- support@ddgear.com
- North 3F, Building 13-2, Zhixin Park, NO.1099 Xianhua South Street, Wucheng, Jinhua, Zhejiang, China.
Custom Gear
Shaft
A shaft is a rotating machine element that transmits power and torque from one location to another and supports rotating components such as gears, pulleys, sprockets and couplings. In powertrain systems, transmission shafts are subjected to combined torsion and bending from gear forces, chain or belt loads, and their own weight, so they must be designed for fatigue strength and stiffness over long service lives. DD Gear focuses on custom transmission shafts and gear shafts produced to customer drawings. These include input shafts, output shafts, gear shafts with integral gears, spline shafts and intermediate shafts used in EV drives, truck and off-highway gearboxes, industrial gearboxes, AGV drive units and automation equipment. Typical designs use forged alloy steels such as 42CrMo4 / AISI 4140 / SCM440 and related grades, which are widely used for heavily loaded shafts due to their strength and toughness. Shaft performance depends not only on material and heat treatment, but also on accurate bearing seats, fits and runout. DD Gear machines shaft journals, shoulders, splines and gear seats to tight tolerances based on ISO 286 fits for holes and shafts, helping customers achieve stable alignment, low vibration and long bearing and gear life. With small-module precision gearing capability inside the same plant, we can also supply integrated gear-shaft components, reducing assembly interfaces and improving concentricity.
Bevel Gear
The Bevel Gear – Custom Bevel & Hypoid Gears for Angular Power Transmission is used to transmit motion and torque between intersecting or crossing shafts, typically arranged at a right angle. Bevel gears have teeth formed on the surface of a truncated cone, allowing power to “turn a corner” while maintaining a defined speed ratio. According to international standards such as ISO 23509, the term “bevel gears” includes straight bevel, spiral bevel, zerol bevel and hypoid gears. Straight bevel gears have straight teeth and are widely used where speeds and noise requirements are moderate, while spiral bevel gears use curved teeth to provide more gradual engagement, higher contact ratio and greater load capacity. Hypoid bevel gears, with offset axes, are commonly applied in automotive differentials and drive axles to handle high torque with smooth operation. DD Gear designs and manufactures custom bevel and hypoid gear sets based on customer drawings and specifications. Typical applications include automotive and EV differentials, steering systems, right-angle gearboxes for machinery, robotic joints and AGV drive axles, where compact angular transmission, efficiency and durability are essential. Geometry is designed in line with ISO 23509 and related bevel gear standards, while accuracy follows recognized systems such as DIN 3965 and the ISO bevel gear accuracy tables published via AGMA/ISO. With DD Gear’s focus on small-module precision gearing for emerging industries, we help customers build reliable angular drives with consistent contact patterns and long service lifePrecision Gears Built for the Future.
Trusted by Global OEMs, Proven in Every Application.
Your Custom Gear Solution Starts Here.
LOVE TO HEAR FROM YOU GET IN TOUCH!
