Fabien Bourgeois

First results on vibration feeding of small parts in the presence of adhesive forces

In this paper, a flexible solution for part feeding in assembly is analysed for its suitability to feed small parts with typical dimensions between 0.5 and 5.0 mm. The feeding concept is based on a tooling plate, which vibrates to separate and reorient the parts. A vision system is used to determine the position of parts in a correct orientation. A robot picks these parts and assembles them. The conditions for a successful reorientation of parts are studied. The influence of adhesive forces on the ability to re‐orientate is investigated. A prototype is built to determine empirically the magnitude of the adhesive forces and the influence of these forces on the feeding process.

Constraining deformable templates for shape recognition

This paper addresses the problem of robust shape recognition in the presence of shape deformation as well as changes in part position, orientation and scale. Point Distribution Model (PDM) are deformable templates that have interesting features for industrial inspection tasks, since they are built by statistical analysis of a training set and they define a prototype shape as well a set of possible, acceptable deformations. To further improve their classification capabilities, these deformable templates are extended by adding a constraint on the amount of deformation. A constrained optimization procedure is proposed and successfully tested on an industrial inspection task.

What is the best way to increase efficiency in precision assembly

Assembly of high precision products is often done manually. The main reasons are the complexity of automation and the production volumes that often remain small to medium. Watches, medical devices and sensors are some examples of products requiring high precision assembly: often expensive products with high margins. It is interesting to notice that achieving higher assembly yield allows for relative quick pay-back of equipment. This is also the reason why western European countries remain competitive in this field. In this paper, the important points to remember when selecting a solution to efficiently assist operators in their assembly tasks are highlighted. Good assistance should lead to higher yields, higher throughputs and better quality. One should take into account assembly processes and their difficulties, as well as production volume and economic profitability.

New Designs for Submillimetric Press-Fitting

Press-fitting is a very common assembly process used in many fields, especially in the watchmaking industry. It consists of introducing a shaft in a hole (also called receptor) with a certain value of tightening (or interference). However, this process is not straightforward and it is often observed that some assemblies do not manage to hold out the time and function they are meant to. In order to solve this problem, influent parameters had been searched and are now studied. The shape of the receptor has appeared as a critical one. Indeed, new machining processes have been developed this last decade and we are now able to make new designs which could cope perfectly with this application. The article will deal with the influence of the two main parameters involved in a press-fitting assembly: the maximal press-fitting force, measured axially; and the resistive torque exercised between the shaft and the receptor. The main purpose will be to find which kind of design allows the contact to become less stiff, which means less internal constraints. Thus, the tolerances, especially those of the receptor (they are less well controlled than those of the shaft) could be enlarged and this would be a great improvement for the industrial world.

When Manufacturing Capability Exceeds Control Capability: The Paradox of High Precision Products, or is it Possible to Assemble Functional Products out of Components we are Unable to Measure?

Sorting and mating is a very common practice in high precision manufacturing, as well in the watch industry, biomedical or automotive industry. This strategy helps to increase the assembly yield, but is costly and timeconsuming. The question is, when is it necessary to apply sorting and mating, and when can it by avoided without loss in product quality? We furthermore show in this paper that the measurement precision is often lower than that of manufacturing. New and more precise manufacturing equipment and assembly devices allow for narrower distributions, and this raises many questions: is it possible to stop sorting? how can we be sure of the quality of the components and of the products? A case study at the company MPS AG, manufacturer of miniature ball bearings, illustrates this trend. We propose another manufacturing and assembly strategies, and show what the conditions are that are necessary to permit this approach.