Automatic weight exchanger for series design calibration

An automatic weight exchanger for series design calibration of a decade weights is described. The vertical pan with 6 loading positions is hanged down from a balance hook. Weights are loaded on and lifted off vertically. Every weight has its own vertical guide for lifting and loading. The vertical motion is realized by 6 synchronous stepping motors. The weight exchanger is installed with a commercial balance of 205 g capacity and 0.01 mg readability. The full operation is automated with a personal computer. The performance tests were carried out. The present status results indicate: Calibration time and labor could be reduced significantly. Uncertainty could be reduced with less random error. Calibration series of 100-50-20-20′-10-10′ g was tested successfully to give the maximum Type A uncertainty of 0.014 mg. The apparatus could be incorporated with Internet web for remote calibration and training.