Theory of constraints

The Goal - Theory of ConstraintsThink it was back in 1993 I first read The Goal by Eliyahu Moshe Goldratt. The book was one of the first and most notable in the genre of business novels. The book – The Goal – introduces the theory of constraints (TOC) process for improving organisations. The book is set in a manufacturing company. However the book provides the context for a more generic approach to continuous improvement.

Theory of constraints

The theory of constraints is a paradigm that states that the output of a process is limited by a very small number of constraints. In a process there is always at least one constraint. TOC offers a process to determine the bottleneck/constraint and than restructure either the constraint or the work around it so the constraint can deliver it’s maximum output. Since the bottleneck’s output determines the output of the business process, other optimisation are local suboptimal interventions that do not generate any real business value.

The theory of constraints boils down to:

A chain is as strong as its weakest link.

More verbose: An organisation (especially a process or a business) is only as strong or powerful as its weakest activity or person. A group of associates is only as strong as its laziest member.

Constraint

A constraint is anything that prevents the system from achieving its goal. In TOC, the constraint is used as a focusing mechanism for management of the system. The concept of the constraint is analogue to the one in mathematical optimisation. In optimisation, the constraint is written into the mathematical expressions to limit the scope of the solution (X can be no greater than 5).

Types of (internal) constraints:

  • Equipment: The way equipment is currently used, is the limit to the ability of the system to produce more saleable goods/services.
  • People: Lack of skilled people limits the system. Mental models held by people can cause behaviour that becomes a constraint.
  • Policy: A written or unwritten policy prevents the system from creating more output.

Throughput

In general the throughput is seen as the movement of inputs and outputs through a production process. Bottomline it can described as the rate at which a system generates its products or services per unit of time.

In the theory of constraints throughput is the rate at which a system achieves its goal. Mostly this is a monetary revenue and not the items or volume created to be sold or kept as inventory.

Continuous improvement

Goldratt - on-going improvementAs said before the theory of constraints offers an approach for continuous improvement. Optimising the utilisation of the constraint is an important part of the process. Of course this could lead to the discovery that another resource became the constraint. So we continu the optimisation.

As Goldratt states in The Race:

In the midst of a competitive race we should not look for an improvement, we should look to implement a process of on-going improvement.

Beyond manufacturing

IT Operations

The Phoenix Project borrows both content and genre from The Goal. It is a business novel that explains how the theory of constraints can be applied to IT operations. The Phoenix Project describes the problems that almost every IT organisation faces, and then shows the practices (based on the Theory of Constraint, Lean and more) of how to solve these problems.

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