My last post on the understanding of SAM and SMV attracted a lot of people to discuss on the two concepts- widely used but also widely confused in the apparel industry. We call it standard time but there exists so many variants on the concept of the two.
If we go by the books, the famous book on apparel manufacturing by Glock and Kunz talks about production standard rate. It goes like this, “A production standard is a rate, stated in Standard Allowed Minutes or Standard Allowed Hours, which reflects the time period for a normal operator to complete one operation using a specific method.”
The allowances which are added to SAM are defined as “An allowance factor is the percentage of time added to the normal time to cover the short delays and interruptions in work that are part of the operations. Allowances are made in production standards to include non-productive time that occurs as the part of the production process.”
Another renowned book ‘Introduction to Work Study’ by G.Kanawaty defines standard time as “the total time in which a job should be completed at standard performance- i.e. work content, contingency allowance for delay, unoccupied time and interference allowance, where applicable.”
When it comes to the difference between the SAM and SMV, there’s one article by Prof. Prabir Jana which very nicely puts various thoughts on the variations:
“There are three school of thoughts:
First, both are same;
Second, SAM is an extension of SMV; and
Third, SAM and SMV are completely different measures.”
This is what the 3 opinions talk about:
1. There is only a reference of standard time given in all work study books and there is neither any definition nor any mention of the terms SAM and SMV. These terms are used variedly in American and European books. So, all American books mention SAM and factories under the influence of American consultants use the term SAM, while European books mention SMV and factories in Asia which are under the influence of European consultants use the term SMV.
2. When SAM is used as an extension to SMV, then allowances like policy allowances are added to the standard time (SMV) which makes the SAM as the allocated time rather than measured time.
3. The third notion states that standard allowed minutes is the time that is assigned to a specific operation after doing time study or using PMTS. While Standard Minute Value is the cost factor (in cost/minute) that is multiplied with SAM to get the cost of the operation.
To summarize this important and rather confusing topic, I would like to put forward my point of view on this. First of all, Let’s just use the term standard time, this should be calculated using any of the 2 methods:
1. PMTS – Pre-determined motion time study using any of the standard systems that provide time units for every motion. This should be done by properly trained personnel. This is one of the most accurate and fair ways to determine time.
2. Time study with the factor of rating applied to it. This completely depends on the operator being observed and the rating being provided by the observer based on his/her experience. This is often prone to questioning about its fairness and accuracy.
Once standard time is determined we need to add certain allowances. These allowances can vary on various parameters such as, work environment, work station, bundle size etc. We can go into the details of these allowances in a separate discussion. Once these allowances are added this gives us standard allowed minutes or SAM. This is the time measure which defines a fair time to do a job @ 100% efficiency. This time measure then becomes the base of various other calculations in the factory such as production targets, current efficiency, capacity etc.
If we use the correct mathematics and procedure that should solve for all practical considerations.