Batch Testing
An Integral Part Of The Safety Chain
Batch testing is an integral part of Wild Country's quality system.
But what does 'batch testing' mean? And how does it work?
Effectively, this means that each 'batch' of any material / product / or safety critical part of product, whether there are 10 made or 500 made, are tested to a to 3 Sigma standard. (See 3 Sigma page for an explanation of this term.)
And we use a recognised standard statistical formula used to determine how many of each 'batch' need testing to give us this valid and valuable result.
The results must then be compared with either the CE norm - if applicable - or the standards set out in our own design specifications.
Thus this test would be used on, for example:
- A roll of 12mm Dyneema that has arrived from our supplier - this would be tested against our own design specifications supplied to the manufacturer.
- A batch of 'safety critical' parts for a larger product i.e. the belay loops for harnesses are made in seperate operation. These are then batch tested before they can be put into ‘Stock' – from where they can be taken to be added to other ‘parts’ and used to make a finished harness. Tested to CE norm.
- A batch of 12mm slings. Yes they have already been tested for the integrity of the webbing but then when they are sewn to make a finished product they are tested for the integrity of the sewing. Tested to CE norm.
How many are tested in each batch? And which are tested?
For any batch, no matter what the size, with three sigma testing the minimum amount of a material to be tested would always be three. (As an aside, this is why it is very uneconomic to make small batches – as the testing for even a batch of 20 is nearly as time consuming as for a batch of 500)
As the batch get bigger the batch testing can vary in size to take in more testing and this is determined by a statistical formula.
On sewn goods, i.e. slings, or safety critical harness parts, Wild Country for example uses the following:
- Batch size up to 50 – 3 x First Off and 1 x Last Off
- Batch size 50 to 100 – 3 x First Off and 1 x Last Off
- Batch size 101 to 500 – 3 x First Off 1 x Mid Off and 1 x Last Off.
- Batch size 501 to 1000 – 3 x First Off 1 x Mid Off and 1 x Last Off. Retest daily.
(First Off - being the First ones sewn in a batch – essentially this determines that the ‘automat’ sewing machine has been set up correctly.
Last Off – The last one in a batch. To make sure that nothing has changed during the course of a sewn batch.)
Batch Coding – It is important to note that each batch has its own traceability number which is used as part of the results system…see below.
SEE ‘Video of In Process Batch Testing 3 x First Off 12mm Dyneema slings’
SEE ‘In Process Batch Testing Certificate’ for slings
Results and Traceability
As part of the ISO9001 procedures there must be total traceability within the system so it is critical that the results for each test are kept. And indeed these results accompany the product around the factory, making sure that at each stage of production each part can be verified as having been tested, and the results of each test seen.
For example:
When a harness is being made and it has multiple ‘safety critical’ parts, our system is designed so that the results for the testing on all the parts issued or built, accompany the product around the factory on a single sheet that each operator has to use, fill in, sign and date.
And even when the product has been sold the results are stored for 10 years.
This means that in the future if there was an ‘incident’, of sling failure for instance, Wild Country would be able to trace any sling by its ‘Batch Code’ to prove that it had been statistically reliable when it left the factory.
We would know:
When the webbing was supplied / By whom / Who tested the original webbing for it’s ‘Goods In’ certificate.
When it was sewn / Who sewed it / Who tested it / The test results.
SEE ‘Harness In Process Test Sheet’ PDF below.
Athough this is obviously a little complex to follow, it basically shows how many procedures the harness goes through in its journey around the factory and in its stages of construction...
