Multi-Spindle Gun Drilling Reduces Cycle Time for Automotive Crankshaft Oil Holes

Customer Background

Our customer is a Tier 1 automotive powertrain manufacturer supplying crankshafts to major OEMs in Europe and North America. With increasing production targets for next-generation engine platforms, they needed to significantly increase throughput of crankshaft oil hole drilling while maintaining strict quality standards.

The Challenge

Crankshaft oil passages present some of the most demanding deep hole drilling challenges in automotive manufacturing:

Angled, intersecting geometry. Oil holes must be drilled at acute angles (typically 15–30°) into the crank pin journal surface, intersecting with pre-existing cast oil galleries. Any positional error can compromise engine lubrication and lead to catastrophic failure.

Deep hole aspect ratio. Oil passages typically have depth-to-diameter ratios exceeding 20:1, requiring specialized gun drilling techniques for chip evacuation and tool stability.

Hardened material. Crankshafts are forged from 4140 or manganese steel hardened to 45–52 HRC. The combination of high hardness and low thermal conductivity causes rapid tool wear — conventional gun drill life averaged only 60 parts between resharpening.

Burr control. When gun drills break through into the pre-cast oil gallery, burrs can dislodge and block the oil duct. Deburring is extremely difficult in these inaccessible internal locations.

Production volume. The customer required 600+ crankshafts per day, each with 4–6 oil holes — over 3,000 deep holes daily.

The Solution

After a thorough process analysis, RuidCNC engineered a RD500-C2 Two Spindles Crank Shaft Gun Drilling Machine with the following configuration:

• Dual independent spindles — two crankshaft oil holes drilled simultaneously, cutting per-hole cycle time in half
• Custom angled fixturing — precision indexing head positions each crank pin at the correct drilling angle automatically
• High-pressure through-spindle coolant — 120 bar coolant system ensures effective chip evacuation from deep, angled holes
• MQL (Minimum Quantity Lubrication) capability — enables feed rates exceeding 660 mm/min while consuming only 10–20 ml/hr of oil
• In-process gauging — automatic bore measurement with real-tool wear compensation

Key Machine Specifications

Parameter	Specification
Spindle configuration	Dual independent (2+2 optional)
Drilling diameter	Ø4 – Ø12 mm
Max drilling depth	500 mm
Spindle speed	0 – 8,000 rpm
Coolant pressure	Up to 120 bar
Positioning accuracy	±0.01 mm
Angle positioning	±0.1°

Results

After installation and production ramp-up, the RD500-C2 delivered the following results:

Metric	Before	After	Improvement
Cycle time per hole	45 seconds	27 seconds	40% reduction
Holes per day (single shift)	640	1,066	66% increase
Tool life (parts between regrinds)	60	85	42% improvement
Positional accuracy	±0.02 mm	±0.01 mm	50% better
Scrap rate	2.1%	0.4%	81% reduction
Machine uptime	—	94%	Reliable

Customer Feedback

“The RD500-C2 exceeded our expectations. The dual-spindle configuration alone transformed our production economics, and the overall precision improvement has virtually eliminated scrap from oil hole positional errors. RuidCNC’s team supported us through every stage of the installation and ramp-up.”

Conclusion

The RD500-C2 demonstrates how application-specific machine engineering can solve the unique challenges of crankshaft oil hole drilling. By combining dual-spindle efficiency with advanced coolant systems and precision fixturing, RuidCNC delivered a solution that dramatically improved both quality and productivity.