Smartscope 600

Citation

(1999), "Smartscope 600", Aircraft Engineering and Aerospace Technology, Vol. 71 No. 4. https://doi.org/10.1108/aeat.1999.12771dab.007

Smartscope 600

Smartscope 600

Keywords: Disc, Measurement

How do you measure a component which is too delicate to touch, is manufactured in volume, has dimensions which range from 0.6mm to 1.1mm diameter and needs to be tightly controlled in three dimensions? For the Cho-Form business unit of Parker Chomerics, Marlow, the OGP Smartscope FOV 600 video based 3-D measuring system supplied by Disc (GB) of Hatton, provided the answer (Plate 8). Alan Goswell Chomerics operations manager comments:

We've been highly satisfied with both the performance of the machine and the back-up from Disc GB. While our machine was on order we were loaned a machine so that we could develop programs and train personnel in good time for production to start.

The instrument provides the capability to carry out 100 per cent measurement of critical features within the process time of the company's Cho-Form electromagnetic interference (EMI) shielding gasket application line. Cycle time for a pallet is around four minutes but the Smartscope can normally carry out a full feature check in around 3.5 minutes. More important is its role in assisting development of a capable process which now achieves Cpk of 2.36.

Alan Goswell continued:

The Smartscope FOV has demonstrated itself to be an excellent machine. On one contract we had to lay down an "impossible" bead of material in that the part geometry did not lend itself to our process. Using the Smartscope we were able to check each part made to ensure that our customer had a perfect product.

Plate 8 OGP's Smartscope FOV 600 video based 3D measuring system

Chomerics is a leading company in EMI shielding and thermal management technology for electronic and semiconductor products. The Cho-Form process has been developed specifically for portable electronic devices such as mobile telephones. EMI shielding is critical in these devices as it is necessary to avoid internal interference via cross-talk between the transmit and receive circuitry, and also to avoid interference by the device with other electronic systems. In-car electronics such as ABS, fuel injection and air bags can be affected by EMI, as can the fly-by-wire and navigation systems of aircraft, and hospital equipment.

The process depends on the precise application of an electrically conductive elastomer to provide a joint between internal metal or metallised plastic EMI shields within either half of the main chassis shell assembly. When properly applied, this renders the conductive layer continuous over the internal and external surfaces of the enclosure, providing a Faraday's cage. This confines electromagnetic radiation generated by the device inside, and also provides a measure of protection from external EMI sources. Alan Goswell said:

The deposition process has to be controlled with extreme precision so that dimensions are maintained within 0.1mm of nominal. Too thin a gasket means the system will not operate while being too thick means any automated assembly by our customer becomes difficult or in the worst case, impossible.

The pattern of the gasket layout resembles the room plan of a house but with wall thickness measured in fractions of a millimetre. In addition, the surface to which the elastomer is applied is three-dimensional. In order to complete the task the company has developed a three-axis CNC controlled applicator system with adjustable pressure on the syringe-type applicator head which can cope with application of material onto slope angles up to 45ú. Alan Goswell said:

We aim to establish optimum conditions for application of the "perfect" gasket. So far as measurement is concerned we are looking at height, width, radius and position relative to the workpiece. On some dual bead "figure of eight" gaskets, it is also necessary to assess the position of the second run relative to the first. Apart from the speed of operation we also find that OGP's MeasureMind software is very easy to use, so we can develop or modify programs quite quickly if the need arises.

Measurement is performed with the workpieces on dedicated process pallets, for which locations have been supplied on the Smartscope stage, which has a 610mm X-axis that is just large enough to accommodate them. Detailed measurement of first-off components is carried out prior to the material being oven cured and "cured" pallets are then subject to SPC monitoring of critical features.

Developments of the system include continual charting of inspection results for failure mode effects analysis. And there is the capability to feed Smartscope results directly back to the process line for closed-loop control of production.

Alan Goswell concluded:

The Smartscope is invaluable; without it we could not check our production with anything like the same degree of certainty. In addition, it provides us with a fast, foolproof means of checking components supplied by our customers.

Details from Disc (GB) Limited. Tel: +44 (0)1283 520127.