{"id":1519,"date":"2026-07-14T05:54:01","date_gmt":"2026-07-14T05:54:01","guid":{"rendered":"https:\/\/gearrack.top\/product\/rolling-mill-double-helical-gear-42crmo-50-55-hrc-oem\/"},"modified":"2026-07-14T05:54:32","modified_gmt":"2026-07-14T05:54:32","slug":"rolling-mill-double-helical-gear-42crmo-50-55-hrc-oem","status":"publish","type":"product","link":"https:\/\/gearrack.top\/ja\/product\/rolling-mill-double-helical-gear-42crmo-50-55-hrc-oem\/","title":{"rendered":"Rolling Mill Double Helical Gear – 42CrMo, 50-55 HRC, OEM"},"content":{"rendered":"
\n

<\/p>\n

Product Overview<\/h2>\n
\n
\n \"Rolling\n <\/div>\n
\n

Rolling mill double helical gears<\/strong> are among the most demanding applications in industrial gear manufacturing. A rolling mill pinion stand \u2014 the gearbox that distributes the main drive motor torque equally to two or more work rolls \u2014 must transmit very high torque continuously, absorb the shock load when the workpiece enters the roll gap, and do so in both the forward and reverse rolling directions. The double helical (herringbone) tooth form is the standard choice for rolling mill drives precisely because it eliminates the axial thrust that single helical gears would impose on the mill housing and roll chocks.<\/p>\n

Korea Ever-Power produces rolling mill double helical gears<\/a> in 42CrMo (internationally known as AISI 4140 \/ JIS SCM440 \/ DIN 42CrMo4) with hardening and tempering heat treatment to achieve 50\u201355 HRC tooth surface hardness. Module and tooth count are custom to the customer’s drawing; gear milling or hobbing manufacturing method; tooth grinding optional. OEM marking and wooden case transport packaging. Can be produced as assembly parts (two-piece herringbone) or as a single integral gear.<\/p>\n<\/p><\/div>\n<\/div>\n

Korea Ever-Power’s production capability for this product is the same facility used for the agricultural machinery and heavy machinery double helical gear series \u2014 20 CNC lathes, 10 CNC machining centres, and four testing equipment sets. The alloy steel series in 42CrMo is complemented by the full cross-reference alloy grade range (45# through 40CrNiMoA) for customers whose specifications reference other national standards.<\/p>\n

<\/p>\n

Technical Specifications<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Rolling Mill Double Helical Gear \u2014 General Specifications<\/th>\n<\/tr>\n<\/thead>\n
Application<\/strong><\/td>\nRolling mill pinion stands, marine drives, agricultural machinery, heavy machinery<\/td>\n<\/tr>\n
Hardness<\/strong><\/td>\nHardened tooth surface \u2014 50\u201355 HRC after hardening and tempering<\/td>\n<\/tr>\n
Gear Position<\/strong><\/td>\nExternal gear<\/td>\n<\/tr>\n
Manufacturing Method<\/strong><\/td>\nCut gear \u2014 gear milling or gear hobbing per configuration; tooth grinding optionally available<\/td>\n<\/tr>\n
Toothed Portion Shape<\/strong><\/td>\nDouble Helical Gear (herringbone)<\/td>\n<\/tr>\n
Material<\/strong><\/td>\n42CrMo (AISI 4140 \/ SCM440 \/ DIN 42CrMo4)<\/td>\n<\/tr>\n
Heat Treatment<\/strong><\/td>\nHardening & tempering (high-frequency quenching per the custom transmission configuration)<\/td>\n<\/tr>\n
Tooth Hardness<\/strong><\/td>\n50\u201355 HRC<\/td>\n<\/tr>\n
Module<\/strong><\/td>\nCustom made per drawing<\/td>\n<\/tr>\n
Gear Teeth Number<\/strong><\/td>\nCustom made per drawing<\/td>\n<\/tr>\n
Helix Angle<\/strong><\/td>\nCustom made per drawing<\/td>\n<\/tr>\n
Assembly Type<\/strong><\/td>\nCan be assembly parts (two-piece) or integral single-piece construction<\/td>\n<\/tr>\n
Trademark<\/strong><\/td>\nOEM \u2014 customer marking available<\/td>\n<\/tr>\n
Transport Packing<\/strong><\/td>\nWooden case<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Custom Transmission Gears \u2014 Rolling Mill Double Helical Gear Configuration<\/strong><\/p>\n

