Customer satisfaction surveys consistently point to quote turnaround time as one of the greatest frustrations of electronic manufacturing services buyers. Here's a few things you can do to help speed up the contract manufacturers quote process.
Formatting
Use Excel - One of the simplest things you can do is transmit your BOM and AVL information in Excel format. Excel is the universal language of quoting. When a contract manufacturer receives an RFQ in any other format, the first thing they have to do is translate it into Excel.
Use "flat file" format - This means one line of Excel for all the information pertaining to that line item.
One data point per cell - For example, don't put multiple manufacturer part numbers into a single cell.
Data
Include complete data - At a minimum for each line item you will need your internal part number, quantity per, description, approved manufacturer, and manufacturer part number.
Provide correct manufacturer part numbers - Almost every BOM EMS companies receive has incorrect manufacturer part numbers. To speed up your quote process, update the manufacturer part number when suppliers tell you the part number is not accurate.
Fix obsolescence - A huge amount of time and energy goes into investigating obsolete part numbers. BOM's and AVL's are usually controlled by engineering, not purchasing, so purchasing rarely controls this problem. If quote turnaround is a sufficient priority, getting engineering to update supplier feedback is a must.
Further reading: 4 Documents Required to Quote a PCB Assembly