Exploring The Science of Precision Gears
What Makes a Gear Efficient: Understanding Key Structure Basics
Machines today run faster, lift more, and squeeze into tighter spaces than anyone thought possible a few years ago. At the center of almost every one of them sits a gear (sometimes no bigger than a coin, sometimes the size of a dinner table). Get the gear right, and the whole system hums along quietly for years. Get it wrong, and you burn power, make noise, and watch parts wear out way too soon. The Fundamental Role of Gears in Modern Machinery Gears do one basic job: take the speed and twist coming out of a motor and turn it into exactly the speed and push the machine needs. The trick is doing that job while wasting as little energy as possible and staying tough enough to last. Modern gear sets face demands that would have broken old designs in weeks: Motors that spin 15,000 rpm or higher all day long. Robot arms that have to stop dead-on within a hair’s width every single time. Warehouse robots that start and stop thousands of times a shift while hauling a ton or more. Everything is packed smaller, lighter, and quieter than the last generation. Core Structural Components Defining Gear Performance The real difference between a cheap gear and a great one shows up in three places: tooth profile, metal choice and heat treatment, and how accurately the part is made. Tooth Profile and Engagement The curve and angle of each tooth decide how smoothly power moves from one gear to the next. Spur gears are simple and cheap, but the teeth slam together all at once. That bang turns into noise and vibration, especially once speeds climb. Helical gears fix most of that by cutting the teeth on a slant. One tooth starts touching before the last one leaves, so the handover is gradual and quiet. The downside is a little side thrust, but good bearings handle it easily. Even helical gears can whine if they’re not shaped exactly right. That’s why high-end makers add tiny crowning, tip relief, and lead corrections. Those little tweaks, often just a few microns, spread the load evenly, no matter how much torque you throw at the gear. Result? Far less noise and longer life. Surface finish matters too. A ground and polished flank can cut friction losses enough to add a percent or two to overall drivetrain efficiency (real money when you’re talking about an electric truck fleet). Material Science and Durability A gear tooth sees huge bending stress at the root and crushing stress at the pitch line every single rotation. Pick the wrong steel, and it pits or snaps. Most heavy-duty gears today start life as forgings of alloys like 18CrNiMo7-6 or 20MnCr5. Then comes carburizing: pack carbon into the surface, quench it hard (usually 58–62 HRC), but leave the core tougher (around 35–45 HRC). The hard skin laughs at wear; the softer middle soaks up shock without cracking. A well-controlled carburizing run can push case depth within 0.05 mm every time, and that consistency is what lets a gear set survive three to five years of round-the-clock running instead of failing the first winter. Module and Precision The module is just tooth size. Big module = big teeth = can carry big loads, but needs big space. Small module (0.3–0.8 is common now) lets you pack huge reduction ratios into a coffee-cup-sized box. But tiny teeth are unforgiving. A couple of microns of shape error, and the gears howl or wear out fast. That’s why top shops grind every tooth after heat-treat and check them on machines that measure to one micron or less. Anything better than ISO Grade 5 is good; Grade 4 or higher is what robots and EVs demand. Diversity in Design: Key Gear Types and Functions Cylindrical Gears: Spur and Helical Spur gears are the old reliable for parallel shafts. Simple, cheap, 98–99% efficient. Helical gears cost more but run quieter and carry heavier loads in the same space. Almost every electric car gearbox and robot joint uses helical gears somewhere in the train. High-Ratio & Compact Designs: Planetary and Worm Gears Planetary sets give you a 100:1 reduction in one compact package (sun, planets on a carrier, outer ring). Perfect for robot elbows and AGV wheels that need massive torque without a huge motor hanging off the side. Worm gears turn 90 degrees and can hit crazy ratios in one stage. They also self-lock (wheel won’t spin the worm backward), so they’re great for lifts and gates that have to stay put when power is off. Angular Transmission: Bevel Gears Need power to turn a corner? Bevel gears do it. Straight bevels are noisy; spiral and hypoid versions run smoothly and strongly. You’ll find them in car differentials and right-angle robot drives. The Demands of Next-Generation Applications Robotics and Zero-Backlash Requirements Robot joints can’t have even one arc-minute of slop, or the hand drifts. That means zero-backlash designs (harmonic, cycloidal, or ultra-precise planetary) built with 0.3-module teeth. One micron of error in tooth shape shows up as visible shake on a 1-meter arm. For engineering teams looking for deeper technical standards, the AGMA provides globally recognized gear design guidelines, helping ensure