{"id":2388,"date":"2026-06-26T03:47:24","date_gmt":"2026-06-26T03:47:24","guid":{"rendered":"https:\/\/helicalcutgears.top\/?p=2388"},"modified":"2026-06-26T03:57:53","modified_gmt":"2026-06-26T03:57:53","slug":"helical-gears-for-rubber-mixer-and-extruder-gearboxes","status":"publish","type":"post","link":"https:\/\/helicalcutgears.top\/et\/helical-gears-for-rubber-mixer-and-extruder-gearboxes\/","title":{"rendered":"Helical Gears for Rubber Mixer and Extruder Gearboxes"},"content":{"rendered":"
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Helical Gears for Rubber Mixer and Extruder Gearboxes \u2014 High-Torque, Low-Speed Drive Design<\/h1>\n

See spiraalne k\u00e4ik<\/strong> drives inside rubber mixer and plastic extruder gearboxes are among the highest-torque applications in industrial gear manufacturing: output torques of 50,000\u2013500,000 N\u00b7m at output speeds of 10\u201330 RPM, combined with frozen-charge restart loads that can reach 400\u2013500% of rated torque without warning. The spiraalne k\u00e4ik<\/strong> specification that results \u2014 module M20\u2013M50, 42CrMo4 induction hardened or 17CrNiMo6 carburized, service factor KA up to 4.0 \u2014 is matched by few other industrial applications outside mining and cement.<\/p>\n

Request Mixer Gear Specification \u2192<\/a><\/p>\n<\/div>\n<\/div>\n

Mixer and Extruder Types \u2014 Where Helical Gears Are Used<\/h2>\n

Three distinct machine types in the mixing and extrusion industry use large-module spiraalne k\u00e4ik<\/strong> drives, each with different load characteristics:<\/p>\n

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Internal (Banbury) Rubber Mixer<\/strong><\/p>\n

An internal mixer kneads rubber compounds between two counter-rotating rotors inside a closed chamber. Rotor speed: 15\u201340 RPM. The critical load event \u2014 frozen charge restart \u2014 occurs when mixed compound solidifies during an unplanned shutdown. Restarting against the frozen charge generates torque peaks of 3\u20135\u00d7 rated torque at essentially zero speed. The spiraalne k\u00e4ik<\/strong> output shaft torques reach 150,000\u2013600,000 N\u00b7m on large 600-litre machines. This is the most demanding peak torque event in any industrial gearbox application.<\/p>\n<\/div>\n

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Twin-Screw Extruder<\/strong><\/p>\n

Co-rotating or counter-rotating twin screws process plastics, food compounds, or adhesives in continuous operation. Screw speed: 100\u2013600 RPM (higher than rubber mixers). Output torque per screw: 1,000\u201330,000 N\u00b7m. Shock events: metal contamination in feed (tramp iron) causes instantaneous load spikes. The spiraalne k\u00e4ik<\/strong> distribution gearbox must distribute equal torque to both screws \u2014 requiring matched output spiraalsed hammasrattad<\/strong> and a common input pinion.<\/p>\n<\/div>\n

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Planetary or Sigma Blade Mixer<\/strong><\/p>\n

Chemical, pharmaceutical, and food mixers rotate a blade or anchor impeller at 10\u201360 RPM. Output torques are moderate (5,000\u201350,000 N\u00b7m) compared with rubber mixers, but the gearbox must handle frequent batch processing with variable filling levels \u2014 creating a varying load profile that requires accurate service factor assessment. The spiraalne k\u00e4ik<\/strong> gearbox typically includes a mechanical torque limiter to protect the mixer vessel and drive from overload during a material jam.<\/p>\n<\/div>\n<\/div>\n

Service Factor \u2014 Why KA Reaches 3.0\u20134.0 in Rubber Mixer Drives<\/h2>\n

The service factor for mixer and extruder spiraalne k\u00e4ik<\/strong> drives is the highest of any application category in regular industrial service, for two independent and cumulative reasons:<\/p>\n

