This guide isn’t theory. It’s shop-floor truth \u2014 what actually works, what doesn’t, and how to decide without needing an engineering degree.<\/p>\n Let’s get the basics straight before we dive into the weeds.<\/p>\n \u041e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0430 \u043d\u0430 \u0441\u0442\u0430\u043d\u043a\u0430\u0445 \u0441 \u0427\u041f\u0423<\/strong> is subtractive. You start with a solid block of material \u2014 aluminum, steel, plastic, whatever \u2014 and a cutting tool removes everything that isn’t your part. Think of it like sculpting: you’re chipping away until the shape emerges. The machine follows G-code generated from your CAD model, and the spindle spins at thousands of RPM while the tool carves out features with ridiculous precision.<\/p>\n 3D-\u043f\u0435\u0447\u0430\u0442\u044c<\/strong> is additive. You build the part layer by layer from nothing \u2014 plastic powder fused with a laser, resin cured by UV light, or filament melted through a nozzle. No block, no waste (well, minimal waste). The part literally grows on the build platform, 0.05 to 0.3 millimeters at a time.<\/p>\n Here’s the fundamental difference that actually matters on the shop floor: CNC gives you the final material properties from day one. 3D printing doesn’t.<\/strong> When you machine a block of 6061-T6 aluminum, your part inherits that alloy’s full strength, fatigue resistance, and thermal properties. When you print the same geometry in nylon PA12, you’re getting properties that depend heavily on print orientation, layer adhesion, and post-processing. It’s not worse \u2014 it’s just different. You have to account for it.<\/p>\n Another thing most comparison articles gloss over: geometry dictates everything.<\/strong> A part that’s a machinist’s dream \u2014 flat faces, through-holes, simple contours \u2014 is often a nightmare to print. And vice versa. Internal lattice structures are free with 3D printing. With CNC? You’ll need five setups, specialty tooling, and a lot of patience.<\/p>\n Not all 3D printing is the same thing. Not all CNC machining is either. Here’s what’s actually on the floor and when you’d reach for each.<\/p>\n The thing nobody tells you about metal 3D printing: you almost always need to CNC-machine the critical surfaces afterward anyway. The as-printed surface finish on DMLS parts is rough \u2014 think sandpaper, not mirror. So in practice, many production metal parts use a hybrid approach: print near-net-shape, then machine to final tolerance. We do this regularly for customers who need internal cooling channels that can’t be drilled.<\/p>\n Here’s where theory meets practice. I’ve organized this by industry so you can find your lane.<\/p>\n Material availability is the single biggest differentiator between these two processes, and it’s where most comparison charts fall short. Let me give you the real picture.<\/p>\n \u041e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0430 \u043d\u0430 \u0441\u0442\u0430\u043d\u043a\u0430\u0445 \u0441 \u0427\u041f\u0423<\/strong> works with virtually any rigid material you can buy in block form. Aluminum (6061, 7075, 5083, MIC-6), stainless steel (304, 316, 17-4PH), mild steel, tool steel, brass, copper, titanium, Inconel, PEEK, Ultem, Delrin, nylon, PTFE, acrylic, polycarbonate \u2014 if it comes in plate or bar stock, we can machine it. The material properties are known, certified, and traceable with mill test reports. No surprises.<\/p>\n 3D-\u043f\u0435\u0447\u0430\u0442\u044c<\/strong> is more limited. Here’s the reality:<\/p>\n Critical point: AlSi10Mg is not 6061-T6.<\/strong> If your print says “aluminum,” check which aluminum. The printed alloy has about 70-80% the fatigue strength of wrought 6061. For most brackets and housings, that’s fine. For a structural aerospace component, you need to verify.<\/p>\n Money talks. Here’s how these processes stack up where it hurts \u2014 the invoice.