consistent accuracy and reliability in robotic gear systems. EV Drivetrains and NVH Control Electric vehicles are dead quiet, so any gear whine sticks out like a sore thumb. Reducers spin at 10,000–18,000 rpm input, so the teeth have to be ground, polished, and perfectly matched. One bad tooth pitch and the whole cabin hears a high-pitched scream at 60 mph. Automation and High-Cycle Durability AGVs in warehouses haul 1–2 tons, yet stop and start every few seconds. Shock loads hit 400–600 Nm at the wheel. Ordinary gears pit and spall in months. Case-hardened helical planets with polished flanks keep running shift after shift. Achieving Efficiency Through Customized Precision Off-the-shelf gears rarely hit all three targets (quiet, strong, tiny) at once. The best setups are drawn from scratch for the exact load, speed, and space. DD Gear works only on custom, build-to-print projects. You send the drawing (or even just a worn-out sample), and we quote it. What we bring to the table: Engineers who live for tooth modifications and know which tiny change drops NVH 6 dB or adds 30% pitting life. Reishauer and Klingelnberg grinders that hold Ra 0.4 or better every run. Full Klingelnberg P40 inspection and in-house noise chamber testing so you know it’s quiet before it leaves the dock. Carburizing furnaces dialed in to 0.05 mm case depth, 60+ HRC skin, tough core every single batch. We make: Super-quiet helical gears to Grade 4–5 for EV boxes. Tiny planet and ring sets that carry 50–100 Nm in the space of a soda can. Worm sets in hardened steel and bronze that lock tight and run smoothly. From humanoid robot joints to warehouse AGVs and city electric buses, if it moves and needs to stay quiet and last, chances are there’s a DD Gear part inside keeping it happy. FAQ Q: What is the main cause of gear noise in high-speed applications? A: Tiny shape errors on the tooth flank that make the teeth bump instead of rolling smoothly. Even a couple of microns shows up as whine once you’re past 10,000 rpm. Q: Why are small-module gears required for modern equipment? A: Because robots and EVs have to pack huge torque and big speed reduction into tiny spaces. Only small teeth let you do that without the gearbox turning into a brick. Q: Does DD Gear support prototyping and small-volume customized orders? A: Yes—prototypes usually ship in 2–3 weeks, and we’re happy with anything from one piece to full production runs. Q: What industries are your precision gears applied to? A: Humanoid robots, electric passenger cars, warehouse AGVs, factory automation lines, and medical equipment—anywhere size, noise, and life really matter.
DD Gear High-Precision Gears Boost Electric Vehicle Efficiency
The Silent Revolution: Why Precision Defines the EV Drivetrain Electric cars are quiet, right? Mostly. The big growl from the old engine is gone, but now drivers hear something new: a high-pitched whine coming straight from the gearbox at 70-100 km/h. Without the engine noise to cover it up, every little mistake in the gears turns into an annoying tone inside the cabin. Passengers notice it on long trips, kids complain, and reviewers knock points off the score. At the same time, every watt you waste in the drivetrain is range you don’t get back. A one-percent loss in the reducer can easily shave 4-8 km off a real-world charge, and that’s money out of the customer’s pocket. That’s why the gears themselves have become the make-or-break part. Get them right, and the car feels premium, stays quiet, and goes farther on the same battery. Get them wrong and the whole project suffers. DD Gear builds nothing but small-module, high-precision gears for exactly this job—electric drive units, two-speed boxes, and e-axles. We’ve been doing it for over fifteen years, and we know the difference a couple of microns makes when the motor is spinning at 15,000 rpm. The High-Speed Challenge: Noise, Vibration, and Harshness (NVH) Electric motors spin fast—way faster than a gasoline engine ever did. A typical EV motor hits 12,000–18,000 rpm, and even minor micro-geometry deviations can create noticeable NVH issues. According to leading gear research institutions such as Gleason, transmission error is the primary contributor to tonal noise in EV drivetrains. The Efficiency Imperative: Maximizing Range per Charge Friction is the enemy of range. Rough tooth surfaces or bad contact patterns heat the oil and rob power. In bench tests, we routinely see 0.6-1.2 % efficiency gain just by moving from Grade 7-8 gears to Grade 4-5 with properly polished flanks. On a 70 kWh pack, that’s another 5-12 km of real range, sometimes more in city driving where the reducer runs all the time. Carmakers fight for every kilometer these days; shaving a few tenths off the kWh/100 km figure can decide who wins the sales chart. DD Gear’s Precision Engineering: The Core of EV Performance We run two plants, both IATF 16949 and ISO 9001 certified, full of modern Höfler and Klingelnberg grinders. Every gear that leaves the floor has been measured on a Klingelnberg P26 for profile and lead, run on a single-flank tester, and spun in a real NVH chamber before it goes in the box. Helical