\n\n\n\n\n\n\n\n\n
Load Event<\/th>\nTorque Multiple<\/th>\nDuration<\/th>\nFrequency<\/th>\nKA Contribution<\/th>\n<\/tr>\n<\/thead>\n
Normal mixing cycle peak<\/td>\n120\u2013150% rated<\/td>\n10\u201330 s per cycle<\/td>\nEvery batch<\/td>\nKA \u2248 1.50 base<\/td>\n<\/tr>\n
Sudden temperature drop (compound stiffening)<\/td>\n150\u2013200% rated<\/td>\n2\u20135 min<\/td>\nSeveral times per shift in cold weather<\/td>\n+0.25\u20130.50 to KA<\/td>\n<\/tr>\n
Normal cold startup with partially cured charge<\/td>\n200\u2013300% rated<\/td>\n5\u201320 s<\/td>\nEvery shift startup<\/td>\n+0.50\u20130.75 to KA<\/td>\n<\/tr>\n
Frozen charge restart (worst case)<\/strong><\/td>\n400\u2013500% rated<\/strong><\/td>\nUp to 30 s until charge breaks loose or protection trips<\/strong><\/td>\nRare but must be survived<\/td>\nGoverns static tooth fracture check<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Recommended KA values for mixer\/extruder helical gear drives (AGMA 2101 \/ Korea Ever-Power field data):
\nTwin-screw extruder (DOL motor, no tramp protection): KA = 1.75\u20132.25
\nChemical\/pharmaceutical planetary mixer: KA = 1.75\u20132.50
\nRubber mixing mill (open mill, 2 rolls): KA = 2.00\u20132.50
\nInternal (Banbury) rubber mixer (fluid coupling): KA = 2.50\u20133.00
\nInternal rubber mixer (DOL motor, no fluid coupling): KA = 3.00\u20134.00<\/p>\n

Note: The frozen charge torque peak (400\u2013500%) must additionally be checked against
\nthe tooth root static bending stress limit using the static safety factor S_F_stat \u2265 1.0
\nat the peak overload \u2014 separate from the fatigue KA check at rated torque.<\/p>\n

Material and Module Selection for Mixer Helical Gears<\/h2>\n

\"large<\/p>\n

Suurmoodul spiraalne k\u00e4ik<\/strong> for rubber mixer gearbox \u2014 42CrMo4 forged, induction hardened HRC 50\u201355, module M24. At output torques of 150,000\u2013500,000 N\u00b7m and rotor speed 15\u201330 RPM, the required module and face width are determined by the frozen charge restart torque (400\u2013500% of rated), not the normal operating load, making this one of the highest unit-load spiraalne k\u00e4ik<\/strong> applications in industrial manufacturing<\/p>\n

Section Size and Heat Treatment Constraints<\/h3>\n

A rubber mixer output shaft spiraalne k\u00e4ik<\/strong> at M32 with z = 30 teeth has a pitch diameter of approximately 1,000 mm and a blank cross-section of 900\u20131,100 mm diameter. This section size is beyond the hardenability capability of 20CrMnTi (which reliably hardens through sections to approximately 300\u2013400 mm diameter). The correct material choice depends on the required surface hardness and the available heat treatment:<\/p>\n

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42CrMo4 + Induction Hardening<\/strong><\/p>\n

The standard choice for large-section mixer spiraalsed hammasrattad<\/strong> (OD 500\u20132,000 mm). The blank is QT to HB 280\u2013320 through-section, then individual teeth or tooth zones are induction hardened to HRC 50\u201355. The QT core at HB 280\u2013320 provides the toughness needed for frozen charge restart impacts. Induction hardening acts locally \u2014 no through-section thermal distortion. \u03c3_H lim = 820\u2013950 MPa; \u03c3_F lim = 340\u2013380 MPa at tooth root.<\/p>\n<\/div>\n

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17CrNiMo6 + Gas Carburizing (Smaller Modules)<\/strong><\/p>\n

