Fully automated density measurement using the MIM method - An introduction

What awaits you here:

1. INTRODUCTION
2. THE IMPORTANCE OF DENSITY DISTRIBUTION IN THE MIM PROCESS
3. ARCHIMEDEAN DENSITY MEASUREMENT: BASICS AND CHALLENGES
4. THE FULLY AUTOMATED DENSITY MEASUREMENT SYSTEM
5. CONCLUSION

Introduction

Metal injection moulding (MIM) has established itself as an efficient process for manufacturing complex metal parts. A critical aspect here is the uniform density distribution in the so-called green parts, i.e. the component that has not yet been sintered. A homogeneous density distribution is crucial as it determines the shrinkage behaviour and thus the dimensional accuracy of the end product. In collaboration with Arburg GmbH & Co. KG, Dimensionics Density GmbH has developed a fully automated density measurement system that enables precise process monitoring and optimisation.

The importance of density distribution in the MIM process

The MIM process consists of four main steps: compounding, injection moulding, debinding and sintering. Firstly, a feedstock consisting of metal powder and an organic binder is produced. This is then injection moulded into the desired shape. The green compact is then debinded, whereby the binder content is greatly reduced, before the component is compacted and hardened at high temperatures in the final sintering step. The density distribution plays a decisive role here, as uneven density can lead to irregular shrinkage and warping.

Archimedean density measurement: basics and challenges

Archimedean density measurement is an established method in which the weight of a solid body is measured in air and in a liquid. The difference corresponds to the buoyancy experienced in the liquid, from which the volume and ultimately the density of the body can be calculated. For accurate measurements, environmental influences such as temperature and pressure must be taken into account.

One challenge when measuring density in practice is human influence, which can affect the accuracy and reproducibility of the measurements. This is where the fully automated system from Dimensionics Density comes in, enabling highly precise and reproducible measurements by recording all relevant environmental influences and excluding external interference.

The fully automated density measurement system

The fully automated density measurement system from Dimensionics Density is designed for use in production environments and is not limited to laboratory conditions. It enables fast density measurement and integration into production lines, allowing short reaction times for process customisation. The system processes components in a tray with up to 18 places and records all relevant data such as worker, order and component numbers.

Thanks to the fully automated handling of the components and the constant maintenance of the measuring conditions, even minor deviations in the density distribution can be precisely recorded. This leads to a significant reduction in rejects and costs, as test sintering is avoided and continuous optimisation of production parameters is possible.

Conclusion

The introduction of fully automated density measurement in the MIM process represents significant progress. It enables resource-saving process control with less time and energy expenditure and contributes to more economical production. Future investigations will concentrate on further validating the results achieved so far and on researching the relationship between density gradients in the green compact and the shrinkage behaviour in the sintered state.