Overview - ISO 10791-9:2001 (Tool change & pallet change times)
ISO 10791-9:2001 is the ISO test method for measuring and comparing the operating times of automatic tool change and pallet change functions on machining centres. It defines standard test conditions, terminology and procedures so different CNC machining centres can be evaluated consistently for cut-to-cut tool change time (CTC) and pallet change time (PCT). The standard is intended for comparison, acceptance testing, benchmarking and to establish conventional change-time data in technical literature.
Key topics and technical requirements
- Definitions
- CTC (cut-to-cut tool change time): time between start of removal of a tool from a reference position and the end of approach of the next tool to that same position.
- PCT (pallet change time): analogous interval for pallet removal and approach.
- Measuring units: linear dimensions in millimetres and time in seconds.
- Test set-up
- Machine should be fully assembled and guarded where practicable.
- Movable auxiliary components (quills, sliding spindles) kept retracted if not required for the change.
- Reference and tool-change positions
- For machines with a horizontal Z-axis: X at mid-travel, Y at 1/4 of Y-travel from lower limit, Z with spindle nose at table edge nearest the column.
- For machines with a vertical Z-axis: X, Y and Z at mid-travel positions.
- CTC process elements: movement to/from tool-change position, tool search, tool exchange, opening/closing covers - spindle accel/decel are assumed part of approach/return.
- Tool store configurations: descriptions of common store types (drum/chain bidirectional, drum/chain unidirectional, box/matrix).
- Tool store management: fixed access (tools returned to fixed slots) and random access (two-position changer or robot-assisted).
- Test procedure essentials
- Minimum test equipment: two tool holders and a stopwatch (dial gauge optional).
- Typical test execution: a sequence of ten tool-change cycles under NC control to record min/max times and repeatability.
- Reporting: methods for presenting measured results and identifying maximum/minimum change times.
Practical applications
- Benchmarking CNC machining centre performance for purchasing decisions.
- Acceptance testing between buyers and manufacturers to verify advertised change times.
- Production planning and cycle-time estimation in process engineering.
- Maintenance and performance monitoring: detect degradation in tool/pallet handling over machine life.
- Input for simulation/lean manufacturing studies to optimize cell throughput.
- Machine tool manufacturers and OEM test labs
- Plant engineers, production planners and process engineers
- Machine tool acceptance inspectors and procurement teams
- Research labs and standards organizations documenting machining-centre performance
Related standards
- ISO 10791 series (Parts 1–3, etc.) - geometric and performance tests for machining centres
- ISO 230 - Test code for machine tools (referenced for related test methods)
Keywords: ISO 10791-9, machining centres, tool change time, cut-to-cut tool change (CTC), pallet change time (PCT), CNC tool magazine, tool store configurations, test conditions, machine acceptance testing.