Gear Design: DD Gear’s Approach to Low-Noise Operation Spur gears are cheap and simple, but in an EV, they scream. Helical is the only realistic choice once you care about noise. The teeth slide into the mesh instead of slamming together, so the shock is spread out. We run two-stage helical layouts on most e-axles. The trick is getting the micro-geometry right—tip relief, crown, root relief, and a touch of helix modification. Do it properly, and the contact pattern stays in the middle of the tooth even when the shaft deflects under 300-400 Nm of torque. That keeps the whine down exactly where customers cruise, 80-120 km/h. Material Science and Durability: Meeting High-Torque Demands Most of our EV gears are 18CrNiMo7-6, case-hardened and shot-peened. You get 62-64 HRC on the surface and a tough core that doesn’t snap when the driver floors it from a stop. We carburize, quench, and temper in controlled-atmosphere furnaces so the case depth is spot-on every time. Oil temperature in an EV box can hit 120 °C easily; this steel just shrugs and keeps running. Manufacturing Excellence: Guaranteeing ISO Grade 4 Accuracy Grade 4 isn’t marketing talk—it’s measured. Profile tolerance under 4 µm, lead under 6 µm, pitch deviation under 5 µm. That’s what it takes to stay quiet above 10,000 rpm input. We grind after heat treat on machines with temperature-controlled coolant because a two-degree swing in the shop can throw the helix off. Every single gear gets a full inspection report; if it’s not Grade 4 or better, it goes back to scrap. DD Gear’s Customized Solutions for EV Drivetrain We don’t keep warehouses full of standard gears. Every set is made for one customer’s housing, one motor curve, and one NVH target. High-Precision Gears for Torque Transfer and Safety The Main Reduction Gear – High Precision Gear for EV This is the big pair that turns a 15,000 rpm motor speed into something the wheels can actually use. The module usually sits between 1.5 and 3.5. We tune the macro geometry for the exact torque curve and then dial in the micro mods so the mesh stays quiet from 800 rpm wheel speed all the way to top whack. The Input Shaft – High Precision Gear for EV First gear on the motor spline. Has to survive constant 300-400 Nm and still hold Grade 4 accuracy after a million kilometers. We harden the splines, grind the teeth, and balance the whole shaft so the motor bearings live longer. The Parking End Gear – High Precision Gear for EV The parking pawl gear looks simple, but it has to take a 5-6 g shock when the driver slams it into Park at 5 km/h with a kid in the back seat. We put extra root radius and shot-peen the hell out of it so the teeth don’t chip. Precision Shafts for Motor Alignment and Drivetrain Stability The Drive Motor Shaft – High Precision Rotor Shaft for EV This shaft carries the rotor stack inside the motor. At 18,000 rpm, any runout turns into vibration that kills bearings fast. We grind the bearing seats to under 3 µm and dynamically balance to G1.0 or better. The Intermediate Drive Shaft Assembly – Precision for EV Keeps both half-shafts the same length, so the car doesn’t pull when you punch it. We machine the splines and bearing journals in one setup so everything stays concentric. Driving Forward with Customized Manufacturing Excellence The Advantage of Customized Gear Solutions We’re set up for fast reaction. Tell us the envelope, give us the torque curve and the sound target, and we’ll have prototypes in three weeks. Minimum order can be as low as 50 sets if you’re a startup testing a new e-axle. Big OEM run thousands, small teams run hundreds—doesn’t matter, the gears come out the same Grade 4. Conclusion: Powering the Future of Mobility Better gears mean longer range, quieter cabins, and gearboxes that simply last. That’s not a nice-to-have anymore—it’s table stakes for any EV that wants to sell. DD Gear lives in the small-module world where every micron counts. We grind, measure, test, and ship gears that make the difference between “good enough” and “class-leading.” Drop us a mail or give the engineers a call. We’ll figure out exactly what your drivetrain needs and get prototype gears spinning in your test rig in a couple of weeks.We also supply high-performance truck gears built for heavy-duty loads. Visit our website PairGears if you’re interested. FAQ Q: What industries do DD Gear’s precision gears primarily serve? A: Mostly electric passenger cars, commercial vehicles, robots, AGVs, and some medical equipment—anywhere small, fast, quiet gears matter. Q: How does DD Gear ensure the precision and quality of its gears? A: Modern CNC grinders, temperature-controlled shops, 100 % inspection on Klingelnberg P machines, and real NVH testing on every batch. Q: Do you support small-volume custom orders for new EV projects? A: Yes, all the time. Prototypes in 2-3 weeks, small runs of 50-200 sets, no problem. Q: Why are helical gears preferred in EV transmissions over spur gears? A: Helical teeth slide together instead of banging. That cuts noise dramatically and spreads the load, which is exactly what you need when the motor spins five times faster than an old gasoline engine.
