High Accuracy Pressure Transmitter Increases Machine Productivity
A leading British car manufacturer at the forefront of the luxury automotive industry is upgrading pressure measurement equipment used to control actuator force on their hydraulic press lines. The press lines produce unique aerodynamic aluminium and steel body panels used in the manufacture of their range of sports and saloon cars and operate continuously to meet the continual growth in market demand.
Hydrotechnik Pressure Transmitters are now being used to measure the applied actuator forces by means of the corresponding high pressure hydraulic loading. These measurements are critical to ensure consistently accurate monitoring and control of the press stamping function and ultimately quality of the body panels produced.
The hydraulic load is equivalent to a pressure of up to 400 bar and the pressure transmitters have to deliver an accurate, stable and reliable electronic output whilst operating in a physically demanding environment with considerable shock and vibration loadings.
The original pressure transmitters employed a silicon measuring element with a fluid filled stainless steel isolation diaphragm to transmit the applied pressure value. The 4-20mA output electronics were supplied with internal adjustable zero and span potentiometers. Due to signal drift experienced when used in the application, each transmitter would require periodic checks and adjustment to ensure that it’s performance is kept within the precise tolerances. The potentiometers are very small and located inside the transmitter body, so the required adjustments could not be carried out in-situ, necessitating removal of each transmitter from the machines as and when required. This inevitably meant a significant machine downtime with corresponding loss in overall production efficiency.
The replacement pressure transmitters from Hydrotechnik’s HT-SML range feature thin film silicon technology. This uses a thin layer of silicon sputtered directly onto a stainless steel diaphragm to produce a single integrated measuring element with no fluid isolation. The result is a highly rugged and reliable sensor that is very suitable for high pressure hydraulics and proven to be significantly more accurate, stable and reliable in this application. In turn this has meant that interim zero and span adjustments have not been necessary to maintain the required measurement tolerances so avoiding process downtime. The Hydrotechnik HT-SML is also a much lower cost than the previous transmitter, an additional benefit for the customer.