Essential Robot Components: Parts, Materials & Manufacturing Processes
Every robot — from a 6-axis industrial arm to an autonomous delivery vehicle — is built from the same 12 categories of mechanical components. This guide covers each one from a manufacturing perspective: what it is, which materials and processes to use, what tolerances to specify, and the mistakes that cost teams time and money.
The 12 Component Categories
California's robotics ecosystem raised over $2B in Series B+ funding in 2025–2026, all flowing into mechanical hardware procurement. Below, we cover each category with alloy-grade materials, process selection, and critical tolerances.
Structural Components
The skeleton — load-bearing members that define the robot's shape and rigidity
Motion & Power Transmission
Converting motor torque into controlled movement at each axis
Actuators & End-of-Arm Tooling
Housing motors, engaging workpieces, and mounting drives to the structure
Sensing & Protection
Protecting sensitive electronics and managing the wiring that connects them
Structural Components
The skeleton — load-bearing members that define the robot's shape and rigidity
Structural Links & Arms
Structural links are the rigid members that connect joints in a kinematic chain — the "bones" of the robot. In a 6-axis industrial arm, there are typically 6 links ranging from 150 mm (5.9 in.) wrist links to 800 mm+ (31.5 in.+) upper arms. In mobile robots and AMRs, the structural frame serves the same load-bearing role.
Teams building humanoid robots (like Figure AI in Sunnyvale, which raised over $1B in Series C funding in September 2025) need dozens of unique structural links per unit — each with different load paths, cable routing channels, and joint interfaces.
Materials
Best general-purpose choice. Yield strength ~276 MPa (40 ksi), density 2.70 g/cm³. Anodizes well. Covers ~70% of robot link applications.
When stiffness-to-weight ratio matters. Yield ~503 MPa (73 ksi) but poor weldability and anodizing. Used on high-load upper arms and shoulder links.
Up to 60% lighter than aluminum at equivalent stiffness. Common for lightweight cobots and drones. Requires bonded aluminum inserts at joint interfaces.
Washdown environments (food processing, pharma). Higher density (8.0 g/cm³) limits use to shorter links where corrosion resistance is non-negotiable.
Manufacturing Process
CNC milling (3-axis for simple links, 5-axis for sculptured profiles with internal cable channels). Larger links for mobile robot chassis may use sheet metal weldments (laser-cut 6061-T6 or mild steel, MIG/TIG welded, then machined at joint interfaces). Carbon fiber tubes are typically procured and bonded to CNC machined aluminum end fittings.
Critical Tolerances
Common Mistake
Designing hollow links with internal pockets too thin to machine without chatter. Minimum recommended wall thickness for CNC machined 6061-T6 links: 0.060 in. (1.5 mm) for small parts, 0.100 in. (2.5 mm) for parts over 300 mm (12 in.) long.
Chassis & Base Frames
The chassis is the structural foundation — it carries all other subsystems, absorbs dynamic loads, and defines the robot's overall rigidity. For industrial arms, this is a cast or machined base plate anchored to the floor. For mobile robots (AMRs), it's a welded or sheet-metal enclosed frame housing batteries, controllers, and drive components.
Autonomous construction robots (like Bedrock Robotics' autonomous excavator retrofits, now deploying at scale) need chassis structures that survive continuous vibration, dust ingress, and thermal cycling from –10°C to 55°C (14°F to 131°F).
Materials
Default for AMR chassis panels. Excellent formability for deep draws and complex bends. Typical gauge: 0.063–0.090 in. (1.6–2.3 mm).
For heavy-duty mobile robots above 200 kg (440 lb) gross weight. Lower cost, easier to weld (MIG), inherently stiffer. Powder coat for corrosion protection.
For industrial arm base plates and precision mounting platforms. 0.5–1.5 in. (12.7–38 mm) thick plate, CNC machined on both faces for flatness.
Production-volume industrial arm bases (above 500 units/year). Investment-cast or sand-cast, finish-machined at mounting interfaces.
Manufacturing Process
AMR chassis: sheet metal fabrication — laser-cut panels, CNC press brake bending, MIG/TIG welded assembly, PEM hardware insertion, powder coat or anodize. Industrial arm bases: CNC machined from 6061-T6 plate (prototype), transition to A356-T6 casting with CNC finish machining at volume.
