{"id":7028,"date":"2026-03-30T03:03:32","date_gmt":"2026-03-30T03:03:32","guid":{"rendered":"https:\/\/le-creator.com\/?p=7028"},"modified":"2026-03-30T03:22:41","modified_gmt":"2026-03-30T03:22:41","slug":"cnc-milling-service","status":"publish","type":"post","link":"https:\/\/le-creator.com\/es\/blog\/cnc-milling-service\/","title":{"rendered":"Servicio de fresado CNC: gu\u00eda de proceso, costo y selecci\u00f3n"},"content":{"rendered":"
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What Engineers and Buyers Need to Know About CNC Milling Services<\/strong><\/p>\n

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\ud83d\udcd0 Quick Specs \u2014 CNC Milling at a Glance<\/p>\n\n\n\n\n\n\n\n\n
Axis Range<\/td>\n3-axis, 4-axis, 5-axis<\/td>\n<\/tr>\n
Standard Tolerance<\/td>\n\u00b10.05 mm (ISO 2768-m)<\/td>\n<\/tr>\n
Precision Tolerance<\/td>\n\u00b10.01 mm<\/td>\n<\/tr>\n
Surface Finish<\/td>\nRa 1.6\u20133.2 \u03bcm (as-machined)<\/td>\n<\/tr>\n
Spindle Speed<\/td>\n8,000\u201330,000 RPM<\/td>\n<\/tr>\n
Materials<\/td>\n50+ metals and plastics<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

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Determining your ideal CNC milling provider is about far more than currency-to-currency (or dollar-to-dollar). Part qualities, leadtime, and costs add up to more than most design engineers realize – especially for selecting the right number of axes, material grade, or tolerance class for your part. Between toolpath generation to final inspection, this guide discusses the CNC machining process, compares costs region-by-region and machine-by-machine, and offers a real-world baseline for decision-making – so you can order under the certainty you need, rather than guesswork.<\/p>\n

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What Is CNC Milling and How Does It Work?<\/h2>\n

\"What<\/p>\n

CNC milling, a subtractive manufacturing process, includes many CNC machine types and techniques. Because it removes unwanted material through a rotating cutting tool to generate custom parts, machinist instructions throughout the process: from choosing the tool’s speed to controlling where each cutter bit travels.<\/p>\n

The machining process moves through three key stages:<\/p>\n

Design Stage – CAD. Using either native SolidWorks\/Fusion 360 or neutral formats like IGES or STEP, the smooth operation of CNC milling depends on accurately dimensioned CAD models. Inaccurate CAD models are like broken machinery – the result is lost hours chasing machining tolerances.<\/p>\n

Toolpath Stage – CAM. While CNC mills run on G-code files (a series of instruction sets specifying the precise movement of the tool, including when it should slow down or stop) to create custom CNC parts, the primary logic behind milling is an experienced programmer who selects tools, plans stepovers, chooses roughing and finishing cycles, and programs the toolpath.<\/p>\n

Execution Stage – CNC machining. Hard machines drill, cut, and perform precision machining on raw stock. Cutting (Vc) varies depending on the composition of the substrate: aluminum alloys at 200-400 m\/min, carbon steels at 80-150 m\/min, and titanium alloys at 30-70 m\/min. This is limited by the thermal stability of carbide machining tools, such as carbide drills, going too fast will simply burn the inserts and wear them out.<\/p>\n

Today’s milling centers feature spindle speeds from 8,000 to 30,000 RPM and maintain positioning accuracies of as fine as 0.005 mm in high-end applications. Combining the rigidity of the machine body, the precision of the ball screws, and the rapid feedback of the control provide the ability for a single CNC machine to repeatedly generate identical 1000 piece quantities of same parts.<\/p>\n

Answering the questions; How many axes should I choose? How many parts should I be producing? What tolerance class is needed? How can I best save lead time? literally turns a CNC mill into a real-world tool of part creation – the implications of your selection process cut themselves right down through surface finish, tool wear, and cycle time.<\/p>\n

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3-Axis, 4-Axis, and 5-Axis CNC Milling Compared<\/h2>\n

