Sunday, November 3, 2013

Lean Manufacturing System Implementation - Case Studies

Steps in Lean Manufacturing

The first step is to group products into families of similar production processes

The second step is to establish the Takt time. The Takt time is the demand rate and consequently the time between
completion of each product off of the production line. It is first necessary to find the available capacity of the
production line:

Takt time = Available Capacity/ Number of Units Sold

The third step is to review the work sequence by:
♦ Observing the sequence of tasks each worker performs,
♦ Break operations into observable elements,
♦ Identify value added versus non value added elements and minimize or eliminate non value added operations, and
♦ Study machine capacity, cycle times and change over times
In IE words, conduct methods and standards studies.

The fourth step is to balance the line using the calculated Takt times found in step two.

Step five is to design and construct the cell to:
♦ Implement a ìUî shaped line to assure one way flow and maximize visibility,
♦ Provide a flexible layout to account for all members of the production family,
♦ Decrease distance between operations and integrating process operations wherever possible for simplicity,
minimizing both transportation and production lot sizes, integrate in point of use storage next to each assembly
♦ Minimize material handling by concentrating on value added motion
♦ Establish replenishment procedures for point of use storage using the A-B-C rule
♦ Assure the personnel understand their role and are cross trained to use their skills at a variety of tasks and work
♦ Provide visibility to allow operator decisions on problem solving, moving to where work needs to be performed,
and focus management attention on production disruptions.

USA Vacuum
USA Vacuum is a manufacturer of residential and commercial vacuum cleaners for The Tacony Corp, in St. Louis, Missouri.  The plant currently employs approximately 60 people from the St. James and Rolla,
Missouri area.

The initial activity with the project involved identification and time study of all operations involved in the vacuum cleaner assembly. With this information, the production lines were broken down into workstations with assigned operator activity for each station, bringing balance and consistency to the assembly process. The production staff was organized into improvement teams that focused on process and workstation design improvements. Utilizing the information gathered during team meetings, two new production lines were designed with connected subassembly cells and Kanban materials replenishment for the workstations.
Support areas, including the warehouse and receiving department were also redesigned to support the new production lines. Over a two-month period, Missouri Enterprise and USA Vacuum personnel implemented the new designs to the physical plant.

The bottom line result to the project is that USA Vacuum is now able to meet their customer demand for
vacuum cleaners. The line balances create an atmosphere of smooth, predictable production. Additionally, they have a system in place to control all of their production activity and implement changes in a controlled manner. The use of instructional process graphics assist operator training, and limit operator error due to model changeover. The Kanban replenishment system for workstation materials has reduced model changeover time, as all models' materials are present at the workstation. The reusable Kanban containers have greatly reduced the assembly line housekeeping issues by reducing the presence of cardboard boxes. Subassemblies are produced on an as needed basis, reducing WIP and scheduling headaches. As a result of these changes, USA Vacuum believes they will save $1.5 million in inventory costs and $100,000 in labor costs.


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