Mitsubishi M700-M70 Mold Machining: SSS Parameter Guide

CNC operators and CAM programmers working in mold machining tend to run into the same three problems: scratches, step marks and facets on the mold surface that translate into hours of hand polishing; the machine hesitating at corners and fine-tolerance micro-segments even though the CAM program calls for a high feedrate (F); and vibration or tool breakage caused by axes suddenly accelerating and decelerating (jerk) at high speed.

This guide explains the SSS (Super Smooth Surface) control used on Mitsubishi M700 / M700V and M70 series CNC controls to improve mold machining performance, raise surface quality and shorten cycle times, along with the related NC parameters and the commissioning steps. Parameter numbers and default values were cross-checked against Mitsubishi’s own M700-70 Programming Manual; a few settings that could not be confirmed against that source are flagged separately below.

Which Mitsubishi Controls Does This Guide Apply To?

This content is based on the Mitsubishi M700 / M700V and M70 series controls. SSS control and high-speed high-accuracy control II (G05 P10000) are optional functions; if the option is not fitted on your machine, turning the related parameters on will not enable the function and will instead raise an alarm. Before changing anything, confirm with your machine builder (OEM) that the SSS / high-speed high-accuracy option is actually present on your parameter list.

Mold Machining vs. Standard Part Machining

Standard prismatic parts are dominated by straight lines and circular pockets. Mold surfaces, by contrast, are broken by CAM software into thousands of fine line segments to represent a 3D surface. If the control isn’t configured for this, every micro-segment transition produces a microscopic deceleration and jolt in the axes — which shows up on the surface as visible lines or steps. SSS control looks ahead across this micro-segmented toolpath over a wider window, estimates the optimum speed in advance, and suppresses sudden speed changes.

High-Speed, High-Accuracy G-Codes

The core commands used for mold machining on the M700/M70 series:

G61.1 — High-accuracy control mode; commanded on its own line.
G08 P1 / G08 P0 — Turns high-accuracy control on/off (valid when parameter #1267 ext03/bit0 is “0”).
G05 P10000 / G05 P0 — Turns high-speed high-accuracy control II — the mode SSS control runs under — on/off.

Per the manual’s own note, G05 P10000 / G05 P0 and G61.1 must always be given on an independent line; if any address other than G/Q and P/N appears on the same line, a program error (P33) results. Cutter compensation must be switched on and off within this mode — if it isn’t cancelled before the mode is turned off, error P34 is raised.

Sample Mold Finishing Program

G90 G21 G17 G40 G80
T1 M06
S10000 M03
G00 X0 Y0 Z50.
G05 P10000  (Turns on SSS control and high-speed mode)
G01 Z-2. F1500
... (fine-segment lines produced by CAM)
G05 P0      (Turns off SSS control)
G00 Z100. M05
M30

This example represents the general flow only; tool change, work coordinate selection, and safe approach/retract lines will vary with your CAM output and machine setup.

Core Machining Parameters for SSS Control

The following parameters are defined under “Machining Parameters” (#80xx group) in Mitsubishi’s M700-70 Programming Manual.

Parameter	Name	Default	What it does
#8090	SSS ON	0 (factory)	Enables SSS control. Must be set to “1” for the `G05 P10000` command to work.
#8091	StdLength	—	Sets the distance over which the path direction is recognized (shape recognition range) for SSS control; increasing it reduces the effect of step-mark errors.
#8092	ClampCoeff	—	Coefficient balancing accuracy vs. speed on curved sections. A larger value = less accuracy, more speed; a smaller value = more accuracy, less speed.

Verification note: the “Coefficient = Square root(#8092)” formula and the “1-100” value range given in the source document could not be confirmed against our copy of the official M700-70 Programming Manual, which only states the direction of the effect (larger value → less accuracy, higher speed). Verify the exact formula and allowed range against your machine’s current parameter manual or Mitsubishi technical support before relying on it.