Critical Tolerances
Common Mistake
Designing an AMR chassis as a flat plate without torsional reinforcement, then discovering that the frame twists when one wheel hits a bump — causing sensor misalignment and navigation errors. Add diagonal gussets or a closed-section tunnel along the chassis centerline.
Bearing Blocks & Pillow Blocks
Bearing blocks house rolling-element or plain bearings and provide the structural interface between a rotating shaft and the robot frame. They appear at every supported shaft: wheel axles on AMRs, idler shafts in belt-driven axes, output shafts on gearboxes, and pivot points on linkages. Pillow blocks (pedestal-mounted) are common in XY gantries; flange blocks are used where space is tight.
Mobile robots operating on uneven terrain (warehouse floors, construction sites, outdoor paths) put asymmetric shock loads through bearing blocks at every bump — making material selection and bore tolerance critical for bearing life.
Materials
Standard for light to moderate loads. CNC machined with precision bores for bearing OD press-fit or slip-fit with retaining compound.
For heavy-duty pillow blocks carrying loads above 2,000 N (450 lbf). Superior vibration damping and fatigue resistance vs. aluminum.
For washdown and corrosive environments. Free-machining grade allows precision boring. Passivate per ASTM A967.
Manufacturing Process
CNC milling for custom bearing blocks. The bore is the critical feature — typically bored (not drilled) to ±0.0005 in. (±0.013 mm) with Ra 16–32 μin. (0.4–0.8 μm). Mounting face is surface-ground or fine-milled for flatness. At 1,000+ units, consider ductile iron casting with CNC finish machining at bore and mount surfaces only.
Critical Tolerances
Common Mistake
Specifying a bearing bore tolerance without specifying the surface finish. A bore at ±0.0005 in. (±0.013 mm) but with Ra 63 μin. (1.6 μm) finish will have the bearing OD sitting on surface peaks — creating uneven load distribution and premature failure. Always call out both.
Motion & Power Transmission
Converting motor torque into controlled movement at each axis
Joint Assemblies
A robot joint converts motor torque into controlled rotation (revolute joint) or linear motion (prismatic joint). Mechanically, a joint assembly includes: an output flange, bearing preload mechanism, cross-roller or angular-contact bearings, seals, and a housing that bolts to the adjacent link. Collaborative robots typically have 6–7 revolute joints; SCARA robots use 2 revolute + 1 prismatic.
Industrial automation platforms (like RobCo, which raised $100M in Series C and now operates from San Francisco) build modular joint assemblies that must be interchangeable across robot configurations — driving tight tolerance requirements on every interface.
Materials
Joint housings carry high bending loads at the output flange. 7075-T6's yield strength (~503 MPa / 73 ksi) handles the stress concentrations around bearing bores. Hard-anodize (Type III) adds ~0.001 in. (0.025 mm) of wear-resistant surface.
For high-torque industrial joints exceeding 200 Nm. Heat-treated to Rc 28–32 for output flanges and cross-roller bearing races. Black oxide or zinc-nickel plating for corrosion protection.
Bearing preload nuts, lock rings, and small precision-turned components. Free-machining grade keeps cycle times down on Swiss-type lathes.
Manufacturing Process
CNC turning + milling on a mill-turn center for cylindrical joint housings. The bore for cross-roller bearings requires ±0.0005 in. (±0.013 mm) tolerance with Ra 16 μin. (0.4 μm) finish — typically achieved with a finish boring bar or ID grinding. Output flanges are 5-axis CNC milled from billet to hold bolt-circle concentricity.
Critical Tolerances
Common Mistake
Specifying an interference fit for bearings without accounting for thermal expansion during operation. A joint running at 60°C (140°F) in 7075-T6 aluminum will see ~0.0003 in. (0.008 mm) bore growth per inch of diameter — enough to loosen a light press fit. Design for the operating temperature range, not room temperature.
Gearboxes & Speed Reducers
Robot joints rarely connect motors directly to output — a speed reducer multiplies torque and reduces speed. The three dominant types in robotics are: harmonic drives (strain-wave, 50:1–160:1 ratios, near-zero backlash), cycloidal reducers (high shock tolerance, 30:1–120:1), and planetary gearboxes (compact, 3:1–100:1, moderate backlash). The gearbox housing is the structural interface between the reducer and the robot link.
