What a Used Robot Cell Cycle-Time Demonstration Should Include

A fast-moving robot arm does not by itself prove that a second-hand workcell will meet a production target. The gripper has to acquire and release each part, other equipment may need to signal readiness, and the next part must be available. When comparing a used system with a production requirement, ask the seller to demonstrate the complete cycle and explain the boundaries of the measurement.

Define exactly when the clock starts and stops

Begin with one observable event, such as the gripper closing on a part at a defined pickup point. End at the same event on the following completed part. This full-cycle interval can include movement to the destination, release, return travel, waiting for a new part and the next grip. If the test instead times only motion between two points, label it as a motion interval. Both measurements may be informative, but they answer different questions.

Write down whether the demonstration starts with the feeder full, whether an operator manually positions parts, and whether the output station remains ready throughout. Identify any operations outside the timed boundary. A short video alone may not reveal a pause that occurred before recording began, or the time needed to replenish a fixture after a small batch.

Describe the cell that produced the result

Record the robot and controller model, gripper, payload, part shape, pickup and placement locations, and the approximate movement path. Note whether a vision system, conveyor, fixture or external machine participates in the cycle. Speed settings and program versions also matter. A demonstration with a light, rigid object close to the robot base should not be presented as proof for a heavier part at a distant location.

Simulation can help assess a proposed layout before installation. FANUC's ROBOGUIDE product description explains that its picking simulation tools can evaluate part rates under different part-flow conditions, conveyor speeds and layouts. A simulation is a planning aid; it does not establish the condition or actual throughput of a particular used machine. Save the model assumptions so that the result can later be compared with a physical test.

Measure a sequence rather than one ideal run

Agree on the number of consecutive cycles before testing. Record the elapsed time and the number of successfully completed parts, as well as rejected parts, missed grips and stops. For example, the average time per successful part can be calculated by dividing the measured elapsed time by the number of accepted parts. Keep the raw observations as well: an average can conceal a slow restart or a recurring pause.

If timing individual cycles, note the shortest, longest and typical observed intervals, together with the size of the sample. Describe interruptions separately rather than silently removing them. A small demonstration batch cannot establish long-term availability, and a test without representative parts cannot establish quality for the buyer's process. Repeat the test with a representative part and agreed settings where practical.

Account for waiting and handshakes

A workcell often waits for a part-present signal, clamp confirmation, machine-ready signal or operator action. Ask the seller which signals are simulated and which are generated by real equipment. If an external machine is absent, record the assumed wait and explain how it was supplied. A controller program that runs without those dependencies may be useful for demonstrating motion, but it does not demonstrate the performance of the complete production line.

FANUC's pick-and-place simulation lesson describes adding a robot, tool, parts and fixtures, and programming pickup and drop-off steps in a loop. This illustrates why the modeled equipment and sequence must be described alongside a predicted cycle. The lesson is a simulation example, not a certification of the used system offered for sale.

Turn the demonstration into an acceptance record

Keep a dated test sheet with the equipment identifiers, program revision, part description, agreed start and end events, measured intervals and exceptions. Ask both parties to note any temporary wiring, substituted tooling or disabled external equipment. If the purchaser requires a particular performance threshold, put the method and threshold in the acceptance agreement before the test rather than inferring them from an advertisement.

Safety functions, guarding and site integration need their own assessment by qualified people; a cycle-time test is not a safety inspection. Do not change limits or remove protective measures to obtain a faster number. After installation, repeat the agreed measurement with the actual feeder, downstream equipment and operating conditions, then document any differences from the seller's demonstration.

Compare quotations on the same basis

Two systems can report different cycle times because they handle different loads, distances or external waits. Ask each seller to provide the timing boundary, part details, sample count and test conditions in the same format. If a seller cannot run the buyer's part, treat the demonstration as provisional evidence and record what remains to be verified before acceptance.

For other preparation topics, review our used-equipment notes and browse the equipment articles. A transparent test record makes a quoted figure more useful and gives both parties a clear basis for resolving discrepancies.