As an electric vehicle manufacturer (EVM), the pursuit of competitive excellence in a rapidly evolving market demands innovative solutions to unique manufacturing challenges. This paper explores how power skiving technology, particularly through the expertise of Sandvik Coromant, addresses critical needs in producing lightweight, compact, and low-noise transmissions—cornerstones of modern EV performance. By integrating advanced machining techniques and cutting-edge tooling, EVMs can overcome traditional limitations, enhance operational efficiency, and secure a decisive edge in a fiercely competitive landscape.
1. The Evolving Landscape for Electric Vehicle Manufacturers
The exponential growth of the EV market has reshaped automotive manufacturing priorities. EVMs face dual imperatives: reducing vehicle weight to extend range and improving drivetrain precision to meet strict noise, vibration, and harshness (NVH) standards. Unlike internal combustion engine (ICE) vehicles, EVs lack engine noise to mask transmission imperfections, making gear precision non-negotiable .
Key Challenges for EVMs:
| Challenge | Impact on EV Performance | Traditional Solutions’ Limitations |
|---|---|---|
| Weight Reduction | Critical for energy efficiency and range | Reliance on heavy materials; limited design flexibility |
| Compact Drivetrain Design | Space constraints in EV platforms | Inflexible machining processes for complex geometries |
| Low Noise Requirement | Directly affects passenger comfort | Inadequate precision in traditional gear cutting |
| Cost Efficiency | Pressures to scale production without compromising margins | High equipment costs; lengthy setup times |
For EVMs, the transmission—specifically the planetary gear reducer—represents a focal point of these challenges. The internal ring gear, a thin-walled component with stringent roundness requirements, is notoriously difficult to machine using conventional methods like hobbing or broaching. These techniques often require multiple machines, frequent retooling, and extensive coolant use, leading to higher costs and lower flexibility .
2. Limitations of Traditional Machining Processes
Traditional gear manufacturing for EV transmissions relies on sequential processes across dedicated machines, creating a rigid “process route” that hinders adaptability. For example:
- Multi-Machine Setups: Each operation (e.g., roughing, finishing) requires a separate machine, increasing setup time and the risk of dimensional errors from multiple workpiece clampings .
- High Costs: Specialized equipment for each step (e.g., hobbing, shaping, grinding) incurs significant capital expenditure. Post-heat treatment grinding adds further costs, as does the use of cooling lubricants .
- Inflexibility: Design changes necessitate reconfiguring entire production lines, delaying time-to-market for new models .
Mathematically, the total production cost (\(C_{traditional}\)) for traditional methods can be expressed as:\(C_{traditional} = (C_{machine1} + C_{machine2} + \dots + C_{machineN}) + C_{labor} + C_{coolant} + C_{rework}\) where \(C_{machineN}\) represents costs for each dedicated machine, and \(C_{rework}\) accounts for errors from multiple setups.
3. Power Skiving: A Paradigm Shift in Gear Manufacturing
Power skiving, a hybrid of hobbing and shaping, offers a breakthrough for EVMs. This single-setup process combines continuous cutting motion with multi-tooth engagement, enabling high-precision machining of both internal and external gears in significantly less time .
Core Advantages of Power Skiving:
- Single-Setup Efficiency: By integrating roughing and finishing into one operation on a multi-functional machine, power skiving eliminates the need for sequential machine transfers. This reduces setup time by up to 70% and minimizes dimensional variations from re-clamping .
- Material and Design Freedom: The process accommodates thin-walled components (e.g., ring gears with wall thicknesses <3mm) with tight tolerances (e.g., roundness <5μm), enabling lighter, more compact drivetrain designs .
- Noise Reduction: Precise tooth profiling reduces NVH levels by up to 10 dB compared to traditional methods, aligning with EVs’ silent operation requirements .
- Cost Savings: Sandvik Coromant’s solutions have helped EVMs reduce production costs by at least 30% through minimized machine downtime, reduced tool wear, and eliminated coolant use in dry machining setups .
The cost efficiency of power skiving (\(C_{power skiving}\)) can be modeled as:\(C_{power skiving} = C_{multimachine} + C_{tooling}\) where \(C_{multimachine}\) is the cost of a single multi-functional machine, and \(C_{tooling}\) (e.g., CoroMill 178/180 tools) is optimized for longevity and performance .
