A defect caught at the workstation costs the least

A call from a customer: some of the products in a delivery are defective. The salesperson promises a quick explanation and calls production. That is where the fact-finding begins: which batch, which shift, which workstation. The inspection sheets from that week say everything was in order - they were filled in in bulk, at the end of the shift, after the products had already been packed.

Two days later, this much is known: the defect may have originated at one of two workstations, further batches from the same period are waiting in the warehouse, and one has gone to another customer. Each of them has to be checked by hand. The cost of this single defect grows by the hour, even though the defect itself arose several weeks earlier and could have been detected throughout that entire time.

Why end-of-process inspection fails

In many plants, quality control works at the end: the product goes through all the operations, and only before it is handed over to the warehouse does someone check whether it is good. This arrangement has an economic flaw built in. Each operation adds labour, energy and machine time to the product, so a defect that originated in the first operation and is detected at the end costs all of that added value. Detected at the customer's, it additionally costs transport, repeat production and trust, which does not appear on any document.

The second weak point is the way results are recorded. Measurements end up on a paper inspection sheet, often in bulk and after the fact. Such a sheet meets the formal requirement, but it does not link the result to a specific order, raw material batch or machine settings. When a complaint arrives, the documentation exists, yet the answers have to be sought outside it: in the operators' memories and in the dates on printouts. On top of that comes the knowledge of proven machine settings, which lives in the head of the most experienced person on the shift.

The solution in three elements

The first element is a measurement recorded at the moment it is taken, at the workstation. The operator has a tablet or a scanner, scans the order code, enters the measurement result and documents a defect with a photo in a single step. The record links itself to the order, the raw material batch, the workstation and the time. The inspection sheet stops being a separate task at the end of the shift - it builds itself from the records collected during the day.

The second element is tolerance limits and holds. Each measured characteristic has a defined range. A result outside the range immediately flags the product as on hold and sends a notification wherever it is needed: to the foreman, the process engineer or the production manager. The mechanism also enforces the sequence: the next operation will not accept a product with an open hold, so the defect stops where it originated and no longer flows further through the process.

The third element is a quality history attached to the order. When a complaint comes in, the answers to the questions of when the defect arose, what else may have it and where those products are now follow directly from the records: you can see the batches produced under similar conditions, those waiting in the warehouse and those that have already shipped. Trends are visible too: a characteristic that has been edging towards the tolerance limit for weeks signals a problem before the first piece falls outside the range.

What this means for the business owner

The calculation is worth doing on your own numbers. How many quality complaints did the company handle in the last year, and how much did each one cost: transport, repeat production, the time of people taken off their day-to-day work? How many products managed to pass through subsequent operations before the defect was detected? How many days did it take to establish the cause, and how many customers were waiting for an answer in the meantime?

On the other side of the calculation stands a change that is small from the shop floor's perspective: a measurement that is taken anyway is recorded straight away, where it was made. Hardly any new activities are added, while retyping and filling in sheets in bulk disappear, and handling complaints stops resembling an “investigation”.

Where to start

With one characteristic that complaints depend on: a dimension, a weight, a process parameter or a visual assessment. One workstation, one tablet, tolerance limits taken from the product documentation or agreed with the process engineer. For two weeks, measurements are recorded at the workstation and compared with the existing routine. A review after that period shows how many results fell outside the range, how many products were put on hold and how many of those holds were justified. Then the scope grows to further characteristics and workstations - always following the process the company already has.

How people from manufacturing companies in Poland and in Germany, Austria and Switzerland describe problems in work organisation in their own words - from documentation kept “for the audit” to knowledge held in one person's head - is what I show in the report “Excel, paper notes and the one person who knows” - you can download it there as well.

If this description sounds like your company, write to me or book a meeting - we will walk through your inspection process and check which measurements are worth recording at the workstation.