{"id":1863,"date":"2026-07-20T05:34:56","date_gmt":"2026-07-20T05:34:56","guid":{"rendered":"https:\/\/gearrack.top\/?p=1863"},"modified":"2026-07-20T05:34:56","modified_gmt":"2026-07-20T05:34:56","slug":"steel-spur-gears-for-cnc-machine-tools","status":"publish","type":"post","link":"https:\/\/gearrack.top\/ko\/steel-spur-gears-for-cnc-machine-tools\/","title":{"rendered":"Steel Spur Gears for CNC Machine Tools"},"content":{"rendered":"
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GEAR APPLICATION GUIDE \u00b7 SPUR GEAR \u00b7 S03<\/span><\/p>\n

Steel Spur Gears for CNC Machine Tools:
\nAccuracy, Backlash and Spindle Drive Design<\/span><\/h1>\n

CNC machine tool gear drives must combine precise tooth geometry with minimal transmission error to avoid surface finish defects and dimensional errors in machined workpieces. This guide covers spur gear specification for CNC machining centre spindle drives, axis feed gearboxes, tool changer drives, and rotary indexing tables \u2014 from DIN quality class selection through to backlash elimination and lubrication requirements.<\/p>\n

20CrMnTi \u00b7 Cronidur 30 \u00b7 42CrMo4<\/span>
\nDIN 4\u20137 \u00b7 Backlash <0.05 mm \u00b7 M1\u2013M8<\/span>
\nMachining Centre \u00b7 Lathe \u00b7 Grinding \u00b7 EDM<\/span><\/div>\n<\/div>\n<\/div>\n
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DIN QUALITY<\/p>\n

DIN 4\u20137<\/p>\n

CNC machine tool spur gear quality class range. DIN 7 for slow tool changer and axis drives; DIN 5\u20136 for spindle gearboxes; DIN 4 for precision grinding and EDM machine drives<\/p>\n<\/div>\n

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MODULE RANGE<\/p>\n

M1 \u2013 M8<\/p>\n

CNC machine tool spur gears. Spindle speed-change gearbox: M2\u2013M5. Axis feed gearbox: M3\u2013M6. Tool changer drive: M2\u2013M4. Rotary indexing table: M2\u2013M6<\/p>\n<\/div>\n

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BACKLASH TARGET<\/p>\n

<0.05 mm<\/p>\n

Normal backlash for precision CNC machine tool spur gear drives. Axis positioning drives: <0.02 mm with backlash compensation. Spindle gearbox: 0.05\u20130.10 mm acceptable<\/p>\n<\/div>\n

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PLV RANGE<\/p>\n

1 \u2013 20 m\/s<\/p>\n

Pitch line velocity of CNC machine tool spur gear drives. Above 6 m\/s requires DIN 5\u20136 ground quality. Spindle gearboxes at high speed range: PLV up to 15\u201320 m\/s<\/p>\n<\/div>\n<\/div>\n

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Spur Gears in CNC Machine Tool Design<\/h2>\n

CNC machine tool drive systems impose two requirements on spur gears that industrial conveyor or motor reducer applications do not: transmission error must be minimised to prevent workpiece surface finish defects, and gear geometry must be repeatable from batch to batch so that replacement gears restore the original machine accuracy without hand-fitting or adjustment. A spur gear with high transmission error in a CNC spindle gearbox produces a periodic torque fluctuation at the mesh frequency that appears as machined surface chatter marks. In a CNC rotary indexing table, tooth spacing error in the spur gear drive introduces angular indexing error that directly limits the positional accuracy of the machined features.<\/p>\n

Korea Ever-Power’s steel spur gears for CNC machine tools<\/a> are manufactured in 20CrMnTi case carburized (standard), 42CrMo4 through-hardened (medium-duty), and Cronidur 30 (stainless-bearing steel, for washdown-tolerant machine tools) \u2014 all ground to the specified DIN quality class after heat treatment, with 100% tooth profile and spacing measurement before shipment. Every CNC machine tool spur gear order from Korea Ever-Power is supplied with an individual gear measurement report in the format required by the machine tool builder’s purchasing specification.<\/p>\n

