Most small manufacturers conjure up visions of CNC
routers and other sophisticated machines whenever the term "cell" is used. They
think of a work cell as a complicated machine or a group of machines that
requires highly skilled industrial engineers to design. If you are mystified by
the reference to celts, this article is for you. More than five years have
passed since I last wrote about this subject; so, let me start with the basics.
The Way It Was
Thirty to 40 years ago the focus in manufacturing was to
maximize the output of machinery. This was the engine that
drove
industrial output and growth. A plant that made furniture or other products
would accumulate orders and forecast future demand in order to produce a
quantity of products that would justify setting up the various pieces of
machinery required to manufacture that product. Because each machining operation
did not take the same amount of time to perform its required task--which is
stilt the case today--the quantity was calculated not only to minimize the
downtime of the machinery, but also to serve as a buffer as the parts moved from
machine to machine.
The woodworking plants then, and many now, had machinery
grouped by type or function. A typical small shop would group saws together in
one area and tightly duster shapers in another. Likewise, routers and sanding
machines would be grouped in separate areas. Thus was born the reference to
"cutting rooms," "machining rooms" and "sanding rooms." Typically there would
also be an assembly area that would include designated areas for sub-assemblies
and final assembly.
Machines were most often tined up in what I cart the
Roman legion formation--much like the charging lancers and bowmen of Roman
history with tines of legions appearing to stretch on forever. The above photo
shows a new Asian woodworking plant with a bad case of this Roman legion
mentality. Note that there are nine sanders tined up in this one machine
location. The plant is fitted with similar rows of machines designed to do the
same kind of processing.
You can picture these machines as one of the tines of
sanders represented in Figure 1 on page 30. This drawing illustrates the diverse
routes parts and sub-assemblies took as they worked their way through a factory
of the 1960s.
Inefficiency and Waste
Many of the woodworking plants in this country are still
doing it the Roman region way. Let's look at the results of this mode of
operation. Read carefully to see if your plant has some of the symptoms of the
Roman legionnaires' disease.
First, any part or product that moves from machine to
machine in batches would take a lot of time to work its way through the maze of
machines. As Figure 1 illustrates, the part's path would include a lot of
backtracking because all of the machines were not grouped to accommodate the
many product flow variations. Instead, they were arranged in a loose order of
machine sequence such as cut, surface, machine, sand, assemble, finish and pack.
When a manufacturer has a pallet of parts that needs to be processed, the
biggest challenge is to get them completed on time to meet the customer's
delivery schedule.