For extruder and pharmaceutical mixer gears in M8\u2013M20 (OD 200\u2013600 mm), 17CrNiMo6 carburized to HRC 58\u201362 provides \u03c3_H lim = 1600\u20131800 MPa \u2014 enabling more compact, lighter gearboxes for the same torque capacity. Carburizing is feasible for sections up to approximately 500 mm diameter in 17CrNiMo6. For larger sections, 42CrMo4 induction is the only practical route.<\/p>\n<\/div>\n<\/div>\n

Module and Face Width Selection<\/h3>\n

The module and face width for a mixer spiraalne k\u00e4ik<\/strong> are typically governed by the frozen charge peak torque rather than the rated operating torque \u2014 the static tooth root bending check at 400\u2013500% of rated torque with S_F_stat \u2265 1.0 sets the minimum module:<\/p>\n

Static tooth root bending check (at frozen charge peak torque T_peak):
\nF_t_peak = 2 \u00d7 T_peak \/ d\u2081
\n\u03c3_F_static = F_t_peak \/ (b \u00d7 Mn) \u00d7 Y_Fa \u00d7 Y_Sa \u00d7 Y_\u03b5 \u00d7 Y_\u03b2 \u00d7 KA_static
\nwhere KA_static = T_peak \/ T_rated (peak overload factor) \u00d7 KA_base = 4.0\u20135.0<\/p>\n

Required: \u03c3_F_static \u2264 \u03c3_F_lim_static (ISO 6336-3 static allowable \u2248 2.0 \u00d7 \u03c3_F_lim_fatigue)<\/p>\n

Example: 600-litre rubber mixer, T_rated = 150,000 N\u00b7m, T_peak = 600,000 N\u00b7m
\nWith M32, z=30, b=500mm, 42CrMo4 induction, \u03c3_F_lim_static \u2248 760 N\/mm\u00b2:
\n\u03c3_F_static \u2248 (2 \u00d7 600,000,000)\/(d\u2081 \u00d7 500 \u00d7 32) \u00d7 geometry factors \u00d7 1.0
\n\u2192 Module M32 is just adequate; M36 provides comfortable S_F_stat \u2265 1.2<\/p>\n

Drive Architecture and the Fluid Coupling’s Role<\/h2>\n

Most large rubber mixer spiraalne k\u00e4ik<\/strong> drives include a fluid coupling (hydrodynamic coupling) between the motor and the gearbox input shaft. The fluid coupling limits the transmitted torque during startup \u2014 when the motor torque would otherwise be 250\u2013350% of rated at stall \u2014 and provides a degree of impact protection during frozen charge restart. However, the fluid coupling does NOT eliminate the frozen charge torque peak: as the coupling fills and approaches synchronous speed, it briefly passes through a torque multiplication zone that can transmit 150\u2013200% of rated torque to the gearbox. The frozen charge peak load still governs the spiraalne k\u00e4ik<\/strong> tooth root bending check even with a fluid coupling in the drive line.<\/p>\n

Without a fluid coupling (direct DOL motor):<\/strong> The frozen charge peak torque passes to the spiraalne k\u00e4ik<\/strong> at its full value \u2014 400\u2013500% of rated. With a fluid coupling, the transmitted peak is limited to approximately 200\u2013300% of rated. Korea Ever-Power requests information about the presence and rating of any fluid coupling when specifying mixer gearbox spiraalsed hammasrattad<\/strong>, as the fluid coupling rating directly affects which KA value is correct for the gear tooth calculation.<\/div>\n

Lubrication for Low-Speed, High-Torque Helical Gear Drives<\/h2>\n

Mixer and extruder spiraalne k\u00e4ik<\/strong> drives operate at very low pitch-line velocities (0.5\u20133 m\/s) where churning loss is negligible but the EHL film thickness is significantly thinner than in high-speed gearboxes. The EHL film thickness h_min \u221d v^0.68 \u2014 at v = 1 m\/s, the film is approximately 8\u201310\u00d7 thinner than at v = 10 m\/s for the same oil viscosity. To compensate, mixer gearboxes specify significantly higher oil viscosity than fast-running gearboxes:<\/p>\n

