Measure against the original promise, or the number means nothing
This is the single most common measurement error in SME procurement.
The supplier commits to week 32. In week 30 they ask to move to week 34. You agree, because you have no choice. The order ships in week 34 and the system records it as on time.
Your OTIF looks fine. Your production plan was still disrupted twice.
Record two dates on every purchase order. The first promised date, and the actual despatch date. Measure against the first. Track the number of rebaselines separately, because a supplier who moves the date three times is telling you something a percentage will not.
In full matters as much as on time. A part-shipment of 40 out of 50 is not delivered. If your assembly needs 50, you have nothing.
Benchmarks worth holding suppliers to
| Metric | World-class | Workable for an SME supplier | What it tells you |
|---|---|---|---|
| OTIF against original promise date | 95 percent or better | 90 percent with visible improvement | Whether planning is real |
| Quality PPM (precision work) | Below 500 | Below 1,000 with a working corrective action process | Whether process control is real |
| Rebaselines per order | Under 0.1 | Under 0.3 | Whether the promise dates are honest |
| Notice before a missed date | 5 or more working days | Any notice before the due date | Whether they know their own schedule |
The 95 percent OTIF figure and the sub-500 PPM target for precision work are standard supplier relationship management benchmarks and are widely used in automotive and aerospace scorecards. The last two rows are ours, and they are the ones that predict the others.
There is good evidence that supplier development works rather than just supplier switching. A publicly funded Midlands Aerospace Alliance programme supporting 29 SC21 participants reported an average seven percent improvement in on-time delivery and 99.15 percent overall quality performance, alongside a 19 percent turnover increase across those businesses. Fixing a supplier is often cheaper than replacing one.
Why suppliers are chronically late
They quote the date you asked for. Sales does not want to lose the enquiry, so the promise is set by your request rather than by their schedule.
They have no finite capacity view. A shop planning on a whiteboard cannot see that three jobs all need the same machine in week 32 until week 32.
Your order is not the priority. A large customer's call-off outranks your 50-off. This is rational and nobody will tell you.
The chain is longer than the machining. Machining finishes on Tuesday, then the parts go to anodising with a two-week queue that nobody planned for. Multi-process parts are late in the finishing stage far more often than in the machining stage.
Material did not land. Stockist shortages, mill lead times, or a grade nobody checked availability on before quoting.
Only the second and third are about capacity. The rest are about planning and honesty. The silence that usually comes with a slipping date is its own pain point, with its own guide.
How to choose a supplier that will actually hit dates
If your parts are single-process and your volumes are steady, buy direct from a shop with a proper ERP system and a scheduler. Ask what software they plan in. If the answer is a spreadsheet, expect variability.
If your parts touch three or more processes, buy from someone who owns the whole chain end to end. The failure mode in multi-process work is the handover between businesses, and if you own those handovers you will spend your week chasing anodisers.
If your requirement is genuinely urgent and one-off, pay for expedite openly and get it in writing. Hoping is not a plan.
The counter-argument to managed supply is real, so here it is. Adding a coordinator adds a margin and, done badly, adds a layer of telephone. It only pays when the coordinator holds the schedule and the sub-supplier relationships, rather than passing messages. Ask directly whether they carry the delivery risk or simply relay it.
What this looks like in practice
TrueNorth quotes a typical three-week lead time on standard machined parts, with a one-week rush route available when the job justifies it. Those numbers go on the quotation, before the order, rather than being discovered later.
Every order sits in an MRP system with a job number and a promised despatch date. That is what makes a weekly status update a lookup instead of five phone calls.
Where we hold the risk is at the handovers. On multi-process parts we own the movement between the machinist, the finisher and inspection, so the two-week anodising queue is our problem to schedule around rather than a surprise that arrives in your week eight.
We also inspect before dispatch. On one square flange order the parts failed at that gate rather than at your goods-in, which cost us the schedule but not your line.
When to switch supplier
Switch when the pattern is dishonesty rather than difficulty. Everyone has a bad quarter. Not everyone hides it.
Concrete triggers worth acting on:
- Two consecutive orders where you learned about the delay after the due date.
- A rebaseline requested with less than five working days' notice, twice.
- A corrective action response that blames operator error and changes nothing.
- Refusal to give you a named contact or a delivery date in writing.
Before you switch, price the switch. Requalification, first article, tooling and the learning curve are real costs. Supplier development is often the cheaper route, provided the supplier engages honestly with the first conversation. If the part is critical either way, read the single-source risk guide before you decide.