<\/p>\n For 1-10 parts:<\/strong> 3D printing usually wins on cost and speed, especially for plastic parts. No fixturing, no CAM ming, no tool changes. Upload the file Friday afternoon, pick up parts Monday morning. But if the design is simple \u2014 a flat plate with some holes, a basic bracket \u2014 CNC can be surprisingly competitive even at low volumes because there’s essentially zero CAM time.<\/p>\n For 10-100 parts:<\/strong> This is the gray zone. SLS\/MJF printing stays flat on per-part cost regardless of volume (no tooling, no setup). CNC per-part cost drops as volume increases because setup is amortized across more units. At around 30-50 units for plastic parts, CNC often crosses over and becomes cheaper.<\/p>\n For 100-1,000+ parts:<\/strong> CNC machining pulls ahead dramatically for metal parts. For plastic parts, at this volume you should be looking at injection molding \u2014 the per-part cost drops to pennies once the mold is paid for. 3D printing can’t compete on unit economics at scale, though it’s fantastic for bridge production while your mold is being cut.<\/p>\n Speed comparison<\/strong> (real numbers from our floor):<\/p>\n Surface finish reality check:<\/strong> As-machined aluminum looks beautiful \u2014 clean tool paths, consistent finish, ready for anodizing. As-printed parts look… printed. SLS nylon feels like fine-grit sandpaper. SLA can look injection-molded if you dial in the orientation. FDM layer lines are visible from across the room. If cosmetics matter, CNC wins every time unless you budget for post-processing.<\/p>\n Quality isn’t about the process \u2014 it’s about the controls. But the controls are different.<\/p>\n For CNC machining:<\/strong> We use calibrated micrometers, CMMs, and in-process probing. First-article is standard. ISO 2768-m (medium) is our baseline tolerance; ISO 2768-f (fine) or tighter is achievable with the right setup. Material certs are straightforward \u2014 the mill test report from the metal supplier covers it. Surface finish is measurable with a profilometer, and Ra 0.8 \u03bcm is routine off the machine.<\/p>\n For 3D printing:<\/strong> Quality is harder to verify. Dimensional accuracy depends on part orientation, layer height, and how well the machine was calibrated that morning. We typically hold \u00b10.15mm on SLS\/MJF, which sounds loose compared to CNC but is excellent for additive. Density verification (for metal prints) requires CT scanning or destructive cross-sectioning \u2014 expensive but necessary for flight-critical parts.<\/p>\n Best practices we’ve learned the hard way:<\/strong><\/p>\n If you’re reading this and need to make a decision today, here’s the pragmatic checklist I use with customers:<\/p>\n Step 1: Ask yourself what matters most.<\/strong> Is it strength? Pick CNC. Surface finish? CNC or SLA. Complex internal geometry? 3D printing. Speed to first prototype? 3D printing. Production cost at scale? CNC or injection molding. Metal with flight certs? CNC with certified material. Lightweight lattice structures? 3D printing. Rank your requirements \u2014 the answer often becomes obvious.<\/p>\n Step 2: Count your features.<\/strong> Does the part have undercuts, internal channels, or organic curves? If yes, lean toward 3D printing. Is it mostly prismatic \u2014 flat faces, round holes, simple pockets? That’s a machining job.<\/p>\n Step 3: Look at your quantity.<\/strong> 1-10 parts: 3D printing for plastic, CNC for metal. 10-100: cross-over zone, get quotes for both. 100+: CNC for metal, injection molding for plastic.<\/p>\n Step 4: Send us the file.<\/strong> Seriously. Our engineers review every geometry before recommending a process. Sometimes the answer is “print the complex section and machine the precision surfaces” \u2014 a hybrid approach that gives you the best of both worlds. You don’t need to figure this out alone.