In short: A qualification target and a qualification cycle time are the same arithmetic, so four hundred approvals across thirty six months at a seventy percent audit pass rate needs roughly sixteen audits a month, and a team running six will miss whatever attention it receives. Little's Law, from John Little's 1961 proof, sets work in progress as throughput multiplied by cycle time, so eleven approvals a month on a nine month cycle requires about a hundred suppliers inside the process at all times. Stages that do not depend on each other, such as financial checks and technical document review, can run in parallel, and serialising them adds elapsed time without adding assurance. Risk tiering keeps process depth proportionate to exposure, so a low spend supplier does not consume an audit slot a critical one needs.
A localisation programme commits to four hundred qualified suppliers over three years. The qualification process, measured honestly from first contact to an approved vendor record, takes about nine months. The team running it processes roughly six audits a month with the auditors it has. Everyone in the steering committee has seen the target and the timeline. Almost nobody has multiplied them together.
Four hundred over thirty six months is eleven approvals a month at steady state. If the audit stage passes about seven suppliers in ten, you need somewhere near sixteen audits a month to yield eleven approvals, against a current capacity of six. The programme is short by a factor of two and a half at one stage, and no amount of executive attention on the other stages changes that.
There is a second consequence of the same arithmetic that gets noticed even less often. Little's Law, from John Little's 1961 proof, gives work in progress as throughput multiplied by cycle time. Eleven approvals a month with a nine month cycle means about a hundred suppliers have to be somewhere inside the process at all times. If the team is currently carrying thirty, the shortfall is a pipeline problem rather than a pace problem. The programme has never had enough work in the pipe to hit the number, and adding urgency to the thirty will not create the missing seventy.
The stages, and where the queue actually forms
A real qualification in a plant or a project environment has five gates, and they are not equally expensive.
Commercial and financial screening. Registration, legal standing, ownership and sanctions checks, financial statements, insurance, and basic compliance. Mostly document collection and verification. Fast when the supplier responds and slow when they do not, which makes supplier responsiveness the dominant term rather than internal effort.
Technical capability assessment. Can this supplier make the thing to the specification. Equipment list, process capability, engineering capacity, certifications relevant to the scope, sometimes a technical questionnaire that runs to hundreds of lines. This is engineering time, and engineering time is committed to projects.
Quality system audit. An on-site assessment against ISO 9001, or a sector standard such as ISO 29001 for petroleum, petrochemical and natural gas, or API Spec Q1 for manufacturers and Q2 for service supply organisations. Auditor time plus travel plus report writing plus a corrective action cycle with the supplier. This stage carries the longest internal resource commitment per supplier.
Sample and trial production. A first article, a production part approval submission of the kind formalised in the automotive PPAP process, a trial batch, a witnessed test, a field trial. This needs the supplier's plant, your inspection presence, and frequently a slot on your own operating plant to consume or test the output.
Final approval and vendor record creation. Category assignment, terms, master data setup, and the approvals to make the supplier orderable in the ERP.
Ask where the queue forms and most programmes will say the supplier is slow. Measure it and the answer is usually the third and fourth gates, for the same underlying reason: they are the two stages that consume a scarce internal resource with an external scheduling dependency. An auditor cannot audit two suppliers at once and a trial cannot run without plant time. Everything else is document handling that can be scaled by adding coordinators.
The distinction worth holding on to is between stages bounded by effort and stages bounded by a resource with a calendar. Effort-bounded stages respond to headcount and to better tooling. Calendar-bounded stages respond only to more of the resource or to fewer suppliers needing it.
Parallelising the independent stages
The default design is sequential, and the default has a reason. Each gate is owned by a different function, each ends in a decision, and nobody wants to spend their function's effort on a supplier who is going to fail an earlier gate. So procurement finishes screening, then hands to engineering, then engineering hands to quality, and each handover sits in a queue waiting for the receiving function's next planning cycle.
Sequencing optimises for effort avoided. It pays for that with cycle time, twice over: once in the work itself and once in every handover queue between stages. In a nine month process, the intervals between stages are frequently longer than the stages.
Most of these gates are technically independent. Financial screening and technical capability assessment share no inputs. A quality system audit can be scheduled while a technical assessment is in progress. The only genuinely dependent pair is that trial production usually needs the technical assessment complete, since you have to agree the specification before you can make a sample against it.
The cost of parallelising is wasted effort on suppliers who fail. That cost is calculable rather than theoretical, and the calculation usually favours parallelising. Take the stage conversion rate: if eighty percent of suppliers pass technical assessment, running the quality audit in parallel wastes an audit on one supplier in five. Compare that against saving six weeks of cycle time on all five. The comparison depends on the audit's marginal cost and on what the six weeks are worth to the programme, and in a programme that is behind on a committed target, the six weeks are usually worth considerably more.
There is a middle path that gets used less than it should. Run the cheap screens sequentially and fan out only after the first gate, so you eliminate the obviously unsuitable at low cost and then compress everything that remains. This preserves most of the effort saving and captures most of the cycle time reduction.
