Assembly & Screwdriving

Application Category

OnRobot Assembly & Screwdriving

End-of-arm tooling for cobot fastening, insertion, and small-part handling — OnRobot Screwdriver with integrated Screw-bit System and 0.15–5 Nm programmable torque, RG2 and RG6 flexible 2-finger grippers (force-fit and form-fit gripping), and HEX-E QC / HEX-H QC 6-axis force/torque sensors with 200 N rated force capacity. Right-sized for UR3e, UR5e, UR7e, and UR10e benchtop assembly cells.

Assembly is where cobot ROI is decided on three axes: torque accuracy (a screw at 0.8 Nm is a different operation than one at 5 Nm — and over-torque scraps the assembly), force feedback (insertion, snap-fit, and PCB connector mating need contact force in newtons, not encoder counts), and part handling at small scale (RG2-class grippers grip 2 kg force-fit or 5 kg form-fit with custom fingertips that adapt to specific part profiles). OnRobot's assembly toolkit covers all three. The OnRobot Screwdriver delivers 0.15–5 Nm tightening torque with ±3% accuracy through a magnetic Screw-bit System that pre-aligns each screw before driving — meaning fewer dropped screws and fewer cycle errors than gripper-pickup approaches. The RG2 and RG6 use integrated Safety switches to detect contact and pair with custom fingertips for specific part profiles. The HEX-E QC and HEX-H QC 6-axis sensors mount between the robot flange and any custom tool, giving you 200 N rated force capacity across all 6 degrees of freedom. Below: pick the right tool for your assembly profile.

Choose the right assembly EOAT

Assembly Task Profile Best OnRobot Tool Capability Why
Screwdriving — automotive, electronics, white goods OnRobot Screwdriver 0.15–5 Nm / M1.6–M6 Magnetic Screw-bit System pre-aligns the screw before driving; ±3% torque accuracy; 340 RPM max; ESD-safe; supports self-tapping screws for aluminum and plastic
Light assembly, small-part pick-and-place RG2 2-finger gripper 2 kg force fit / 5 kg form fit, 110 mm stroke 3–40 N adjustable gripping force; integrated Safety switches; 0.1 mm position resolution; customizable fingertips for specific part profiles
Larger parts, heavier sub-assemblies RG6 2-finger gripper 6 kg force fit / 10 kg form fit, 160 mm stroke 25–120 N adjustable gripping force; integrated Safety switches; same configurable fingertip system as RG2; UR10e / UR12e applications
Force-sensitive insertion, peg-in-hole, mating RG2-FT smart gripper * F/T + proximity in gripper Built-in 6-axis F/T and proximity sensors at fingertips — single tool replaces gripper + separate F/T sensor stack
High-sensitivity force control: sanding, pin insertion HEX-E QC force/torque sensor 200 N / 10 Nm Txy / 6.5 Nm Tz Higher sensitivity (0.2 N noise-free Fxy resolution); IP67; recommended for force-control applications and shorter tools / lighter payloads
Higher payload or longer tools — assembly, polishing HEX-H QC heavy-duty F/T sensor 200 N / 20 Nm Txy / 13 Nm Tz Double the torque capacity of HEX-E; IP67; recommended when payload exceeds ~3 kg or tool length exceeds ~300 mm

* RG2-FT availability: The RG2-FT smart gripper has been discontinued by OnRobot effective 1/26/26. Final order date is 7/26/26; product support continues through 1/26/31. For new force-sensitive assembly applications starting after the final order date, the recommended replacement is an RG2 paired with a HEX-E QC force/torque sensor — same capability, separate components. Contact our application engineering team to discuss migration if you have RG2-FT in production.

Browse Assembly & Screwdriving EOAT

OnRobot Screwdriver and Screw-bit System sparepart kits (M1.6 through M6, screw fixes, screw carriers, bits, bit holders A and B, bit extenders 50 / 100 mm; covers DIN912, ISO4762, ISO14579, ISO14580, ISO14581, DIN7985A, ASME B18.3, ASME B18.6.3, plus self-tapping standards DIN 7981 C/F, WN 5251, WN 1411, WN 5451, ISO 4042, DIN 7500 M, DIN 14586 C, DIN 7982 C, DIN 7983 C). RG2 and RG6 grippers with standard fingertips, X-Shape fingertips for cylindrical workpieces, and 50 / 100 mm fingertip extensions. RG2-FT smart gripper (until 7/26/26). HEX-E QC and HEX-H QC 6-axis force/torque sensors with cables, mounting adapter plates, and EtherCAT converter variants.