Verification note: the #8093 StepLeng (microscopic step width, 0.005 mm) and #8094 DccWaitAdd (deceleration wait time) parameters mentioned in the source document could not be located in our copy of the M700-70 Programming Manual. These two may belong to a different Mitsubishi control series (e.g. M800) or a different manual revision; confirm the parameter number and function against your machine builder’s current parameter list before using them.

Tolerance, Spline and Fairing Parameters

This group corrects the micro-segments generated by CAM and smooths the angular breaks between them; the manual refers to it as the spline (“Kama”) and fairing (“Kaplama”) functions.

Parameter	Name	Default	What it does
#8025	SPLINE ON	0	Enables spline interpolation; when set to “1”, spline mode can be used with the `G05.1 Q2` command.
#8027	Toler-1	—	Maximum chord error on blocks that contain an inflection point. Should match your CAM’s micro-segment tolerance.
#8028	Toler-2	—	Maximum chord error on blocks without an inflection point.
#8033	Fairing ON	0	When set to “1”, smooths out short protruding (zigzag) lines below the set length so the preceding/following path connects smoothly. Applies only to continuous linear (G01) commands.
#8029	Fairing L	0	Lines shorter than this value are faired.
#8034	AccClampt ON	0	When set to “1”, cutting feedrate is clamped by the calculated acceleration limit instead of the corner-deceleration function (derived from `#1206`/`#1207`).
#8036	CordecJudge	0	Controls how corners are judged; when set to “1”, very short (fine) blocks are excluded from the corner-angle decision.
#8037	CorJudgeL	0	Blocks shorter than this value are excluded when judging a corner.

Base Specification Parameters (Pre-Interpolation Acceleration/Deceleration)

Parameter	Name	Default	What it does
#1148	I_G611	0	When set to “1”, the machine starts automatically in G61.1 high-accuracy mode at power-on.
#1205	G0bdcc	0	Enables pre-interpolation acceleration/deceleration control on G00 (rapid) moves; reduces axis knocking.
#1206	G1bF	—	Target acceleration/deceleration value for pre-interpolation (mm/min).
#1207	G1btL	—	Time (ms) required to reach the target speed. Combined with `#1206`, this yields the allowed acceleration (#1206/#1207).
#1267 bit0	ext03	1 (factory)	Selects the high-speed/high-accuracy command type. Per the manual, the spline function applies when this bit is “1”, while some G08 P1–related behavior applies when it’s “0” — confirm the value in effect on your own machine’s parameter list.

Soft Acceleration/Deceleration Filters

Parameter	Name	Default	What it does
#1568	SfiltG1	0 (factory), 0-200 ms range	S-shaped soft acceleration/deceleration filter on G01 cutting feed; smooths sudden acceleration changes on mold surfaces.
#1569	SfiltG0	0 (factory), 0-200 ms range	Same S-shaped smoothing filter on G00 rapid positioning.
#1572	Cirorp	0	When set to “1”, suppresses speed fluctuation at an arc-to-line or arc-to-arc junction; recommended in high-speed/high-accuracy mode II.
#2068	G0fwdg	70 (%)	Feed-forward gain for G00; shortens positioning time. This is an axis specification parameter.

Important: per the manual, #1568 and #1569 cannot be changed from the screen while a program is running; if changed via a programmable parameter command (G10), the change only takes effect once the axes have stopped.

A Note on Servo-Level Settings

The source document also referenced servo drive settings — speed-loop gain, integral gain, ball-screw pitch/encoder verification, and lost-motion (backlash) / quadrant-protrusion compensation — as ways to reduce line marks on the surface. These settings are defined in Mitsubishi’s separate Servo Parameter Manual, not the NC Programming Manual; the specific servo parameter numbers and suggested numeric values referenced (VGN1, VIA, PIT, RNG1/RNG2, SSF1, SSF3, LMCT and similar) could not be verified against the source available to us.

