Flow: Going against the psychological grain
In the previous article, we discussed some of the fundamental reasons that batching is typically slower than the most popular alternative process: the flow process. In this section, we will briefly discuss the main reason behind the human tendency toward batching: a confirmation bias toward an appeal to tradition.
Batching is a process that likely arose during hunter-gatherer times. Since then, it has propagated down history. We are predisposed to it. When someone batches, (due to confirmation bias) they will be paying close attention to its perceived benefits and ignoring any tangible detriments. Have you ever noticed how productive and expedient a process feels during certain stages of batching? This sentimental experience keeps us coming back to batching again and again.
We actively ignore the higher costs of setup, fatigue, and errors in favor of that sentimental belief that it is somehow faster. We are even disinclined to measure batching up against an alternate method since "of course our way is the best way!"
A brief definition
As stated previously a batched process can be defined as:
We can give a similar definition for a flow process as:
A flow process only runs in response to real demand in real time. This is its relation to the just-in-time philosophy which pervades manufacturing in the East.
An example from the previous case study
With our working definitions in place, let's look at an example taken from the previous blog article, albeit in an unapologetically handwaving fashion.
While processing orders in a batch pick/pack format, we discovered that the potential for errors were incredibly high due to the packer having so many choices which led to errors and defects. Recall that given a set of 10 invoices and 10 labels, there is 1 way to produce the correct invoice & label pair for the first order and nearly 200 incorrect ways.
The most significant difference in the flow process is that all of these choices are eliminated. Instead of relying on the employee to make this 1:200 choice, they are presented with no choice: they are only given the products, invoice, and label for a single order. This implementation alone results in exceptionally low error rates.
Second, this continuous flow process eliminates the time sink created by "double checking". We saw in the previous article that this action was costly in many dimensions: time, money, business reputation.
A continuous flow methodology is typically more efficient and effective than a batched process attempting the same final product. In order to know which is best for your particular business needs, however, you must experiment! Measure the relative costs of each method with a sufficient number of trials and variations and you will have your answer!
Happy businessing, internet!