Using Direct Part Mark (DPM) technology to apply bar codes to a part is a small piece of the larger system that needs to be considered. Marking the part is less than half of the system – reading the part is a much bigger consideration and far more difficult.
Most of the DPM solutions create a bar code mark that provides only a low contrast differential from the surrounding material – a grey-on-grey situation – and for an optical technology like bar code this makes reading very difficult. A manufacturer who marks the part when it is brand new may have no understanding of what his Customer has to go through to read that same part when it is in-service and dirty.
The whole system of marking and reading in the real world has to be considered before making a final choice on which DPM technology to use on which part so that it will be usable for many years in actual service.
DPM technology solutions take two basic methods: Non-intrusive and Intrusive technologies, each with their strengths and weaknesses, to be considered below: