| Tow-tension stability | Process tension varies with tow size, speed, creel friction, guides and material sizing. | Closed-loop control within approximately ±1% of the operator-set tension during steady-state production. | Run a continuous production trial and record tension at the creel, spreader and take-up. Report average, minimum, maximum and standard deviation. | Stable tension reduces tow slack, excessive compaction, filament damage and variation in fiber placement. |
| Tension measurement | Load-cell capacity should be selected according to the tow and process range rather than using one oversized sensor for every product. | Use a calibrated load cell with a measurement range appropriate to the target tow tension; keep normal operation away from the bottom and top limits. | Check calibration with traceable test weights or a certified reference device before and after the trial. | An oversized sensor can reduce resolution, while an undersized sensor can overload or saturate during starts and stops. |
| Tow-size compatibility | Commercial carbon-fiber tows are commonly identified by nominal filament counts such as 1K, 3K, 6K, 12K, 24K and 50K; actual availability varies by material specification. | Select a line that supports the intended filament-count range without changing the basic tension-control architecture. | Confirm compatible tow width, filament count, sizing type, spool geometry and maximum package mass in the equipment specification. | Different tow sizes require different guide geometry, spreading force, tension settings and detection thresholds. |
| Automatic fiber-break detection | Detection may use optical, tension-based or combined sensing. A single sensor can miss breaks hidden inside a wide tow. | Use automatic detection with an alarm, event timestamp and controlled line stop or safe-speed mode. | Introduce controlled single-filament and partial-tow breaks at representative line speeds. Confirm detection, alarm, response and restart behavior. | Early detection prevents long defect sections and reduces the risk of undetected strength or continuity loss. |
| Detection response time | The required response depends on line speed and the maximum acceptable defective length. | Set the response requirement from the formula: response time ≤ allowable defect length ÷ line speed. Validate the complete sensor-to-stop sequence. | Example: at 60 m/min, material moves 1 m per second. A 100 mm maximum undetected length requires a response of about 100 ms or less. | Response time should be specified as a measurable production requirement rather than described only as “real-time.” |
| Line-speed range | Stable speed depends on tow size, process temperature, impregnation method, winding geometry and allowable tension variation. | Specify both the normal operating speed and the validated minimum and maximum speeds for each tow family. | Test acceleration, steady running, deceleration and emergency-stop recovery using production-representative material. | A line that is stable only at one speed may create defects during ramp-up, recipe changes or material transitions. |
| Guide and contact surfaces | Guides should be smooth, aligned and compatible with the tow width and sizing chemistry. Damaged surfaces can abrade filaments. | Use low-friction, wear-resistant guides with no sharp edges, burrs or abrupt changes in wrap angle. | Inspect guide surfaces, measure alignment and examine the tow under magnification after a representative production run. | Mechanical abrasion can increase fuzz, broken filaments, width variation and downstream cleaning requirements. |
| Tow spreading | Spreading performance is material- and process-dependent; excessive spreading force can damage filaments. | Specify a repeatable target tow width and width variation for each tow type, rather than one universal width. | Measure tow width at several positions and speeds using calibrated imaging or a suitable contact-free gauge. | Uniform spreading supports consistent resin access, fiber volume fraction and deposition quality. |
| Control-loop performance | Open-loop braking is sensitive to spool diameter, acceleration and friction changes. | Use closed-loop tension control with recipe-based setpoints, automatic ramp profiles and limits for over-tension and slack. | Log tension and speed during spool changes, acceleration, deceleration and normal operation; review overshoot and settling behavior. | Closed-loop control compensates more effectively for changing package diameter and transient operating conditions. |
| Data logging and traceability | Useful process records include tension, speed, alarms, line state, recipe, operator action and material identification. | Record time-stamped tension and break events at a sampling rate sufficient to identify short process disturbances. | Export a production record and confirm that alarms can be linked to spool, recipe, shift and product batch information. | Traceable data simplifies root-cause analysis and helps distinguish material defects from machine-induced defects. |
| Alarm and stop logic | Different events require different actions: single-break warning, repeated breaks, high tension, low tension and sensor failure. | Configure separate warning, controlled-stop and emergency-stop thresholds with clear operator messages. | Simulate each alarm condition and verify the resulting machine state, notification, event record and restart authorization. | Clear logic prevents both unnecessary downtime and continued production after a serious continuity fault. |
| Calibration and maintenance | Sensor accuracy can drift because of mechanical loading, contamination, temperature and cable damage. | Provide documented calibration intervals, zero checks, sensor health checks and spare wear components. | Review calibration certificates, maintenance procedures, diagnostic screens and the recommended spare-parts list. | Repeatable tension control and reliable break detection require maintained sensors, clean guides and verified settings. |
| Changeover capability | Changing tow size or material can alter tension, width, sensor thresholds and guide requirements. | Use recipe-based settings for tow type, tension setpoint, speed profile, detection threshold and alarm limits. | Perform a documented changeover between at least two representative tow sizes and compare setup time and first-pass quality. | Recipe control reduces operator variation and improves repeatability across products and shifts. |
| Acceptance criteria | Acceptance should cover both steady-state quality and transient events. | Define measurable limits for tension variation, break-detection response, tow width, alarm function and restart quality before purchase. | Run a signed factory or site acceptance test using production-representative material and operating conditions. | Predefined criteria make equipment comparisons objective and reduce disputes during commissioning. |
