What is One Piece Flow?
→ One Piece Flow is moving one workpiece at a time between a workstation within a cell or shop.→ In opposite conditions, we might process an entire batch or lot at each station before moving it to the next station.
→ In simple language, it means that the parts are moved through operations from station to station with no work-in-process (WIP) at any station.
→ This tool works best in combination with a cellular layout.
→ In Cellular Layout, all necessary equipment is located within a cell in the sequence in which it is used.
→ It is a very popular Lean Manufacturing Tool.
Is one piece always remains one piece in production?
→ It is not necessary that it always remains one piece but in an ideal system, it remains one piece.→ The size of one piece should be fitted to our capabilities as implemented in our facility.
→ If our machine can produce six elements in a single operation, then it is obvious that I won’t produce only one.
→ Let we can produce six elements in a single operation.
→ So we have to take less often parts/products that are possible.
Batch Production Flow vs One Piece Flow:
→ We can easily understand the comparison between batch production and the single product flow is mentioned in the below picture.
Requirements for Successfully Implementing Single Piece Flow:
→ The processes must be able to consistently produce a good product.→ If there are many quality issues then this lean tool cannot be implemented
→ The processing time must be repeatable, if there is much more variation in processing then we can not implement.
→ The equipment must have a very high uptime (near 100 %) which means the equipment must always be available to run at any time.
→ OEE (Overall Equipment Effectiveness) increases by this.
→ Processes must be able to match with takt time or fulfill the rate of customer demand.
→ For example, if takt time is 30 seconds then our processes should be able to produce a product less than 30 seconds.
Benefits:
→ It improves Quality and reduces defects in manufacturing and also reduces inventory and other Lean Manufacturing Wastes.→ It improves the morale of all employees and enhances overall manufacturing flexibility
→ By this, we can get a benefit to implementing Lean Manufacturing in a factory.
→ It easily identifies the kaizen or improvement
→ It provides a safer work environment
→ Continuous flow Requires less space
→ It keeps WIP at the lowest possible level and encourages work balance.
Seven steps to creating Single piece flow:
- Decide the Products
- Calculate Takt Time
- Determine the Cycle Time
- Equipment can meet Takt Time or not
- Create a lean layout
- Determine the number of the operator is required
- Balance the work between operators
→ Decide which products or product families will go for production into your working station or cells, and determine the type of working station or cell.
[2] Calculate Takt Time:
→ Takt Time = Available working-time per shift / Customer demand per shift
→ Ex: Work time/Shift = 27,000 seconds
→ Demand/Shift = 900 units
→ Takt Time = 27,000/900 = 30 sec.
→ The customer's demand for 1 unit every 30 seconds.
[3] Determine Cycle Time:
→ Determine the required work elements, resources and time required for making 1 Nos. (i.e. determine the cycle time).
[4] Equipment can meet Takt Time or not:
→ In this step, we have to determine if your equipment can meet takt time or not?
→ The customer's demand for 1 unit is every 30 seconds.
→ So, our facility is able to produce 1 good part in less than 30 seconds.
→ Ensure that our cycle time must less than takt time.
[5] Create a lean layout:
→ You can choose any of the below layouts which is suitable for your process.
→ U-shaped layout - the best layout or S-shaped layout
[6] Determine the number of the operator is required:
→ Determine the number of the operator is required to meet customer demand.
→ Decide the optimum size of the operators.
[7] Balance the work between operators:
→ Find our the bottleneck processes and balance the work between operators.
→ Balancing gives us a smooth production.
Some Common Reasons for Single Piece Flow Failure:
→ If we can’t get materials in quality, in quantity or in time.→ An unexpected breakdown causes downstream processes to run out of parts.
→ Our people will not adopt this change.
→ In general, our people are not cross-trained for multitasking.
→ The long changeover period fails this tool.
→ There is too much distance between the process steps.
→ The process produces defects that will stop the line if we have no buffer.
→ Variable process cycle times create an imbalance between workers.
→ If our machines are not designed as per this lean tool.
→ Sometimes our occasional work interrupts the process.
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