In the precision transformation of a crankshaft from roughing to finishing, one process plays a critical role in connecting the two-CNC semi-finish grinding. It is neither as aggressive as rough milling nor as meticulous as finish grinding, but rather builds a bridge of accuracy between them, creating ideal conditions for the final grinding process. Recently, the technical team of Zhejiang Weilin Mechanical Co., Ltd. conducted an in-depth on-site shooting of the CNC semi-finish grinding process for a CAT320 crankshaft (example part number: 125 3005) in the workshop, capturing this key bridging process through the lens and continuing our Crankshaft Manufacturing Process Series.
CNC Semi-Finish Grinding: The Bridge Builder of Accuracy
Before semi-finish grinding, the crankshaft has undergone rough milling and heat treatment, but the journal surfaces still bear deep tool marks, and dimensional accuracy is far from final requirements. Proceeding directly to finish grinding would not only be inefficient but also accelerate grinding wheel wear and potentially cause grinding burns. The mission of CNC semi-finish grinding is to accomplish the following before finish grinding:
· Rapid Stock Removal: Semi-finish grinding efficiently removes the stock left after roughing, bringing journal dimensions closer to final targets, typically leaving 0.05-0.10mm for finish grinding.
· Geometric Error Correction: Semi-finish grinding corrects roundness, cylindricity errors, and heat treatment deformation from roughing, providing a "semi-finished" product with good geometry for finish grinding.
· Surface Quality Improvement: Semi-finish grinding reduces journal surface roughness to Ra0.8-1.6μm, eliminating deep tool marks and scale, creating ideal surface conditions for finish grinding.
On-Site Shooting: The Transfer of Accuracy Under the Lens
Recently, at Zhejiang Weilin Mechanical's production workshop, the technical team conducted a comprehensive shooting session of the CNC semi-finish grinding process for a CAT320 crankshaft (corresponding to part number 125 3005). Through high-definition lenses, we can clearly observe:
· Stable Operation of High-Precision CNC Grinding Machine: The crankshaft is precisely clamped between dual centers, with the grinding wheel rotating at optimized linear velocity. The CNC system controls the wheelhead's axial movement along the journal, automatically completing rough, semi-finish, and spark-out phases according to a preset grinding cycle. Under the lens, coolant uniformly flushes the grinding zone, removing heat and chips, with sparks flying in an orderly manner.
· In-Process Measurement and Dynamic Compensation: During grinding, measuring devices monitor journal diameter in real-time. When the dimension approaches the semi-finish target, the system automatically switches to the spark-out phase until the preset tolerance is reached. Measurement data is fed back in real-time, with the system automatically compensating for wheel wear and thermal deformation, ensuring consistency for every crankshaft.
· Multi-Axis and Non-Circular Grinding: For crankpins, our grinding machine employs non-circular technology, with the wheelhead moving synchronously with the crankshaft's rotation angle, achieving efficient and stable semi-finish grinding. Under the lens, the wheelhead's motion is like a precise dance, perfectly coordinated with the crankshaft's rotation.
In the video, each journal of a CAT320 crankshaft is sequentially semi-finish ground. Technicians use pneumatic gauges to casually inspect the ground diameters, with data consistently falling within the semi-finish tolerance band. The journal surfaces exhibit a uniform metallic luster, with roughness significantly better than after roughing.
BEFORE
AFTER
Technical Value: Paving the Way for Finish Grinding
In semi-finish grinding the CAT320 crankshaft, Zhejiang Weilin Mechanical employs:
· High-Rigidity CNC Crankshaft Grinding Machines: Equipped with hydrostatic guides and high-power spindles, capable of withstanding the higher cutting forces of semi-finish grinding while ensuring processing stability.
· CBN Grinding Wheels: Using cubic boron nitride (CBN) wheels for high grinding efficiency and long life, capable of stably performing semi-finish grinding tasks.
· In-Process Measurement and Compensation Systems: Real-time monitoring of dimensional changes, automatically compensating for wheel wear and thermal deformation to ensure consistency of semi-finish dimensions.
· Optimized Grinding Parameters: Scientifically setting wheel linear velocity, feed rates, and number of passes based on crankshaft material and hardness, achieving the best balance between efficiency and quality.
Customer Value: The Invisible Guardian of Quality
Although semi-finish grinding is not directly visible on the finished surface, it has a profound impact on the final quality of the crankshaft:
· Ensures Finish Grinding Accuracy: Provides uniform stock allowance and good geometry for finish grinding, enabling stable achievement of micron-level tolerances and mirror finishes.
· Improves Production Efficiency: Semi-finish grinding efficiently removes stock, significantly shortening finish grinding time and increasing overall processing efficiency.
· Extends Grinding Wheel Life: Semi-finish grinding bears the main grinding load, reducing the burden on finish grinding wheels and extending their service life.
· Reduces Scrap Rate: Early detection of anomalies from roughing or heat treatment through semi-finish grinding prevents issues from flowing into finish grinding and causing scrap.
Video & Image Access: Feel Free to Contact Us
To more intuitively demonstrate the precise process of CNC semi-finish grinding, we have compiled high-definition videos and images from the on-site shooing into a technical information package. If you are interested in the manufacturing process of the CAT320 crankshaft or wish to obtain technical parameters related to 125 3005, please feel free to contact our technical team anytime. We will provide you with detailed technical support and product solutions.
About Zhejiang Weilin Mechanical Co., Ltd.
Zhejiang Weilin Mechanical Co., Ltd. is a National High-Tech Enterprise specializing in the R&D, manufacturing, and sales of high-performance forged steel crankshafts. Our products are widely used in construction machinery, heavy-duty trucks, generator sets, and marine propulsion. Committed to providing reliable and efficient core powertrain solutions to global customers through excellent materials science, precision manufacturing processes, and a complete quality traceability system.