Important factors affecting the quality of weighing sensors

The quality of the elastomer in a load cell largely determines its stability and accuracy. The processing of elastomers for load cells involves a multi-stage precision manufacturing process, the core of which is ensuring the mechanical stability and deformation consistency of the elastomer through material processing and machining. The following is a detailed description of the key process steps:

1. Material Selection and Forging Process
Elastomers are typically made of alloy steel (such as 40CrNiMoA) or aircraft aluminum alloy, which combine high elastic modulus and fatigue resistance. The forging process requires strict temperature control (e.g., heating at 1180°C and final forging temperature ≥ 850°C). Uniaxial stretching refines the grain size, aligning the metal flow lines with the direction of force and preventing grain overlap. After forging, air cooling or slow cooling is required. The metallographic structure should achieve sorbite and tempered α phase, with a hardness of approximately HRC

2. Machining and Stress Control
Machining requires low-cutting processes (such as finish turning and grinding) to reduce surface degradation and residual stress. Typical structures, such as a double-hole cantilever beam elastomer, require guaranteed geometric tolerances and strain concentration to ensure a linear relationship between force and deformation. After processing, stress relief annealing (200-300°C/12 hours) is required to eliminate internal tension under argon protection. Temperature fluctuations must be controlled within ±3°C.

3. Triple Heat Treatment Process
Quenching and Tempering (800-950°C oil quenching + 550°C tempering): This imparts both rigidity and flexibility through phase transformation from austenite to martensite.
Aging (120-150°C/72 hours): This precipitates nanoscale strengthening phases, controlling temperature sensitivity to below 0.0015%/°C.

Environmental Control: Nitrogen protection is used throughout the process to prevent oxidation. Surface oxide layers exceeding 5μm are considered scrapped.

4. Surface Treatment and Mounting Process
The elastomer must be thoroughly cleaned before attaching constantan or semiconductor strain gauges in an ultra-clean environment. A specialized adhesive is used to ensure synchronized deformation.
Before mounting, the assembly must be screened and matched, and rough performance testing performed through bridge assembly and wiring.

5. Stability Verification
Finally, aging treatment, moisture-proof sealing, and calibration are required to ensure long-term stability (e.g., no significant drift over a 20-year service life). For example, a certain sensor model can maintain zero-point temperature drift within 0.03% F.S./10°C within the -10°C to 60°C range.