\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/th>\nValue<\/th>\n<\/tr>\n<\/thead>\n
Module<\/strong><\/td>\nCustom made<\/td>\n<\/tr>\n
Gear Teeth Number<\/strong><\/td>\nCustom made<\/td>\n<\/tr>\n
Material<\/strong><\/td>\n42CrMo<\/td>\n<\/tr>\n
Gear Manufacturing Method<\/strong><\/td>\nGear milling or gear hobbing<\/td>\n<\/tr>\n
Heat Treatment<\/strong><\/td>\nHigh-frequency quenching<\/td>\n<\/tr>\n
Gear Teeth Grinding<\/strong><\/td>\nOptions \u2014 available on request for higher accuracy specification<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Steel Grade Cross-Reference \u2014 42CrMo International Equivalents<\/strong><\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
China \/ GB<\/th>\nISO<\/th>\n\u0413\u041e\u0421\u0422<\/th>\nASTM<\/th>\nJIS<\/th>\nDIN<\/th>\n<\/tr>\n<\/thead>\n
45<\/td>\nC45E4<\/td>\n45<\/td>\n1045<\/td>\nS45C<\/td>\nCK45<\/td>\n<\/tr>\n
40Cr<\/td>\n41Cr4<\/td>\n40X<\/td>\n5140<\/td>\nSCr440<\/td>\n41Cr4<\/td>\n<\/tr>\n
20CrMo<\/td>\n18CrMo4<\/td>\n20\u0425\u041c<\/td>\n4118<\/td>\nSCM22<\/td>\n25CrMo4<\/td>\n<\/tr>\n
42CrMo<\/td>\n42CrMo4<\/td>\n38XM<\/td>\n4140<\/td>\nSCM440<\/td>\n42CrMo4<\/td>\n<\/tr>\n
20CrMnTi<\/td>\n\u2014<\/td>\n18X\u0413\u0422<\/td>\n\u2014<\/td>\nSMK22<\/td>\n\u2014<\/td>\n<\/tr>\n
20CrNiMo<\/td>\n20CrNiMo2<\/td>\n20XHM<\/td>\n8720<\/td>\nSNCM220<\/td>\n21NiCrMo2<\/td>\n<\/tr>\n
40CrNiMoA<\/td>\n\u2014<\/td>\n40XH2MA<\/td>\n4340<\/td>\nSNCM439<\/td>\n40NiCrMo6<\/td>\n<\/tr>\n
20CrNi2Mo<\/td>\n20NiCrMo7<\/td>\n20XH2MA<\/td>\n4320<\/td>\nSNCM420<\/td>\n\u2014<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

42CrMo (highlighted) is the standard material for Korea Ever-Power rolling mill double helical gears.<\/p>\n

<\/p>\n

Why 42CrMo at 50\u201355 HRC for Rolling Mill Drives<\/h2>\n

\"Ever-Power<\/p>\n

The material and hardness specification for rolling mill double helical gears reflects the specific duty profile of the rolling mill pinion stand \u2014 a duty cycle unlike that of any other gear application.<\/p>\n

\n

42CrMo (AISI 4140) \u2014 The Rolling Mill Standard Alloy<\/strong><\/p>\n

42CrMo is the chromium-molybdenum medium-carbon alloy steel that combines good hardenability with adequate toughness after through-hardening. At the 50\u201355 HRC target achieved through high-frequency quenching and tempering, the 42CrMo tooth surface provides good pitting resistance against the rolling contact fatigue imposed by the high Hertzian stress in rolling mill gear meshes. The molybdenum content prevents temper brittleness during the tempering stage, ensuring the tooth retains impact resistance after the hardening cycle.<\/p>\n<\/div>\n

\n

50\u201355 HRC \u2014 Between Soft and Hard Tooth Flank<\/strong><\/p>\n

The 50\u201355 HRC range positions this gear between the fully carburised hard tooth flank (58\u201362 HRC) and the through-hardened soft tooth flank (\u2264350 HB \/ \u226437 HRC). At 50\u201355 HRC, the tooth surface has significantly higher pitting resistance than a soft tooth flank gear while retaining more impact toughness than a fully carburised case-hardened gear. For rolling mill applications where the biting shock is a real but manageable load event (not a catastrophic overload), this intermediate hardness level is a deliberate design choice \u2014 not a compromise.<\/p>\n<\/div>\n

