Views: 105 Author: Site Editor Publish Time: 2025-11-07 Origin: Site
Content Menu
● Machine Configurations for Simultaneous Motion
● Tool Path Strategies That Cut Time
● Software and Programming Workflow
● Case Study 1: Camshaft Milling
● Case Study 2: Injection Mold Cavity
● Case Study 3: Titanium Hip Implant
● Operator Training and Safety
● Frequently Asked Questions (FAQ)
Manufacturing engineers often face parts that demand precision across multiple surfaces, angles, and features. A typical 3-axis CNC machine can handle flat or prismatic work, but when geometry includes undercuts, compound curves, or intersecting bores, the process breaks into several setups. Each repositioning adds handling time, alignment checks, and risk of tolerance drift. Multi-axis CNC systems—especially those capable of simultaneous motion—address this by allowing the tool and workpiece to move together in coordinated paths. The result is a single setup that machines complex features in one continuous operation.
Cycle time in CNC work includes loading, fixturing, cutting, and unloading. The largest variable is often the number of setups. Reducing setups from four to one can cut total time by 30% or more, depending on part size and material. Simultaneous multi-axis machining makes this possible by interpolating linear and rotary axes at the same time. The tool follows a smooth trajectory that maintains constant engagement, avoids air cuts, and eliminates indexing pauses.
Real production data supports the shift. One study on camshaft milling used virtual simulation to plan 3-axis roughing and 4-axis finishing. The combined process ran on a single machine with no manual intervention between stages. Cycle time dropped from 68 minutes to 52 minutes. Another example from tooling showed a mold cavity finished in 2.5 hours instead of 4 hours when 5-axis simultaneous paths replaced sequential 3-axis operations. These cases come from peer-reviewed journals and reflect common gains in aerospace, automotive, and medical components.
The discussion ahead covers machine configurations, path strategies, software tools, and practical examples. Each section includes specific setups, feeds, speeds, and measured outcomes. The goal is to give engineers clear benchmarks and methods they can apply directly to their own parts.
A 5-axis CNC machine has three linear axes (X, Y, Z) and two rotary axes. The rotary axes can be arranged in several ways. Table-table machines mount both rotaries on the worktable, ideal for heavy parts like engine blocks. Head-table designs place one rotary in the spindle head and one in the table, offering flexibility for smaller workpieces. Head-head configurations, though less common, suit very large components.
Kinematic chains determine how the machine interpolates motion. In a trunnion-style 5-axis mill, the A-axis tilts the table and the C-axis rotates it. The tool remains vertical while the part moves. This keeps the spindle short and rigid, reducing deflection during aluminum or titanium cuts. Spindle-head machines tilt the tool itself (B-axis) and rotate the table (C-axis). The choice affects reachable volume, collision risk, and programming complexity.
For example, a DMG Mori NTX 1000 turns small turbine wheels. The B-axis swivels ±120° and the C-axis spins continuously. Simultaneous motion lets a 6 mm ball end mill finish blade roots and hubs in one pass. Feed rate holds at 1200 mm/min with 0.1 mm stepover. Total machining time per wheel is 18 minutes, compared to 34 minutes on a 3+2 setup with indexed rotations.
Calibration matters. Rotary axis accuracy must stay within 5 arc-seconds to hold 0.01 mm tolerances on a 200 mm diameter part. Laser trackers or ballbar tests run daily in high-volume shops. Any drift adds seconds of compensation or risks scrap.
Simultaneous machining relies on tool paths that keep the cutter engaged. Traditional zig-zag patterns waste motion when the tool lifts to clear features. Modern strategies use trochoidal loops, constant cusp height, and adaptive stepover.
Trochoidal roughing maintains a fixed chip load by moving the tool in circular arcs. A 12 mm indexable mill in 4140 steel runs at 180 m/min surface speed and 0.8 mm radial depth. The path loops every 8 mm axially, removing material in thin slices. Air time drops below 5%, and spindle load stays between 45% and 55%. Roughing a 150 mm deep pocket takes 22 minutes instead of 38 minutes with conventional slots.
Finishing paths follow the part surface at constant scallop height. Software calculates stepover dynamically—wider on flat areas, tighter on steep walls. A 10 mm ball nose in Inconel 718 finishes an impeller channel at 800 mm/min feed and 0.05 mm cusp. The tool tilts 15° to 45° as the surface curves, keeping the effective diameter consistent. Total finish time per channel is 7 minutes, down from 14 minutes with fixed stepover.
