Under contract with a large automotive supplier, MS3D has developed a special Roller Inspection machine. It can be integrated in the production line and automatically inspects parts for surface defects.
Mesure-Systems-3D (MS3D) was founded in 2010 by Dr. Marc Rosenbaum and Didier Le Néel in order to give an answer to the growing demand of the manufacturing industry for a way to guaranty zero-defect production.
Since its creation MS3D has delivered over 30 machines to the automotive, aerospace, defense, watch, energy and semi-conductor industries.
MS3D offers fully automatic 3D conformity measuring machines, installed directly on the manufacturing line -- able to control in the production cycle time, parts with complex geometries demanding very high accuracy inspection because of extremely tight dimensional tolerances.
This 3D inspection addresses a wide variety of mechanical parts. It is implemented usually in a few seconds corresponding to volumes of 10,000 to 20,000 parts per day.
Two concerns can arise with the use of inspection machines:
These two factors have been addressed in the development of the new contact-free in line inspection system from the French manufacturer Mesure-Systems-3D (MS3D). The Roller Inspection machine can be integrated directly in the production line and identifies surface defects as small as 0.5 µm deep.
Even tiny scratches on the surface of a roller can cause vibrations and impacts, which sooner or later will lead to loss of functionality.
Because roller bearings can bear a greater compressive load than ball bearings, they are used in many machine tools, in automotive bearings, and in aircraft. Even tiny scratches on the surface of a roller can cause vibrations and impacts, which sooner or later will lead to loss of functionality. In the worst-case scenario, the machine can fail, which can result in high costs and great danger.
The image-processing machines that are typically used to discover defects on the surface of rolling elements, however, are not able to distinguish between a real depth defect and dust, water spots, or fingerprints. Each part therefore has to be re-inspected by a human inspector. Because this type of defect is extremely small, optical magnification is required, such as a type of lighted magnifier. This method is physically strenuous for the inspector, however, and the results do not have the necessary reliability and precision.
Differentiation Between Real and False Defects
Because an automated solution is not only better at meeting these requirements but also enables substantial savings over the long term, a large automotive supplier contracted MS3D to build a special Roller Inspection machine.
Using different sensors, millions of data points are generated that the software collates into a 3D model. This is the basis for very fast computing of the required features and checking for deviations from reference requirements.
It not only ignores "false" defects, but it can also indicate the precise depth of the actual defects. The limit value for the machine that has been delivered was 0.8 µm for the maximum allowed depth of the defect. To achieve this, additional white light sensors were installed in a standardized Ring Inspection machine from MS3D -- in addition to the existing laser sensors -- in order to ensure the necessary precision.
For the actual measurement, the parts do not need to be precisely positioned. Rather, they rest on a type of stand under their own weight and the stand rotates through 360°. Each sensor generates about 3.5 million data points per second. Therefore in just a few seconds a very dense cloud of points is created, consisting of millions of data points synchronized with the rotation.
A Roller Inspection machine can be integrated directly in the production line and controls the parts automatically to identify surface defects.
While a robot brings the part back to the pallet, a special software program collates the information into a 3D model and calculates directly from the cloud of points useful geometrical features. This is the basis for very fast computing of the required features and checking for deviations from reference requirements.
Detecting Shape Defects with Precision from 0.1 to 0.3 µm
Instead of the one to one-and-a-half revolutions typical for the Ring Inspection machine, the part is rotated as often as needed to collect sufficient data for detecting errors down to 0.5 µm, or in this case 0.8 µm, in depth. This corresponds to just a few hundredths of a micrometer on the surface. The precision error of the reproducible results is about 0.1 µm. Depending on requirements, this takes 20 to 40 seconds -- which is much faster than inspection using image-processing machines. The new system from MS3D, however, makes it possible to set a very low threshold that is impossible to see with the naked eye. Parts that do not meet this criterion are detected automatically.
Instead of the one to one-and-a-half revolutions typical for the Ring Inspection machine, the part is rotated as often as needed to collect sufficient data for detecting errors.
There is also an option to measure the entire surface in three dimensions using the Roller Inspection machine, so that additional shape defects such as cylindricity and circularity can be determined. The length can be determined using an additional sensor. Wherever it is relevant, precision of 0.1 to 0.3 µm can be achieved. If the longer cycle time is not a problem for production, it may make sense to use one Roller Inspection to check for surface defects and another identical unit to measure diameter and height. In the aircraft industry, quality requirements are so high that this delay is not a problem, due to the improved level of security.
In automotive production, the automated inspection for surface defects alone reduces the number of cases where scratched parts are installed. This enables suppliers to save costs in production, reduce scrap right from the start, and provide buyers with a zero-defect guarantee.
Since its creation MS3D has delivered over 30 machines to the automotive, aerospace, defense, watch, energy and semi-conductor industries. Its customers are mostly 1st tier suppliers dealing with powertrain parts such as Bosch, Delphi and Valeo. Major players such as Airbus, Snecma, Areva are also among MS3D customers.
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