\"Steel<\/p>\n

CNC machine tools also drive spur gears at higher pitch line velocities than most industrial applications at equivalent module and power \u2014 a 10,000 RPM CNC machining centre spindle with a 2:1 spur gear speed-change stage at M3 will have a pitch line velocity of approximately 14 m\/s at the high-speed stage input, requiring DIN 5 or better to avoid dynamic noise and bearing life reduction from the mesh dynamic force increment at this speed. Spur gears for CNC machine tool use are always specified with ground teeth rather than shaved teeth above PLV 6 m\/s.<\/p>\n

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Transmission Error \u2014 Surface Finish Impact<\/h3>\n

Gear transmission error (TE) at the mesh frequency directly modulates the spindle or axis speed, producing a periodic velocity variation. In a turning centre, spindle TE causes waviness on the finished bore or OD surface at a spatial frequency determined by the mesh frequency \u00f7 surface speed. At 3,000 RPM spindle and M3 module 30T gear (mesh frequency 1,500 Hz), a workpiece turned at 100 m\/min surface speed shows waviness with a spatial period of 100,000 mm\/min \u00f7 1,500\/min = 67 mm \u2014 a visible surface pattern. Reducing TE from DIN 7 to DIN 5 reduces this amplitude by approximately 60\u201370%, typically bringing it below the surface finish specification limit.<\/p>\n<\/div>\n

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Backlash in CNC Axis Drives<\/h3>\n

CNC controllers provide software backlash compensation \u2014 when the axis reverses direction, the controller commands additional motor movement equal to the programmed backlash value before beginning the actual move. This compensates for the angular dead band of the spur gear drive. Effective backlash compensation requires: (a) the actual backlash must be measured and entered accurately; (b) the backlash must be consistent and not vary with load, temperature, or wear. Korea Ever-Power CNC machine tool spur gears are supplied with backlash measured at room temperature under no-load, giving the machine tool builder a reliable starting value for backlash compensation programming.<\/p>\n<\/div>\n

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Material for CNC Machine Tool Gears<\/h3>\n

20CrMnTi case carburized (HRC 58\u201362) is the standard material for CNC machine tool spur gears requiring maximum fatigue life and wear resistance. 42CrMo4 through-hardened (HB 280\u2013340) is used for medium-duty spindle gearboxes and tool changer drives where the lower cost justifies the reduced load rating at PLV below 5 m\/s. Cronidur 30 (a martensitic stainless bearing steel, similar to X30CrMoN15-1) is specified for CNC machine tools in coolant-rich environments where standard alloy steel gears would rust between production shifts \u2014 Cronidur 30 achieves HRC 58\u201360 through martensitic hardening without case carburization, simplifying heat treatment and minimising distortion.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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CNC Machine Tool Drive Applications<\/h2>\n
\"ground
Korea Ever-Power precision ground gears for CNC machine tool applications \u2014 20CrMnTi case carburized, HRC 60\u201362 tooth surface, profile and lead ground to DIN 5 quality class on CNC gear grinding machine. Tooth spacing error <4 \u03bcm, profile form deviation <3.5 \u03bcm, lead deviation <3.5 \u03bcm, surface roughness Ra <0.4 \u03bcm. Individual gear measurement report in AGMA 915 or DIN 3960 format supplied with each gear for machine tool builder traceability. Available in spur and helical tooth form for CNC spindle gearbox, axis drive, and tool changer applications.<\/figcaption><\/figure>\n
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DRIVE 01<\/p>\n

SPINDLE
\nGEARBOX<\/p>\n<\/div>\n

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Spur gear specification:<\/strong> M2\u2013M5, 20CrMnTi or 42CrMo4, DIN 5\u20136, PLV 5\u201315 m\/s, 2 or 3 speed ranges via sliding or synchro-mesh spur gears. CNC machining centre spindle gearboxes provide torque multiplication at the low-speed range (heavy milling, drilling) and direct drive bypass at high speed (high-speed finishing). The spur gears used in the low-speed stage operate at moderate PLV and must have minimal transmission error to avoid chatter at low spindle speeds where vibration modes are most easily excited. Ground DIN 5 spur gears with tip relief 4\u20138 \u03bcm are specified to minimise mesh-frequency torque ripple in the machining spindle gearbox across all speed ratios.<\/p>\n<\/div>\n<\/div>\n

