1-Types of Gear Materials
S45C (Carbon Steel for Structural Machine Usage)
Heat Treatment and Hardness
Heat Treatment | Hardness |
---|---|
None | less than 194HB |
Thermal Refining | 225 – 260HB |
Induction Hardening | 45 – 55HRC |
SCM440 (Chrome-molybdenum Alloy Steel)
Heat Treatment and Hardness
Heat Treatment | Hardness |
---|---|
Thermal Refining | 225 – 260HB |
Induction Hardening | 45 – 60HRC |
SCM415 (Chrome-molybdenum Alloy Steel)
SUS303 (Stainless Steel:18Cr-8Ni Stainless Steel)
Copper Alloy Casting
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Worm gears |
2- Heat Treatments
What is Quenching?
What is Thermal Refining?
What is Induction Hardening?

What is Carburizing ?

What is Nitriding ?
Heat treatment of gears (Carburizing, Induction hardening, Nitriding)
- Carburizing
- Induction hardening
- Nitriding
1. Carburizing
2. Induction hardening
3. Nitriding
Table: Types of Gear Materials
The table lists the mechanical properties and characteristics of gear materials most commonly used.JIS Material No. : S15CK
Tensile Strength N/mm2 More than : 490
Elongation (%) More than : 20
Drawability (%) More than : 50
Hardness HB : 143-235
Characteristics, heat treatments applied : Low-carbon steel. High hardness obtained by Carburizing.
Material : Carbon Steel for Structural Machine Usage
JIS Material No. : S45C
Tensile Strength N/mm2 More than : 690
Elongation (%) More than : 17
Drawability (%) More than : 45
Hardness HB : 201-269
Characteristics, heat treatments applied : Most commonly used medium-carbon steel. Thermal refined / induction hardened.
Material : Alloy steel for Machine Structural Use
JIS Material No. : SCM435
Tensile Strength N/mm2 More than : 930
Elongation (%) More than : 15
Drawability (%) More than : 50
Hardness HB : 269-331
Characteristics, heat treatments applied : Medium-carbon alloy steel (C content: 0.3-0.7%). Thermal refined and induction hardened. High strength (High bending strength / High surface durability). Used in gear manufacturing, except for worm gear.
Material : Alloy steel for Machine Structural Use
JIS Material No. : SCM440
Tensile Strength N/mm2 More than : 980
Elongation (%) More than : 12
Drawability (%) More than : 45
Hardness HB : 285-352
Characteristics, heat treatments applied : Medium-carbon alloy steel (C content: 0.3-0.7%). Thermal refined and induction hardened. High strength (High bending strength / High surface durability). Used in gear manufacturing, except for worm wheels.
Material : Alloy steel for Machine Structural Use
JIS Material No. : SNCM439
Tensile Strength N/mm2 More than : 980
Elongation (%) More than : 16
Drawability (%) More than : 45
Hardness HB : 293-352
Characteristics, heat treatments applied : Medium-carbon alloy steel (C content: 0.3-0.7%). Thermal refined and induction hardened. High strength (High bending strength / High surface durability). Used in gear manufacturing, except for worm wheels.
Material : Alloy steel for Machine Structural Use
JIS Material No. : SCr415
Tensile Strength N/mm2 More than : 780
Elongation (%) More than : 15
Drawability (%) More than : 40
Hardness HB : 217-302
Characteristics, heat treatments applied : Low-carbon Alloy Steel (C content below 0.3%). Surface-hardening treatment applied (Carburizing, Nitriding, Carbo-nitriding, etc.) High strength (Bending strength / Surface durability).
Material : Alloy steel for Machine Structural Use
JIS Material No. : SCM415
Tensile Strength N/mm2 More than : 830
Elongation (%) More than : 16
Drawability (%) More than : 40
Hardness HB : 235-321
Characteristics, heat treatments applied : Low-carbon Alloy Steel (C content below 0.3%). Surface-hardening treatment applied (Carburizing, Nitriding, Carbo-nitriding, etc.) High strength (Bending strength / Surface durability).
Material : Alloy steel for Machine Structural Use
JIS Material No. :SNC815
Tensile Strength N/mm2 More than : 980
Elongation (%) More than : 12
Drawability (%) More than : 45
Hardness HB : 285-388
Characteristics, heat treatments applied : Low-carbon Alloy Steel (C content below 0.3%). Surface-hardening treatment applied (Carburizing, Nitriding, Carbo-nitriding, etc.) High strength (Bending strength / Surface durability).
