4th-Axis Rotary Module Middle & Base Plate Process Milling, Grinding, Measurement, and Assembly

 Applications of 4th-Axis Modules in Precision Manufacturing 

In aerospace, mold, automotive, and medical industries, the 4th-axis CNC rotary table is an essential device for improving machining efficiency and multi-face processing capability. It enables cutting operations on different angles and surfaces in a single setup, reducing workpiece repositioning time and errors, while ensuring machining accuracy and productivity.

Design Functions of the Middle Plate and Base Plate  The middle plate serves as the structural interface between the 4th-axis rotary platform and the tailstock. It must withstand the weight of the workpiece and machining loads, ensuring the accuracy of fixture and workpiece installation. The base plate acts as the mounting reference for both the 4th axis and the tailstock. In addition to providing stable support, it also absorbs vibration and reinforces the structure, reducing chatter and deflection during machining and improving overall rigidity and stability.

 
 Raw Material Inspection and Milling Process 

Before starting the process, various types of calipers and measuring tools are used to confirm that the raw material’s length, width, and height meet the design specifications.
Prior to CNC milling, a 3D dial gauge is used to set the workpiece coordinate system, ensuring precise positioning. During machining, multiple cutting tools are applied in sequence according to the program to complete operations such as threaded holes and countersunk holes.
Each tool operation is controlled by the CNC program, including feed rate, cutting depth, and tool change order, ensuring machining consistency and precision. Although the base plate primarily serves as a spacer, its flatness and hole position accuracy must also be strictly controlled to avoid interference or misalignment during assembly.

Grinding and Surface Accuracy Inspection  After milling, the process proceeds to grinding, where a surface grinder equipped with a grinding wheel removes a small amount of material to eliminate tool marks and deformation errors, reducing the surface roughness to below the Ra standard value. Coolant is applied during grinding to control heat buildup, preventing thermal deformation from affecting accuracy. After grinding, multiple precision inspections are carried out: ◆ Height gauge and probe – Check thickness and parallelism. ◆ Outside and inside micrometers – Verify bore diameters and thickness accuracy. ◆ MarSurf roughness tester – Measure Ra and Rz to ensure surface performance. ◆ Digital microscope – Inspect grinding patterns and detect surface defects. ◆ WENZEL CMM – Verify hole pitch, flatness, parallelism, and perpendicularity with micron-level accuracy.

 4th-Axis Modular Assembly Process 

Assembly begins with installing the L-shaped mounting base of the rotary platform. A dial indicator is used to check face runout, ensuring positioning accuracy. The tailstock is then installed, aligned with the center of the rotary platform, and secured to keep the workpiece tail end stable and free from vibration during machining.

The 4th axis and tailstock are mounted onto spacer blocks or the base plate, followed by dual-axis alignment. A dial indicator measures the shaft height and position at both ends, with repeated adjustments until the coaxiality error meets the required standard.

Finally, the middle plate, motor cover, and side panels are installed in sequence, the brand logo is fixed, and the final test run is performed.

 Quality Commitment and Technical Expertise 

Since its establishment in 2008, Herbao Machinery has specialized in the research, development, and manufacturing of high-precision CNC rotary indexing tables. With multiple patents and a complete process control system, every stage—from design, machining, and inspection to assembly—is strictly monitored to ensure long-term stable operation, meeting the high precision manufacturing standards demanded by various industries.

For more practical applications and technical knowledge about 4-axis and 5-axis systems, visit our website, follow us on social media, or subscribe to our YouTube channel to receive the latest insights and hands-on sharing.

( (Related Reading: How to Maintain a 4th Axis? Knowledge Sharing Ep. 8-How to Maintain a CNC 4th-Axis Rotary Table? )