Precision Gear Selection Guide for EV, Robotics & Automation
Why Precision Gears Matter in Modern Machines Today’s factories, warehouses, and roads look nothing like they did ten years ago. Robots walk beside people, electric cars zip past gas stations, and automated carts never stop moving. In every one of these machines, a small set of metal teeth decides whether the whole system runs smoothly or breaks down fast. Those teeth belong to high-precision gears.Pick the wrong ones, and you pay for it in noise, lost power, and expensive repairs. Pick the right ones, and everything just works—day after day. The Demands of Next-Generation Industries New machines ask gears to do things old ones never had to do. Electric motors spin at 15,000 rpm or higher. Robot arms must stop within a few microns every single time. An AGV in a warehouse might start and stop thousands of times in one shift. All of this has to happen inside a box that keeps getting smaller. That is why small-module, high-precision gears have become the only realistic choice for anyone building serious equipment. The True Cost of Gear Failure: Backlash, Noise, and Downtime A little extra play in a robot joint means the hand wobbles when it tries to insert a screw. A noisy gearbox in an electric scooter makes customers complain on the first ride. Worn teeth on an AGV drive can shut down an entire picking line for hours. We build custom precision gears so customers don’t have to learn those lessons the hard way. Key Factors in Selecting Precision Gears Good gear choice starts long before anyone opens a catalog. You need to know exactly what the machine will do, hour by hour. Load & Torque Some machines crawl slowly but carry tons. Others spin fast with lighter loads. A warehouse AGV, for example, often needs 300–600 Nm at the wheel while moving only 1–2 m/s, and it starts and stops every few seconds. That kind of duty cycle beats ordinary gears to death in months. DD Gear uses case-hardened steel and controlled carburizing so the surface stays hard while the core absorbs shocks. Customers running 24/7 shifts regularly get three to five years from a set instead of one. High-Speed & NVH Control Electric motors hate noise. At 12,000 rpm, even tiny tooth errors sound like a dentist’s drill. Helical gears solve most of the problem because the teeth slide into mesh instead of slamming together like spur gears. DD Gear’s CNC gear grinding service provides small-module helical gears to ISO 1328 grade 4–5, so they stay quiet even after a million kilometers. Space & Small Module Design Space is always the enemy. A humanoid robot elbow has maybe 80 mm to fit everything. The only way to get a 100:1 ratio in that space is a planetary stage or two. DD Gear machines and grinds tiny planet gears so accurately that the gearbox can still handle 50–100 Nm continuous torque. Precision Gears for EV Applications Critical EV Components: EV Reducer and Input Shafts The main reduction gear in a typical e-axle sees both high speed and high torque. Forged blanks, carburizing, and precision grinding ensure total composite error stays under 10 µm. EV Reducer: Choosing Gears for High-Speed, Low-Noise Operation Must withstand 8,000–18,000 rpm input. NVH is critical; tiny tooth errors create loud whine. Helical gears preferred for reduced noise and smoother engagement. Material must handle high temperature and long cycles. Focus on precision grinding, helix modification, and dynamic balancing. Precision Gears for Robotics Zero-Backlash Requirements in Robot Joints DD Gear supplies planetary reducer gears for high-ratio cycloidal and harmonic drives. Some teeth are only 0.2 mm thick, yet profile errors stay within 3–4 µm. Robot Joint: Choosing Gears for Zero Backlash and High Repeatability Even 1 arc-minute of backlash ruins accuracy. Requires extremely small modules (0.2–0.8). Planetary, harmonic, and cycloidal systems dominate. Gears must resist torsional windup and meet micron-level tolerances. Focus on sub-micron profile accuracy, matched gear sets, and rigidity. Robotics startups often see joint backlash and wobble ruin assembly accuracy in their first prototypes. After integrating DD Gear precision gears, their arms achieve consistent, repeatable performance from day one. Precision Gears for AGVs Durability in Automated Guided Vehicles (AGVs) Heavy AGVs often carry 1–2 tons all day. Their wheel drives combine helical and planetary stages. DD Gear manufactures both sets