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G76: Lathe threading cycle

Automatic cycle for lathe threading.

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
Lathe cycles
Machine
Turning, Mill-turn
Risk
High
Example
G76 P020060 Q100 R0.05
E.g.:
G76 P020060 Q100 R0.05

Parameters

P (1er bloque)
Seis dígitos PmmrrAA: mm = pasadas de acabado, rr = salida de rosca en décimas de paso (chaflán), AA = ángulo de la punta (60, 55, 30, 29, 00).Ejemplo P020060: 2 pasadas de acabado, salida 0, ángulo 60°.
Q (1er bloque)
Profundidad mínima de pasada. · µm sin punto decimal (Q100 = 0,1 mm)
R (1er bloque)
Creces para las pasadas de acabado. · mm
X(U) Z(W)
Diámetro de fondo de rosca (X) y final de la rosca en Z. · mm
R (2º bloque)
Conicidad: diferencia de radio entre inicio y fin (0 en roscas cilíndricas). · mm
P (2º bloque)
Altura del filete (profundidad total de rosca, en radio). · µm sin punto decimal (P1227 = 1,227 mm para M20×2,5)
Q (2º bloque)
Profundidad de la primera pasada; las siguientes van decreciendo. · µm sin punto decimal
F
Paso de la rosca (avance por vuelta). · mm
Haas: K D A P I
En Haas es un solo bloque: K altura de rosca, D primera pasada, A ángulo de punta, P método de penetración (1-4), I conicidad.Mismo ciclo, sintaxis distinta: no copiar un G76 Fanuc en una Haas sin adaptarlo.

Machine: Turning, Mill-turnRisk: High

Fanuc

G76 P... Q... R... / G76 X... Z... P... Q... F...
  • Very sensitive to the format and units of P/Q.

Haas

G76 X... Z... K... D... F...
  • Haas syntax may be different from classic Fanuc.

Siemens

CYCLE97/CYCLE99
  • Siemens uses specific threading cycles.

Fagor

Ciclos de roscado Fagor
  • Confirm parameters by manual.

Related:

Other codes in Lathe cycles

See the full list of G and M codes

Frequently Asked Questions (FAQ)

What does G76 mean in a CNC program?

Automatic cycle for lathe threading. In the catalogue it appears as "Lathe threading cycle", within the Lathe cycles family.

How is G76 written on each control?

Fanuc: G76 P... Q... R... / G76 X... Z... P... Q... F... · Haas: G76 X... Z... K... D... F... · Siemens: CYCLE97/CYCLE99 · Fagor: Ciclos de roscado Fagor. The exact syntax depends on the control version and the machine parameters: always confirm with the manufacturer's manual.

Can you give me an example of G76?

G76 P020060 Q100 R0.05 — Automatic cycle for lathe threading.

Which other codes is G76 combined with?

In practice G76 appears alongside these codes: G32, G92. It is worth reading them together, because the state one leaves behind conditions what the next one does.

Which machines use G76?

G76 is used in: Turning, Mill-turn.

What should you watch out for with G76?

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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