\n

Two-Piece Assembly vs Integral Single Piece<\/strong><\/p>\n

Rolling mill double helical gears can be produced as assembly parts \u2014 two separate helical gears of opposite hand assembled on a common hub \u2014 or as a single integral herringbone blank. The two-piece assembly approach allows hobbing of each half separately (eliminating the groove-width constraint that limits hobbing in integral herringbone gears) and allows independent replacement of each helical half if only one shows wear or damage. The integral single-piece is more compact and eliminates the assembly interface, at the cost of requiring gear milling rather than hobbing for the tooth cutting. Korea Ever-Power produces both configurations.<\/p>\n<\/div>\n

\n

Optional Tooth Grinding for Assembly Parts<\/strong><\/p>\n

Tooth grinding is available on request for the assembly parts configuration, where each helical half can be ground independently before assembly. For the integral single-piece configuration, tooth grinding of the complete herringbone is possible but is limited by the grinding wheel access to the tooth flanks adjacent to the central groove \u2014 a configuration-dependent constraint that is confirmed at the drawing review stage.<\/p>\n<\/div>\n

<\/p>\n

Applications<\/h2>\n

\"types<\/p>\n

\n
\n
\ufe0f<\/div>\n

Hot Strip Rolling Mills<\/h3>\n

Pinion stands in hot strip roughing and finishing mills. The double helical form eliminates axial thrust from the work roll drives; 42CrMo at 50\u201355 HRC provides pitting resistance at the sustained high contact stresses of hot strip rolling.<\/p>\n<\/p><\/div>\n

\n
\u2744\ufe0f<\/div>\n

Cold Rolling Mills<\/h3>\n

Pinion stands in cold rolling mills for strip, sheet, and coil. Cold rolling generates higher roll separating forces per unit of strip width than hot rolling \u2014 the tooth load in cold mill pinion stands is severe, and the 50\u201355 HRC tooth surface is required to achieve adequate pitting life at these contact stresses.<\/p>\n<\/p><\/div>\n

\n
\u2699\ufe0f<\/div>\n

Plate Mills and Section Mills<\/h3>\n

Pinion stands in heavy plate mills and structural section mills. The reversing nature of plate and section rolling \u2014 where the workpiece is passed back and forth through the rolls \u2014 makes the zero-thrust property of the double helical gear particularly important, as axial thrust direction reverses with roll direction.<\/p>\n<\/p><\/div>\n

\n
\u2693<\/div>\n

Marine Machinery<\/h3>\n

Main reduction gearboxes and deck machinery drives in marine vessels. 42CrMo at 50\u201355 HRC with wooden case transport packing for protection during sea freight transit. OEM marking for marine equipment builders who brand their drivetrain components.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

Agricultural Machinery<\/h3>\n

Heavy-duty agricultural drive gearboxes in combine harvesters and large tractors where the 42CrMo at 50\u201355 HRC specification provides higher surface hardness than the induction-hardened 40\u201345 HRC agricultural series \u2014 appropriate for the highest-load agricultural drive stages.<\/p>\n<\/p><\/div>\n

\n
<\/div>\n

General Heavy Machinery<\/h3>\n

Any heavy industrial gearbox application where 42CrMo at 50\u201355 HRC, double helical form, and wooden case transport packing are specified. Custom module and tooth count to drawing; OEM marking available.<\/p>\n<\/p><\/div>\n<\/div>\n

<\/p>\n

Frequently Asked Questions<\/h2>\n
\n
\n

What is the difference between high-frequency quenching and furnace carburising for rolling mill gears?<\/p>\n

High-frequency (induction) quenching heats only the surface of the tooth by electromagnetic induction to above the austenitising temperature, then quenches rapidly \u2014 producing a hard surface (50\u201355 HRC in 42CrMo) over a tough, less fully hardened core. Furnace carburising introduces carbon into the tooth surface by diffusion at elevated temperature, producing a hardened case (58\u201362 HRC) over a tough low-carbon alloy steel core. The key practical difference is the hardening depth: induction quenching achieves 1\u20134 mm effective case depth; carburising achieves 0.8\u20133 mm. For large-module rolling mill gears, the larger tooth section means more heat input is required to achieve adequate depth by induction quenching than carburising. Korea Ever-Power confirms the appropriate hardening process for each specific gear size and tooth geometry at the drawing review stage.<\/p>\n<\/div>\n