A complete assembly cell

A typical OnRobot assembly cell pairs four parts:

  1. Cobot: Universal Robots UR3e or UR5e for benchtop screwdriving and small-part assembly; UR7e or UR10e when reach matters more than precision; UR16e for heavier sub-assembly. Doosan A-Series and Techman/Omron TM are strong alternatives for shops standardized on those platforms.
  2. EOAT: OnRobot Screwdriver for fastening; RG2 / RG6 for part picking and small-assembly handling; HEX-E or HEX-H when you need force feedback under a custom tool.
  3. Part presentation: Screw feeders attached to the Screwdriver (M1.6 through M6 rails), parts trays or pallets at fixed positions for the gripper, and a fixturing jig that holds the assembly base while the cobot works on it.
  4. Tool changer (optional): The Dual Quick Changer lets the cobot run pick-and-place with the gripper on side A and screwdriving with the Screwdriver on side B in a single program — useful for full sub-assembly cells where the same cobot handles parts and fastening.

Software layer: Universal Robots integration is the deepest, via OnRobot's Unified URCap (PolyScope 5 and PolyScope X both supported). Other robot brands integrate via the OnRobot Compute Box and a brand-specific cable kit. Browse the full OnRobot brand catalog →

Assembly & Screwdriving FAQ

What screw sizes and standards does the OnRobot Screwdriver support?

The Screwdriver delivers 0.15–5 Nm tightening torque with ±3% accuracy (or ±0.04 Nm under 1.33 Nm) at up to 340 RPM, and supports M1.6 through M6 metric screws plus US-standard sizes #1 through 1/4". Standards covered include DIN912 / ISO4762 (socket head), ISO14579 / ISO14580 (Torx socket), ISO14581 (countersunk Torx), DIN7985A (pan head), and ASME B18.3 (HEX cylinder) and ASME B18.6.3 (Cross recessed and Torx Button head, Torx Counter sunk). For self-tapping applications, the Screwdriver supports DIN 7981 C/F (ISO 7049), WN 5251, WN 1411, WN 5451, ISO 4042, DIN 7500 M, DIN 14586 C, DIN 7982 C, and DIN 7983 C — covering aluminum die-cast and plastic enclosure assembly. Each screw size has its own bit, screw fix, screw carrier, and bit holder set, so configuring for a new screw type is a parts-swap.

RG2 vs RG6 — which 2-finger gripper for assembly?

The RG2 is the lighter, lower-payload gripper — 2 kg force-fit / 5 kg form-fit payload, 0–110 mm stroke, 3–40 N adjustable gripping force, the standard choice for benchtop assembly cells running UR3e or UR5e cobots. It handles small parts, electronic sub-assemblies, and most light insertion tasks with 0.1 mm position resolution. The RG6 triples the payload — 6 kg force-fit / 10 kg form-fit, 0–160 mm stroke, 25–120 N adjustable gripping force — the right choice when you're handling larger sub-assemblies or running a UR10e or UR12e cobot. Both grippers double their effective payload when X-Shape fingertips and form-fit gripping are used (the geometry holds the part rather than the friction). Both ship with integrated Safety switches that detect contact and prevent unsafe gripping. Both use the same Quick Changer interface.

RG2-FT vs RG2 + HEX-E — which is the right force-sensitive assembly stack?

The RG2-FT integrates 6-axis force/torque sensors and proximity sensors directly into the gripper fingertips — one tool, no stack. It's the cleanest solution for force-sensitive insertion, peg-in-hole assembly, and PCB connector mating where you want gripper feedback at the point of contact. Important: the RG2-FT was discontinued effective 1/26/26 with a final order date of 7/26/26 and support through 1/26/31. For new applications starting after that date, the equivalent capability is an RG2 paired with a HEX-E sensor mounted between the robot flange and the gripper. The combined RG2 + HEX-E stack provides the same force feedback and proximity capability with two components instead of one — the trade-off is slightly more vertical stack height and a separate Compute Box channel for the HEX-E.

