Assembly robot

01

Know whether you need repeatability or accuracy

A3, the automation trade association, explains that repeatability is how consistently a robot returns to the same position, while accuracy is how close it gets to a commanded coordinate. It gives typical repeatability of ±0.02 to ±0.1 mm and uncalibrated accuracy of about ±1 to ±5 mm for industrial robots. [2]

A3 says "for most industrial applications, repeatability matters more than accuracy because processes are taught by moving the robot to desired positions": the robot returns to the taught point even if that point is offset from the model. A3 notes that accuracy becomes important for offline programming and vision-guided moves, and can be improved by kinematic calibration, while repeatability is built into the design. [2]

Ask the supplier how repeatability and accuracy were measured and under which standard; ISO 9283 test methods were not read for this page.

If parts are located by a camera or programmed offline, specify absolute accuracy or calibration, not just repeatability.

02

Size payload, reach and arm type for the task

OSHA notes that industrial robots "are available in a wide range of sizes, shapes, and structures" with different numbers of axes, which set their working space, and that an industrial robot system includes the end-effector, controller, power, sensors and interfaces as well as the arm. [1]

Count the gripper or tool, cables and the heaviest part in the payload, and check the reach to every fixture and feeder. Suppliers linked to this page list SCARA robots for fast planar assembly and six-axis arms for reaching around parts; Topstar, for example, lists six-axis arms with 715 to 1,813 mm reach and 7 to 35 kg payload. [5] [4]

OSHA describes parallel (delta) robots as suited to very high-speed pick-and-place and assembly. [1]

03

Plan guarding, collaborative use and programming safety

OSHA separates collaborative applications, designed for direct interaction with workers, from non-collaborative ones separated by traditional machine safeguarding, and notes that robots can make fast, powerful movements through a volume larger than their base. It cites ANSI/RIA R15.06-2012 Parts 1 and 2 as the robot safety standard. [1]

OSHA reports that studies in Sweden and Japan found "many robot accidents do not occur under normal operating conditions, but instead during assembly, installation, and testing", with errors showing up during initial programming and maintenance. Its examples include a programmer struck during an unexpected motion with no enabling device on the teach pendant, a worker inside inadequate perimeter guarding, and a service worker struck after cleaning a sensor that restarted the cycle. [1]

OSHA advises that no servicing be done in automatic mode unless safeguarding prevents operation, and that safeguarding responsibilities run from the robot maker through the integrator to the employer. Ask who integrates the cell, who does the risk assessment, and what safety functions and guarding are included. [1]

04

Compare what suppliers offer

Suppliers linked to this page list SCARA, six-axis, delta and collaborative robots and assembly cells. [3] [4] [5]

EVST lists assembly robots and a 12 kg, 1,300 mm collaborative arm; SIASUN lists SCARA robots with 4 kg at 400 mm and 7 kg at 500 mm reach alongside collaborative robots and assembly automation. Treat speed and repeatability figures as supplier statements to confirm on the data sheet. [3] [4]

05

Trace the assembly robot system

This is a functional reference built from the sources cited; it is not one maker's parts list.

06

Fill the specification fields with values for your cell

A robot quotation needs task-specific values. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

07

Send the task, parts and cell data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Task: [operations; parts and weights; tolerances; cycle time]
Arm: [type; payload with tool; reach; repeatability; accuracy if vision-guided or offline-programmed]
Tool: [gripper or tool; mass; utilities]
Vision: [camera; calibration]
Cell: [layout; fixtures; feeders; conveyors]
Safety: [collaborative or guarded; guarding; safety functions; risk assessment; integrator]
Controls: [controller; teach pendant with enabling device; PLC interface]
Documents: [data sheet; payload diagram; manuals; safety documentation]

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