die Casting<\/strong><\/td>\n1.6\u20133.2 um<\/td>\n+\/-0.05\u20130.2 mm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Takeaway:<\/strong>\u00a0CNC delivers the best precision. Die casting offers surprisingly good surface finish due to the polished steel mold. 3D printing requires post-machining for tight-tolerance and smooth-surface requirements. Investment casting sits in the middle.<\/p>\n

Material Availability<\/h2>\n

Not every alloy is available for every process. Here is a summary of commonly available metals at FacFox:<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n
Material Family<\/th>\n3D Printing<\/th>\nCNC<\/th>\nInvestment Casting<\/th>\nDie Casting<\/th>\n<\/tr>\n<\/thead>\n
Stainless Steels (304, 316L, 17-4PH)<\/td>\nYes<\/td>\nYes<\/td>\nYes<\/td>\nLimited<\/td>\n<\/tr>\n
Aluminum Alloys<\/td>\nAlSi10Mg, AlSi7Mg<\/td>\n6061, 7075, 2024, etc.<\/td>\nA356, A357<\/td>\nA380, ADC12<\/td>\n<\/tr>\n
Titanium (Ti6Al4V)<\/td>\nYes<\/td>\nYes<\/td>\nYes<\/td>\nNo<\/td>\n<\/tr>\n
Tool\/Mold Steels<\/td>\nMaraging, H13<\/td>\nH13, P20, S7<\/td>\nLimited<\/td>\nNo<\/td>\n<\/tr>\n
Copper Alloys<\/td>\nCuCrZr, Pure Cu<\/td>\nC101, C110, Brass<\/td>\nBronze, Brass<\/td>\nBrass, Zinc alloys<\/td>\n<\/tr>\n
Nickel Superalloys (Inconel 625\/718)<\/td>\nYes<\/td>\nYes<\/td>\nYes<\/td>\nNo<\/td>\n<\/tr>\n
Cobalt Chrome<\/td>\nYes<\/td>\nLimited<\/td>\nYes (dental\/medical)<\/td>\nNo<\/td>\n<\/tr>\n
Zinc Alloys<\/td>\nNo<\/td>\nLimited<\/td>\nYes<\/td>\nYes (Zamak)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

When to Use Which Process<\/h2>\n

Choose Metal 3D Printing when:<\/h3>\n