Recommended viscosity for mixer\/extruder helical gear drives (DIN 51517 CLP mineral oil):
\nv < 0.5 m\/s (extremely slow, rubber mixer final stage): ISO VG 680\u20131000
\n0.5\u20132 m\/s (slow, typical mixer intermediate stage): ISO VG 320\u2013680
\n2\u20135 m\/s (extruder intermediate speed): ISO VG 220\u2013320<\/p>\n

The high viscosity mineral oils specified for slow mixer spiraalsed hammasrattad<\/strong> have excellent boundary lubrication additive packages (extreme pressure EP sulphur-phosphorus) that protect the tooth surfaces during the brief elastohydrodynamic film breakdown events that occur at the frozen charge peak load. PAO synthetic oils are increasingly used in mixer gearboxes to extend oil change intervals (3\u20135 years vs 1\u20132 years for mineral oil) and to maintain oil flow at cold startup in winter conditions.<\/p>\n

Korea Ever-Power \u2014 Large Module Mixer Helical Gear Capability<\/h2>\n

\"Korea<\/p>\n

Korea Ever-Power manufacturing and inspection of large-module spiraalsed hammasrattad<\/strong> for mixer and extruder gearboxes \u2014 M16\u2013M50 in 42CrMo4 induction hardened or 17CrNiMo6 carburized, with frozen charge static bending check, hardness survey, and gear analyser measurement included in the order documentation<\/p>\n

Korea Ever-Power toodab spiraalsed l\u00f5igatud hammasrattad<\/strong> for rubber mixer and extruder gearboxes in M8\u2013M50, OD 200\u20132,500 mm, in 42CrMo4 induction hardened (HRC 50\u201355) and 17CrNiMo6 carburized (HRC 58\u201362), with the frozen charge static bending check (S_F_stat at T_peak) included in the order documentation as standard \u2014 ensuring the gear is sized for the actual worst-case event, not just the rated operating torque. As a direct spiraalhammasrataste tootja<\/a>, Korea Ever-Power requests the fluid coupling rating (if present) and confirmed peak torque value at every mixer gear order \u2014 the two inputs that most strongly affect the required module. Browse the double helical gear product range<\/a> for all module and material options.<\/p>\n

Korduma kippuvad k\u00fcsimused<\/h2>\n
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What is the difference in helical gear specification between a co-rotating and a counter-rotating twin-screw extruder?<\/strong><\/p>\n

The gear arrangement differs significantly. In a co-rotating extruder (most common for compounding), both screws turn in the same direction \u2014 the distribution gearbox uses an intermediate shaft with two identical output gears driven from a single input pinion, so the spiraalne k\u00e4ik<\/strong> pair ratios are identical and torque distribution is inherently balanced. In a counter-rotating extruder, the two screws turn in opposite directions \u2014 the distribution gearbox reverses one output shaft through an idler gear, introducing an additional gear mesh that must be rated and inspected. The idler gear in a counter-rotating extruder sees twice the tooth contact frequency of the main gears (it meshes with both the driver and driven gears) and must be specified at the idler fatigue correction factor Y_M = 0.7 for reversed bending if it is a true idler.<\/p>\n<\/div>\n

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Should the rubber mixer helical gear gearbox be specified for the frozen charge peak torque or the normal rated torque?<\/strong><\/p>\n

Both checks are mandatory and independent. The gear must pass: (1) the fatigue contact stress check at rated torque with KA = 2.5\u20133.0 (pitting resistance over the design service life of 40,000\u2013100,000 hours); and (2) the static tooth root bending check at the frozen charge peak torque T_peak = 4\u20135 \u00d7 T_rated with safety factor S_F_stat \u2265 1.0 (no fracture at the one-time peak event). For large rubber mixer spiraalsed hammasrattad<\/strong>, the static check at frozen charge torque typically governs the module selection \u2014 the gear is larger than the fatigue rating alone would require, specifically to survive the rare frozen charge event. Korea Ever-Power performs both checks and reports both safety factors in the order documentation.<\/p>\n<\/div>\n

