G62 Corner Deceleration at Inside Corners G-Code Guide: Siemens SINUMERIK

Introduction

Executing geometry axis switchovers or indexing the tool revolver (turret) with parameter MD 10604 set to 0 deactivates active coordinate system working area limitations (WALIMON). When automatic cycle execution resumes, the tool revolver travels along a shifted trajectory beyond its soft safety limits. This axis deviation drives the cutting tool directly into table-mounted fixture clamps, a workpiece vise jaw, or the rotating jaws of a spindle chuck, causing a catastrophic hard collision (crash). The impact shatters the carbide insert, bends the axis ball screws, triggers an axis overload shutdown, and instantly transforms raw material into a ruined scrap part. To mitigate separate physical forces during inside profiling under active tool radius compensation (G41/G42), programmers implement G62 inside corner deceleration. This modal function automatically scales down path feedrate as the cutter wraps inside corner walls, neutralizing cutting load spikes and preventing structural tool deflection.

Technical Summary

Quick Read

• Activate G62 modally before machining inside pocket profiles to automatically moderate cutting feedrates.
• Ensure tool radius compensation (G41 or G42) is active, as G62 will not apply deceleration to uncompensated paths.
• Combine G62 with continuous-path mode (G64/G641–G644); exact stop modes (G60/G9) completely deactivate G62 behavior.
• Program FENDNORM modally to deactivate corner deceleration and restore default feedrate behavior on straight contours.
• Set machine data MD 10604 to 1 to retain active coordinate system working area limitations during geometry axis switchovers.
• Program a non-zero path feedrate (F word) in preceding blocks to prevent Alarm 14800 or Alarm 61003 when G62 is active.

Basic Concepts

Practical programming of the G62 inside corner deceleration command on Siemens controls provides dynamic feedrate moderation at inside workpiece profiles under active tool radius compensation (G41 or G42). During inside contouring, the physical volume of raw material being removed increases rapidly because the tool is wrapped by the corner wall. Without corner deceleration, this sudden spike in the cutting load can deflect the tool, distort the machined surface, and degrade dimensional accuracy. When G62 is active under continuous-path mode (G64), the Siemens motion kernel automatically identifies inside corner transitions and scales the feedrate down, ensuring constant tool loading, uniform surface finish, and preventing tool breakage. If the corner is non-critical or external, programmers can restore normal continuous blending by calling FENDNORM to deactivate corner deceleration modally.

The SINUMERIK control evaluates the workpiece geometry and cutter compensation parameters to calculate the tool center path. When Group 57 corner override functions are active, the interpolation planner determines the exact deceleration zones preceding the corner transition. This automatic calculation prevents tool overloading without requiring manual feedrate override adjustments by the machine operator. The integration of G62 within continuous-path rounding modes ensures that block transitions are smooth and dynamic, preserving physical axis health during high-speed machining operations.

Command Structure

The command G62 is a modal preparatory function belonging to Group 57 (Automatic corner override) in native Siemens mode (G290). When programmed, the control automatically moderates the feedrate at inside corners to prevent tool deflection. The function remains active until it is overridden by another Group 57 command such as G621 for all-corner deceleration or FENDNORM to deactivate corner deceleration modally.

Programmers can switch between Siemens native syntax and legacy ISO dialect syntax. Switch the NC interpreter to native Siemens mode via G290 to access advanced continuous-path rounding and Group 57 commands. Conversely, commanding G291 activates the ISO dialect mode, where G62 behaves as a Group 13 or Group 15 modal corner override command. Machine data MD 18800 must be set to 1 to compile external NC languages, and the reset default G-code for Group 57 is defined by MD 20150.

; Native SINUMERIK Mode Syntax
G290 ; Switch to native Siemens mode
G62 ; Enable inside corner deceleration modally
G621 ADIS=0.5 ; Enable all-corner deceleration with transition rounding
FENDNORM ; Disable corner deceleration modally (default)
; ISO Dialect Mode Syntax
G291 ; Switch to ISO dialect mode
G62 ; Enable automatic corner override modally

Brand Applications

Siemens

Siemens SINUMERIK controls implement G62 as part of Group 57, modulating feedrates at inside corners when continuous-path mode and tool radius compensation are active. The reset default behavior of Group 57 is set by channel machine data MD 20150.

To program, switch the interpreter to native mode with G290 and call G62 or G621 modally:

; Native Siemens Mode
G290
G17 G64 G41 T="CUTTER_8" D1 G01 X100.0 Y50.0 F1500
G62 X150.0 Y120.0

Key machine data parameters, associated alarms, and control version differences govern G62 execution:

• MD 20150 $MC_GCODE_RESET_VALUES[7]: Default active G-code for Group 57.
• MD 18800 $MN_MM_EXTERN_LANGUAGE: Interpreter activation for G291 ISO dialect mode.
• MD 10604 $MC_WALIM_GEOAX_CHANGE_MODE: Working area limitation behavior during axis switchover.
• Alarm 14800: Triggered when G62/G621 is active with path velocity F0 and no fixed feedrates are configured.
• Alarm 61800: Triggered when switching to G291 mode if MD 18800 is disabled.
• 840D sl vs. 802D sl: MD 10604 is adjustable on 840D sl but hard-locked on 802D sl. Advanced multi-edge G-codes G50.2/G51.2 are omitted on 802D sl.

Warning: Resuming automatic cycle execution after geometry axis switchovers with MD 10604 set to 0 deactivates coordinate limitations, risking a hard tool collision.