<\/p>\n Here’s the thing: you don’t have to pick sides. The best manufacturers don’t \u2014 they pick the right tool for each job. Sometimes that’s a 5-axis CNC mill making chips at 12,000 RPM. Sometimes it’s an SLS printer fusing nylon powder in the dark. Sometimes it’s both, on the same part.<\/p>\n The decision comes down to three things: geometry, quantity, and material requirements.<\/strong> If you know those three things about your part, you’re 90% of the way to the right answer. For the other 10%, that’s what our application engineers are here for.<\/p>\n Next time you’re holding that napkin sketch wondering which way to go \u2014 send it over. We’ll tell you straight up what makes sense, no sales pitch, just shop-floor truth.<\/p>\n![\"CNC](\"https:\/\/nylonplastic.com\/wp-content\/uploads\/2026\/05\/np-ai-072-6db87551a4-1.jpg\" "\\"3D")
Core Concepts & Fundamentals<\/h2>\n
Key Processes & Technologies<\/h2>\n
![\"CNC](\"https:\/\/nylonplastic.com\/wp-content\/uploads\/2026\/05\/np-ai-073-25bdacb281-1.jpg\" "\\"3D")
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\n \n\u0422\u0435\u0445\u043d\u043e\u043b\u043e\u0433\u0438\u044f<\/th>\n How It Works<\/th>\n Typical Accuracy<\/th>\n \u041b\u0443\u0447\u0448\u0435\u0435 \u0434\u043b\u044f<\/th>\n Watch Out For<\/th>\n<\/tr>\n<\/thead>\n \n CNC Milling (3-axis)<\/strong><\/td>\n Rotating cutting tool removes material from a clamped block<\/td>\n \u00b10.005 mm \u2014 \u00b10.05 mm<\/td>\n Metal parts, tight tolerances, production runs, functional prototypes<\/td>\n Undercuts and deep pockets need specialty tooling; setup time adds cost<\/td>\n<\/tr>\n \n CNC Milling (5-axis)<\/strong><\/td>\n Same as 3-axis but the workpiece can rotate and tilt<\/td>\n \u00b10.005 mm \u2014 \u00b10.05 mm<\/td>\n Complex geometry, reduced setups, impellers, aerospace components<\/td>\n Higher machine cost; not always faster than 3-axis for simple parts<\/td>\n<\/tr>\n \n CNC Turning<\/strong><\/td>\n Workpiece spins while a stationary tool cuts the profile<\/td>\n \u00b10.005 mm \u2014 \u00b10.025 mm<\/td>\n Shafts, bushings, fasteners, anything round<\/td>\n Only works for rotationally symmetric parts<\/td>\n<\/tr>\n \n FDM (Fused Deposition Modeling)<\/strong><\/td>\n Thermoplastic filament melted and extruded layer by layer<\/td>\n \u00b10.1 mm \u2014 \u00b10.5 mm<\/td>\n Quick concept models, jigs and s, low-cost prototyping<\/td>\n Visible layer lines; anisotropic strength (weak between layers)<\/td>\n<\/tr>\n \n SLA (\u0441\u0442\u0435\u0440\u0435\u043e\u043b\u0438\u0442\u043e\u0433\u0440\u0430\u0444\u0438\u044f)<\/strong><\/td>\n UV laser cures liquid resin into solid layers<\/td>\n \u00b10.05 mm \u2014 \u00b10.15 mm<\/td>\n Smooth cosmetic prototypes, mold patterns, dental\/medical models<\/td>\n Resin is brittle long-term; needs UV post-curing; limited functional use<\/td>\n<\/tr>\n \n SLS (\u0441\u0435\u043b\u0435\u043a\u0442\u0438\u0432\u043d\u043e\u0435 \u043b\u0430\u0437\u0435\u0440\u043d\u043e\u0435 \u0441\u043f\u0435\u043a\u0430\u043d\u0438\u0435)<\/strong><\/td>\n Laser fuses nylon powder into solid parts<\/td>\n \u00b10.1 mm \u2014 \u00b10.2 mm<\/td>\n Functional prototypes, end-use plastic parts, complex assemblies<\/td>\n Grainy surface finish; limited material palette; powder handling is messy<\/td>\n<\/tr>\n \n MJF (Multi Jet Fusion)<\/strong><\/td>\n Fusing and detailing agents + infrared heat on nylon powder<\/td>\n \u00b10.1 mm \u2014 \u00b10.2 mm<\/td>\n Production-grade nylon parts, consistent mechanical properties<\/td>\n Similar constraints to SLS; color is always gray or black<\/td>\n<\/tr>\n \n DMLS\/SLM (Metal 3D Printing)<\/strong><\/td>\n Laser melts metal powder into fully dense parts<\/td>\n \u00b10.05 mm \u2014 \u00b10.1 mm<\/td>\n Complex metal parts impossible to machine; conformal cooling channels<\/td>\n Very expensive per part; requires post-machining for critical surfaces; build size limited<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n \u041f\u0440\u043e\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u043e\u0435 \u043f\u0440\u0438\u043c\u0435\u043d\u0435\u043d\u0438\u0435<\/h2>\n