\n
\n

Should rolling mill pinion stand gears be two-piece assembly or integral single piece?<\/p>\n

Both are valid configurations for different situations. Two-piece assembly gears allow each helical half to be hobbed separately (which is simpler and potentially achieves higher accuracy than milling a narrow-groove integral herringbone), and allow independent replacement of each helical half \u2014 useful in a reversing mill where one side may wear faster than the other. Integral single-piece gears are more compact, eliminate the assembly interface, and have no risk of fretting between the two halves under reversing load. The choice is typically driven by the original mill design’s housing arrangement \u2014 provide the existing drawing or worn sample and Korea Ever-Power will produce in the same configuration.<\/p>\n<\/div>\n

\n
\n

Is tooth grinding available for rolling mill double helical gears?<\/p>\n

Tooth grinding is available on request and is noted as an option on the specification table. For two-piece assembly configurations, tooth grinding of each helical half before assembly is straightforward and confirms the highest accuracy achievable. For integral herringbone configurations, tooth grinding is limited by the central groove width \u2014 the grinding wheel must pass through the groove without fouling the opposite tooth set. Specify the required accuracy grade on the drawing and Korea Ever-Power will confirm whether grinding is feasible for the specific configuration and what accuracy grade is achievable.<\/p>\n<\/div>\n

\n
\n

Can other alloy steels besides 42CrMo be used for rolling mill gears?<\/p>\n

Yes \u2014 all grades in the cross-reference table above are available. For rolling mill gears that require higher core toughness than 42CrMo provides (for example, in mills with severe biting shock loads), 40CrNiMoA (ASTM 4340) provides higher impact energy after hardening and tempering at comparable surface hardness. For carburised rolling mill gears at 58\u201362 HRC, 20CrNiMo or 20CrMnTi are the standard case-hardening grades. Specify the required material grade or the required hardness and toughness combination and Korea Ever-Power will confirm the material recommendation.<\/p>\n<\/div>\n

\n
\n

What transport packing is used for rolling mill gears?<\/p>\n

Rolling mill double helical gears are packed in wooden cases for transport. The wooden case is designed to support the gear without contact between tooth flanks and the case walls, preventing fretting damage during sea freight transit. For precision-ground tooth flanks (where the surface finish must be maintained), additional protective wrapping of the tooth surfaces is applied inside the wooden case. Contact our team<\/a> with your drawing and we will confirm the packing design for the specific gear size and transit route.<\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Customer Reviews<\/h2>\n
\n
\n

“We maintain hot strip finishing mill pinion stands and needed 42CrMo double helical gears at 50\u201355 HRC as two-piece assembly configuration. Korea Ever-Power produced each helical half with hobbing and confirmed the hardness at every tooth by portable Rockwell tester before assembly. Wooden case packing arrived undamaged after sea freight from China to South Korea \u2014 tooth flanks showed no transport fretting at incoming inspection.”<\/p>\n

Kim Byeong-su<\/strong>  |  Rolling Mill Maintenance Manager, Pohang Hot Strip Plant  ·  Q1 2026<\/em><\/p>\n<\/div>\n

\n

“We supply cold rolling mill pinion stands to flat product producers and qualify 42CrMo double helical gear<\/a> sets from Korea Ever-Power. The two-piece assembly configuration allows us to replace only the worn helical half at service intervals, reducing replacement cost by approximately 40% compared with replacing the full integral herringbone. OEM marking confirmed to our part number on all deliveries.”<\/p>\n

Lee Sang-cheol<\/strong>  |  Drivetrain Engineer, Incheon Cold Rolling Equipment Co.  ·  Q4 2025<\/em><\/p>\n<\/div>\n