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How frequently should the gear oil in a rubber mixer gearbox be changed?<\/strong><\/p>\n

With ISO VG 680 mineral oil, Korea Ever-Power recommends annual oil changes for mixer spiraalne k\u00e4ik<\/strong> gearboxes in continuous production (24 hours, 350 days\/year) or at 2,000 operating hours \u2014 whichever comes first. The high oil viscosity and EP additive package degrade from thermal cycling and from the mechanical shear in the high-torque low-speed contact zone. An oil analysis (viscosity, acid value, particle count, metal content) at 1,000 hours confirms whether the annual interval is adequate for the specific operating condition. Switching to PAO synthetic ISO VG 680 extends the oil change interval to 5,000\u20138,000 hours \u2014 often making a 3\u20135 year interval feasible with continued oil analysis monitoring.<\/p>\n<\/div>\n

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Can the helical gears in an older rubber mixer gearbox be upgraded to a higher material grade without changing the housing?<\/strong><\/p>\n

Yes \u2014 replacing 42CrMo4 QT soft-flank gears (HB 280\u2013320, \u03c3_H lim \u2248 570 MPa) with 42CrMo4 induction-hardened gears (HRC 52, \u03c3_H lim \u2248 900 MPa) increases the contact fatigue limit by approximately 57% without any change to module, tooth count, or centre distance. The standard module, face width, and housing geometry are all unchanged because the upgrade is in the material tier \u2014 not the gear geometry. In most cases, this upgrade also removes the need for the operating speed restriction that many older soft-flank rubber mixer gearboxes are running under because their tooth flanks have worn and the operator has reduced the mix RPM to extend gear life. Korea Ever-Power has executed this upgrade for several rubber mixer gearboxes where the original OEM parts were unavailable at acceptable cost.<\/p>\n<\/div>\n

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Rubber Mixer and Extruder Helical Gear Specification<\/h2>\n

Provide your mixer type, rated output torque, maximum peak torque (or frozen charge estimate), output speed, and fluid coupling rating if present. Korea Ever-Power performs both the fatigue check at rated torque and the static bending check at frozen charge peak before confirming the specification.<\/p>\n

Submit Mixer Gear Enquiry<\/a>
\nSpiraalk\u00e4igukasti tootevalik<\/a><\/div>\n

M8\u2013M50 \u00b7 42CrMo4 induction \u00b7 17CrNiMo6 carburized \u00b7 KA 2.5\u20134.0 \u00b7 Static bending check \u00b7 Frozen charge survival \u00b7 MOQ 1 piece<\/p>\n<\/div>\n

Toimetaja: Cxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Helical Gears for Rubber Mixer and Extruder Gearboxes \u2014 High-Torque, Low-Speed Drive Design The helical gear drives inside rubber mixer and plastic extruder gearboxes are among the highest-torque applications in industrial gear manufacturing: output torques of 50,000\u2013500,000 N\u00b7m at output speeds of 10\u201330 RPM, combined with frozen-charge restart loads that can reach 400\u2013500% of rated […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[3082],"tags":[],"class_list":["post-2388","post","type-post","status-publish","format-standard","hentry","category-helical-gears"],"_links":{"self":[{"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/posts\/2388","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/comments?post=2388"}],"version-history":[{"count":3,"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/posts\/2388\/revisions"}],"predecessor-version":[{"id":2392,"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/posts\/2388\/revisions\/2392"}],"wp:attachment":[{"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/media?parent=2388"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/categories?post=2388"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helicalcutgears.top\/et\/wp-json\/wp\/v2\/tags?post=2388"}],"curies":[{"name":"t\u00f6\u00f6leht","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}