Case

Case Highlights
A European OEM of CNC sheet-metal cutting machines was facing premature gear wear and growing backlash on the X/Y gantry axes of its plasma and fiber-laser lines. This led to cut-edge steps, more scrap, and rising maintenance costs.
DD Gear designed a small-module helical gear set that fits into the existing servo gearbox envelope, improving smoothness and durability. After retrofit and one year of production use, the customer’s maintenance data showed around 30% longer gear life and about 50% fewer unplanned gearbox-related stoppages, while maintaining the required positioning accuracy of the cutting line. High-precision helical gears are widely used in industrial machinery because their angled teeth engage gradually, which reduces impact, vibration, and noise compared with spur gears.

Customer Background & Project Scope

• Customer industry: European manufacturer of CNC plasma and fiber-laser cutting machines for steel fabrication shops.
• Application: Servo drives for the X/Y gantry feed and Z-axis lifting of the cutting head on a high-duty production line.
• Machine requirements
  • Positioning accuracy and repeatability in the order of ±0.02 mm across long travel, in line with common CNC machine-tool expectations.
  • 16–20 hours of daily operation, with frequent rapid reversals.
  • Stable motion and low vibration to protect cutting quality.

The OEM had used a compact spur-gear reducer for many years, but as cutting speeds and duty cycles increased, the geartrain became a weak point.

Challenges

1. Fast gear wear and pitting

   • The existing small-module spur gears developed surface pitting and wear after roughly 12–15 months in high-duty shops.

   • Backlash growth translated directly into contour errors and visible “steps” on laser-cut edges.

2. Noise and vibration near the gantry

   • At higher traverse speeds, operators noticed pronounced gear whine.

   • Spur gears engage suddenly tooth-to-tooth, which tends to generate more vibration and noise at speed.

3. Limited space for redesign

   • The OEM wanted better performance without redesigning the whole gearbox housing or servo layout.

   • Any solution had to drop into the existing mounting envelope and keep the same ratios.

DD Gear Solution

1. Design Optimization

• Switch from spur to helical gears
  DD Gear’s engineering team replaced the spur gear pair with small-module helical gears, increasing the contact ratio so that multiple teeth share the load. This design is known to enable quieter, smoother operation and higher load capacity in industrial drives.

• Micro-geometry & backlash control

  • Applied profile and lead modifications to keep transmission error low over the full face width.

  • Set backlash to a tight but safe window so that the servo system maintains stiffness without risk of jamming under thermal expansion.

• Drop-in compatibility

  • Maintained shaft centers and hub interfaces to fit the customer’s existing cast housing.

  • Gear ratio tolerance kept within the servo tuning range, avoiding changes to control software.

2. Materials & Heat Treatment

• Carburizing steel for long life

  • Selected 20CrMnTi carburizing steel, a standard high-performance alloy widely used for automotive and industrial gears thanks to its hard wear-resistant case and tough core.

  • Case depth set to 0.8–1.0 mm depending on tooth size.

• Heat treatment & finishing

  • Carburizing + quenching followed by precision gear grinding on the tooth flanks.

  • Target surface hardness HRC 58–62 for high contact-fatigue strength; core hardness matched to resist bending loads.

3. Manufacturing & Quality Control

• Small-module precision machining

  • Modules in the m 1.5–2.5 range require careful control of tool wear, rigidity, and burrs; these aspects are critical to avoid premature failure in small-module gears.

• Accuracy grade

  • Tooth profile, lead, and runout controlled to ISO 1328 Grade 5–6, consistent with high-precision cylindrical gears for industrial applications. 

• Verification

  • 100% inspection of key dimensions and sampling of tooth-form data on a CNC gear measuring center.

  • Trial gearboxes run under load on DD Gear’s test stand to confirm noise and temperature behavior before shipment.

Results

Within the first full year of operation across several customer sites, the OEM reported:

• Approx. 30% longer service life before reaching wear limits, based on comparison with older spur-gear sets in similar duty.

• About 50% fewer unplanned stoppages due to gearbox issues, helping fabricators keep cutting lines running to schedule.

• Notable reduction in gear whine, especially at high traverse speeds; operators described motion as smoother and “less harsh”. This aligns with widely documented advantages of helical gears for noise reduction in industrial machinery.

• The OEM has since adopted the DD Gear helical set as the standard configuration on all upgraded plasma and fiber-laser cutting machines of this platform.

Typical Technical Specifications

Exact values are tuned per machine model; the table shows a representative configuration.

Case Summary

By combining helical gear design, carburizing alloy steel, and ISO Grade 5–6 precision grinding, DD Gear helped this CNC cutting-machine OEM:

• Extend gear life and reduce unplanned downtime.

• Maintain tight positioning accuracy as machines age.

• Improve operator comfort and perceived machine quality through quieter motion.

This solution is directly relevant for other CNC cutting, laser processing, plasma cutting and high-precision machine tool applications where small-module gears see high-speed reversing loads.

Planning an upgrade for your CNC cutting machine gearbox?
Contact our engineers to discuss a custom small-module helical gear set for your motion axes.