Estimate the effective cycle time of a welding cell by combining weld/process time, part handling, inspection, and batch-level changeover allocation. The result expresses seconds required per completed part and converts that pace into a theoretical hourly rate.
This is useful for manual, robotic, or mixed welding cells where the arc-on or robot program time is only one part of the operating cycle. Separating recurring per-part tasks from changeover time makes it easier to see whether fixture handling, inspection, or small batch sizes are driving the effective cycle.
Inputs
sec
sec
sec
min
parts
Result
—
effective cycle time per part
Base recurring time—
Allocated changeover—
Theoretical rate—
1. Enter weld or process time Use the recurring time spent making the welds for one part.
2. Add handling time Include recurring loading, unloading, positioning, or fixture handling per part.
3. Add inspection time Enter in-cell inspection time that occurs for each part.
4. Allocate batch changeover Enter setup or changeover minutes for one batch and the corresponding batch size.
5. Review effective cycle time The main result adds recurring time and the per-part share of batch changeover; the hourly rate is its theoretical reciprocal.
Formula:
Recurring time = Weld time + Handling time + Inspection time
Allocated changeover per part = Changeover minutes × 60 ÷ Batch size
Effective cycle time = Recurring time + Allocated changeover per part
Theoretical hourly rate = 3,600 ÷ Effective cycle time
All per-part times are seconds. Changeover is entered in minutes per batch and converted to seconds before allocation.
The hourly rate assumes continuous repetition of the average effective cycle. Breaks, downtime, starvation, blocking, and quality losses are not included unless their time is built into the inputs.
What the result means
The result estimates the average cell time consumed per part after spreading batch changeover across the batch quantity.
Use a throughput or OEE calculation when you need to add operating utilization, downtime, or quality losses to this cycle basis.
Given: 55 seconds welding, 22 seconds handling, 8 seconds inspection, a 15-minute changeover, and 40 parts per batch.
Result: Effective cycle time is 107.50 seconds per part.
The batch changeover adds 22.5 seconds to each part on average, showing how batch size affects realized cycle time.
Should robot travel time be included in weld time?
Include any recurring machine motion that is required to complete the part. The field can represent the entire automatic process sequence, not only arc-on time.
What if inspection is performed outside the welding cell?
Exclude it if the inspection does not hold up the cell or consume cell resources. Include it when the cell cannot start the next part until inspection is complete.
Why allocate changeover by batch size?
A setup is a batch-level time cost. Dividing it by batch quantity converts that loss into an average seconds-per-part contribution that can be combined with recurring cycle elements.
Does the hourly rate equal actual throughput?
Not necessarily. It is a theoretical rate based on the entered average cycle and does not independently account for downtime, quality loss, material shortages, or shift breaks.
Can I use this for a two-station welding cell?
Yes if the entered times represent the effective cell cycle and account for overlapping work correctly. If stations work simultaneously, do not simply add times that occur in parallel; model the controlling sequence or bottleneck instead.