Before touching any servo-level setting: (1) consult your machine builder’s servo parameter manual or technical support, (2) back up the current parameter set before changing anything, (3) never change a servo parameter without the manufacturer’s sign-off. Incorrectly tuned servo gains can cause axis vibration, overcurrent alarms, or mechanical damage.

Mold Machining Setup Procedure — Step by Step

Unlock the parameters. On the M700/M70 screen, go to Setup / Parameter and remove the parameter-change lock.
Check SSS and related parameters. Set #8090 SSS ON to “1” (if the option is present on your machine); set #8025 SPLINE ON and #8033 Fairing ON to “1” as needed; match #8027 Toler-1 and #8028 Toler-2 to your CAM tolerance.
Define the soft filters. Increase #1568 SfiltG1 gradually based on the machine’s mechanical rigidity and test as you go (within the 0-200 ms range); turn on #1205 G0bdcc to reduce jolting on rapid moves.
Match your CAM settings to the NC. Keep the chordal tolerance in your CAM software in the same order of magnitude as #8027/#8028.
Run a test cut. Try it first in graphic/simulation mode and single-block at low feed; during a dry run, check the axes for vibration or abnormal noise, then evaluate surface quality on a circular/curved test piece.

Common Issues and Fixes

I’m getting a “P127 No spec: SSS Control” alarm

This alarm occurs when #8090 SSS ON is set to “1” while the SSS control option is not present on the machine. Fix: if the option isn’t installed, set #8090 back to “0” and use standard G08 P1 or G61.1 mode instead; confirm with your machine builder whether the option is actually present.

Gouging or excess stock left at corners

This usually means the #8027/#8028 tolerance values are set too loose. Tighten them (e.g. down toward 0.005 mm) or lower #8092 ClampCoeff to increase accuracy in corner/curved areas — consistent with the manual’s own table relationship (“larger value = less accuracy, more speed”).

Machining time is longer than expected

Gradually increase #8092 ClampCoeff to shift the accuracy/speed balance toward speed, and try lowering the #1568 SfiltG1 filter time. Re-check surface quality after every change — if the speed gain degrades the surface, back the value off.

Corner Rounding and Curve Transitions: The Accuracy-vs-Speed Trade-Off (Corner/Curve Comp)

SSS control takes care of overall surface smoothness, but a separate mechanism decides how much the machine slows down and speeds back up where two lines meet at a corner, or across a curved (free-form) transition; the manual calls this “optimum corner deceleration.” The control looks ahead at the angle of the next block, slows the axes before the corner, then accelerates back to the commanded feed once the corner is cleared. What the operator feels on the shop floor is exactly this: the machine seems to “hesitate” at a corner, or glides through it as if it were rounded. The following parameters tune that behavior.

#8020 DCC ANGLE is the threshold angle that decides whether the angle between two program blocks counts as “sharp” enough to trigger deceleration. If the angle between blocks is larger than this value, corner deceleration kicks in; if it’s smaller, the transition is already considered smooth and the machine keeps its feed rate.

#8022 CORNER COMP tunes accuracy at straight-line corner joints, while #8023 CURVE COMP does the same for curved, free-form transitions. Both work the same way: increase the value and the tool tracks the corner or curve more tightly — accuracy goes up, speed goes down; decrease it and the machine moves through faster, at the cost of a small deviation tolerance at the corner or curve. Because mold surfaces are almost entirely made up of curved transitions, the manual recommends tuning #8023 CURVE COMP first for mold work; #8022 CORNER COMP is aimed more at sharp, straight-to-straight corners.

