In Part 1 of this series we exposed the dangers of asking a sourcing agency to conduct inspections and audits. We also explained why working on a man-day rate is better than a % of PO value when contracting inspection services.
Now let’s take a look at how man days are calculated.
This is critical knowledge for buyers because we want to make sure our inspection agent is checking enough units to give us an accurate assessment of the order’s overall quality but we also want to keep the man days to a minimum and control costs.
The “man day” system explained
Here is an excerpt from a related Asia Quality Focus blog post:
“A unit of one day’s work by one person”
In the quality control industry the man-day is considered as a workload unit.
From the buyer’s point of view, the “man-day” is a system that allows direct and quick QC cost calculations.
“Man”: both women and men work as inspectors. Qualified staff is crucial for reliable quality control. Inspectors spend their time checking products quality and conformity in factories in order to protect the importers’ interests.
“Days”: A meaningful inspection takes four to six hours. Inspectors should only perform one QC per day, to ensure reliable results.
1 man-day is one day work for 1 QC staff,
2 man-days can be: two days work for 1 QC staff or 1 day work with 2 QCs
It’s fairly easy to understand the term “man-day”, so let’s now turn our attention to a more complex topic: “what is the relation between man-days and the AQL table?”
The standard definition of AQL (Acceptance Quality Limit) is “the maximum defective percent (or the maximum number of defects per hundred units) that, for purpose of sampling inspection, can be considered satisfactory as a process average”. A sampling size, based on the AQL tables, will be selected and then inspected for defects. Defects are broken into 3 categories: Minor, Major and Critical. According to the number of defects found for each type and according to the number of defects allowed (figures given by the AQL tables), your inspector will advise you to accept or to reject your shipment.
Visit here to see the AQL tables and learn how to use them.
Let’s say we have an order of X units. AQL tables will tell us to inspect Y number of random samples. But “how many man days are needed to inspect Y samples” you may be asking. Here is an excerpt from an inspection blog which offers some useful benchmarks:
For a basic consumer hardlines, an inspector is able to check between 200 and 315 pieces in a day.
For a basic consumer electronics item, an inspector can usually check between 125 and 200 pieces in a day.
For garment inspections the QC inspector is able to inspect 80 to 125 pieces per day.
In the three examples above, the inspection cost would be 1 man-day. For larger sample sizes, the inspection cost would increases to 2 man-days or more.
But in terms of the time needed to complete the inspection, it comes down to how staff is allocated. You could send 1 inspector for multiple days or multiple inspectors for 1 day.
About the author: Mike Bellamy
Advisory Board Member & Featured Blogger at the not-for-profit China Sourcing Information Center (www.ChinaSourcingInfo.org). Author of “The Essential Reference Guide to China Sourcing” and founder of PassageMaker Sourcing Solutions.