Collision avoidance is built into the path. Virtual machine models in Vericut or NCSimul flag gouges before metal is cut. One aerospace shop caught a 3 mm overtravel on a fixture clamp during simulation. Correcting it in CAD saved a $12,000 titanium blank.
CAD/CAM packages drive simultaneous machining. Mastercam, Siemens NX, and Autodesk PowerMill generate 5-axis code with built-in kinematics. The workflow starts with a solid model—usually STEP or Parasolid. Feature recognition tags pockets, bosses, and freeform surfaces. The software then proposes tool paths based on stock material and remaining allowance.
Post-processors translate generic APT code into machine-specific G-code. A Fanuc 31i-B5 control needs rotary axis scaling and tool center point control (TCPC) enabled. G43.4 or G68.2 commands activate TCPC so the controller tracks the tool tip regardless of rotary position. Without TCPC, programmers must compensate manually, adding hours to setup.
Simulation inside the CAM system shows axis limits, collisions, and cycle time estimates. A typical session for a 300 mm aerospace bracket takes 20 minutes to program and 15 minutes to verify. The verified program loads directly to the machine via DNC or USB. First-part run time matches simulation within 3%.
Cloud-based CAM is gaining ground. Fusion 360 stores tool libraries and machine definitions online. Multiple engineers can collaborate on the same part file. Version control prevents overwrite errors. One medical shop reduced programming lead time from 3 days to 4 hours for hip implant revisions.
A mid-size automotive supplier machines V6 camshafts from 1045 steel billets. The part has six lobes per journal, 38 mm diameter, and 420 mm length. Tolerance on lobe profile is ±0.015 mm.
Initial process used two 3-axis vertical mills. Roughing removed 60% of material in 28 minutes. The part then moved to a 4-axis horizontal for lobe finishing—another 40 minutes including setup. Total cycle time per shaft was 68 minutes.
Engineers modeled the cam in SolidWorks and imported it to Mastercam. Roughing stayed on the 3-axis mill but used high-feed end mills to cut time to 22 minutes. Finishing moved to a Doosan DNM 5-axis with trunnion table. Simultaneous 4-axis paths followed each lobe contour with a 6 mm ball nose at 2500 rpm and 600 mm/min feed. Indexing between lobes was eliminated; the C-axis rotated continuously while the tool traced the profile.
Simulation predicted 30 minutes for finishing. Actual run time was 29.5 minutes. Combined cycle time fell to 51.5 minutes. Surface finish improved from Ra 1.6 µm to Ra 0.9 µm, removing a secondary grinding step. Annual savings on 15,000 shafts exceeded $180,000.
A tooling shop builds a four-cavity mold for polypropylene housings. Each cavity has ribs, bosses, and 8° draft angles. Core and cavity halves are 7075 aluminum, 250 mm × 180 mm × 90 mm.
Traditional approach used 3-axis machining with four setups per half. Roughing took 2 hours, semi-finishing 1.5 hours, and finishing 1.2 hours per setup—total 19.6 hours for both halves. Electrode machining for EDM added another 8 hours.
The shop switched to a Hermle C42 5-axis mill with PowerMill CAD/CAM. Roughing used a 16 mm bull nose at 12,000 rpm and 3 m/min feed in trochoidal loops. All cavities roughed in one setup—3.2 hours total. Semi-finishing with a 10 mm ball nose at 0.3 mm stepover took 2.1 hours. Finishing applied constant cusp paths at 0.08 mm height—1.8 hours. Grand total: 7.1 hours, a 64% reduction.
No electrodes were needed; surface finish hit Ra 0.4 µm directly. Mold trial produced parts within 0.02 mm of CAD. Lead time shrank from 5 days to 2 days.
A medical device manufacturer machines Ti6Al4V femoral stems. The part has a tapered shaft, curved neck, and porous coating zones. Overall length is 180 mm; critical tolerances are ±0.010 mm on the taper.
Previous process used 3+2 positioning on a 5-axis machine. Roughing removed bulk material in 3-axis mode. The part indexed 12 times for neck and head features—total machining 72 minutes plus 18 minutes setup.