Supply chain robotics companies (like Mytra in Brisbane, CA, which raised $120M in Series C in January 2026) rely on planetary and cycloidal reducers in their picking and material-handling robots where torque density and shock resistance matter more than zero-backlash precision.
Materials
Gearbox housings see high cyclic loads and must maintain concentricity under torque. 7075-T6 is the standard for housings up to ~150 Nm output torque.
For internal ring gears and wave generator cams in harmonic drives. Case hardened to Rc 58–62 surface, Rc 30–35 core for fatigue resistance.
At production volumes above 500 units/year, investment-cast A356-T6 housings reduce per-unit cost by 30–50% vs. billet CNC. Machined only at critical interfaces.
Manufacturing Process
CNC milling + turning for prototype and low-volume housings (under 500 units/year). Internal gear teeth are wire-EDM cut or hobbed depending on module and quantity. At higher volumes, the housing transitions to investment casting or die casting with CNC finish machining at bearing bores, mounting faces, and seal grooves. Gear teeth ground to AGMA Q10–Q12.
Critical Tolerances
Common Mistake
Ignoring thermal expansion mismatch between an aluminum housing and steel gears. At operating temperature (50–70°C / 122–158°F), an aluminum housing expands ~2× faster than steel internals — potentially changing gear mesh and preload. Design bearing fits for the operating temperature range.
Linear Motion Components
Linear motion systems convert rotary motor output into straight-line movement — used in prismatic joints, Z-axis lifts, XY gantries, and pick-and-place stroke axes. The key manufactured components are: ball screw support blocks, linear rail mounting plates, lead screw nut housings, and carriage adapters. The ball screws and linear rails themselves are typically procured from vendors (THK, Hiwin, NSK, Bosch Rexroth).
Supply chain and warehouse robotics systems rely heavily on linear motion for picking, sorting, and palletizing. The precision of ball screw support blocks directly determines the repeatability of the entire motion axis.
Materials
Standard for support blocks and carriage adapters in clean environments. Adequate stiffness for axes under 1,000 mm (39 in.) travel.
For heavy-duty axes carrying loads above 500 kg (1,100 lb). Superior vibration damping (3–10× internal damping vs. aluminum). Cast and finish-machined.
Ball screw end-support bearing blocks on high-speed axes (above 1,000 RPM). Heat-treated to Rc 28–32 for the bearing seat.
Manufacturing Process
CNC milling from billet. Ball screw support blocks require: precision-bored bearing seats (±0.0005 in. / ±0.013 mm), datum surfaces ground or fine-milled to Ra 16 μin. (0.4 μm), and dowel pin holes for alignment. Rail mounting surface flatness across full rail length is critical — typically within 0.001 in. per 12 in. (0.025 mm per 300 mm).
Critical Tolerances
Common Mistake
Machining the linear rail mounting surface and ball screw support blocks in separate setups, then assembling — introducing alignment error. Machine both features in a single setup from a common datum, or specify a ground-in-assembly approach where alignment is verified with a dial indicator.
Couplings & Adapters
Couplings connect rotating shafts (motor-to-gearbox, gearbox-to-output) while accommodating misalignment. Three common types: bellows couplings (zero-backlash, angular and axial compliance), jaw/spider couplings (vibration damping, moderate misalignment), and rigid couplings / adapters (maximum torque transfer when shafts are precisely aligned). Tool changer adapters provide a standardized quick-connect interface between robot flange and interchangeable end effectors.
Every robot with a motor-driven joint uses at least one coupling. In a 7-axis humanoid arm, that's 7+ couplings — each a potential source of backlash, misalignment, and failure if under-specified.
Materials
For custom rigid couplings and adapters. Free-machining, corrosion-resistant, strong enough for most robotic torque requirements.
For lightweight custom couplings (cobot and drone applications). Hard-anodize for wear resistance on clamping surfaces.
For bellows coupling hubs that require good fatigue properties. Higher fatigue strength than 6061-T6.
Manufacturing Process
CNC turning for cylindrical couplings (bore, keyway, set-screw flats). Multi-axis mill-turn for tool changer adapters with bolt circles, locating pins, and pneumatic pass-through ports. Bellows couplings are typically COTS (Ruland, R+W, Huco) — you manufacture the adapters that interface to non-standard shafts.