Material : Alloy steel for Machine Structural Use
JIS Material No. : SNCM220
Tensile Strength N/mm2 More than : 830
Elongation (%) More than : 17
Drawability (%) More than : 40
Hardness HB : 248-341
Characteristics, heat treatments applied : Low-carbon Alloy Steel (C content below 0.3%). Surface-hardening treatment applied (Carburizing, Nitriding, Carbo-nitriding, etc.) High strength (Bending strength / Surface durability).
Material : Alloy steel for Machine Structural Use
JIS Material No. : SNCM420
Tensile Strength N/mm2 More than : 980
Elongation (%) More than : 15
Drawability (%) More than : 40
Hardness HB : 293-375
Characteristics, heat treatments applied : Low-carbon Alloy Steel (C content below 0.3%). Surface-hardening treatment applied (Carburizing, Nitriding, Carbo-nitriding, etc.) High strength (Bending strength / Surface durability).
Material :Rolled Steel for General Structures
JIS Material No. : SS400
Tensile Strength N/mm2 More than : 400
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : –
Characteristics, heat treatments applied : Low strength. Low cost.
Material :Gray Cast Iron
JIS Material No. : FC200
Tensile Strength N/mm2 More than : 200
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : Less than 223
Characteristics, heat treatments applied : Low strength than steel. Suitable for bulk production.
Material : Nodular Graphite Cast Iron
JIS Material No. : FCD500-7
Tensile Strength N/mm2 More than : 500
Elongation (%) More than : 7
Drawability (%) More than : –
Hardness HB : 150-230
Characteristics, heat treatments applied : Ductile Cast Iron with high strength. Used in the manufacturing of large casting gears.
Material : Stainless Steel
JIS Material No. :SUS303
Tensile Strength N/mm2 More than : 520
Elongation (%) More than : 40
Drawability (%) More than : 50
Hardness HB : Less than 187
Characteristics, heat treatments applied : Has more machinability than SUS304. Increases seizure resistant.
Material : Stainless Steel
JIS Material No. : SUS304
Tensile Strength N/mm2 More than : 520
Elongation (%) More than : 40
Drawability (%) More than : 60
Hardness HB : Less than 187
Characteristics, heat treatments applied : Most commonly used stainless Steel. Used for food processing machines etc.
Material : Stainless Steel
JIS Material No. : SUS316
Tensile Strength N/mm2 More than : 520
Elongation (%) More than : 40
Drawability (%) More than : 60
Hardness HB : Less than 187
Characteristics, heat treatments applied : Has corrosion resistance against salty seawater, better than SUS304.
Material : Stainless Steel
JIS Material No. : SUS420J2
Tensile Strength N/mm2 More than : 540
Elongation (%) More than : 12
Drawability (%) More than : 40
Hardness HB : More than 217
Characteristics, heat treatments applied : Martensitic stainless steel, quenching can be applied.
Material : Stainless Steel
JIS Material No. : SUS440C
Tensile Strength N/mm2 More than : –
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : More than 58HRC
Characteristics, heat treatments applied : High hardness can be obtained by quenching. High surface durability.
Material : Nonferrous Metals
JIS Material No. : C3604
Tensile Strength N/mm2 : 335
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : More than 80HV
Characteristics, heat treatments applied : Free-Cutting Brass. Used in manufacturing of small gears.
Material : Nonferrous Metals
JIS Material No. : CAC502
Tensile Strength N/mm2 : 295
Elongation (%) More than : 10
Drawability (%) More than : –
Hardness HB : More than 80
Characteristics, heat treatments applied : Phosphor bronze casting. Suitable for worm wheels.
Material : Nonferrous Metals
JIS Material No. : CAC702
Tensile Strength N/mm2 : 540
Elongation (%) More than : 15
Drawability (%) More than : –
Hardness HB : More than 120
Characteristics, heat treatments applied : Aluminum-bronze casting. Used for worm wheels etc.
Material : Engineering Plastics
JIS Material No. : MC901
Tensile Strength N/mm2 : 96
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : 120HRR
Characteristics, heat treatments applied : Used for machined gears. Lightweight. Anti-rust.
Material : Engineering Plastics
JIS Material No. : MC602ST
Tensile Strength N/mm2 : 96
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : 120HRR
Characteristics, heat treatments applied : Used for machined gears. Lightweight. Anti-rust.
Material : Engineering Plastics
JIS Material No. : M90
Tensile Strength N/mm2 : 62
Elongation (%) More than : –
Drawability (%) More than : –
Hardness HB : 80HRR
Characteristics, heat treatments applied : Used for injection-molded gears. Suitable for bulk production at low cost. Applied for use with light load.