from the same heat of steel to ensure perfect expansion matching. AGV Drive: Choosing Gears for Shock Load and 24/7 Duty Cycles Frequent start-stop cycles cause rapid fatigue. Must endure 300–600 Nm torque continuously. Needs both impact resistance and long-life wear properties. Helical + planetary combinations are most common. Focus on case hardening consistency and surface durability. DD Gear: Your Partner for High-Precision Gear Success DD Gear Application Requirements Overview DD Gear is a custom precision gear manufacturer in China, supplying EV transmission gears, robotic gearbox gears, and AGV drive gears worldwide. Application Key Requirement Common Failure DD Gear Solution EV Reducer High speed & low noise Whining noise, vibration Ground helical gears, ISO Grade 4 Robot Joint Zero backlash Position error, shaking Planetary & harmonic gears AGV Drive High torque & shock Early pitting & breakage Carburized helical + planetary gears DD Gear Manufacturing & Quality Control Pretty drawings mean nothing if the shop floor cannot make the part the same way every time. DD Gear has spent fifteen years turning that idea into daily practice. Forged rings go straight to carburizing furnaces controlled within 0.05 mm carbon depth. Surface hardness 60+ HRC, core at 35–45 HRC. Reishauer and Klingelnberg grinders finish teeth to Ra 0.4 or better. Super-finishing is available for ultra-low NVH. Every gear is measured on Klingelnberg P40 machines. Noise testing in a semi-anechoic chamber ensures consistent performance. Why Choose DD Gear as Your Gear Supplier Whether you are designing a new EV drive train, robot joint, or AGV drive system, DD Gear supports you from prototype to mass production.Our engineers suggest tooth modifications, materials, and cost-saving tweaks based on thousands of gearbox projects. Fast quotation within 48 hours Prototype delivery in 2–3 weeks Small batch & mass production supported Contact DD Gear now to get your custom precision gear solution.If you also need gears for agriculture, construction machinery, or heavy trucks, our sister brand PairGears can help. Feel free to contact us for these applications as well. FAQ Q: What level of gear accuracy does DD Gear typically guarantee? A: We guarantee Grade 4 or better under ISO 1328, DIN, and AGMA standards, backed by modern CNC grinding machines. Q: What main industries are DD Gear’s precision gears applied to? A: Humanoid robots, electric vehicles (EVs), Automated Guided Vehicles (AGVs), general factory automation, and medical equipment. Q: Does DD Gear support prototyping and small-volume custom orders? A: Absolutely. Flexible minimum order and fast prototypes—most sets ship in 2–3 weeks. Q: How does DD Gear ensure the quality and durability of gears for challenging applications like EVs? A: Certified IATF 16949 processes, carefully chosen case-hardening steels, tightly controlled heat treatment, and final checks that include noise, vibration, and endurance runs.
Quality Control in Precision Gear Manufacturing
Introduction Quality control is the backbone of precision gear manufacturing. For gears used in demanding applications such as robotics and EVs, consistent reliability is ensured only through a rigorous quality management system spanning design, production, and delivery. 1.Design Stage Control From profile optimization to material selection, all design elements are evaluated to ensure manufacturability, durability, and performance. 2.Process Control Real-time monitoring, statistical process control (SPC), and automated inspections are applied throughout machining to minimize deviations and maintain tolerances. 3.Final Inspection Profile and lead measurement Noise and vibration testing Endurance and wear verification These checks ensure that every gear meets both functional and quality standards. 4.Certifications & Standards Precision gears comply with global standards such as ISO 1328, DIN, and AGMA. Certified systems like ISO 9001 and IATF 16949 ensure consistent quality for international customers. Conclusion Strict quality control guarantees not only the accuracy and durability of precision gears but also builds long-term customer trust. By adhering to the highest global standards, precision gear manufacturers support the reliability of next-generation robotics, EVs, and intelligent automation.
Driving Precision Forward with
Custom gear solutions
Please fill out the form below and we will get back to you as soon as possible.
