Bottlenecks are probably as old as the manufacturing enterprise itself, and they usually mean trouble. Bottlenecks are usually associated with late deliveries, excess overtime, inventory pile-ups, shifting priorities, firefighting and other problems, all of which cause headaches for the entire organization.
Since bottlenecks usually appear in the manufacturing process, most managers view them as manufacturing's responsibility. The tendency, therefore, is to expect manufacturing personnel to fix the problem, which often creates friction between manufacturing and other functions within the organization. As a result, the organization not only has to deal with the "physical" aspects of the bottleneck, but also its effects on employee morale.
Most top managers try to resolve the problem of corporate infighting by first attempting to make peace among the different functions and people. Then, they try to give manufacturing personnel the means to overcome the bottleneck – for example, by authorizing special overtime, or by providing better maintenance support or extra tooling. This approach, however, results in a short-term solution, and the process will soon start again with the appearance of a new bottleneck. Is there a way out, and can we change that reality?
Overcoming the tendency to try to apply "Band-Aid" solutions to bottleneck problems can yield long-term cost reductions, productivity increases, and improvements in customer service. To gain these benefits, however, we first need to change the way we view bottlenecks.
The tendency to view bottlenecks as the cause of a problem stems from the natural tendency to look at the short term and at the visible symptoms of a problem rather than at its real cause. The fact is, bottlenecks are usually symptoms of a larger problem and not the cause.
The experience of one mid-western company illustrates the broader organizational problems that can lead to manufacturing bottlenecks. A special management meeting was called, prompted by complaints from the sales and marketing group of late deliveries to customers. The manufacturing manager immediately identified the bottleneck: a CNC turning machine that was running behind schedule. The marketing manager quickly asked why the problem wasn't fixed. The manufacturing manager blamed the scheduler for exceeding the machine's capacity. The scheduler pointed out that the late arrival of raw materials forced him to overburden the machine to meet the customers' due dates. The purchasing manager closed the loop by saying marketing had quoted too short a lead time, leaving him little chance to get raw material on time. The meeting soon became emotional, and it became impossible to sort between facts and perceptions.
At that point I asked the group to step back and take a more global view of operations, from the customer order all the way to shipping. After further discussion, it became clear that the CNC machine – the apparent bottleneck – was really just the visible symptom of a problem occurring much earlier, at the order-taking stage. Relieving the bottleneck at the turning center would do little to solve the real problem.
As managers, we need to step back and realize that bottlenecks, in most cases, are just a symptom of a larger problem. By overcoming problems at their true source, we can eliminate bottlenecks and their compounding negative effects.
This can be achieved by managing the organization as a total system. We need to regulate order input into the system, taking into account the capacities of machines and other resources. We need to respect customer lead times without violating purchasing and manufacturing lead time, and we need to create communication tools for all functions that can serve as an early warning system for potential conflicts. Most importantly, we must take a broader view of our organization, and get out of the “firefighting” mode of operation.
Bottlenecks are a natural part of the manufacturing organization. They can be eliminated at no cost by managing in advance the flow of work through the organization.