Critical Tolerances
Common Mistake
Using a rigid coupling where a bellows coupling is needed. If the motor shaft and gearbox input have even 0.002 in. (0.05 mm) of radial offset, a rigid coupling transmits that as a once-per-rev radial load on both bearings — dramatically reducing bearing life.
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Get Free Quote FastActuators & End-of-Arm Tooling
Housing motors, engaging workpieces, and mounting drives to the structure
Actuator Housings
The actuator housing encloses the motor, encoder, and brake assembly while providing precise mounting interfaces for bearings and output shafts. It must dissipate motor heat, seal against the operating environment, and maintain alignment under load. This is one of the most tolerance-critical components in any robot.
Autonomous construction equipment (like Bedrock Robotics in SF, which raised $270M in Series B in February 2026) operates in dust, rain, and vibration — demanding IP67-rated actuator housings with aggressive thermal management.
Materials
Thermal conductivity of ~167 W/m·K makes it the default for motor housings. Anodizes to Type II or Type III for corrosion and wear protection.
When the housing doubles as a structural member carrying high bending loads. Lower thermal conductivity (~130 W/m·K) than 6061 — requires more fin area for equivalent heat dissipation.
Marine, surgical, and washdown applications where aluminum corrosion is a concern. Passivate per ASTM A967. Significantly heavier (8.0 vs. 2.70 g/cm³) and harder to machine.
Manufacturing Process
CNC milling (typically 5-axis to machine the motor cavity, bearing bores, O-ring glands, and mounting bosses in a single setup). Tight-tolerance bearing bores may require a finish boring operation. O-ring glands machined per AS568 / ISO 3601 groove dimensions.
Critical Tolerances
Common Mistake
Placing the O-ring gland too close to a bolt hole, leaving insufficient wall thickness for the seal to compress properly. Minimum recommended distance from O-ring gland centerline to nearest bolt hole edge: 2× the O-ring cross-section diameter.
End Effectors & Grippers
The end effector is what the robot actually touches the workpiece with — grippers, tool changers, vacuum cups, welding torches, or specialized tooling. Grippers come in three main types: pneumatic (fast, simple, limited force control), electric (precise force/position control, higher cost), and vacuum (for flat surfaces, film-sealed parts). The tool-changer interface plate is often the most dimensionally critical part.
AI-driven manufacturing automation companies use custom end effectors on industrial robots to form, weld, and machine complex metal structures — each tool requiring a precision tool-changer interface.
Materials
Default for gripper bodies and mounting plates. Light weight keeps payload capacity available for the workpiece. Hard-anodize (Type III) gripper jaws for wear resistance.
Gripper jaw inserts and wear surfaces in high-cycle applications. A2 at Rc 58–60 for general use; D2 at Rc 60–62 for abrasive workpieces (cast iron, ceramics).
For custom gripper fingers at prototype and low-volume (under 200 units). MJF or SLS delivers ±0.012 in. (±0.3 mm) accuracy with enough stiffness for payloads under 2 kg (4.4 lb).
Over-molded or bonded onto aluminum jaws for soft gripping of delicate parts (PCBs, glass, food items). High friction coefficient without marring surfaces.
Manufacturing Process
Gripper bodies and tool-changer plates: CNC milled from 6061-T6 billet. Jaw inserts: CNC milled tool steel, heat-treated, surface-ground to final dimension. Custom fingers for prototype: SLS or MJF in PA12 or PA12-GF. At 1,000+ units/year, consider injection-molded glass-filled nylon for fingers and covers.
Critical Tolerances
Common Mistake
Designing gripper fingers without considering workpiece variability. A 3D-printed PA12 finger that works on a sample part may crack after 5,000 cycles when actual production parts have ±0.020 in. (±0.5 mm) spread. Test with worst-case dimensions, not nominal.
Motor Mounts & Brackets
Motor mounts provide the rigid mechanical interface between a servo motor (or stepper) and the robot structure. They must maintain shaft alignment under dynamic loads, isolate vibration from the frame, and provide a thermal path for motor heat dissipation. NEMA frame sizes (NEMA 17, 23, 34) and IEC metric frames (IEC 60072) define the bolt pattern and pilot diameter.
