The button on a seat belt buckle in the car must meet high quality standards to ensure that this safety-relevant component works faultlessly. Even though it is subjected to frequent mechanical stress in daily use, the button's stability over the life time of the car must be 100% guaranteed.
Quality assurance for the button should ideally be as comprehensive as possible and should be performed immediately after its manufacture in the plastic injection mold. Otherwise, defects are only identified after the button has been installed, leading to high subsequent costs because the entire safety-relevant module must be exchanged. In a worst-case scenario, this defect can impair safety, e.g. because the seat belt can no longer be used.
Regular random sampling guarantees the quality of the production process because, for financial and technical reasons, it is not possible to inspect every seat belt button. Defined component dimensions are captured regularly and deviations are monitored exactly overtime. Statistical analysis enables the process to be stopped at the ideal moment as well as the early identification of gradual deterioration in the process. The shape of the value progression also provides information about potential defect causes.
These features predominantly determine the quality of the button:
- The dimensional stability of the shape, i.e. the correspondence to the defined nominal values in the CAD model.
- Stability which could be potentially limited by cavities, if applicable.
Dimensional accuracy is checked as standard using a coordinate measuring machine with tactile or optical sensors. The more dimensions are to be recorded, the more time-consuming the inspection is. If necessary, the component may also have to be reclamped. In addition, hidden structures are difficult or impossible to measure with a coordinate measuring machine without destroying the component. Pores inside cannot be examined.
The time required for regular inspections is multiplied by the sampling frequency. On the other hand, more frequent measurements help to stabilize the process, minimize tolerance deviations and reduce scrap and follow-up costs of faulty production.
With a ZEISS METROTOM computertomograph, all dimensions to be captured within the scope of process control can be inspected with just a single scan. It is even possible to insert multiple components into the CT system at once and inspect them. Depending on the component size, a complete shot is also possible. Moreover, additional dimensions can be inspected at any time using the voxel data generated to perform supplementary analyses. If necessary, a color-coded display of the nominal/actual comparison provides an overview of the dimensional accuracy of the entire component. The particular strength of the ZEISS METROTOM: the measuring results are traceable and dependably meet the current metrology standards.
The ZEISS METROTOM 1 is the perfect way to get started with CT technology, which is often perceived as complex.