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DRIVE 02<\/p>\n

TOOL CHANGER
\nDRIVE<\/p>\n<\/div>\n

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Spur gear specification:<\/strong> M2\u2013M4, 20CrMnTi or 42CrMo4, DIN 6\u20137, moderate PLV below 5 m\/s, ratio 10:1\u201340:1 total reduction from servo motor to tool magazine carousel. Automatic tool changer (ATC) magazine spur gear drives operate at low speed but with high cycle rates \u2014 a 30-tool magazine on a high-productivity machining centre can complete 3,000\u20135,000 tool change cycles per day. The spur gears in the ATC drive must maintain tooth geometry accuracy over tens of millions of load cycles without developing significant backlash increase. Hardened 20CrMnTi spur gears are specified for tool changer magazine drives in production machining centres with >2,000 tool changes per day.<\/p>\n<\/div>\n<\/div>\n

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DRIVE 03<\/p>\n

ROTARY
\nINDEXING TABLE<\/p>\n<\/div>\n

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Spur gear specification:<\/strong> M2\u2013M6, 20CrMnTi ground DIN 5\u20136, zero or near-zero backlash through tight centre distance or spring-loaded anti-backlash gear pair, tooth spacing error <3 \u03bcm. CNC rotary indexing table spur gear drives convert servo motor rotation to table angular position with minimum angular positioning error. The cumulative tooth spacing error of all gear stages between the servo encoder and the table worm or ring gear directly limits the achievable angular positioning accuracy. For CNC 4th-axis rotary tables with <5 arcsec positioning requirement, the intermediate spur gear drive stages must be DIN 4\u20135 with individual tooth spacing error below 3 \u03bcm \u2014 measured and reported on each gear individually before table assembly.<\/p>\n<\/div>\n<\/div>\n

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DRIVE 04<\/p>\n

GRINDING &
\nEDM MACHINE<\/p>\n<\/div>\n

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Spur gear specification:<\/strong> M1\u2013M3, 20CrMnTi or Cronidur 30, DIN 4\u20135, ultra-low transmission error, anti-backlash scissor gear or preloaded split gear. Precision cylindrical grinding and CNC EDM machines impose the most demanding requirements of any CNC machine tool on gear accuracy: the workhead gear drive (which rotates the workpiece relative to the grinding wheel or wire) must produce a perfectly uniform angular velocity to avoid periodic errors in the ground or eroded surface. Any residual TE in the workhead spur gear drive directly creates lobing on the ground bore or OD. DIN 4 spur gears with tooth spacing error below 2.5 \u03bcm and TE below 3 \u03bcrad are specified for cylindrical grinding machine workhead drives at Korea Ever-Power’s highest accuracy capability.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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DIN Quality Class Selection for CNC Machine Tool Spur Gears<\/h2>\n
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CNC MACHINE TYPE \/ DRIVE<\/th>\nPLV<\/th>\nDIN QUALITY<\/th>\nFINISH<\/th>\nBACKLASH<\/th>\n<\/tr>\n<\/thead>\n
Lathe \/ turning centre (tool slide)<\/td>\n<3 m\/s<\/td>\nDIN 7<\/td>\nHobbed \/ shaved<\/td>\n<0.10 mm<\/td>\n<\/tr>\n
Machining centre (tool changer)<\/td>\n1\u20134 m\/s<\/td>\nDIN 6\u20137<\/td>\nHobbed \/ ground<\/td>\n<0.06 mm<\/td>\n<\/tr>\n
Machining centre (spindle gearbox)<\/td>\n5\u201315 m\/s<\/td>\nDIN 5\u20136<\/td>\nGround<\/td>\n<0.05 mm<\/td>\n<\/tr>\n
CNC rotary indexing table (axis drive)<\/td>\n1\u20136 m\/s<\/td>\nDIN 5<\/td>\nGround<\/td>\n<0.02 mm<\/td>\n<\/tr>\n
Cylindrical grinding \/ EDM (workhead)<\/td>\n1\u20135 m\/s<\/td>\nDIN 4<\/td>\nGround + lapped<\/td>\n<0.01 mm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
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BACKLASH REDUCTION METHODS<\/h3>\n