One Piece Flow | Single Piece Flow | Lean Tool | Lean Manufacturing

One Piece Flow | Single Piece Flow | Lean Tool | Lean Manufacturing


One Piece Flow or Single Piece Flow is a lean tool

Single Piece Flow is moving one workpiece at a time between a work station within a work cell or workshop.
→ It also referrers as a continuous flow.
→ It is a very popular Lean Manufacturing Tool.


What is One Piece Flow or Single Piece Flow?

→ It is moving one workpiece at a time between a work station within a work cell or workshop.
 In opposite condition, we might process an entire batch or lot at each work station before moving it to the next work station.
 In simple language, one-piece flow means that the parts are moved through operations from station to station with no work-in-process (WIP) at any station.
 One Piece Flow refers to one piece at a time or a small batch at a time.
 Single Piece Flow system 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. 
What is One Piece Flow or Single Piece Flow



Is one piece always remains one piece in production?

 It is not necessary that one piece always remain one piece.
 In an ideal system, it remains one piece.
 The size of one piece should be fitted to our capabilities as per implemented 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 one single operation.
 So we have to take less often pieces that is possible.


Batch Production Flow vs One Piece Flow:

 The comparison between batch production flow and one piece flow is mentioned in the below picture.
 From the below picture we can easily understand, why single piece flow is better than the batch production.
Batch Production Flow vs One Piece Flow



➤ Requirements for Successfully implementing One Piece Flow:

→ The processes must be able to consistently produce a good product. 
 If there are many quality issues then one-piece flow cannot implement.
 The processing time must be repeatable, if there is much more variation in processing time then we can not implement.
 The equipment must have a very high uptime (near 100 %) that 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 of Single Piece Flow in Lean Manufacturing:

  • It  Improves Quality and reduces defects in manufacturing.
  • Single Piece Reduces inventory
  • It  improves the morale of all employee
  • Single Piece enhances overall manufacturing flexibility
  • By this, we can get a benefit to implement 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.
  • Single Piece Flow encourages work balance.

Seven steps to creating one piece flow or continuous flow in manufacturing cells or workplace:

  1. Decide the Products
  2. Calculate Takt Time
  3. Determine the Cycle Time
  4. Equipment can meet Takt Time or not
  5. Create a lean layout
  6. Determine the number of the operator is required
  7. Balance the work between operators


➤ 1. Decide the Products:

→ Decide which products or product families for will go for production into your work station or cells, and determine the type of work station or cell.


➤ 2. Calculate Takt Time:

→ Calculate Takt Time for the product or product family.
→ 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 one unit every 30 seconds.


➤ 3. Determine the Cycle Time:

→ Determine the required work elements, resources and time required for making one piece (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 one unit every 30 seconds.
 So, our facility is able to produce one 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 below layout which is suitable for your process.
→ U-shaped layout - the best layout or S-shaped layout


➤ 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.


➤ 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 One Piece Flow Failure:

     01. If we can’t get materials in quality, in quantity or in time.
     02. An unexpected breakdown causes downstream processes to run out of parts.
     03. Our people will not adopt this change.
     04. In general, our people are not cross-trained for multitasking.
     05. Long changeover times fails Single Piece Flow.
     06. There is too much distance between processes to move one piece at a time.
     07. The process produces defects that will stop the line if we have no buffer. 
     08. Variable process cycle times create an imbalance between workers.
     09. If our machines are not designed as per One Piece Flow production.
     10. Some times our occasional work interrupts the process.