Technical Interpretation: Engineering Logic Behind the +10%/5% Tolerance of Disc Spring Standard Force Value

The GB/T 1972 "Disc Spring National Standard" and international standards employ an asymmetric +10%/5% design for force tolerance in disc springs. This seemingly unconventional tolerance specification reflects profound engineering considerations spanning theoretical calculations to practical applications. Jiangsu Sunzo Spring will systematically analyze the scientific rationale behind this standard formulation from a technical perspective.

1、Benchmark Comparison of Theoretical Calculation and Finite Element Analysis

In the pure theory level, the finite element analysis (FEM) can simulate the mechanical behavior of the disc spring most accurately. Based on this, the finite element solution is set as the theoretical exact value F.

Through a large number of comparative analysis, it is found that:

The calculation result of the traditional Almanraz formula is usually about 5% higher than the finite element solution, which is about 1.05F.

The measured force values typically range from 1.05F to 1.1F, with variations in lever arm caused by rounded corners and friction between the test plate and the pressure plate.

The measured value is often greater than the finite element reference value, and even slightly higher than the calculated value of the AL formula.

2、Comprehensive Evaluation and Balance of Engineering Factors

In addition to the above main factors, other possible influences were also considered in the development of the criteria:

1. Offset Effect of Manufacturing Tolerance

High tolerance: Positive tolerance is usually twice the negative tolerance

Thickness tolerance: A negative tolerance is usually twice the positive tolerance.

The outer diameter has negative tolerance, and the inner diameter has positive tolerance.

These tolerances are designed to be mutually restricted and balanced, and their systematic influence on the final force value can be basically offset.

2. Evaluation of the effect of residual stress

After systematic process control and evaluation, the residual stress produced by reasonable manufacturing process has little effect on the macroscopic force value performance of disc spring, and it can be ignored in tolerance setting.

3、Engineering Significance of Tolerance Setting

Based on the above analysis, setting the tolerance at +10%/5% demonstrates clear engineering rationality.

Positive tolerance (+10%): includes the conservative factor of AL formula, the measured friction and the rounding corner which increase the force value.

Negative strictness (5%): ensures the minimum bearing capacity of the disc spring, meeting the design safety baseline.

This setting respects the engineering practice and guarantees the reliability of the design, which reflects the scientificity of the standard.

4、The Practice of Quality Control of Three Groups of Elastic Materials

In production and quality control, Jiangsu Sunzo Spring not only strictly complies with the national standard tolerance requirements for disc springs, but also employs refined process control and a comprehensive testing system to minimize force value fluctuations in its products.

We understand that tolerance refers to the permissible deviation range, while consistency represents a higher-level quality pursuit. We achieve this through:

Precision control of raw materials ensures batch stability

Optimization of Process Parameters to Reduce Systematic Deviation

Full-process testing ensures traceable quality.

We are committed to delivering disc spring products with enhanced stability and consistency, while meeting all standards, to provide your designs with reliable technical support.