Control systems
Heidenhain
Heidenhain TNC controls are common on high-precision machining centres, particularly German-built machines from Hermle and DMG. Their proprietary conversational programming and compact hardware have distinct service requirements, whether on older TNC 410PA, TNC2500, and TNC426 systems or the current TNC 620 and TNC 640 platforms.
Heidenhain's older control generation — including the TNC 410PA, TNC 2500 (dating from 1990), and TNC 426 — is still found on legacy machines in UK workshops. The TNC 410PA featured digital speed control and integrated current control, while the TNC 426 offered digital drive control for up to five axes. These systems use proprietary conversational programming and RS-232 serial data interfaces, and CRT displays on the oldest units are increasingly prone to failure.
The transition from these older TNC platforms to the current generation brought significant changes in hardware architecture. The iTNC 530 — a fully PC-based control with a separate industrial PC unit — bridged this gap and is still encountered on mid-2000s machine builds. The PC hardware side is typically where faults occur on these systems, while the real-time NC kernel is generally reliable.
The current Heidenhain lineup centres on the TNC 620 (compact milling control, standard on Hermle, Deckel Maho, and Geist machining centres) and the TNC 640 for high-specification 5-axis and HSC applications. Both feature the iHMI interface with touchscreen-capable displays and Heidenhain's Conversation, ISO, and Klartext programming modes.
Heidenhain-specific issues include display and keyboard membrane faults on older models, battery-backed memory loss, axis feed faults related to the proprietary Heidenhain linear scale and encoder interfaces, and hard drive or PC hardware failures on the iTNC 530. Their service manuals and TSM (TNC Support Message) utility are essential tools for parameter-level work on all platforms.
For breakdowns, PPM, or control-related faults on Heidenhain machines, please contact me with the machine model and fault description.