Brand Comparison

Technical Analysis

Siemens operates on a bilingual toggled compiler model, using G290 and G291 to parse standard G-codes. While legacy controls interpret overrides within a single coordinate block, SINUMERIK requires the programmer to explicitly switch the compiler to ISO Dialect mode via G291 to compile legacy blocks containing ISO styles, such as G10 offset inputs or G62 corner overrides. The program must command G290 to return to native Siemens mode to process advanced parametric frames (TRANS, ROT, SCALE, MIRROR) and zero offsets.

Siemens isolates corner deceleration within Group 57 (G62, G621, FENDNORM) separately from continuous-path rounding modes (G641–G644). While other controls assign corner overrides to static parameter registers, Siemens allows programmers to dynamically toggle between inside-only deceleration (G62) and all-corner deceleration (G621) with transition rounding tolerances governed by MD 33100.

The Siemens preprocessor generates implicit exact stop checks during continuous-path mode (G64/G641). Any program command accessing machine status data (such as system variables starting with $A...) or executing text outputs with MSG triggers a preprocessor stop. This stop halts the preceding block with an exact stop deceleration check (similar to G9), a look-ahead behavior unique to the SINUMERIK stack.

Program Examples

; Siemens: G290 ; Switch compiler to native Siemens SINUMERIK mode
; Siemens: G17 G64 G41 T="CUTTER_8" D1 G01 X100.0 Y50.0 F1500 ; XY plane, continuous-path, TRC left, and offset call
; Siemens: G62 X150.0 Y120.0 ; Enable automatic corner deceleration modally for inside corners along the path

; Siemens: G290 ; Switch compiler to native Siemens SINUMERIK mode
; Siemens: G621 ADIS=0.5 X200.0 Y100.0 ; Enable corner deceleration at all corners with transition rounding
; Siemens: FENDNORM X250.0 ; Deactivate corner deceleration modally (returns to Group 57 default)
; Siemens: G291 ; Switch compiler to ISO Dialect mode to parse legacy blocks
; Siemens: G62 ; Activate ISO corner override modally
; Siemens: G41 G01 X100.0 Y50.0 F200.0 ; Execute linear interpolation with compensation and override active

Dry run: The control switches to native Siemens mode with G290. Line 2 selects the XY plane (G17), activates continuous-path mode (G64), enables tool radius compensation left (G41), selects cutter offset D1, and begins cutting at 1500 mm/min. When G62 is commanded, inside corner deceleration becomes modally active. As the tool interpolates toward coordinates X150.0 Y120.0, the motion controller detects the inside corner, scaling down the path feedrate dynamically to prevent tool deflection. Switch back to native G621 ADIS=0.5 applies corner deceleration at all corners with a transition rounding of 0.5 mm. FENDNORM deactivates corner overrides modally. Switch to G291 toggles the compiler to ISO dialect, where G62 acts as a standard ISO corner override.

Error Analysis

Application Note

A catastrophic hard collision shatters the cutting tool, damages the axis ball screws, generates an axis overload shutdown, and converts raw stock into a completely ruined scrap part when the tool revolver (turret) is driven directly into table-mounted fixture clamps, a workpiece vise jaw, or rotating spindle chuck jaws. This physical crash occurs when geometry axis switchovers or tool indexing operations are executed with machine data MD 10604 set to 0, which automatically deactivates active working area limitations (G25/G26 or WALIMON). Resuming automatic cycle execution under these uncompensated coordinates allows the axis to travel along a shifted trajectory beyond its soft safety limits. Setup operators must verify parameter MD 10604 is configured to 1 to retain coordinate protection limits during switchovers, and perform program dry runs with single-block mode active. Programmers must command G25/G26 working area limitations to establish an electronic protection envelope enclosing the tool revolver (turret), workpiece, and measuring station.

Related Command Network

• G60 Exact Stop (Siemens): Decelerates the axes to a complete stop at block transitions to verify position, which overrides and deactivates modal G62 corner deceleration.
• G61 Exact Stop Mode: Commands the control to verify the exact stop positioning for all subsequent motion blocks, disabling look-ahead corner overrides.
• G53 Suppress Current Frame: Non-modally suppresses active coordinate offsets to traverse axes in the machine coordinate system, independent of active G62 paths.
• G64 Continuous-Path Mode: Activates dynamic path blending and corner rounding, establishing the required operational state for G62 inside corner deceleration to take effect.
• G290 Native Siemens Mode: Switches the NC compiler to native SINUMERIK G-code parsing, assigning G62 to Group 57 corner deceleration.

Conclusion

Deploying G62 inside corner deceleration balances cutting forces and protects cutter geometries along complex pocket paths. Machine tool programmers must configure channel parameters and verify active tool radius compensation limits to prevent structural tool deflection at inside corners.

FAQ

Why does G62 corner deceleration fail to activate on inside corners?

The Siemens motion kernel ignores G62 if continuous-path mode (G64) or tool radius compensation (G41/G42) is inactive. Operators must verify that TRC is enabled and that exact stop modes (G60/G9) are disabled before commanding Group 57 codes.

How does a preprocessor stop affect G62 continuous-path blending?

System status variable reads ($A...) or MSG text commands halt look-ahead buffering, forcing an implicit exact stop check that disables G62 deceleration. Programmers must isolate status checks from active cutting paths to maintain continuous feedrates.

What is the function of MD 20150 in corner deceleration defaults?

Machine data MD 20150 determines the default Group 57 state (typically 1 for FENDNORM) active upon channel reset or power-up. Setup technicians must modify MD 20150 to value 2 if G62 corner override must remain active as the system default.