The difference between Quality Assurance and Quality control

One of the very first doubts that tormented me from the day I was made part of the "Quality" team in my company is- what is the difference between Quality Assurance and Quality control???? And it has taken me a little less than 3 years to really understand the difference!!! I want to present the essence of this understanding to you, dear reader, so you have a good understanding early on.

Generally, any organization is set up to provide either products or services to its customers. For my explanation, i am going to choose as an example, ABC Inc., an organization that makes a simple thing as a ball point pen.

In order to make the body of the pen, ABC inc. has to procure the plastic for making the body of the pen, machinery to mould the body of the pen and so on.

Before ABC Inc. buys the plastic, they should (ideally) have researched on which plastic will best suit the features of the pen, and then look at who are the raw material manufacturers in the market who can provide this particular plastic. Then, after listing out potential raw material vendors, ABC Inc. would see, shich of them has a reputation of standing, which of them have established processes to supply the correct plastic everytime, on time and at the most competitive price and a host of other considerations. Once such a thorough evaluation is done, ABC Inc. decides to go for Trans- Plastics as their vendor. Similar exercise follows for all items obtained from other vendors. AS for machinery, they would list out the specifications of the machinery that can make the exact pen they have designed, look for machinery manufacturers, evaluate the manufacturer and machinery cost etc. and then zero down on a particular machine.

Then ABC Inc. would run a trial production run to see if the machinery and plastic together product the pen that will meet all the quality requirements listed out during the design of the pen. Once all concerned authorities accept that the pen prototype meets all requirements, a GO will be given for mass production.

All these activities- namely, systematic listing of specifications of the plastic and machinery, scouting for the right supplier and accepting a supplier after objective evaluation, and the prototype production to validate the production process- all happen before the actual marketable pens are made. All these are done to ensure that the pens can be produced to be acceptable for sale. These activities can all be termed as Quality Assurance Activities.

Now, everything is set up and ABC Inc. begins production run. they produce 10 batches of the pen- each batch containing 500 pens. AS soon as the plastic body is created by the machinery, a mechanism is put in place to check if the plastic body is in perfect shape- no deformations, no discolorations, threading on the bottom edge of the plastic is proper etc. (this list of things to be checked are all pre-listed). Suppose a specimen is found with some feature that makes it unusable, the specimen is termed as "Non-conforming" and is separated from the acceptable specimens. This exercise is repeated for the pen cap, the refill, the Ball point tip and so on.
Only those pen parts that meet all the specified list of criteria for acceptance will be put together into a complete pen, which again will be checked for acceptance-( is the ink flow just right?, for example).

These activities, during and after the actual making of the product can be collectively called as Quality Control Activities.

Activities such as the maintenance of the machinery also fall under Quality Assurance, because, this activity ensures that the machine is in proper health to produce the acceptable product.

In short,

Activities that precede the actual making of the tangible product, which activities are undertaken so that all of man and machinery required for the making of the product are of the best quality, to ensure that the end product is one of acceptable quality are all QA.

Activities that follow the making of the actual tangible product, to check that all criteria for the acceptability of the product are met, and to undertake a next course of action in case of unacceptable product fall under QC.