4. Sandvik Coromant’s Cutting-Edge Tooling Solutions
Sandvik Coromant’s portfolio of power skiving tools is tailored to the unique demands of EV drivetrain manufacturing:
CoroMill 178
- Materials: Available in PM-HSS (powder metallurgy high-speed steel) for general applications and full carbide for high-volume, high-precision tasks.
- Design: Prismatic blade holders ensure repeatable accuracy, with coolant channels optimized for heat dissipation and chip evacuation .
- Applications: Ideal for internal/external gears, splines, and worm gears in EV transmissions.
CoroMill 180
- Modular Design: Indexable inserts allow quick replacement, reducing downtime and tooling costs.
- Stiffness and 悬伸性能 (Overhang Performance): Engineered to minimize deflection during deep cutting, ensuring precision in large-diameter gears .
Tool Performance Comparison:
| Tool Type | Material | Max Cutting Speed (m/min) | Tool Life (Parts/Reconditioning) | Precision (ISO Class) |
|---|---|---|---|---|
| Traditional HSS | High-Speed Steel | 50-80 | 500-800 | 8-9 |
| CoroMill 178 (PM-HSS) | Powder Metallurgy HSS | 100-150 | 1,500-2,000 | 6-7 |
| CoroMill 178 (Carbide) | Tungsten Carbide | 150-200 | 3,000-5,000 | 5-6 |
5. Case Study: Transforming Gear Production for an EVM
A leading EVM specializing in low-alloy steel transmissions sought to replace its time-intensive broaching process for internal ring gears. Key objectives included:
- Reducing cycle time from 45 minutes to <5 minutes per part.
- Eliminating four dedicated machines to save floor space and energy.
- Achieving ISO 6-level gear precision for noise reduction.
Solution:
- Implemented two Sandvik Coromant multi-functional machines with CoroMill 180 carbide tools, replacing four traditional broaching and hobbing machines.
- Adopted dry power skiving to eliminate coolant costs and improve sustainability.
Results:
| Metric | Traditional Process | Power Skiving Process | Improvement (%) |
|---|---|---|---|
| Cycle Time per Part | 45 minutes | 4.5 minutes | 90% |
| Machine Count | 4 | 2 | 50% |
| Tool Life | 800 parts/regrind | 5,000 parts/replace | 525% |
| Noise Level (dB(A)) | 72 dB | 62 dB | 13.9% |
Mathematically, the cycle time reduction is calculated as:\(\text{Reduction (\%)} = \left( \frac{T_{traditional} – T_{skiving}}{T_{traditional}} \right) \times 100 = \left( \frac{45 – 4.5}{45} \right) \times 100 = 90\%\)
6. Strategic Implications for Electric Vehicle Manufacturers
For EVMs, adopting power skiving technology translates to tangible competitive advantages:
- Design Agility: Rapid prototyping of new gear designs without retooling entire lines, accelerating EV model iterations.
- Scalability: Single-machine versatility supports high-mix, low-volume production or mass production, adapting to market fluctuations.
- Sustainability: Reduced energy use (fewer machines), minimal coolant waste, and longer tool life align with ESG goals.
- Cost Leadership: As illustrated in the case study, total cost of ownership (TCO) can be reduced by up to 60% over five years compared to traditional setups.
The return on investment (ROI) for power skiving equipment can be approximated by:\(ROI = \frac{(C_{traditional\_annual} – C_{skiving\_annual}) \times \text{Production Volume}}{\text{Initial Investment}}\) Where annual cost savings from reduced labor, energy, and rework drive profitability.
7. Future Trends and Innovations
As EVs evolve toward higher power densities and autonomous driving, power skiving will continue to advance:
- AI-Driven Process Optimization: Machine learning algorithms to predict tool wear and optimize cutting parameters in real time.
- Additive Manufacturing Integration: Hybrid systems combining 3D-printed gear blanks with power skiving for near-net-shape production.
- Ultra-Hard Materials: Development of diamond-like carbon (DLC)-coated tools for machining advanced alloys like magnesium and titanium.
Conclusion
For electric vehicle manufacturers, power skiving technology represents more than a manufacturing upgrade—it is a strategic enabler of competitive differentiation. By addressing the core challenges of weight, precision, and cost, Sandvik Coromant’s solutions empower EVMs to deliver superior drivetrain performance while optimizing operational efficiency. As the EV market continues to grow, those who embrace innovative machining technologies will lead the charge in defining the future of automotive manufacturing.