\"3-Axis,<\/p>\n

More axes on a CNC machine means all the work happens in a single setup. For complexity, if you need to add undetermined angles or get to undercuts, the more axes a CNC mill has the less re-fixturing becomes \u2014 CNC machining applications from aerospace brackets to medical housings benefit from this, and thus the more money you save overall.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n
Feature<\/th>\n3-Axis<\/th>\n4-Axis<\/th>\n5-Axis<\/th>\n<\/tr>\n<\/thead>\n
Axes of Motion<\/td>\nX, Y, Z<\/td>\nX, Y, Z + A (rotation)<\/td>\nX, Y, Z + A + B (rotation)<\/td>\n<\/tr>\n
Best For<\/td>\nFlat\/prismatic parts, brackets<\/td>\nCylindrical features, cam lobes<\/td>\nTurbine blades, impellers, medical implants<\/td>\n<\/tr>\n
Typical Tolerance<\/td>\n\u00b10.05 mm<\/td>\n\u00b10.03 mm<\/td>\n\u00b10.01 mm<\/td>\n<\/tr>\n
Setup Changes<\/td>\n3\u20136 per part<\/td>\n1\u20133 per part<\/td>\n0\u20131 per part<\/td>\n<\/tr>\n
Relative Cost<\/td>\n$35\u201355\/hr<\/td>\n$50\u201390\/hr<\/td>\n$75\u2013250\/hr<\/td>\n<\/tr>\n
Typical Parts<\/td>\nEnclosures, plates, jigs<\/td>\nShafts, gear blanks, fixtures<\/td>\nAerospace brackets, impellers, surgical tools<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

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\u2699\ufe0f Engineering Note \u2014 3+2 Indexed vs. Simultaneous 5-Axis<\/p>\n

In 3+2 (positional) machining, the two rotary axes are held at a fixed angle, but machining is carried out using the three linear axes. This method is used for most multi-face parts and is faster in programming time. Simultaneous 5 axis refers to the five axes being constantly in motion during the cut,ideal for sculptured surfaces such as turbine blades or contours for bone implants where continually changing tool vectors are necessary in order to keep tool tangent to surface.<\/p>\n<\/div>\n

High volume shops suggest 5-axis for all parts featuring undercuts, compound angles of draft or additional features that could otherwise be machined with more than 4 setups on 3 axis. For extended information please visit 5-axis CNC machining for complex components<\/a>.<\/p>\n

main point to remember: match axes of movement to shape of part. 3 axis will do 60-70% of average CNC machined parts, while 5 axes pays it’s own way on any part that might have to be done in multiple setups.<\/p>\n

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Best Materials for CNC Milling: Metals and Plastics<\/h2>\n

Materials determine machining cost, cycle time and functional performance. CNC machining facilities generally maintain stock of well over 50 forms of metal and plastic, yet six account for nearly 80% of all CNC millings placed. The most popular are summarized below.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
Material<\/th>\nTensile Strength<\/th>\nMachinability Rating<\/th>\nBest For<\/th>\nCost Tier<\/th>\n<\/tr>\n<\/thead>\n
Aluminum 6061-T6<\/td>\n310 MPa<\/td>\n90% (excellent)<\/td>\nEnclosures, brackets, prototype parts<\/td>\n$<\/td>\n<\/tr>\n
Aluminum 7075-T6<\/td>\n572 MPa<\/td>\n70%<\/td>\nAerospace structural, high-stress fixtures<\/td>\n$$<\/td>\n<\/tr>\n
Stainless Steel 304<\/td>\n515 MPa<\/td>\n45%<\/td>\nFood-grade equipment, marine hardware<\/td>\n$$<\/td>\n<\/tr>\n
Stainless Steel 316L<\/td>\n485 MPa<\/td>\n40%<\/td>\nMedical devices, chemical processing<\/td>\n$$$<\/td>\n<\/tr>\n
Titanium Ti-6Al-4V<\/td>\n950 MPa<\/td>\n22%<\/td>\nAerospace, medical implants<\/td>\n$$$$<\/td>\n<\/tr>\n
Brass C360<\/td>\n340 MPa<\/td>\n100% (reference)<\/td>\nConnectors, valve bodies, fittings<\/td>\n$$<\/td>\n<\/tr>\n
POM (Delrin)<\/td>\n70 MPa<\/td>\n95%<\/td>\nGears, bushings, low-friction guides<\/td>\n$<\/td>\n<\/tr>\n
PEEK<\/td>\n100 MPa<\/td>\n55%<\/td>\nHigh-temp seals, semiconductor fixtures<\/td>\n$$$$<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