HEX-E QC vs HEX-H QC — which force/torque sensor do I need?

Both are 6-axis F/T sensors with the same 200 N rated force capacity (Fxy and Fz), IP67 rating, and Quick Changer interface. The difference is sensitivity vs torque/payload capacity. The HEX-E QC has finer resolution — 0.2 N noise-free Fxy resolution and 0.8 N for Fz, with rated 10 Nm Txy and 6.5 Nm Tz — recommended for high-precision force-control applications like sanding, polishing, and pin insertion. The HEX-H QC has double the torque capacity — 20 Nm Txy and 13 Nm Tz — recommended when payload exceeds roughly 3 kg or tool length exceeds roughly 300 mm. OnRobot's own guidance: HEX-E for sensitivity-driven applications, HEX-H for higher payload or longer tools. Re-calibration interval is 15,000 hours (HEX-E) vs 7,500 hours (HEX-H), reflecting the higher mechanical stress on the heavier-duty sensor.

What makes the OnRobot Screwdriver different from a third-party cobot screwdriver?

Three things. First, the integrated Screw-bit System — a magnetic bit holder + screw carrier + screw fix assembly that pre-aligns the screw on the bit before driving. The cobot picks up the screw with magnetic capture (Bit Holder A for larger screws, Bit Holder B for smaller ones), the screw carrier holds the head stable, and the bit drives directly without a separate gripper-pickup step. This eliminates the misalignment errors common when using a 2-finger gripper to pick screws. Second, real-time error detection — the Screwdriver returns specific error codes for "torque dropped unexpectedly" (broken screw) or "torque exceeded prematurely" (under-spec hole), which feeds directly into your robot program for retry logic. Third, self-tapping support for aluminum and plastic with full torque-gradient analysis, useful for plastic injection-molded enclosure assembly and aluminum die-cast applications. The trade-off: it's a single-screw-size-per-rail design, so high-mix screwdriving applications need a parts-swap between SKU types.

How are OnRobot grippers designed for collaborative operation?

The RG2 and RG6 ship with integrated Safety switches — contact-detection switches built into the gripper body that prevent unsafe gripping when the gripper contacts a long workpiece or unexpected surface. Workpiece height limits depend on grip width: at 20 mm width the RG2 handles workpieces up to ~50 mm tall, dropping as width increases. Both grippers have IP54 protection and operate within the broader collaborative robot safety envelope (per ISO 10218-1 / ISO/TS 15066) when paired with a cobot rated for collaborative operation. Other OnRobot tools (Screwdriver, HEX sensors, RG2-FT) are similarly designed to integrate with the cobot's safety system rather than carrying their own gripper-specific safety guards. For application-level safety review (force limits, pinch points, cell layout), our integrator partners can support a full risk assessment.

Can a single OnRobot cobot handle parts and screwdriving in the same cycle?

Yes. Mount an RG2 on side A for picking and placing parts, and the OnRobot Screwdriver on side B for fastening, and the cobot can switch between them in roughly five seconds inside a single program using the Dual Quick Changer. Typical sub-assembly cells use this pattern: pick the base part with RG2, place it in the fixture, pick the secondary component, place it on the base, then swap to the Screwdriver for fastening — all without a manual tool change or a second cobot. Plan for the payload overhead: the Dual Quick Changer itself is 0.41 kg, and each Tool Side adapter is 0.14 kg, so a fully populated dual stack adds about 0.69 kg (~1.5 lb) to the cobot's payload budget. The Dual Quick Changer is rated for 30 kg payload and 600 N permissible force, with ±0.02 mm repeatability across tool changes.

Speccing an assembly cell?

Send us your assembly profile (screw size and torque spec, part weight and dimensions, force-feedback requirements, target cycle time). We'll spec the cobot, Screwdriver or gripper, HEX sensor if needed, and Dual Quick Changer config — and price the complete cell.

Get a Cell Quote Call 1-888-600-3080