If a company is contemplating hiring a lean manufacturing consultant, they probably need one. If the expertise does not exist within the corporation, valuable time will be lost and money spent unnecessarily until the lean manufacturing consultant is hired.

If the company has lean manufacturing expertise in-house, the question then becomes one of execution and implementation. Can the in-house expert execute the lean implementation plan within the required time frame and budget? Additionally, will the expert receive the required management commitment to implement lean manufacturing?

It is common to see organizations hire a consultant and commit the resources that otherwise not be committed. Is that fair to the in-house consultant? No, but as they say, "it is what it is". If it takes an outside lean manufacturing consultant to launch a system of massive waste elimination and value creation, does it really matter in the long run?

From a corporate view, all that matters is that the waste elimination occurs and value is created.
Lean manufacturing consultants are often good at motivating the organization into action. Sure, one reason is the corporation is paying for services so it is more compelled to make the most of it. Also, unless the lean manufacturing consultant is going to be paid to wander around, the corporation will probably make a concerted effort to implementation.

If the organization has an in-house lean manufacturing expert and top management commitment, the only reason to hire an outside lean manufacturing consultant would be for additional resources or ideas. A good outside consultant has seen many improvements in various types of organizations with different products. The consultant has undoubtedly witnessed or been involved with a few failures, and thus has the experience and knowledge to prevent or minimize it.

The first step in determining the need for a lean manufacturing consultant is an operational analysis. All areas of the organization should be assessed, including manufacturing, maintenance, engineering, shipping, purchasing, administration, and sales. The magnitude of the waste should be quantified.

Upon completion of the assessment, the need for a lean manufacturing consultant will become transparent.

It is critical for the organization and managers to keep an open mind. This cannot be mandated, but encouraged through written examples, benchmarking visits to and from other companies with successful lean manufacturing implementations.

It is not uncommon for a good lean manufacturing consultant to reduce cost of good sold by 10%. This extremely large number should not be shown to the entire organization up front. It shouldn't be hidden, but any large number would initially bring fear into the organization.

All lean manufacturing implementations should be preceded with a promise of no job loss as a result. The company should be up front and hones about waste elimination, job combinations, and position elimination, but should also commit to keeping all employees through the process.
Obviously, potential outside circumstances would not permit a guarantee, but if a corporation wants total involvement and maximum success, they will not put people out of work as a result of a lean manufacturing initiative.

When positions are eliminated through lean manufacturing tools, those employees should become part of the 5S or kaizen teams. This only increases the resources and focus enabling more waste elimination.

Almost all successful lean implementations will lead to business growth, enabling the displaced workers to again become direct labor.

When companies "do the right thing", they are almost always rewarded. The excellent morale and pervasive commitment will fuel additional business, products, or markets.