Engineers programmed full simultaneous 5-axis in NX. A 12 mm rougher took 0.8 mm radial depth at 80 m/min cutting speed. The tool tilted up to 50° to clear undercuts. Finishing used a 6 mm tapered ball mill with 0.05 mm stepover and adaptive tilt to maintain 30° lead angle. Entire program ran in one clamping—48 minutes machining, 6 minutes load/unload.
In-process probing with a Renishaw OMP400 checked taper diameter every 10 parts. Feedback adjusted offset tables automatically. Reject rate fell from 4% to 0.5%. Annual output rose from 2,800 to 4,200 stems.
Spindle power and torque set limits. Aluminum roughing needs high rpm (20,000+); titanium finishing needs torque at low rpm (below 2,000). Direct-drive rotary tables deliver 0.001° resolution and 60 rpm continuous rotation. Through-spindle coolant at 70 bar clears chips from deep pockets and extends insert life 30%.
Tool holders matter. HSK-63A tapers with hydraulic chucks hold runout below 3 µm. Shrink-fit for finishing tools resists deflection on long reaches. Balanced assemblies rated G2.5 at 18,000 rpm prevent vibration spikes.
Coolant strategy affects time. Flood coolant works for steel; minimum quantity lubrication (MQL) suits titanium to avoid thermal cracks. One shop cut 4140 cycle time 12% by switching to 1000 psi through-tool coolant that cleared stringy chips instantly.
A new 5-axis VMC costs $180,000 to $350,000. Annual maintenance runs $8,000. Programming training adds $5,000 per engineer. Payback depends on part mix.
Example: 20,000 brackets per year, current cycle 45 minutes on 3-axis, target 28 minutes on 5-axis. Time saved per part is 17 minutes or 0.283 hours. Labor and machine rate $120/hour. Savings = 20,000 × 0.283 × 120 = $679,200 per year. Machine pays for itself in under 6 months.
Include scrap reduction and quality gains. Tighter tolerances mean fewer secondary operations. One shop eliminated $42,000 in annual rework after moving aero fittings to 5-axis.
Simultaneous motion increases collision risk. Operators train on virtual machines before touching real iron. Key skills: loading programs, setting work offsets with TCPC, and interpreting collision alarms.
Safety interlocks stop motion if a rotary axis stalls. Tool length sensors verify stick-out before each run. Emergency retract macros pull the tool clear on spindle overload.
Digital twins now simulate entire cells. Siemens MindSphere collects spindle load, vibration, and temperature in real time. Machine learning predicts tool wear and adjusts feed 5-10% to extend life without slowing the cycle.
Additive-subtractive hybrids build near-net shapes then finish in the same fixture. A Renishaw system prints Inconel lattice, cools, then mills to final tolerance. Cycle time for a 300 mm burner can drops 60%.
Multi-axis CNC machining with simultaneous operations transforms complex part production. The core advantage is fewer setups and continuous tool engagement. Real examples—camshafts, mold cavities, hip implants—show cycle time reductions of 25% to 64%. Supporting technologies include modern CAD/CAM, high-speed spindles, and adaptive controls.
Engineers choosing this path need accurate machine models, verified programs, and trained staff. The investment returns through higher throughput, lower scrap, and shorter lead times. Shops that master simultaneous 5-axis gain a clear edge in aerospace, medical, and high-precision markets. The capability is proven, the tools are available, and the results speak for themselves.
Q1: What is the minimum machine size for effective 5-axis simultaneous work?
A: A 500 mm × 400 mm table with ±110° tilt and 360° rotation handles most parts under 200 mm diameter.
Q2: How do I verify a new 5-axis program before cutting metal?
A: Run full simulation in Vericut or NCSimul with the exact machine kinematics and fixture model.
Q3: Can I retrofit an older 3-axis mill for simultaneous 5-axis?
A: Add a trunnion table and upgrade the control to support RTCP; expect 70% of new-machine performance.
Q4: What surface finish is achievable directly from 5-axis finishing?
A: Ra 0.4 µm to 0.8 µm in aluminum and steel with ball nose tools and constant cusp paths.
Q5: How does coolant type affect cycle time in titanium?
A: High-pressure through-tool coolant (70 bar) clears chips faster and allows 15-20% higher feed rates.
