A batch from a supplier turns out to be defective. Now the question that needs to be answered is: how many products were produced from this batch and who did those products go to?
In a business without a traceability setup, there is no answer to this question. The only option is to recall all products sold during that period.
In this article, we explained how to establish traceability in assembly manufacturing, the relationship between lot and serial numbers, the warranty connection, and the recall scenario.
Table of Contents
What is traceability?
Traceability is having a record of where every component inside a product came from and where that product went.
It works in two directions. Forward tracking shows where products manufactured from a batch went.
Backward tracking, on the other hand, reveals which parts were used in a product you have on hand.
Both directions feed from the same records; once the link is established, both questions become answerable.
Recordsare kept in the production moduleand linked to stock movements.
Which parts should be tracked?
Trying to track every single screw will quickly make the system unusable. The scope must be defined.
The critical metric is the magnitude of the consequence should that part fail.
Safety-critical parts must be monitored in all cases. The possibility of a recall is real for these.
High-value and in-warranty components should also be monitored.
Standard consumables can be excluded from tracking; the benefit does not justify the cost for them.
Lot registration on the incoming side
The traceability chain begins when the material enters the warehouse. If this step is skipped, none of the subsequent records carry any meaning.
The supplier batch number must be recorded at every goods receipt. This number enables tracing all the way back to the supplier.
An in-house lot number can also be assigned; this is more reliable when supplier numbers are inconsistent.
The entry date and expiration date, if applicable, must also be recorded.
We detailed the lot structure in the batch lot tracking article.
Establishing a connection in production
Specifying which lot was consumed when issuing a production order forms the middle link of the chain.
Without this record, it is impossible to know which batch was used in which production run, and the tracking breaks.
Barcode scanning should be used to reduce the recording burden; manual entry is both slow and prone to errors.
Multiple lots of the same material can be used in a single production run; in this case, all of them must be recorded.
Applying the first-in, first-out principle is a practical routine that reduces lot confusion.
Finished product serial number
Assigning a serial number to each manufactured product is the product-side equivalent of traceability.
The serial number is linked to the production record of that product and, consequently, to the lots used.
Numbering should be simple and sequential; codes loaded with meaning create problems over time.
The serial number must be permanently marked on the product; a removed label ends the tracking.
We discussed when serial tracking is necessary in the serial number tracking we discussed in the article.
Connection to the sales side
The final link in the chain is recording which customer the product was sent to.
During shipment, the serial number must be written on the dispatch note. Forward tracking cannot be done without this step.
In sales through a dealer, the chain breaks at the dealer; additional records are needed to reach the end user.
Product registration forms or warranty activation are common methods that close this gap.
The shipment flow shipment preparation we explained in the article.
Warranty and service relationship
The most tangible benefit of traceability in daily operations emerges during warranty processes.
The production date is found from the serial number, and the warranty period is calculated without hesitation.
It is known which parts were used in the product arriving at service; the correct spare part is sent on the first try.
Recurring failures coming from the same lot are also noticed with these records.
The spare parts process warranty and spare parts tracking we discussed in the article.
Recall scenario
The real test of traceability occurs when a recall is necessary.
When the problematic lot is identified, all finished goods produced from that lot can be listed. The scope narrows down clearly.
Then, the customers these finished goods went to are found and only they are contacted.
Without tracking, the entire period is recalled; the cost and loss of reputation multiply manifold.
It is recommended to test this scenario in advance; it must be ensured that the system works in a real situation.
Setup order
Starting traceability setup with all products makes the project unnecessarily heavy.
First, critical parts are identified and lot tracking is opened only for them.
Then, the recording discipline on the receiving side is established; this is the weakest link in the chain.
Next, lot selection comes into play on the production side, and barcode scanning is implemented.
Finally, the serial record on the shipping side is added, and the chain is completed.
Points to consider
The breaking of a single link in the chain renders all traceability useless. Therefore, discipline is required at every step.
The recording load is felt most heavily on the production side; barcode scanning significantly reduces this load.
Keeping the scope broader than necessary also causes the system to be abandoned; staying limited to critical parts is more sustainable.
The durability of the labels should also not be overlooked; an unreadable label renders the record useless.
If your industry has legal traceability obligations specific to you, the scope must be determined accordingly.
Frequently asked questions
Is it mandatory to assign a serial number to every product?
It is not mandatory; depending on the product group, lot-based tracking may also be sufficient.
Can retrospective traceability be established?
It cannot; a link cannot be established for the period when records were not kept. Therefore, starting early is important.
Can the end user be reached in dealer sales?
It is possible only if there is product registration or warranty activation; otherwise, the chain breaks at the dealer.
Is the same structure valid for food production?
Similar; for additional obligations, see the lot traceability in food production article.
Traceability is an investment that is not visible in normal times but multiplies its value when a problem occurs.
Start by keeping the scope limited to critical parts; trying to track every component causes the system to be abandoned from the start.
Pay special attention to the lot record on the receiving side; this is the most frequently broken link in the chain.
Be sure to implement barcode scanning as well; manual lot entry is both slow and prone to errors.
Test the recall scenario in advance; it is too late to find out if the system actually works at the moment of a problem.
By consulting with the EQLEM team, you can plan your traceability setup.