Risk tiering so the process fits the exposure
Applying one process to every supplier is the single largest source of wasted qualification capacity in most programmes. A supplier of general fasteners and a supplier of a critical valve on a hydrocarbon service both take nine months and both consume an auditor.
Tiering means defining the process by what a failure would cost. The dimensions that matter are the criticality of what is being supplied, whether the item is on a safety or an integrity path, whether an alternative source exists, and the spend. A tier one supplier of a critical rotating item gets the full sequence with an on-site audit, a witnessed trial, and periodic re-audit. A tier three supplier of a commodity consumable gets document verification, a certification check, and a conditional approval that becomes full approval after a defined delivery history without a quality event.
The performance-based route is worth calling out because it is underused. A supplier who has delivered acceptably for a year has produced more evidence about its quality system than an audit does, and converting an initial approval into a conditional one with monitored performance criteria moves the assessment burden from a scarce auditor to data you already collect. This works for lower tiers and it does not substitute for an audit where a regulator or a certifying authority requires one.
The governance question that decides whether tiering survives is who assigns the tier. Left to the requesting function, everything becomes critical, because nobody wants to be the person who tiered down the item that later failed. The tier assignment belongs with a category or engineering authority working from a defined criticality rubric, and the rubric should be written down and applied consistently enough that an auditor can reconstruct why a supplier landed where it did.
Turning a rejection into a development plan
A supplier who fails an audit is usually not a supplier who cannot do the work. They are a supplier who lacks a documented calibration system, or a traceability procedure, or a qualified welding procedure specification for the material in question. The gap is specific, it is frequently small, and the standard response is a rejection letter that names none of it.
A capability gap assessment records what the supplier can do against what the scope requires, at the level of individual requirements rather than a pass or fail. The output is a gap list with an effort estimate against each item and an indication of whether the gap is closable in months or in years. Missing documentation is months. Missing metallurgical capability requiring capital equipment is years.
This matters in three ways. It gives the supplier something actionable, which is the difference between a development programme and a filter. It gives the programme a forward pipeline, because a supplier three months from qualification is a known future approval rather than a lost lead. And where the programme has a development budget, whether for training, for certification support, or for shared inspection resources, the gap lists across the whole rejected population tell you where that budget goes. If forty suppliers all fail on the same clause of the same standard, the answer is one training programme rather than forty conversations.
The connection to localisation content targets is direct and it is a separate decision with its own economics, so which capability gaps are worth funding sits with the portfolio question rather than with the qualification process (N2).
Measuring the funnel rather than the count approved
The usual programme metric is the number of suppliers approved to date against target. It is the least informative number available, because it tells you where you are and nothing about whether you will get there.
Two families of measure fix that. Stage conversion tells you the proportion of suppliers entering each gate that clear it, and it identifies where the population is being lost. A ninety percent conversion at screening and a fifty percent conversion at audit is a sourcing problem, since it means the suppliers being brought in are not close enough to qualifiable, and the fix is upstream in identification rather than in the audit.
Stage cycle time tells you where the calendar goes, and it needs to be split into working time and waiting time to be useful. A quality audit stage showing forty five days average is a different problem depending on whether that is forty five days of auditor work or three days of work and forty two days of waiting for a slot. The first needs more auditors. The second needs scheduling.
Together they give you a forward projection: current entry rate, times the conversion rates through the stages, gives an expected approval rate; and the cycle times tell you when those approvals land. Comparing that projection against the committed target is the only version of the programme status report that supports a decision. It converts the conversation from how many have we done into which single stage do we need to unblock, and the answer is usually one stage.
Add cost per approved supplier if the programme has a budget. It falls naturally out of the same funnel data and it is the number that makes the case for tiering, because it shows what full-process qualification of a low-criticality supplier actually costs.
The limit
Cycle time in this process is frequently bound by trial production, and no process improvement compresses a physical trial. A trial batch that takes six weeks to run, cure, test and evaluate takes six weeks. A field trial on a piece of equipment that has to demonstrate performance over a duty cycle takes as long as the duty cycle. Where the trial needs a slot on your own operating plant, it competes with production, and production wins, so the wait for the slot can exceed the trial itself.
This has a consequence for how the programme should be planned. Work backwards from trial capacity rather than forwards from supplier identification. If your plants can absorb four trials a quarter, the programme's ceiling is sixteen a year through that path regardless of how many suppliers you screen, and the honest options are to add trial capacity, to accept trials at the supplier's site or at a third party laboratory where the standard allows it, or to widen the tiers so that fewer suppliers need a trial at all.
The second thing no process change fixes is that some suppliers genuinely cannot meet the requirement. A qualification programme measured on approvals has a standing incentive to lower the bar, and the pressure gets worse as a deadline approaches. The defence against it is that the tier rubric and the acceptance criteria are set by a technical authority who is not measured on the programme's approval count, and that any waiver is recorded with a name against it.
Take last year's qualification records, compute the conversion rate and the average elapsed days at each of the five gates, and split the elapsed days into working and waiting. That table normally fits on one page and it usually identifies the one stage that is setting the programme's ceiling.