How to level the load in production?

The concept of load leveling requires careful analysis of production volumes and schedules so that production makes same quantity of parts both by volume and product mix everyday.

The steps for leveling the load include:
1. Take the total volume of customer orders in a period by product type.
2. Determine the quantity of parts by product so that the same volume needs to be produced by product type.
3. Analyze the time required to make a part by product type and time required for changeover.
4. Plan a stable production schedule so that plant floor doesn't have to deal with fluctuations.

The goal of leveling the load is planning to work at a consistent pace in production making a mix of parts so that the equipment and people are working at the same pace without stopping or being stressed.
Because of this production is not rushed for deliveries giving production folks enough time to implement standard work and avoid errors.

The key to find the mixed model that works for your process/line. Once the mixed model is determined, production has to make the same quantity, mix of products and repeat it everyday.

Load leveling presents many challenges:
- The concept of load leveling is counter intuitive to batch manufacturing where the focus is to run a batch of same product as long as you can and run it efficiently. Load leveling on the other hand says it is okay to changeover from one product to another. In fact load leveling encourages multiple changeovers in a day or a shift.
- Due to the mixed model approach, there may be some amount of finished goods inventory when implementing load leveling. This may make some Lean experts unhappy as they view inventory as waste.
Ultimately it is important to look at the risk of carrying some inventory to satisfy customer demand or make the customer wait for the product they need.
- Load leveling won't be successful without having quick changeovers i.e. reducing changeover time.

Taiichi Ohno explained this with the story of the race between the tortoise and the rabbit. The slow and steady tortoise wins the race. Ohno said it is desirable to be slower but consistent tortoise as it causes less waste than the speedy rabbit who races then stops to rest.

Load leveling is key to becoming lean

The last few posts on our blog focussed on Value Stream Mapping and other lean tools used for waste removal.
Removing waste is the main focus of lean manufacturing.
Value Stream Maps allow lean practitioners to get a true picture of activities done in a process. These maps make waste visible so that it can be removed.
Waste can be removed using lean tools.

In today's world, production volumes change based on customer demand and customer demand fluctuates. Plants practicing Just In Time start producing only when the customer signals for parts. Plants cannot possibly respond to such high variations in demand. So they carry some buffer stock for finished goods.
There may be raw material inventory or WIP necessary to prepare for such demand fluctuations.

Carrying enough inventory is the key to meet customer demands. If plants carry too much they are creating waste and hiding problems.
That is why it is important to level the load so that plants produce at a uniform pace without causing stress to equipment or people. Stressing the equipment could cause breakdowns and stressing people may cause errors or accidents.

But what is load leveling?
Load Leveling is the process of producing the same quantity and mix of parts without responding to every fluctuation in customer demand. This reduces unnecessary stress on equipment or people working in the plant resulting in fewer breakdowns and errors.

The question is how to level the load?
We will try to answer this in our next post.