वन पीस फ्लो सिस्टम: अधिक कुशल उत्पादन प्रक्रिया के लिए व्यावहारिक मार्गदर्शिका
One Piece Flow is one of the key elements with which an organization can become lean. To think of processing one unit at a time usually sends a shudder through the organization which has batch manufacturing as its life blood. The word “one” does not mean one in the literal sense but in terms of customers’ requirements. In this sense, it means that the organization only process what the customer wants, in the quantity he wants and when he wants it.
One piece flow is simply a methodology for manufacturing components in a cellular environment (an area where everything that is needed to process the part is within easy reach, and no part is allowed to go to the next operation until the previous operation has been completed).
The goal of one piece flow is to make one part at a time correctly all the time without unplanned interruptions and lengthy queue times.
One Piece Flow & Batch Processing
While One-piece flow describes the sequence of product or of transactional activities through a process one unit at a time, batch processing creates a large number of products on a large number of transactions at one time – sending them together as a group through each operational step. The focus of One-piece flow is on employees’ efforts on the manufacturing process itself rather than on waiting, transporting products, and storing inventory.
It enables the production process flow smoothly, creating a steady work-flow for all employees involved. One-piece flow methods best functions with short changeover times and in a pull system environment.
Advantages of One Piece Flow
There following are some advantages of incorporating one piece flow method into work processes:
- Helps reduce the time that elapses between a customer order and shipment of the finished product.
- Helps prevent the wait times and production delays that can occur during batch processing.
- Enables reduction of excess inventory, one-piece flow thereby saving the labor, energy, and space that employees would have devoted to storing and transporting large lots.
- Reduces the damage that can occur to product units during batch processing.
- It helps reveal defects or problems in product units early in the production process.
- It provides the organization flexibility required to meet customer demands for a specific product at a specific time.
- It enables reduction of operating costs by making non value- added work more evident. This enables you to eliminate waste.
One piece flow is simply a methodology for manufacturing components in a cellular environment (an area where everything that is needed to process the part is within easy reach, and no part is allowed to go to the next operation until the previous operation has been completed).
Implementing One Piece Flow
Equality of Number of Units
The number of units you produce should equal the number of items your customers order. In other words, your selling cycle time should equal your manufacturing cycle time.
Decide Products or Products Families
This involves deciding which products or product families will go into the cells, and determining the type of cell - Product-focused or mixed model. For product focused cells to work correctly, demand needs to be high enough for an individual product. For mixed model cells to work changeover times must be kept short; a general rule of thumb is that changeover time must be less than one tact time.
Calculate Tact Time
The next step is to calculate tact time for the set of products that will go into the cell. Tact time is a measure of customer demand expressed in units of time.
It is calculated as follows:
Takt time = Available work-time per shift / Customer demand per shift
Determine the work elements and time required for making one piece
In greater detail, each step and its associated time should be listed. Each step should be timed separately several times with the lowest repeatable time used.
Determine if the equipment to be used within the cell can meet tact time
Changeover time, load and unload times, and downtime should all be considered.
Create a lean layout
Design a layout using the principles of 5S which involves eliminating items that are not needed and locating all items/equipment/materials that are needed at their points of use in the proper sequence. Very limited space between processes within a one-piece flow cell is needed to eliminate motion waste and to prevent unwanted WIP accumulation. U shaped cells are generally best; however, if this is impossible due to factory floor limitations, other shapes will also suffice.
Balance the cell and create standardized work for each operator within the cell
This can be done by determining how many operators are needed to meet tact time and then split the work between operators.
The formula below can be used:
Number of operators = Total work content / Tact time
In most cases, an “inconvenient” remainder term will result (e.g., you will end up with Number of Operators = 4.4 or 2.3 or 3.6 instead of 2.0, 3.0, or 4.0). If there is a remainder term, you may consider applying kaizen techniques to the process and reducing the work content. You may also consider moving operations to the supplying process to balance the line.
About the Author
Adebayo is a thought leader in continuous process improvement and manufacturing excellence. He is a Certified Six Sigma Master Black Belt (CSSMBB), Digital Manufacturing Professional and ISO Management Systems Lead Auditor (ISO 9001, 45001 & ISO 22000) with strong experience leading various continuous improvement initiative in top manufacturing organizations.
You can reach him here.
