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Riesgo: G90/G91: Alarm for incorrect absolute/incremental mode

An incremental mode activated by mistake can displace subsequent movements and cause collisions.

For reference only: syntax changes with the control, the post-processor and the machine parameters. Check the official manual and run a simulation before cutting. Legal notice.

Family
Common risks
Machine
Milling, Turning, Mill-turn
Risk
High
Example
G91 G28 Z0 seguido de movimientos sin volver a G90
E.g.:
G91 G28 Z0 seguido de movimientos sin volver a G90

Machine: Milling, Turning, Mill-turnRisk: High

ISO común · Fanuc · Haas · Heidenhain · Siemens · Fagor

  • ISO común: Good practice: declare G90 at the beginning of each important section.
  • Fanuc: Review blocks after G28/G30 returns with G91.
  • Haas: Many accidents come from forgetting to return to G90.
  • Heidenhain: Check whether the block uses incremental coordinates in TNC/ISO format.
  • Siemens: Conceptual equivalent: check the active absolute/incremental modes.
  • Fagor: Conceptual equivalent: check incremental/absolute mode before fast movements.

Related:

Other codes in Common risks

Riesgo: G43/H Incorrect length compensation alarm
See the full list of G and M codes

Frequently Asked Questions (FAQ)

What does Riesgo: G90/G91 mean in a CNC program?

An incremental mode activated by mistake can displace subsequent movements and cause collisions. In the catalogue it appears as "Alarm for incorrect absolute/incremental mode", within the Common risks family.

Can you give me an example of Riesgo: G90/G91?

G91 G28 Z0 seguido de movimientos sin volver a G90 — An incremental mode activated by mistake can displace subsequent movements and cause collisions.

Which other codes is Riesgo: G90/G91 combined with?

In practice Riesgo: G90/G91 appears alongside these codes: G90/G91, G28/G30, G00. It is worth reading them together, because the state one leaves behind conditions what the next one does.

Which machines use Riesgo: G90/G91?

Riesgo: G90/G91 is used in: Milling, Turning, Mill-turn.

What should you watch out for with Riesgo: G90/G91?

High risk: a mistake here can cause a crash, a broken tool or an out-of-tolerance part. Simulate the program and dry-run it before cutting.

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