How to Line balncing or leveling the Production -Heijunka

Dear Friends,

Todays our Topic of  Heijunka-Line balancing or Leveling the production.

In the todays session we can learn about what is Heijunka, what is need of it, how to implement it, Implementation with Practical example (Case study),also benefits to your factory after implement this Heijunka concept.

What is Heijunka?

Heijunka is the “Leveling the type and quantity of production over a fixed period of time. This enables production to efficiently meet customer demands while avoiding batching and results in minimum inventories, capital costs, manpower, and production lead time through the whole value stream.”

Heijunka (pronounced hi-JUNE-kuh) is a Japanese word that means “leveling.” When implemented correctly, Heijunka  helps organizations meet demand while reducing while reducing wastes in production and interpersonal processes.

Relationship Among Predictability, Flexibility and Stability Is Heijunka – When implemented correctly, Heijunka provides predictability by leveling demand, flexibility by decreasing

changeover time and stability by averaging production volume and type over the long term.

Heijunka concept:

Your customer orders will most likely fluctuate from day-to-day. One day they will want 10 black and 5 red parts, the next day could be 12 red and 7 black. The obvious problem in this scenario is that one day the customer will order 15 parts and the next day they require 19. On the third day they may only require 13 parts. Whatever the numbers, they will vary.

Levelized production is used to smooth out that variance. Using the above example, if the level volume is set at 15 parts per day, production would replenish the 15 parts that were ordered. On the second day, as the order is 19 parts (4 parts higher than our levelized production volume) they would still build 15 parts and the shipping area would take 4 parts from an inventory called "Fluctuation stock". On the third day, the order was 13 parts, which is two less than our Heijunka volume, two parts can be rebuilt and put back into fluctuation stock. Heijunka concept applied in two ways as follows.

1) Leveling by Volume or Type

In order to set the level volume for production, you will need a good forecast and a good record of shipping history. The forecasts will be the driving force for setting the volume but the history of customer orders will let you understand the level of fluctuation you can expect from any one of your customers.

This fluctuation is key to setting your fluctuation stock levels. If a customer can vary 30% a day for 3 days, then you will need to be prepared to carry 90% of a day in fluctuation stock. If it can not be replenished throughout the week, it should be rebuilt over the weekend if time allows. This may seem contradictory to the waste of inventory  principle, but this is controlled stock (through the use of kanbans). There is also a huge benefit in other areas that will off-set this inventory.

2) Leveling by Line balancing production (Internal factory)

Here the concept of line balancing come in to picture. Every worker should have to do the  same work to increase the line efficiency. No one should be over burden or no one should be Waiting.

Core Concepts to Guide Heijunka Implementation

Keeping in mind the core concepts about heijunka will help keep a company heading in the right direction.

• Takt time: The time it takes to finish a product in order to meet customer demand; can be thought of as the customer buying rate. It is the guidance for the entire heijunka implementation.
• Volume leveling: Manufacture at levels of long-term average demand and keep a buffer inventory proportional to variability in demand, stability of production process and shipping speed.
• Type leveling: Essentially, make every product every day and reserve capacity for changeover flexibility; use a heijunka box to visualize the production flow and schedule.
• Work slowly and consistently: Taiichi Ohno, founder of the Toyota Production System, says it best: “The slower but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all the workers become tortoises.”
• Changeover time: Efficiency of changeover is the fulcrum of heijunka; narrowing changeover times helps tighten the value stream between supply and demand.

Case Study/Practical Example:

All operator are doing consecutives operation process as Process

 Operator 1 - have 5 Min work to complete Plugging Process

Operator 2 - have 25 Min work to complete Assembly process

Operator 3 - have 15 Min work to complete Taping process

Operator 4 - have 13Min work to complete Testing & Packing

In this condition Operator 1 has very less work to do so he may can produce overproduction or he may ideal.

In case of operator 2 has more work so he required more time he has overburden and pressure

In case of operator 3 has 15 min  work so he waiting for piece to get from Operator 2

In this way all next process are waiting that is wastages.

Here Line balancing Ratio is very Low.

                                         Total work content (Add all times)

Line balancing ratio=       No of station * Longest station

                                      5+25+15+10

Line balancing ratio=     4*25                   = 55%

For improvement purpose we plan to conduct line balancing.

Action-

Time study conducted for each Process.

Sub divided each process as per content wise tact Time

then Redistributed work to each operator as per Tact time

Each operator got almost equivalent work so summary as follows.

Result-

All operator are doing consecutives operation process as Process

 Operator 1 - have 15 Min work to complete Plugging Process

Operator 2 - have 15 Min work to complete Assembly process

Operator 3 - have 1 Min work to complete Taping Process

Operator 4 - have 10Min work to complete Testing & Packing

In this condition Operator 1 has got more additional work of operator 2 so he is not ideal

In case of operator 2 has got balance work so no overburden and pressure

In case of operator 3 has 15 min  work so he not need to wait, he got job on time

In this way all next process are Finished on time without delay, productivity increased.

Here Line balancing Ratio is very Low.

                                         Total work content (Add all times)

Line balancing ratio=       No of station * Longest station

                                      5+25+15+10

Line balancing ratio=     4*15                   = 92%

Benefits of Heijunka Line Balancing-

• Promote one piece flow by line balancing

• Avoid overburden so reduction of stress levels in the production area.

• reduce the wastages like overproduction, rework, motion, over processing

• reduce Variation in the production load and demand

• reduction in inventory levels

• stability of your manpower and reduction of unnecessary overtime.

In this way we can implement the line balancing concept in our factory, we earn more profit also to increase the productivity of the plant. please comments if you have any difficulty in implementing the Heijunka in factory also for any feedback.

Thanks!!!!!