ROBOT 01

6-AXIS INDUSTRIAL
ROBOT

Spur gear specification: M1.5–M3, 20CrMnTi carburized, DIN 5–6 ground, profile tip relief 3–5 μm, backlash ≤ 2 arc-min at J4–J6 wrist joints, ≤ 4 arc-min at J1–J3 shoulder/elbow. 6-axis industrial robots (FANUC M series, KUKA KR series, ABB IRB series, Yaskawa Motoman) use spur gears extensively in the J4, J5, and J6 wrist joint drives — the three smallest and fastest joints that control the wrist roll, pitch, and yaw for tool orientation. These wrist gears are driven by high-speed servo motors (3,000–6,000 RPM at the motor shaft) through a reduction ratio of 50:1–150:1 achieved across multiple stages including a spur gear pre-stage and a harmonic drive final stage. The spur gear pre-stage in the robot wrist runs at the highest pitch line velocity in the joint (often 5–12 m/s at M1.5–M2 module), making it the most noise-sensitive gear in the system and requiring DIN 5–6 ground profile with tip relief to meet the robot manufacturer’s specification for transmitted vibration to the tool flange. Korea Ever-Power wrist spur gears are superfinished after profile grinding to Ra ≤ 0.4 μm to minimise the break-in wear that can occur at high-speed robot wrist operation during the initial 100-hour running period.

ROBOT 02

COLLABORATIVE
ROBOT (COBOT)

Spur gear specification: M1–M2, 20CrMnTi carburized or 17-4 PH stainless (for food-adjacent applications), DIN 5 ground, backlash ≤ 1 arc-min, torque sensing-compatible (low hysteresis), low friction coefficient ≤ 0.08 at the gear mesh for transparency to the joint torque sensor. Collaborative robots (Universal Robots UR series, FANUC CRX, KUKA LBR iiwa, Doosan, Techman) share the workspace with human operators and require the joint drive to be transparent to external forces — the robot must be able to detect the force a human applies to its arm and stop or comply with it before a harmful impact occurs. This safety requirement places unique demands on the spur gear: the gear backlash must be minimised (to prevent the robot controller from misinterpreting backlash dead-band reversal as external force), and the gear friction must be low and consistent (so the joint torque sensor signal is not dominated by gear friction hysteresis). Korea Ever-Power cobot spur gears are individually measured for torque hysteresis (the difference in output torque when the same input torque is applied in CW vs CCW direction), with a maximum specification of 3% of rated torque at the gear mesh — a key parameter not measured for standard industrial gears but essential for collaborative robot safety compliance.

ROBOT 03

SCARA ROBOT
ARM

Spur gear specification: M0.8–M2, 20CrMnTi carburized, DIN 5–6, flat (minimal face width for compactness in the planar SCARA arm structure), high tooth count for smoother transmission. SCARA (Selective Compliance Assembly Robot Arm) robots execute high-speed horizontal pick-and-place operations in electronics assembly, pharmaceutical blister packing, and small parts assembly — cycles of 100–200 picks per minute are standard. The J1 and J2 horizontal arm joints of a SCARA robot use spur gears in parallel-shaft configurations, often driven by belt or gear train from the motor mounted at the base rather than at the joint (to keep the distal arm mass low). Korea Ever-Power SCARA robot spur gears use a high tooth count (≥20T) to increase the contact ratio above 1.7, which smooths the transmission error at the high cycle rates of SCARA pick-and-place operations. The J3 (Z-axis linear, non-rotary) and J4 (wrist rotation) joints use spur gears at M1–M1.5 module for the compact arm profile needed to access tight clearances in electronics assembly fixtures.

ROBOT 04

MEDICAL &
SURGICAL ROBOT

Spur gear specification: M0.5–M1.5, 17-4 PH stainless (H900) or 316L stainless, DIN 4–5 ground, sterilisation compatible (autoclave at 134°C, 3 bar, gamma irradiation for single-use), zero contamination debris, FDA 21 CFR compatible materials. Surgical robotic systems (for laparoscopic, orthopaedic, and ophthalmic surgery assistance) use the smallest and most precisely controlled spur gears of any application — M0.5–M1 module gears with tooth thickness variation below 2 μm between any two teeth in the gear. The medical robot joint gear must not generate debris that could contaminate the surgical field — 17-4 PH stainless in H900 condition provides a tooth surface hardness of HRC 38–43, softer than case carburized steel but generating metallic debris particles that are biocompatible and detectable under fluoroscopy if shed. Korea Ever-Power medical robot spur gears are batch-traceable to individual melt and forging records for post-market surveillance purposes, and are supplied with a material certificate conforming to ISO 13485 medical device manufacturing quality requirements. Autoclave sterilisation compatibility: 17-4 PH does not corrode or dimensionally distort in standard autoclave cycles at 134°C, 3 bar steam for 18 minutes — confirmed by Korea Ever-Power dimensional stability test on sample gears before product release.

Our SCARA robot’s J2 joint is showing increasing position error after 18 months of operation — the ISO 9283 repeatability has degraded from ±0.02 mm to ±0.08 mm. The joint spur gears are worn. What specification should we use for the replacement gears to improve on the original?

