Assembly

Assembly cells join components into a subassembly or a finished product, from a snap-fit clip on a housing to a torqued screw into a threaded insert. The robot places or inserts one part into another, using positional accuracy for loose fits and force or torque feedback for tight ones.

Selection reflects the fit class. A snap-fit or drop-in part runs on position control from a SCARA or small 6-axis with tight repeatability. A press-fit or press-and-verify job wants force feedback at the wrist so the cell can confirm the part seated rather than jammed 3 mm short.

Vision guidance handles inbound part variation. When feeders present parts within a millimeter of nominal, hard tooling is fine; when they arrive from a bin or tray with real position drift, hand-eye calibration and a top-down camera cut the tooling cost significantly.

Tooling is where mixed-model lines live or die. Quick-change end effectors let one cell handle a family of assemblies, and a well-designed change plate swaps a screwdriver for a gripper in under a second. Fixtures on the assembly nest have to hold parts firmly enough for insertion force without deforming the housing.

Common trouble: insertion faults from part-to-part variation the vision missed, torque drift on the driver as bits wear, and cross-threaded fasteners on the first turn. A cell that logs torque and angle per fastener catches the last one on the line rather than at the customer.

Limits are real. Robots are slower per operation than a well-designed manual cell for one-off complex builds, and they struggle when parts are flexible (harnesses, gaskets, fabric) or when the mating sequence needs both hands and a look-and-feel check. Mixed-material stack-ups with wide tolerance also give assembly cells trouble.

On the floor: FANUC LR Mate 200iD for small dense assemblies at the bench, EPSON SCARA T6 for planar pick-place-insert cycles, and Universal Robots UR5e for mixed-model cobot assembly. See also screwdriving, riveting, and part inspection.