Manufacturing Cells

One Piece Flow and the Key to Employee Empowerment and Ownership

WHAT IS A MANUFACTURING CELL? :

A manufacturing cell or work cell comprises a group of equipment usually laid out in the shape of a “U”, that is dedicated to the complete production of a family of similar parts. These manufacturing cells produce parts, one at a time, by linking together a sequence of machine or assembly operations in a smooth production flow known as One Piece Flow production. Work cells generally start with raw material at the first operation and end with a finished part that is ready to be shipped to the customer.

WHAT IS WRONG WITH OUR CURRENT PROCESS-ORIENTED (DEPARTMENT SPECIALIZATION) FACTORY LAYOUTS? :

Figure 7.0 shows the actual equipment layout and material flow (spaghetti diagram) of a facility that manufactured and assembled fluid pumps in a process-oriented environment. The Spaghetti diagram clearly that this layout is a material handling nightmare for a dream come true for the material handling equipment supplier. This layout produced the following problems

• Defects were not detected until the part went to inspection (some defects were not manufacturing defects but were actually created by excessive or sloppy material handling.
• It could take several months for a part to traverse the length of the department (the customer’s expectation for delivery was 5-10 days).
• Raw and work-in-process (WIP) inventory on the floor, including rework and storage areas, occupied 25% of the available manufacturing space. The building had been added onto several times and these additions would not have been necessary had the plant adopted manufacturing cells.
• Identifying the root cause of defects was difficult due to the amount of time that passed between creation of the defect and its discovery and the number of people who had handled the part
• Scheduling the Assembly Department was impossible. Customer satisfaction was dependent on the personal follow-up and expediting of the required parts through manufacturing by committed customer service champions.
• While the plant produced a superbly engineered product, customers were often forced to buy from the plant’s competitors because of long lead times or missed delivery schedules. Some competitors were actually spawned as a result of the plant’s inability its full sales potential because of its poor manufacturing performance.

MANUFACTURING CELL - ONE PIECE MATERIAL FLOW FIGURE 7.2

Work cells can be machining only assembly and test only or both as shown in this figure. During operation, this cell will have one piece of material in process at each machining, assembly and test operation.

MANUFACTURING CELLS RULE # 1

Manufacturing cells will make your plant more productive. Prepare a plan NOW for redeploying the members of the team who become available as a result of this initiative. If you are converting from the traditional factory of Figure 7.0, work cells will reduce your labour requirements by a minimum of 20 percent. Tell your team in advance what will happen to the extra people.

MANUFACTURING CELL – OWNER / OPERATORS IN MOTION FIGURE – 7.3

The Cell operators as a team, decide how often they will rotate jobs. Also, the cell design allows manning to be increased or decreased to match changes in customer requirements.

• Product defects
• Lead times
• Work-in process and finished goods inventory (Figure 7.1 shows the effect on the average inventory levels when a customer’s requirement of 4,000 pieces per month are produced all at one time, in 5-day increments [1000 pieces]. Or in daily increments [200 pieces].
• Required manufacturing space.
• Material handling.

While improving :

• Productivity.
• Manufacturing capacity.
• Manufacturing flexibility

The material flow in a typical manufacturing cell using the same machine routings as the Traditional Factory of Figure 7.0 is illustrated in Figure 7.2. Figure 7.2 also references inventory “Kanbans” which are introduced in Chapter 9. Kanbans enhance the performance of manufacturing cells but are not a prerequisite to implementing cells. Remember that each component of WCM will provide some improvement in your facility, but their real power occurs when all components are working together.

While the above improvements are more than enough justification to support moving from a process orientation into manufacturing cells, they pale in comparison to the other improvements that work cells facilitate. Work cells give management the opportunity to empower and give ownership to the team, and for the team to take that ownership.

WHERE DO THE EXTRA PEOPLE GO :

Manufacturing cells will improve your productivity and reduce your labour requirements by at least twenty percent. We would highly discourage anyone from thinking that any labour savings from implementing WCM can be immediately translated into workforce reductions. Improvement ideas that flow from the teams will stop immediately if they think their ideas may cost them their jobs. Only if the entire plant is about to go under will members of the team understand. As members of the team are made available as a result of the plant’s improvement programmes, they should be moved into Kaizen (Chapter 10) activities. The long-term effect of implementing WCM is for business growth through customer satisfaction and that is when you will need those extra team members. In the short term, only normal or voluntary attrition should be used to reduce the workforce.

\With manufacturing cells, the team will experience and develop (reference Figure 7.3):

• Improved communication and team work – operators are close enough to talk and help each other if necessary
• An understanding of the entire manufacturing process from raw material to the finished product.
• An opportunity to meet and discuss issues with customers if any customers concerns develop.
• An environment where the cell operators, have a greater sense of control in how their business (cell) is run.
• Responsibility and ownership for producing high quality products on time.
• Higher job satisfaction through increased job responsibility and variety.

MANUFACTURING CELLS RULE  # 2 :

A thorough inspection process must be designed into each work cell. Each part will be manufactured and inspected, on piece at a time, by the cell operators.

HOW DO MANUFACTURING CELLS IMPROVE PRODUCTIVITY:

Some members of the team may immediately think that work cells are nothing more than another disguised attempt by management to “get us to work harder”. This is not the case. The productivity improvements that come from work cells are obtained by eliminating waste, the part of each operator’s job that the customer will not pay for, and substituting value-added operations. This substitution is illustrated in Figure 7.4. This figure is similar to the productivity improvement goals of Chapter 6 shown in Figure 6.0 the difference is in the type of waste or losses being eliminated.

Since most members of the team want to feel good about their contribution to the team’s goals, this substitution, when completely understood and implemented, is a welcome change. No one feels good about spending half the day creating waste.