The repeatability degradation from ±0.02 mm to ±0.08 mm over 18 months in a SCARA J2 joint indicates that the combined gear wear and backlash increase have exceeded the controller’s ability to compensate — the dead-band in the position control loop is now ±0.08 mm rather than the designed ±0.02 mm. To achieve the original specification with replacement gears and also improve on the original: (1) Upgrade the material from C45 (if original) to 20CrMnTi carburized: if the original gears were hobbed C45 (often used in cost-optimised SCARA robots), the carburized replacement will have 3–4× higher contact fatigue resistance and will sustain the original backlash for significantly longer than 18 months. (2) Upgrade the quality class from DIN 7 to DIN 6: the tighter profile tolerance of DIN 6 reduces the transmission error contribution to the position error budget, allowing the robot controller to achieve better repeatability even with the same total backlash. (3) Apply crowned tooth profile on the replacement gears: the micro-crowning allows a tighter centre distance setting that reduces the initial backlash from the original design value, giving more wear margin before repeatability degrades to the ±0.08 mm limit again. (4) Record the J2 assembly backlash after replacement: use a dial indicator tangentially against the output gear teeth with the input locked, and record the dead-band in the indicator reading — this establishes the baseline for future maintenance monitoring. Korea Ever-Power can provide matched replacement pairs with individual backlash documentation for the most common SCARA robot J2 gear sizes — submit the SCARA robot model and the worn gear’s tooth count, OD, and bore for cross-reference and quotation.

What is the minimum order quantity and lead time for custom robotic spur gears at M1 and M1.5 module with DIN 5 quality class?

Korea Ever-Power robotic spur gear supply parameters for M1–M1.5, DIN 5: Standard catalogue sizes (M1, M1.5 with tooth counts 12T, 16T, 20T, 24T, 28T, 32T, 36T, 40T in 20CrMnTi carburized): available from stock or in 5–10 working days; minimum order 5 pieces per size. Matched pairs (backlash-documented): minimum 2 pairs (4 gears). Custom specifications (non-standard tooth count, non-standard bore, 17-4 PH stainless, crowned tooth profile, superfinish): lead time 15–22 working days from drawing confirmation; minimum order 5 pairs per specification. The minimum order for custom robotic gears at M1–M1.5 is higher than for larger modules because the setup cost for the profile grinding machine (tool dressing, fixture preparation, test cut and measurement) represents a significant proportion of the unit cost at this small size — the minimum quantity amortises the setup cost to a commercially viable per-piece cost. For prototype quantities (1–2 pairs): prototype supply at M1–M1.5 DIN 5 is possible at a setup premium of 150–200% above the production per-piece price; lead time 20–28 days. This is appropriate for robot designers evaluating a gear specification before committing to a production run. Transmission error (TE) measurement: included as standard for all robotic gear orders of DIN 5 and above — TE test report issued per gear pair with the individual measurement values at four equally-spaced angular positions.

Can PEEK spur gears carry sufficient torque for collaborative robot joints, or are they only suitable for very light-duty applications?

PEEK (Polyether ether ketone) spur gears can carry useful torque in collaborative robot joints when properly specified — the material’s tensile strength of 100 MPa and flexural modulus of 3.8 GPa allow PEEK spur gears at M1.5, 20T to transmit approximately 8–12 Nm of continuous torque and 20–25 Nm of peak torque at moderate speed (below 500 RPM at the PEEK gear). This is sufficient for the J5 and J6 wrist joints of small collaborative robots (e.g. Universal Robots UR3, FANUC CRX-5iA) where the rated wrist torque is 10–28 Nm. For J1–J3 shoulder and elbow joints with rated torques of 50–100 Nm, PEEK is undersized at M1.5 and would require M3–M4 module to carry the load — at which point the gear is large enough to negate the mass advantage of using PEEK over steel. Practical PEEK robot spur gear applications: (1) Food and pharmaceutical cobot wrists (UR3/UR5 food-grade variants) where the FDA 21 CFR 177.2415 compliant PEEK material prevents metallic contamination in case of gear chip generation. (2) Cleanroom assembly robots where the grease-free operation of PEEK (running dry without lubricant for the first 1 million cycles) and zero oil mist generation are required for ISO Class 4 cleanroom compatibility. (3) MRI-compatible surgical robots where ferromagnetic metal gears are excluded. For all PEEK robot gear applications, Korea Ever-Power recommends a duty cycle calculation confirming the operating temperature remains below 220°C (PEEK’s continuous service limit) and the contact stress remains below 40 MPa (the PEEK fatigue endurance contact stress at 10⁷ cycles).

Spur Gears

M0.5–M3 · DIN 4–6 · robot joint

Helical Gears

Low noise · high speed · robot axis

Engrenages coniques

Right-angle · wrist · robot tool change

Worm Gears

Self-locking · robot base · slow axis

Ring Gears

Planetary · harmonic · robot joint

Planetary Gears

Compact · servo · robot joint reducer

Plastic Gears

PEEK · cleanroom · cobot food-grade