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\n \n\u041f\u0440\u043e\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u043e\u0441\u0442\u044c<\/th>\n Application<\/th>\n \u041c\u0430\u0442\u0435\u0440\u0438\u0430\u043b<\/th>\n Key Requirement<\/th>\n nylonplastic.com Advantage<\/th>\n<\/tr>\n<\/thead>\n \n \u0410\u0432\u0442\u043e\u043c\u043e\u0431\u0438\u043b\u0438<\/strong><\/td>\n Intake manifold prototype<\/td>\n Nylon PA12 (SLS) + Aluminum 6061 (CNC)<\/td>\n Heat resistance + dimensional accuracy<\/td>\n SLS for fit-check iterations in 48h; CNC aluminum for dyno testing in 5 days<\/td>\n<\/tr>\n \n \u0410\u044d\u0440\u043e\u043a\u043e\u0441\u043c\u0438\u0447\u0435\u0441\u043a\u0430\u044f \u043f\u0440\u043e\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u043e\u0441\u0442\u044c<\/strong><\/td>\n Bracket with weight-optimized lattice<\/td>\n Titanium Ti-6Al-4V (DMLS)<\/td>\n Strength-to-weight ratio, flight certification<\/td>\n DMLS achieves 40% weight reduction impossible via machining; post-CNC for mounting surfaces<\/td>\n<\/tr>\n \n \u041c\u0435\u0434\u0438\u0446\u0438\u043d\u0430<\/strong><\/td>\n Surgical guide for knee replacement<\/td>\n Biocompatible resin (SLA) or Nylon PA12 (MJF)<\/td>\n Sterilizability, patient-specific geometry<\/td>\n MJF nylon withstands autoclave sterilization; CNC alternative in medical-grade PEEK available for implants<\/td>\n<\/tr>\n \n \u042d\u043b\u0435\u043a\u0442\u0440\u043e\u043d\u0438\u043a\u0430<\/strong><\/td>\n Custom heatsink enclosure<\/td>\n Aluminum 6061 (CNC)<\/td>\n Thermal conductivity, EMI shielding<\/td>\n CNC delivers \u00b10.01mm flatness for component mating; black anodizing for corrosion resistance<\/td>\n<\/tr>\n \n \u041f\u0440\u043e\u043c\u044b\u0448\u043b\u0435\u043d\u043d\u043e\u0435 \u043e\u0431\u043e\u0440\u0443\u0434\u043e\u0432\u0430\u043d\u0438\u0435<\/strong><\/td>\n End-of-arm robot gripper<\/td>\n Nylon PA12 + carbon fiber fill (MJF) or Aluminum 7075 (CNC)<\/td>\n Lightweight, fatigue resistance over 1M+ cycles<\/td>\n Carbon-filled nylon via MJF cuts weight 60% vs aluminum; CNC option for high-cycle steel alternatives<\/td>\n<\/tr>\n \n \u0420\u043e\u0431\u043e\u0442\u0438\u0437\u0438\u0440\u043e\u0432\u0430\u043d\u043d\u0430\u044f \u0430\u0432\u0442\u043e\u043c\u0430\u0442\u0438\u0437\u0430\u0446\u0438\u044f<\/strong><\/td>\n Sensor mounting bracket<\/td>\n Aluminum 6061-T6 (CNC)<\/td>\n \u00b10.02mm positional accuracy<\/td>\n 5-axis CNC in one setup eliminates stacking tolerance errors; clear anodize preserves dimensional stability<\/td>\n<\/tr>\n \n \u041f\u043e\u0442\u0440\u0435\u0431\u0438\u0442\u0435\u043b\u044c\u0441\u043a\u0438\u0435 \u0442\u043e\u0432\u0430\u0440\u044b<\/strong><\/td>\n Product housing with snap-fits<\/td>\n ABS-like resin (SLA) for prototype; PC\/ABS (injection molding) for production<\/td>\n Aesthetic surface + functional living hinges<\/td>\n SLA delivers injection-mold-like finish for investor demos; direct bridge to our injection molding line<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Material Selection \u2014 What Actually Works<\/h2>\n
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Cost & Performance Trade-offs<\/h2>\n
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Quality Standards & Best Practices<\/h2>\n
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Getting Started \u2014 Practical Steps<\/h2>\n
![\"CNC](\"https:\/\/nylonplastic.com\/wp-content\/uploads\/2026\/05\/np-ai-075-1a0787c4e7-1.jpg\" "\\"3D")
\u0417\u0430\u043a\u043b\u044e\u0447\u0435\u043d\u0438\u0435<\/h2>\n
\u0421\u0432\u044f\u0437\u0430\u043d\u043d\u044b\u0435 \u0440\u0435\u0441\u0443\u0440\u0441\u044b<\/h2>\n
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![\"CNC](\"https:\/\/nylonplastic.com\/wp-content\/uploads\/2026\/05\/np-ai-076-db5e2842ce-1.jpg\" "\\"3D")