Sidewalk delivery robots (like Serve Robotics in Redwood City, now publicly traded with over $347M raised) use dozens of motor-driven subsystems — wheel drives, steering actuators, sensor pan/tilt — each requiring a custom mount designed for outdoor shock and vibration.
Materials
Standard for most motor mounts. The 167 W/m·K thermal conductivity helps sink motor heat into the structure. CNC machined from plate or billet.
For simple L-bracket motor mounts at lower cost. Laser-cut and formed on a press brake. Typical thickness: 0.090–0.125 in. (2.3–3.2 mm).
At 2,000+ units/year, injection-molded mounts cut per-unit cost by 50–70% vs. CNC aluminum. Suitable for motors under NEMA 23 in non-structural applications.
Manufacturing Process
Low volume (under 200 units): CNC milled from 6061-T6 plate stock. Medium volume (200–2,000): sheet metal (laser cut + bend + hardware insertion). High volume (2,000+): injection-molded glass-filled nylon with brass threaded inserts molded in.
Critical Tolerances
Common Mistake
Omitting vibration isolation in motor mounts on mobile robots. Without elastomeric isolators or damping pads, motor cogging and gear mesh vibration transmit into the chassis, causing resonances in sensor mounts and affecting LIDAR/camera data quality.
Sensing & Protection
Protecting sensitive electronics and managing the wiring that connects them
Sensor & Vision Housings
Sensor housings protect cameras, LIDAR units, force/torque sensors, and IMUs while providing a precision mounting interface to the robot. They must not interfere with the sensor's field of view, must shield against EMI in electrically noisy environments, and often need IP-rated sealing for outdoor use.
Autonomous delivery vehicles (like Nuro in Mountain View, which closed $203M in Series E in August 2025 at a $6B valuation) carry multiple sensor types — LIDAR, cameras, radar, ultrasonics — each in a custom housing designed for aerodynamics, thermal management, and crash protection.
Materials
Provides EMI shielding (when grounded), structural rigidity, and thermal mass to buffer sensor electronics. Anodize or chem-film (MIL-DTL-5541) for corrosion protection.
At production volumes. Impact-resistant, UV-stable (with additives), and allows complex snap-fit geometries. Typical wall: 0.060–0.080 in. (1.5–2.0 mm).
Prototype and low-volume sensor housings. Design freedom for internal baffles, cable routing, and snap-fits. Not suitable for outdoor UV exposure without coating.
Manufacturing Process
Prototype: CNC machined from 6061-T6 billet or 3D printed (SLS/MJF PA12). Include provisions for optical windows (polycarbonate or glass, bonded with UV-cure adhesive or retained with a bezel). Production: injection molded PC/ABS with EMI shielding via conductive paint, vacuum-metallized coating, or a stamped metal EMI gasket.
Critical Tolerances
Common Mistake
Designing a sensor housing without accounting for thermal-induced pointing drift. An aluminum housing with a camera mounted 4 in. (100 mm) from the datum face will shift pointing angle by ~0.02° per 10°C change. For precision applications, use kinematic mounts (three-point contact) instead of over-constrained 4-bolt patterns.
Cable Management Components
Robot cables carry power, signal, and data across joints that rotate 360°+ and through chassis that vibrate continuously. Cable management components include: drag chains (cable carriers), cable glands (IP-rated pass-throughs), strain relief brackets, routing clips, and custom cable trays. Failure of a $2 cable clip can take down a $200,000 robot — cable management is a reliability concern, not an afterthought.
High-cycle industrial robots execute 10,000–50,000 motion cycles per day. Every cable flex point is a potential fatigue failure. Teams designing for this volume need routing solutions that guarantee 10M+ flex cycles.
Materials
Standard for drag chain links and cable glands. UL 94 V-0 flame rating available. Injection molded at volume, CNC machined or 3D printed at prototype.
For internal cable trays and routing brackets in high-vibration environments where plastic fatigue is a concern. Sheet-metal formed or CNC machined.
Prototype cable clips, custom strain reliefs, and routing brackets. Design freedom enables snap-fits and integrated cable tie anchors. Transition to PA66-GF at volume.
