Published: 2026-09-07 | Technical topic: drying system diagnosis on KBA presses. When the drying system fails to heat up, dries insufficiently, raises delivery stack temperature abnormally, or the console option does not match, do not simply raise the power. The IR dryer, hot-air circulation, UV dryer and delivery control are interrelated; an abnormal option, sensor or air-path element can appear as insufficient ink drying, high stack temperature, back-side marking or an alarm stop. Preserve the alarm and parameter state, confirm the equipment type and configuration, then restart under controlled conditions.
Safety note: before opening the dryer cover, touching lamps and reflectors, checking wiring, removing fans or entering the delivery area, stop the machine, disconnect power, close air supplies, apply lockout/tagout, and confirm high-temperature surfaces, rotating parts and capacitor stored energy have been released. UV sources, IR heaters and hot-air ducts can cause burns; untrained personnel must not dismantle or bypass protections.
1. First confirm which drying system the fault belongs to
The same KBA model may have end IR, inter-unit IR/TL, end UV dryers, or a combined scheme with stack temperature control. Cross-confirm from the nameplate, console pages, site cables and actual installed parts, not only from operator description or a menu name.
Heating display present but ink still not dry: check fan, duct, lamp or heat output; common directions are insufficient air volume, aged lamps, dirty reflectors or changed ink-paper compatibility. Stack temperature keeps rising: check the temperature sensor, control loop and cooling air path; sensor deviation, blocked duct or mismatched control parameters. Console has no drying option: check PLC, software version and hardware configuration; the option may not be enabled, the control component may have a communication fault, or the version may be incompatible. Alarm immediately after start: check the safety circuit, door interlock, over-temperature and air-pressure signals; protection conditions not met, failed switches or poor contact.
2. After stop and power-off, preserve the site state by area
After safe isolation, photograph the console alarm page, dryer selection page and indicator states, and record paper weight, press speed, ink type, drying mode and delivery stack height at the time. If alarms are cleared or configuration changed directly, it becomes hard to tell whether the problem is hardware or parameter change.
Record the alarm code, time and whether abnormal noise, smell or temperature rise accompanied it. Record the actual enabled state of the end dryer, inter-unit dryer and UV unit. Check the dryer exterior for paper dust, ink mist, oil and obvious discolouration. Confirm no residual paper, tools or flammable material in the delivery area, and check the positions of guards and door-interlock switches. Measurements involving high voltage, strong current, UV sources or heating components must be done by qualified personnel; do not "verify" equipment by bridging door interlocks, removing temperature control or forcing output.
3. Configuration check: type first, then the control chain
Check the dryer selection on the console against the actually installed IR, IR/TL or UV unit and confirm the corresponding option is enabled. For an IR scheme with stack temperature control, confirm the temperature-control pages and sensor inputs exist; if an EC500 or other extended control component is configured, check its communication and hardware state.
If the dryer hardware exists but the console has no option, check the PLC configuration, control-component communication and software version first rather than replacing lamps. Save the original parameters, verify inputs, outputs and alarm feedback one by one, and after replacing a PLC or control module, reload and verify per the equipment configuration instead of copying another machine's parameter file.
Drying systems usually need fan running, door closed, temperature feedback and over-temperature protection conditions all satisfied. Use the electrical drawing and actual terminals to confirm signal directions, focusing on inconsistencies such as "console shows started but no air at site" or "air at site but console still reports low air pressure".
4. Hardware and air-path inspection
After safe isolation and state recording, carry out the visual and mechanical checks. Dust on the IR reflector, discoloured lamp ends, paper dust on the fan impeller, blocked filters and leaking ducts all reduce system output. For UV units, check the lamp, reflector, cooling air volume and related protections; do not treat a visibly lit lamp as the only criterion.
Fan and filter: check turning resistance, abnormal noise, blocked filter and air-volume change; clean or replace filter media and confirm fan bearing and motor state. Duct and sealing: check loose flexible connections, leakage, dust accumulation and local overheating; restore sealing, clean the path and check insulation parts. IR heat source: check lamp discolouration, reflector contamination and terminal heating; have professionals measure and replace by type, never work live. UV unit: check lamp life, cooling air path, reflector and door interlock; handle per the maintenance procedure, avoid looking directly at the source and bypassing protection. Temperature sensor: check mounting position, fixing, cable and reading stability; calibrate or replace and re-check the control logic.
5. Low-risk restart and acceptance
After the repair, confirm all covers, guards, earth connections and connectors are restored and count tools and residues. Removal of lockout/tagout must follow the site procedure, then verify in stages at low speed, low load and with a small amount of paper.
Start only the necessary ventilation and control functions and observe for air-pressure, door or over-temperature alarms. Run at low speed, confirm the heat source or UV output builds up, and check that the console display matches the site state. Use test sheets to observe drying, stack temperature and back-side marking without going straight to full-load production. Raise speed gradually and record alarms, temperature, air volume and print changes at each stage. After acceptance, restore production parameters and write replaced parts, adjustments and restart results into the maintenance record.
If the abnormality appears only at high speed, heavy ink or high stack conditions, continue checking process compatibility and heat load rather than concluding a controller fault. If an odour, local overheating, fast temperature rise or repeated protection trips appear, stop immediately and hand over to professionals.
6. Build an executable daily checklist
Per shift: observe fan sound, console alarms, dryer appearance and delivery stack temperature trend. Per week: clean maintainable filters and external dust, check ducts, door interlocks and guards. Per month: re-check temperature feedback, air-volume change, cable terminals and maintenance records, comparing drying performance at the same paper and speed. Per equipment procedure: arrange professional maintenance of lamps, reflectors, UV cooling and high-voltage components; do not replace scheduled maintenance with temporary production recovery.
The stability of a drying system depends not on turning output to maximum, but on closing the loop between configuration, air path, heat source, sensor and process conditions. For KBA service personnel, safe isolation first, state preservation second, system distinction third, and staged restart last can significantly reduce misdiagnosis and repeated stops.
Images in the Chinese version are schematic generated illustrations, clearly marked as such and not representing any specific customer site; specific models and parameters follow the actual equipment configuration and manufacturer maintenance requirements.
