Theory of Constraints

A backlog at the bakery

A backlog I witnessed once occurred at a bakery where I worked. The bakery specialized in the production and distribution of brown bread to restaurants and supermarkets. The procedure had an issue because it frequently delivered late to clients. The stages of bread production and distribution were as follows: dough preparation, baking oven, packing, and loading. The loading procedure entailed organizing the packaged bread into crates and placing them into vans awaiting delivery to the customer, which was where the issue arose. It would take a long time to finish putting the bread into crates and loading them into the vans, which had two consequences: process blocking and process famine. Processing blocking means that there was no longer enough room to store the packaged and sliced bread which was coming in fast. The effect was causing inventory to build up in the previous stages, and baking and packaging had to be stopped to allow for enough time to fully load the vehicles. Process starvation means that the bottleneck caused delivery to stop to the extent that a lot of vans wait to be loaded causing significant delays in delivery.

Improvement of the bottleneck

Workers are the limiting factor in the loading stage. Therefore, improving the bottleneck requires adequate staffing and task levelling and scheduling. Appropriate staffing means getting extra workers, possibly from other departments to lend a hand in the loading process. Insufficient labor might be a reason behind the bottleneck and increasing workers in this stage might alleviate the problem. Task scheduling will involve distributing the workload across the loading team according to task duration (Moon, Lee, Shin, & Ryu, 2016). As pointed out earlier, loading comprises arranging bread into crates and loading into the delivery vans. Organizing bread into crates takes a short process, and fewer workers should be allocated. Carrying the bread into the vans takes a longer duration, and therefore, more workers should be taken on this workload, significantly reducing the time required.

Impact of the theory of constraints (TOC)

TOC is a technique that identifies the constraint that stands in the way of achieving a goal and then improving it until it no longer is the limiting factor. Step five of the TOC is “repeat the process” whereby after improving the bottleneck, the management has to go back at the beginning and start over. The impact of the four stages will be:

Identify the system constraint

In this step, the management has determined that the loading stage is the bottleneck because bread is backing up at the packaging stage. Loading cannot be performed fast enough to keep up with the inflow of packaged bread resulting in slowing down of the delivery process. The management of the bakery has identified loading as the bottleneck. Therefore, the impact is that the management has to understand the effects of the limitation of labor and the poor scheduling of tasks as the limiting factors.

Decide how to exploit the system constraint

In this stage, TOC seeks to ensure that the constraint is made as effective as possible. TOC focuses on ensuring a buffer at this stage, and the effect is that the management should seek for an inventory buffer immediately after packaging (“Focus Improvement on the Manufacturing Constraint”, 2017). For instance, the management should have dedicated a part of the warehouse to storing the bread to ensure that continuous operations, that is, the packaging is not interrupted and loading can continue.

Subordinate and synchronize everything else to the decision

The goal is to shift the non-bottleneck resources to the loading department since attempts to improve efficiency in the baking stage, or any other stage will not alleviate the bottleneck. The impact is that the bakery must move resources from other areas to the loading stage to reduce the backlog of packaged bread to be loaded.

Elevate performance of the constraint

The TOC at this stage focuses on making substantive changes to improve the efficiency and capacity and thereby, loosen the constraint (Cox III, Robinson, & Maxwell, 2014). The impact is that the management must provide more labor to the loading stage. For instance, staff may be moved from the dough preparation or even use the drivers in the loading process. Also, the management has to use performance data to identify which task (between arranging bread and carrying bread to vehicles) is the largest source of lost productive time at the constraint.

References

Cox III, J. F., Robinson, T. M., & Maxwell, W. (2014). Applying the“ Theory of Constraints” to Solve Your Practice’s Most Vexing Problem. Family practice management, 21(5), 18-22

Focus Improvement on the Manufacturing Constraint. (2017). Leanproduction.com. Retrieved 13 August 2017, from http://www.leanproduction.com/theory-of-constraints.html

Moon, I., Lee, S., Shin, M., & Ryu, K. (2016). Evolutionary resource assignment for workload-based production scheduling. Journal of Intelligent Manufacturing, 27(2), 375-388