Manufacturing Process
Prototype: 3D print (SLS/MJF) custom clips and routing brackets — iterate quickly on fit and routing paths. Low volume: CNC machined aluminum cable trays from sheet (laser cut + bend). Production: injection-molded PA66-GF. Cable glands are typically COTS (Lapp, Hummel) — you manufacture the bulkhead plates they thread into.
Critical Tolerances
Common Mistake
Routing cables through a joint without maintaining the minimum bend radius under all joint angles. Check at maximum rotation — not just the home position. A cable that looks fine at 0° may exceed its minimum bend radius at 180° and fatigue-fail within weeks.
Process Selection Matrix
Which manufacturing process for which component, at which volume. For transition details, see our Prototype to Production Scaling Roadmap.
| Component | Prototype (1–10) | Low Volume (10–500) | Production (500+) |
|---|---|---|---|
| Structural links | CNC milling (3- or 5-axis) | CNC milling | CNC milling or casting + finish machining |
| Joint housings | CNC mill-turn | CNC mill-turn | CNC mill-turn or forging + machining |
| Actuator housings | CNC milling (5-axis) | CNC milling (5-axis) | Die casting + CNC finish machining |
| Gearbox housings | CNC milling | CNC milling | Investment casting + CNC finish machining |
| Gripper bodies | CNC milling or 3D printing | CNC milling | CNC milling or injection molding |
| Gripper fingers | SLS/MJF 3D printing (PA12) | 3D printing or urethane casting | Injection molding (PA66-GF) |
| Motor mounts | CNC milling | Sheet metal fabrication | Injection molding (PA66-GF30) |
| Sensor housings | CNC milling or 3D printing | CNC milling | Injection molding (PC/ABS) |
| Linear motion blocks | CNC milling | CNC milling | CNC milling or casting + machining |
| AMR chassis | Sheet metal fabrication | Sheet metal fabrication | Sheet metal fabrication or die casting |
| Couplings / adapters | CNC turning | CNC turning | CNC turning or MIM |
| Cable mgmt components | 3D printing (SLS/MJF) | 3D printing or CNC | Injection molding (PA66-GF) |
| Bearing blocks | CNC milling | CNC milling | Casting + CNC bore finishing |
Volume thresholds are typical guidelines — actual crossover points depend on part geometry, material, and tolerance requirements.
Material Quick Reference
Eight materials cover 90%+ of manufactured robot components. All values per ASM Handbook / MatWeb datasheets. For a full comparison: Material Selection Guide.
| Material | Type | Yield Strength | Density | Thermal Cond. | Typical Use |
|---|---|---|---|---|---|
| 6061-T6 Al | Aluminum | 276 MPa (40 ksi) | 2.70 g/cm³ | 167 W/m·K | Links, housings, mounts, chassis plates |
| 7075-T6 Al | Aluminum | 503 MPa (73 ksi) | 2.81 g/cm³ | 130 W/m·K | Joints, gearbox housings, high-load links |
| 5052-H32 Al | Aluminum | 193 MPa (28 ksi) | 2.68 g/cm³ | 138 W/m·K | Sheet metal chassis panels, covers |
| 304 SS | Steel / Iron | 215 MPa (31 ksi) | 8.00 g/cm³ | 16.2 W/m·K | Washdown links, food/pharma robots |
| 316L SS | Steel / Iron | 170 MPa (25 ksi) | 8.00 g/cm³ | 16.3 W/m·K | Marine, surgical, chemical exposure |
| 4140 steel | Steel / Iron | 655 MPa (95 ksi) HT | 7.85 g/cm³ | 42.6 W/m·K | Ball screw supports, high-torque shafts |
| PA12 (SLS/MJF) | Polymer | 48 MPa (7 ksi) | 1.01 g/cm³ | 0.33 W/m·K | Proto grippers, cable clips, covers |
| PA66-GF30 | Polymer | 90 MPa (13 ksi) | 1.37 g/cm³ | 0.37 W/m·K | Injection-molded mounts, glands, clips |
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Get Free Quote FastFrequently Asked Questions
Common questions about manufacturing robot components — materials, tolerances, process selection, and cost.
What is the most commonly CNC machined robot component?
