日本語

Printed from Kezuriba (kezuriba.net/en/nc/g18/)

G18

Machining center, LatheModal, group 02

ZX plane selection

⌨On machining centers

G18

Diagram: The three planes and the viewing direction for arcs

X+Y+G02G03XY plane (G17)View from +ZZ+X+G02G03ZX plane (G18)View from +YY+Z+G02G03YZ plane (G19)View from +X
Arc direction (G02/G03) and cutter radius compensation are defined on the selected plane, and direction is judged looking from the + side of the axis normal to that plane. On a vertical MC, +Y is the back of the machine, so viewing the ZX plane (G18) from the front makes the rotation look reversed.

◎On lathes: ZX plane selection (lathe standard)

The same number means something different on lathes (FANUC-type G-code system A). Group 16.

Diagram (lathe): ZX plane and arc direction on a lathe

Z+X+G02G03ZX plane (G18)X+ drawn up = seen from +YSeen from aboveX+Front (operator)Seen from aboveX+Front (operator)Rear turret(common onslant beds) X+ awayFrom above, sameas the left figureFront turretX+ toward you, so+Y points downFrom above the rotationlooks reversed
Lathe program drawings put X+ up and Z+ to the right; this is the view from +Y, where G02 looks clockwise. On a front-turret machine +Y points down, so looking from above the arc direction appears reversed.

≠Differences between controls and machines

The same code can be written or assigned differently depending on the CNC control and the machine builder. Always check your machine’s manual.

SourceMachineItemDetail
HaasLatheGroup02
Mitsubishi ElectricLatheGroup02In Mitsubishi's lathe training material table, G17/G18 are group 02

📚Sources

The meaning shown agrees in at least two sources (agreement confirmed). Explanations are written in our own words.

  1. Mitsubishi Electric — The Basics of CNC Machining Programming (for Machining center) e-Learning material (PDF) mitsubishielectric.com
  2. Siemens AG — SINUMERIK 802D sl/840D/840D sl/840Di/840Di sl/810D Programming Manual ISO Milling, 04.2007 Edition (6FC5398-7BP10-0BA0) cache.industry.siemens.com
  3. Haas Automation, Inc. — Mill Operator's Manual – 17 Mill G-Codes (online version) haascnc.com
  4. National Institute of Standards and Technology (NIST), USA — The NIST RS274NGC Interpreter – Version 3 (NISTIR 6556, 2000) nvlpubs.nist.gov
  5. Siemens AG — SINUMERIK 802D sl/840D/840D sl/840Di/840Di sl/810D Programming Manual ISO Turning, 04.2007 Edition cache.industry.siemens.com
  6. Haas Automation, Inc. — Lathe Operator's Manual – 16 Lathe G-Codes (online version) haascnc.com
  7. Mitsubishi Electric — The Basics of CNC Machining Programming (for Lathe) e-Learning material (PDF, BNP-C8027-688) mitsubishielectric.com