Parameter	Name	What it affects	Increasing the value	Decreasing the value
#8020	DCC ANGLE	The corner-angle threshold that triggers deceleration	Fewer corners are treated as “sharp”; deceleration kicks in less often	More corners are treated as sharp; deceleration kicks in more often
#8022	CORNER COMP	Accuracy at straight-line corner joints	Accuracy increases, speed decreases	Accuracy decreases, speed increases
#8023	CURVE COMP	Accuracy on curved (free-form surface) transitions	Accuracy increases, speed decreases	Accuracy decreases, speed increases
#8019	R COMPEN	Directly scales corner speed via a coefficient	Positive value: corner speed drops (more accurate, slower)	Negative value: corner speed rises (faster, slightly less accurate)
#2096	crncsp	Minimum speed each axis is allowed to slow to at a corner (floor speed)	Floor speed rises; less slowdown at corners, but more accuracy risk	Floor speed drops; the machine can slow down more at corners

#8019 R COMPEN comes with a more explicit formula in the manual: corner speed = current corner speed × (100 − coefficient) / 100. Set the coefficient to +20, for example, and corner speed drops by 20% — the machine slows more at the corner, the surface comes out cleaner, but cycle time grows. Set it to −20 and corner speed rises by 20% — the machine clears the corner faster, at some cost to accuracy.

Verification note: A separate parameter selects which coefficient (#8019 R COMPEN or #8022 CORNER COMP) is actually used in that calculation. The source manual gives this parameter two different numbers in two different places — #8021 COMP CHANGE in one table, #8201 COMP CHANGE in the explanatory text. That inconsistency exists in the source document itself; we are not picking one number and presenting it as confirmed. Verify the correct parameter number against your machine’s current parameter list, or with authorized Mitsubishi service, before using it.

A practical tuning order: leave #8020 DCC ANGLE at its factory value first; adjust #8023 CURVE COMP in small steps from the standard value, cut the same test piece, and check the surface each time — if you see marks or stepping, back off to the previous step. Don’t set #2096 crncsp too low, or a mold surface with many small corners will make the machine crawl almost to a stop at every one, stretching cycle time for no real benefit. Only touch finer settings like #8019, #8022 or the COMP CHANGE selector once CURVE COMP alone isn’t giving you the result you need, and only after confirming them against your machine builder’s manual.

Don’t Confuse This With G62 Automatic Corner Override

The parameters above are about surface accuracy and the speed/accuracy trade-off. The manual also defines a separate function, G62 (Automatic Corner Override), which automatically reduces feed rate at inside corners to cut the extra stock and tool load that builds up there (set via #8007 OVERRIDE, #8008 MAX. ANGLE, #8009 DECELERATION RANGE). Its purpose is tool and machine protection, not surface finish — don’t confuse it with the SSS / Corner-Curve Comp settings above when finishing a mold surface.

Conclusion: Golden Rules for Flawless Mold Surfaces

Switch to the right mode: standard G64 mode is fine for roughing; use G05 P10000 for semi-finishing and finishing whenever the SSS option is available.
Match CAM and NC tolerances: the chordal tolerance in your CAM software and #8027 Toler-1/#8028 Toler-2 should sit at the same level of precision.
Don’t skip the soft filters: bring in #1568 SfiltG1 gradually, testing as you go, for a vibration-free surface.
Check with the manufacturer before touching servo settings: servo gains and lost-motion compensation are governed by a separate manual and authorized technical support.
Calibrate the corner and curve accuracy coefficients alongside SSS: On mold surfaces, start by test-adjusting #8023 CURVE COMP in small steps, and don’t overlook the #8020 DCC ANGLE threshold or the #2096 crncsp floor speed.

Applying these parameters gradually and with testing at each step can reduce the polishing workload, extend tool life, and shorten mold finishing cycle times on your M700/M70-controlled machine.

Mentor CNC disclaimer: this content is a general technical guide based on Mitsubishi’s M700-70 Programming Manual; your machine builder’s own parameter manual and machine-specific settings always take priority. Back up your current parameter set before making changes, and test any change in graphic/simulation mode and at low feed first. Parameters marked “could not be verified” in this article were not confirmed against an official source — verify them with your machine builder or authorized technical support before use. Servo and safety-related parameters should never be changed without manufacturer authorization.