SMT007 Magazine


Issue link:

Contents of this Issue


Page 23 of 115

24 SMT Magazine • January 2017 component on the PCB. The engineering data identifies each feeder position with a part num- ber, so the data looks as though it is reporting part number against reference position on each PCB. The assumption, however, is that the cor- rect part number was set up at that feeder po- sition. The material verification records need to be checked to make sure this is true. The set- up verification may have been done by the ma- chine software or by a third-party software. For complete traceability, we need to rewind our re- cording to see the actual events related to the verification. First, we can see that a reel of material was loaded onto a feeder. Usually, verification is done using a barcode on both the feeder and the material being read to associate the two to- gether. The material barcode should provide the part number, which is checked against the engi- neering information for the machine for the in- tended position used. Assuming this process is done correctly, then the machine can have the feeder loaded, which can be then a simple auto- mated confirmation that the material has been loaded in the right place. However, there can still be sources of doubt. The part number used for verification is either a generic "internal" part number, or it could be the material vendor's part number. The latter case is difficult to manage because of the lack of standardization currently with labeling of materials from suppliers. The label format and content have to be "learned" by the verification software, which, if done "on the fly" at the time of material preparation, can lead to a significant risk of error. The barcode labels are notoriously unreliable, and conflicts between material ven- dors can happen. The better approach is to label the materi- al as it comes into the factory, or at least the SMT warehouse area, on a unique material ba- sis. Where this is done, we can gain better trace- ability by rewinding our recording to see these events taking place. As material comes in, the vendor barcode is read, and a conversion is made to the generic internal part number. As is most often the case, materials of the same ge- neric part number can come from two or more suppliers. The shape, size, orientation, and even the way in which the materials are packaged for use on the machine can be different. Simply labeling the material with the inter- nal part number would mean that these differ- ences would not be noticed until the material was at the machine, if you were lucky. The veri- fication process would not record any issue, but a different behavior of the machines, includ- ing an epidemic series of defects, can occur if the differences are not noticed. Instead, unique identification of materials can be used to main- tain a record about not only the part number but also all other information about the mate- rial that may be significant to the operation, in- cluding the physical differences, vendor specific metrics, and things such as moisture sensitivity device (MSD) parameters. With a unique profile maintained for each material in this way, the verification process can be much more secure and reduce variation in the material replenish- ment process, with automated consistent selec- tion of materials by supplier as replenishment materials are needed. Simple verification software at the machine may not provide the higher level of checking re- quired unless it can understand the full profile of each individual material. Therefore, the ma- chine software needs to be closely linked to the material management software of the factory. The smart and lean material management func- SMART FOR SMART'S SAKE, PART 3: UNIFICATION & TRACEABILITY " Usually, verification is done using a barcode on both the feeder and the material being read to associate the two together. The material barcode should provide the part number, which is checked against the engineering information for the machine for the intended position used. "

Articles in this issue

Archives of this issue

view archives of SMT007 Magazine - SMT-Jan2017