Steel Weldment vs Mineral Cast Machine Base for Vibration Damping

PFT, Shenzhen

Abstract

Machine base design plays a crucial role in stabilizing machining accuracy by controlling vibration. This study compares steel weldment and mineral cast bases in terms of vibration damping efficiency. Finite element models were developed, and modal testing was conducted to evaluate natural frequency, damping ratio, and displacement response under simulated cutting loads. Results indicate that mineral cast bases exhibit 18–25% higher damping capacity than steel weldments, particularly in the frequency range of 200–500 Hz. However, steel weldments show advantages in structural rigidity and lower initial cost. The findings provide quantitative evidence for selecting machine base materials according to performance priorities.

1 Introduction

Machine tool bases are fundamental to overall system stability. Vibration arising during high-speed machining directly affects dimensional accuracy, tool wear, and surface quality. Material selection for the base structure determines both stiffness and damping capability. While steel weldments have been widely adopted due to ease of fabrication, mineral cast bases have gained attention for superior damping performance. This paper investigates the quantitative differences between these two materials under controlled experimental conditions.

2 Research Method

2.1 Design Approach

Two prototype bases of identical geometry were constructed: one from welded steel plates and one from mineral cast composite. Both designs adhered to standard machine tool base dimensions (1.2 m × 0.8 m × 0.6 m).

2.2 Data Sources

• Material properties were taken from supplier datasheets and verified by tensile and compressive strength tests.

• Vibration test data were collected from in-house experiments conducted between May–July 2025.

2.3 Experimental Tools and Models

• Finite Element Analysis (FEA): ANSYS 2024 was used to model modal frequencies and stress distributions.

• Modal Testing: An instrumented hammer and accelerometers (PCB Piezotronics, Model 352C) recorded dynamic response.

• Signal Processing: Frequency response functions were analyzed with MATLAB R2024b to extract damping ratios.

All procedures were repeated three times to ensure reproducibility.

3 Results and Analysis

3.1 Natural Frequency

Table 1 summarizes the first three natural frequencies. The steel weldment showed slightly higher values due to greater stiffness.

Table 1 Natural frequencies of steel vs mineral cast bases

3.2 Damping Ratio

Figure 1 illustrates the damping ratio comparison. Mineral cast achieved up to 0.042, while steel remained below 0.034.

Figure 1 Damping ratios for steel and mineral cast bases (measured across 200–500 Hz)

3.3 Displacement Response

Under equivalent excitation force (300 N), mineral cast bases reduced peak displacement amplitude by an average of 21%.

3.4 Comparative Analysis

Existing studies [1–2] reported 15–20% improvements in damping for mineral cast materials. The present findings confirm and extend these results with direct structural prototypes, highlighting consistent performance advantages in mid-frequency ranges.

4 Discussion

The superior damping behavior of mineral cast is primarily attributed to its composite microstructure, where polymer-bound aggregates dissipate vibrational energy through internal friction. Steel weldments, although less efficient in damping, deliver higher structural rigidity, which benefits heavy-load applications.

Limitations:

• Thermal effects were not included in this study, although they may influence long-term stability.

• Only one geometric configuration was tested, limiting generalization to other machine designs.

Practical Implications:

• Mineral cast is recommended for high-speed machining centers where vibration damping directly improves tool life and surface finish.

• Steel weldments remain suitable for cost-sensitive applications with heavy cutting loads.

5 Conclusion

Quantitative testing demonstrated that mineral cast bases provide 18–25% better vibration damping than steel weldments, particularly in the 200–500 Hz range. Steel weldments retain advantages in rigidity and lower production cost. Future research should include thermal cycling tests and hybrid base structures to combine the benefits of both materials.