In this guide 6 sections
Link every purchase line to the machine order it feeds, then compare each promised date with that machine’s assembly start, so late motors surface as machines at risk. Warnings arrive weeks ahead. Begin with motors, gearboxes and drives. Skip the small fasteners.
Why shortages surprise the assembly floor
Most purchase registers answer one question. What did we order from this vendor? The assembly supervisor asks whether the gearbox for machine 14 arrives before the frame is ready for fitting, or after the fitters have moved on.
Part numbers keep them apart. A motor ordered for three machines looks like a single line with a single date, so a late delivery does not reveal which machine stalls first.
The fix is not more chasing. One extra field does it.
Tie each purchase line to a machine order
Add the machine order number, or the serial once it exists, to each purchase line, and where one order covers several machines, split the quantity across them. Four servo motors become four allocations.
Each allocation needs a date. That date is the frame completion date minus the days fitting takes, so it is neither the vendor’s promised date nor the date the order was placed.
Treat sub-kits the same way. A PLC arrives with its I/O cards and HMI panel, and each piece needs its own line because the machine waits for the last one.
- Machine order or serial number
- Need-by date from the assembly plan
- Vendor’s promised date and last confirmation
- Quantity received against quantity allocated
- Inspection status at goods receipt
Read the gap between promised and needed
Now every line has two dates. The gap between them is the slack, and sorting by slack pushes the problems to the top without anyone reading the register line by line.
Negative slack means the machine will wait. Under a week needs a call. Long-lead items, such as gearboxes made to order and servo drives under vendor allocation, should be watched from the day the order is placed.
Log each confirmation date. A date confirmed in March and untouched through the summer is a hope, not information, and the buyer should treat it as unconfirmed.
Decide what to do with a late part
A late part forces a choice. Assembly of that machine might be re-sequenced behind another, the design engineer might approve a near-equivalent motor frame, or the vendor might air-freight part of the lot.
Record who decided it. When the customer asks why the delivery moved, you want dates, the vendor’s reply and the approving engineer’s signature ready to hand over.
A vendor score comes free. Late lines, short deliveries and rejected receipts, counted per vendor, show who deserves a second source before the next order for the same motor or drive is placed.
- Re-sequence assembly behind another machine
- Approve an equivalent part in writing
- Split the delivery and fit the first lot
- Release a second source for the next order
Start with the parts that stop a machine
Skip the washers and fasteners. Begin with the dozen bought-in items that have stopped a machine before, such as motors, gearboxes, drives, PLCs, hydraulic power packs, bearings and limit switches.
Run the new view beside your current register for one month, then compare which shortages each one caught and which each one missed entirely. Expect an untidy first week.
Your first step this week: pick the three machines closest to assembly and write the need-by date beside each open purchase line in the register.
Bought-in parts risk sheet
One row per open line. It covers machines due in ten weeks. Columns are machine order, part, vendor, promised date, need-by date, slack in days, last confirmation date, action taken and owner, and the sheet is sorted by slack.
Open a blank worksheet to printQuestions owners ask
Do we need an ERP to do this?
No. A shared sheet copes with a few machines. Once orders overlap, one purchase line feeds several machines at once, and software saves the hours spent copying dates between files, registers and assembly plans.
What if one purchase order covers several machines?
Split the quantity into allocations, one per machine, each with its own need-by date taken from the assembly plan for that machine. Lateness then shows who waits.
How often should vendors be asked to reconfirm dates?
Never let a date go stale. For long-lead items such as gearboxes and servo drives, reconfirm on a fixed day each week and note the reply in the register.