Lean Manufacturing: Eliminating the 8 Hidden Wastes – Part 3 of 8. The W in DOWNTIME

Waiting wastes come from people, processes or partially finished goods sitting idle while waiting for instructions, information or raw materials. Poor scheduling, poor vendor support or communications and inaccurate inventories cause processes and people to come to a halt and cost valuable time and profit.

LOOK FOR idle people or machines waiting on the preceding or following operation, materials, schedules or information.

REDUCE BY Line Balancing (schedule balancing) workloads and using a Cycle Time/Takt Time Bar Chart for process synchronization.

Line Balancing is simply leveling the cycle time for all operations within a line or process. It is building the cycle time concept into the standardized operations of a production line for maximum efficiency. Line balancing smoothes work tasks and operator motions to create a harmonious and uninterrupted flow of product through the process steps. Workers learn to identify those processes that are out of balance with others and how to bring them back into line. While most companies assign the duties of measuring and improving production lines to process engineers, there ARE things that a team of line personnel can measure and examine for improvement opportunities. These people handle the process daily and understand the impact that balanced flow has on through-put, lead time to the customer and inventory levels, all of which play a very important role in the financial success of the organization.

Cycle time is the time that elapses from the beginning to the end of a process. It is the sum of all value-added processing time AND the all non-value added time.

Takt Time is an expression of your customer demand normalized and leveled over the time you choose to produce. It is not, and never has been, a pure customer demand signal. Customers do not order the same quantity every day. They do not stop ordering during your breaks, or when your shift is over. What Takt Time does do, however, is make customer demand appear level across your working day.

Using chart paper and a stop watch, record the time for each process or operation and the time for all steps or sub-processes. Record the minimum and maximum time for each step as it is completed by more than one operator.

This information can be used two ways. The first is to identify the number of workers and the duties each should accomplish to meet the changing demands of the customers. This information can be used to balance a production line for different levels of production and keep everyone informed. Another way this information can be used is to develop a Takt Time/ Cycle Time Bar Chart. Identification of the maximum and minimum individual process times within an operation points out the variation between the ways different operators complete their duties. Improvement teams can work on developing better SOPs and continued operator education to reduce this variation.

The average cycle time for each operation within a larger overall process needs to be shorter than the customer’s demand time or Takt Time. Analyze lengthy operations to see if there are small incremental sub-processes that can be moved to the operations with a shorter cycle time to help balance the line. Very few production lines will ever be 100% balanced. The goal should be a maximum variance of approximately 10%.

What are your customers and the improvement of your company’s bottom line Waiting for?

Watch for upcoming articles on Lean Manufacturing and the remaining Hidden Wastes of DOWNTIME…