Introduction 1.3: Heavy Manufacturing Constraints

There are constraints associated with any process that involves heavy machines and heavy parts.  The practices of heavy manufacturing must operate within those constraints.

1.    Heavy parts are hard to move.

Because heavy parts are hard to move they don’t have complex flows.  They follow a serial process where each activity is performed one after the other in sequence.  It is not easy to move heavy parts back and forth around the plant.  Nor is it possible to make copies of heavy parts. 

2.    Heavy parts are hard to misplace.

It is pretty easy to spot a heavy part.  They are very visible.  They don’t go missing very often.  It is obvious if a heavy part is not where it is supposed to be and because of its weight if it is not where it belongs chances are it didn’t get very far away.

3.    Heavy machines are hard to move, but once in place they stay there.

No one likes to move heavy machines around a plant.  It can be done but change is hard.  However if a change is necessary, heavy machines will move as required.  And once moved a heavy machine will not try to move back.  It will stay in place and do its job.

4.    Heavy machines just do what they are told.

The operation of a heavy machine is linear in nature.  A heavy machine does not care what changes are made to it or its surroundings.  Heavy machines are predictable.  For every action that occurs with a heavy machine there is a probable reaction.

5.    Heavy machines do only one thing at a time.

Heavy machines have a specific purpose.  They are poor at multi-tasking or doing multiple tasks at the same time.  It can be difficult for heavy machines to quickly switch from one activity to the next.  Once it is working, getting a heavy machine to perform a brand new task can be very challenging.

The constraints of heavy parts and heavy machines provide both advantages and disadvantages in the adoption of Heavy Lean practices.  The lack of complexity of heavy manufacturing processes enables current and future state improvement analysis to be performed in less than a week due to.  Many process enhancements can literally be done overnight.  Process changes can be performed without warning because the machines don’t care.

The disadvantage of a process with heavy parts and machines is the lack of flexibility to adapt to changes in the operational environment.  It is difficult to rapidly handle changes to the mix and volume of work or to the resources available to perform that work.  The multi-tasking of ad-hoc parallel processes by multiple independent interchangeable resources is not an option with heavy manufacturing. 

Heavy manufacturers perform well given the constraints of heavy parts and heavy machines.  The relative simplicity of that operational environment over one that includes primarily information intensive processes has its advantages.  But the opportunities and constraints associated with information processing are not the same as heavy manufacturing processes.  There is much to be learned in principle from manufacturers, but care must be taken to avoid the application of heavy manufacturing practices where they don’t fit.