It makes sense to do almost all CNC milling on aluminum alloys – the 6061 formed the bulk of the CNC work I did, as they will machine quicker and consistently produce good chip formation over other alloys, and the tooling is cheaper. For corrosion resistant metal parts in, say, a marine or medical environment, stainless steel 316L is most common despite being about 2.5 times slower than aluminum in the machine. Brass C360 is the criterion machinability (100%) and is used for, amongst other things electrical connectors and plumbing fittings.<\/p>\n

On the plastics side, POM (Delrin) and PEEK constitute most of the good plastics orders. POM machines as clean as brass for a very much lower cost than PEEK. PEEK can endure continuous temperatures up to 250C – thus it may be the only plastic if it is used at high temperatures in aerospace and semiconductors.<\/p>\n

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\u2699\ufe0f Engineering Note \u2014 Al 6061-T6 vs. 7075-T6<\/p>\n

6061-T6: 310 MPa tensile strength, good weldability and very good anodizing response, default alloy for most production and prototype enclosures. 7075-T6: 572 MPa (84% stronger) alloy for aerospace structural components, not weldable reliably and about 30-40% more expensive per raw stock. Default to 6061, unless the mechanical loading warrants 7075. Read the full mach comparison in our 6061 vs 7075 aluminum<\/a> article.<\/p>\n<\/div>\n

Having trouble choosing the right material for your project?<\/p>\n

The pages for aluminum CNC machining<\/a> and stainless steel CNC machining<\/a> at Le-creator are packed with the technical information for each grade.<\/p>\n

Lesson learned: Use Al 6061-T6 by default for both cost and speed. Use stainless steel or titanium only if the application absolutely requires corrosion resistance, biocompatibility, or high tensile strength.<\/p>\n

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CNC Milling Tolerances and Surface Finish Standards<\/h2>\n

\"CNC<\/p>\n

Specifying tolerance classes and surface finish requirements
\nall have a linear effect on machining time and cost. Overspecifying tolerance classes by one class results in being 30-50% more expensive per part, underspecifying results in assembly failures. Knowing the ISO 2768 tolerance classes enables you to specify only what a part needs – nothing more.<\/p>\n

ISO 2768 General Tolerances (Linear Dimensions)<\/p>\n

\n\n\n\n\n\n\n\n\n
Dimension Range<\/th>\nClass f (fine)<\/th>\nClass m (medium)<\/th>\nClass c (coarse)<\/th>\n<\/tr>\n<\/thead>\n
0.5\u20136 mm<\/td>\n\u00b10.05 mm<\/td>\n\u00b10.10 mm<\/td>\n\u00b10.20 mm<\/td>\n<\/tr>\n
6\u201330 mm<\/td>\n\u00b10.05 mm<\/td>\n\u00b10.10 mm<\/td>\n\u00b10.30 mm<\/td>\n<\/tr>\n
30\u2013120 mm<\/td>\n\u00b10.10 mm<\/td>\n\u00b10.15 mm<\/td>\n\u00b10.50 mm<\/td>\n<\/tr>\n
120\u2013400 mm<\/td>\n\u00b10.15 mm<\/td>\n\u00b10.20 mm<\/td>\n\u00b10.80 mm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Surface Finish Reference Values<\/p>\n

\n\n\n\n\n\n\n\n\n
Finish Type<\/th>\nRa Value<\/th>\nMethod<\/th>\n<\/tr>\n<\/thead>\n
As-machined (standard)<\/td>\nRa 3.2 \u03bcm<\/td>\nStandard CNC milling<\/td>\n<\/tr>\n
Fine machined<\/td>\nRa 1.6 \u03bcm<\/td>\nFinishing pass, lower feed<\/td>\n<\/tr>\n
Polished<\/td>\nRa 0.8 \u03bcm<\/td>\nHand or machine polishing<\/td>\n<\/tr>\n
Mirror<\/td>\nRa 0.4 \u03bcm<\/td>\nMulti-stage lapping<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

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\u2699\ufe0f Engineering Note \u2014 ISO 2768-m vs. ISO 2768-f<\/p>\n

(ISO 2768-m – medium.) Common tolerance class in CNC-manufactured parts. Requires most of the non-critical dimensions. Use (ISO 2768-f – fine.) only for mating surfaces, bearing bores or locating features.<\/p>\n

Dovetailing different tolerance classes on one drawing tight on the critical dimensions and relaxed on the less critical will keep costs down without compromising fit.<\/p>\n<\/div>\n

DFM Tips for Tolerance and Feature Design:<\/p>\n