Structural links and actuator housings account for the highest CNC machining volume in robotics. Both require tight tolerances on bearing interfaces (±0.0005–0.001 in. / ±0.013–0.025 mm) and are almost always machined from 6061-T6 or 7075-T6 aluminum billet through production volumes of several thousand units per year.
When should I 3D print robot components vs. CNC machine them?
Use 3D printing (SLS/MJF in PA12 or PA12-GF) for: custom gripper fingers at under 200 units, cable management clips during prototyping, and sensor housing prototypes where design iteration speed matters more than material properties. Switch to CNC machining when you need: bearing-bore tolerances tighter than ±0.005 in. (±0.127 mm), metal strength, thermal conductivity, or production quantities where CNC cycle time is cost-competitive. See our Prototype to Production Scaling Roadmap for volume crossover points.
What tolerances do robot joint bearings typically require?
Cross-roller bearings in revolute joints typically require a bore tolerance of ±0.0005 in. (±0.013 mm) with cylindricity within 0.0003 in. (0.008 mm) and surface finish of Ra 16–32 μin. (0.4–0.8 μm). Standard radial bearings (in wheel axles, idler shafts) use H7 tolerance class — approximately ±0.0005 in. (±0.013 mm) for bores under 2 in. (50 mm). Always specify both dimensional tolerance and surface finish on bearing bores.
Which aluminum alloy should I use for robot structural parts?
6061-T6 covers ~70% of robotic applications — structural links, motor mounts, sensor brackets, chassis plates. Choose 7075-T6 when you need higher yield strength (503 vs. 276 MPa) for joint housings, gearbox housings, and high-load links. Choose 5052-H32 for sheet metal chassis panels where formability is the priority. See our Material Selection Guide for a full alloy comparison.
How do I transition robot parts from prototype to production?
The typical path: (1) 3D print or CNC machine 1–10 units for EVT, (2) CNC machine 10–100 units for DVT with production-intent materials and tolerances, (3) bridge tooling (urethane casting or soft-tool injection molding) for 100–1,000 units during pilot, (4) production tooling (hard-tool injection molding or die casting with CNC finish machining) above 1,000 units/year. Our Prototype to Production Scaling Roadmap covers this in detail with cost crossover charts.
What IP rating do outdoor robot components need?
IP54 minimum for outdoor mobile robots (dust-protected, splash-resistant). IP67 for actuator housings and sensor housings exposed to rain, washdown, or dusty construction sites (dust-tight, submersion to 1 m for 30 min). Achieving IP67 requires O-ring seals per AS568 / ISO 3601 at every housing interface, sealed cable glands, and proper gasket compression — see our Actuator Housing Design Guide for O-ring gland dimensions.
How do I reduce cost on low-volume robot parts?
Three high-impact strategies: (1) Design for 3-axis CNC instead of 5-axis where possible — 3-axis shop rates are typically $75–125/hr vs. $150–250/hr for 5-axis. (2) Use standard stock sizes — designing a link from 1.0 in. (25.4 mm) plate instead of 1.125 in. (28.6 mm) avoids a custom material order. (3) Consolidate setups — design parts that can be machined in 1–2 setups instead of 3–4 by adding draft angles and avoiding deep internal pockets.
What surface finishes are typical for robot components?
As-machined: Ra 63–125 μin. (1.6–3.2 μm) for non-critical surfaces. Fine-machined bearing seats: Ra 16–32 μin. (0.4–0.8 μm). Type II anodize (5–25 μm): standard corrosion and cosmetic finish for aluminum. Type III hard anodize (25–75 μm): wear surfaces like gripper jaws and joint interfaces. Passivation per ASTM A967: standard for stainless steel. See our Surface Finishes Guide for the full reference.
Continue Learning
Deep-dive guides on the processes, materials, and tolerances referenced throughout this article.
Actuator Housing Design Guide
IP ratings, O-ring glands, thermal management, and housing-specific DFM
Prototype → Production Roadmap
Gantt chart, cost crossovers, and decision triggers for volume scaling
Material Selection Guide
Full alloy comparisons, mechanical properties, and process compatibility
DFM Best Practices
General design-for-manufacturing rules for CNC, sheet metal, and 3D printing
CNC Tolerances Guide
Tolerance tables, achievable accuracy by process and material, GD&T reference
Surface Finishes Guide
Ra values, anodizing, passivation, plating, and post-processing options