The Decline and Fall of the Roman Legions
By Tom Dossenbach
There is a mentality rampant in the woodworking industry. It is quite common in older furniture companies, but is also found in kitchen cabinet, millwork and other wood-processing plant. Antiquated and sometimes fatal, it is characterized by legions of similar machines and work-in-process lined up in neat rows ready for the charge.
It is a way of doing things that often results in sluggish plant through-put, long delivery dates, ulcers in managers and supervisors and frustrated employees.
This mentality usually groups machinery and inventory in the same way legions of Roman soldiers lined up for battle centuries ago. (see Figure 1.) The most effective cure for this way of grouping machinery is the formation of manufacturing cells.
A lot has been written about manufacturing cells, and for good reason. Thinking cellularly requires a major paradigm shift and takes more than a few paragraphs in an article such as this to fully explore. However, I hope that this column will help readers begin to think of different ways of deploying their assets instead of putting all of them in the traditional formations of the past. This will allow businesses to use different tactics to meet their customers’ demands of today.
Prior to the 1980s, manufacturers were taught to maximize the use of resources by running economical lot sizes through machines lined up by side by side. When each subsequent operation was completed, they queued the parts to wait for available time at the next machine. By doing this, they would ensure that there would be material waiting for the next operation, which would result in minimal machine downtime.
Little or no attention was given to the money that was tied up in inventory — much less to the floor space taken up by that inventory — or how long it would ultimately take that inventory to get through the plant. That would all be taken care of, they rationalized, by a complicated production scheduling and tracking system to keep those parts moving.
The focus was to produce the parts at “minimum cost.” Typically, the plant had eight to 10 weeks to produce a cutting after having notified the customer of the time needed to fill the order. The often chaotic production process flow is illustrated in Figure 2.
It has been accepted for about 15 years now that this philosophy lacks responsiveness to today’s rapidly changing market requirements. This includes shorter lead times. However, there are many manufacturers still living within the old paradigm of production (and costing, which is another subject for another day).
Definition and Description of a Cell
A manufacturing cell can be defined as “a mini production line dedicated to processing similar parts or products which require similar or identical operations.” While a cell does not necessarily make the same parts repeatedly, it does make the same family of parts or products.
The machines and fixtures within the cell are typically arranged so close to each other that there is no need to allow for storage between the operations or handling with hand trucks or pallet jacks (see Figure 3).
Usually, the operators multi-task by doing several operations within the cell. While the cells are compact and designed to minimize movement, it is not a sin to have an operator walk around within the cell during his or her normal duties. Finally, products seldom, if ever, stop moving through a cell until completed.
Advantages of Manufacturing Cells
Cells offer a way to simplify production control and scheduling and shorten the manufacturing cycle time required to complete the product. They also reduce inventories and, therefore, manufacturing space required to satisfy production requirements.
It takes fewer people in close proximity to each other to conduct multiple operations in a cell. Since they are responsible for all of the operations on the part or assembly and are not as dependent on other departments, quality management is more reliable and easily attained.
Manufacturing cells can accurately be described as “employee retention centers” because they instill accountability and a sense of pride by empowering cell members, resulting in greater job satisfaction.
About 15 years ago, I visited a plant that changed my manufacturing paradigm forever. It was a relatively new plant with state-of-the-art equipment. Production lead times had been about six weeks. However, customer demands for shorter lead times had become common. As such, they decided to break up their traditional legion manufacturing flow into cells. Not only did they reduce lead times to four days, they also reduced the floor space required by 40 percent.
A Typical Cell Manufacturing Technique
Any millwork manufacturing company that sells directly to builders has as great a challenge to satisfy customers’ requirements as can be found in the woodworking industry.
For example, a company in Northern Virginia manufactures everything builders need to trim the inside and outside of a house, including windows of all types, pre-hung interior and exterior doors, fireplace mantles and exterior pediments.
Typically, a builder will call and want delivery of an exterior package in two days. That means the supplier has the current day to process and schedule the order, tomorrow to build and load it, and the third day to deliver it. It would be more than just a challenge if the plant were arranged in a Roman Legion layout. However, this plant is arranged with logical cells, each designed to produce varied products.
A specific example is the company’s exterior door cell. First, remember that exterior doors can be wood, steel or fiberglass. They can be hinged right or left, be single or double doors and have a number of other considerations. All of the raw materials required, including lumber, are in the cell, as are the saws and other machinery necessary to cut, process and assemble the materials needed to manufacture the complete door unit.
All exterior doors are manufactured in this cell no matter what their configuration. Scheduling is simple. Operators have a list of doors required and for whom according to how they will be loaded that day. Operators within the cell make what is needed for each order. There is little need for tracking because even the most complicated door will exit the cell within an hour of entry.
When reading about an example such as this, some will say, “But Tom, that won’t work with our product line.” On the other hand, others will say, “That’s different than my processing needs, but it gives me an idea.” The latter is an attitude of continuous improvement that everyone needs to adopt, keeping in mind that they do not need to change everything or change it overnight.
A few months ago, I was asked to visit a company that had filed bankruptcy. They had just completed a large addition to their factory, to make room for their growing legions. There were many challenges at this company that led to its demise, and Roman Legion syndrome was one of them. Unfortunately, they just kept building their legions larger and larger.
Cellular manufacturing is not the solution to all problems, just that of grouping machinery in a Roman Legion format. Can a company survive with the problem? Maybe. However, it will have a better chance if it takes at least small doses of the cure. Try breaking the ranks with a few more cells — especially if customers are screaming about lead times or if you are contemplating an expansion.
Have something to say? Share your thoughts with us in the comments below.