Define Heijunka and explain its importance in lean manufacturing. How does Heijunka contribute to achieving a balanced production flow and minimizing waste in the manufacturing process? Provide examples to illustrate its significance.

In a manufacturing facility producing five types of products$-$A$,B,C,D,$ and $E-$the customer demand per month is as follows: $6000$ units of $A,2400$ units of $B,2400$ units of $C,600$ units of $D$ and $600$ units of $E.$ Each product requires the same amount of time to be produced. Assume that there are $20$ working days in a month. The facility operates for $9$ hours per day, with a total break time of $120$ minutes. Using Heijunka levelling by type, determine the production sequence for each product type to meet customer demand. Show your work.