Press Fit Quality Control

This project's objective is to gather data from a press that inserts a high tolerance pin into parts and provide operator feedback indicating whether parts are within tolerance.

The machine's current operation presses a machined pin into a machined hole on a specific part. The press has no method to indicate whether the fit is normal or if the tolerances are incorrect and the pin fit is loose. Measurements verify quality much later in the assembly process: if a problem is found, the repairs are costly and additional labor has been wasted assembling a part that is out of tolerance.

The customer added a load cell to the existing equipment. The data from the load cell is collected with a National Instrument High Speed Data Acquisition card. Using a .NET PC application developed by Hallfield Controls, data from the card is analyzed and displayed on a graph. The peak load from the cycle is recorded and displayed next to the data graph. This peak value is compared to a pre-defined setpoint to determine if the process passed or failed, providing valuable, real-time feedback. With this new system, the error can be found right at the source, preventing wasted assembly time and costs due to non-compliant parts.

The new data acquisition application caused no changes to the machine's operation. Hallfield Controls worked with the customer to tie into existing operator controls to automatically monitor each cycle.

This type of modification could be added to many different applications with various existing PLC or CNC controllers. The add-on could also control additional inputs and outputs to be integrated back into the machine control logic, providing additional feedback and enhanced system control.