\n

“We manufacture plate mill reversal gearboxes. The reversing load direction in plate milling makes axial thrust management critical \u2014 any axial float in the single helical alternative causes housing wear. Korea Ever-Power’s 42CrMo double helical gears at 50\u201355 HRC eliminated the axial float issue that we experienced with a previous supplier’s single helical configuration. Three years of operation without a pinion stand housing wear incident.”<\/p>\n

Park Tae-kyun<\/strong>  |  Heavy Rolling Equipment Design Lead, Gwangyang Plate Mill Systems  ·  Q2 2026<\/em><\/p>\n<\/div>\n

\n

“We needed tooth grinding on a two-piece 42CrMo rolling mill herringbone gear set for higher accuracy in a new finishing mill. Korea Ever-Power confirmed grinding was feasible on each half separately before assembly, produced to the required accuracy grade, and provided the dimensional inspection report. The gear noise at operating speed was the lowest we had measured in this mill generation.”<\/p>\n

Choi Hyeon-min<\/strong>  |  Precision Rolling Systems Engineer, Ulsan Steel Equipment Manufacturing  ·  Q3 2025<\/em><\/p>\n<\/div>\n

\n

“We source 42CrMo double helical gears for marine reduction gearboxes. The wooden case packing is required by our freight insurer for large steel gears during sea freight. Korea Ever-Power provided the packing specification confirming the tooth flank protection arrangement, which satisfied the insurer’s requirement without additional survey. OEM marking applied to hub face as specified.”<\/p>\n

Yoon Sang-wook<\/strong>  |  Marine Gearbox Procurement, Busan Shipbuilding Equipment Co.  ·  Q1 2025<\/em><\/p>\n<\/div>\n<\/div>\n

<\/p>\n

Related Products<\/h2>\n
\n
\n
\n \"Double
\n <\/a><\/p>\n
\n

Helical Gears<\/h3>\n

Korea Ever-Power’s double helical gear range covers rolling mill pinion gears, heavy machinery gears, metallurgy soft tooth flank gears, mining carburised gears, and agricultural machinery gears \u2014 all custom to drawing in alloy steel.<\/p>\n

Browse Helical Gears \u2192<\/a>\n <\/div>\n<\/p><\/div>\n

\n
\n \"Forging
\n <\/a><\/p>\n
\n

\u30d9\u30d9\u30eb\u30ae\u30a2<\/h3>\n

Forged alloy steel bevel gears for right-angle drives in rolling mill auxiliary equipment, coiler drives, and crop shear drives \u2014 the intersecting-shaft complement to parallel-axis double helical pinion stand gears.<\/p>\n

Browse Bevel Gears \u2192<\/a>\n <\/div>\n<\/p><\/div>\n<\/div>\n

\n

Request a Quotation for Rolling Mill Double Helical Gears<\/h3>\n

Send drawing with module, tooth count, helix angle, assembly type (two-piece or integral), and accuracy grade. 42CrMo standard; other grades available. 50\u201355 HRC standard; tooth grinding optional. OEM marking; wooden case packing.<\/p>\n

Get a Quote Now<\/a>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

Korea Ever-Power rolling mill double helical gears are produced in 42CrMo (AISI 4140 \/ SCM 440) alloy steel with hardening and tempering, achieving 50\u201355 HRC tooth surface hardness. External gear, hardened tooth surface, gear milling or gear hobbing manufacturing method. Tooth grinding optionally available for higher accuracy grades. Double helical gears can be produced as assembly parts or as a single integral component. Module, tooth count, and helix angle all custom to drawing. OEM marking; wooden case transport packing. Suitable for hot mills, cold mills, plate mills, bar mills, and section mills \u2014 and for marine, agricultural machinery, and general heavy machinery where the zero-thrust double helical form and hardened 42CrMo teeth are specified.<\/p>","protected":false},"featured_media":1520,"comment_status":"closed","ping_status":"open","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":""},"product_brand":[],"product_cat":[4558],"product_tag":[],"class_list":["post-1519","product","type-product","status-publish","has-post-thumbnail","product_cat-helical-gear","pa_editor-cxm","first","instock","product-type-simple"],"_links":{"self":[{"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/product\/1519","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/comments?post=1519"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/media\/1520"}],"wp:attachment":[{"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/media?parent=1519"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/product_brand?post=1519"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/product_cat?post=1519"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/gearrack.top\/ja\/wp-json\/wp\/v2\/product_tag?post=1519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}