12th Apr 2017 | By : S Badri Narayana | Tags: -

Is there a demand for wide-variety but small-lot production? Are the product lines (batches) not productive enough? Is your Value Adding Ratio less than 5 %? Is there a lot of alterations and low output per hour with the learning curve being high? Is there evidence of each of the 7 wastes (as described in the Lean Manufacturing System) in the production lines? Is there continuous fire fighting for fixing problems rather than preventing problems? Are the problems surfacing down stream rather than as it is happening?


These are indications for the organization to go the Single Piece Flow Way!


Single Piece Flow


Single Piece Flow (SPF) refers to the concept of moving one unit or a garment (piece) at a time between operations within a throughput system consisting of cutting, sewing and finishing or in scientifically arrived at lot size as a function of lead time between the processes of cutting, sewing and finishing, based on outhouse processes. However wherever the processing is ONE AT A TIME the ideal lot size is one at the operation being done (be it stitching or finishing) and one post operation ready  for the next operation.


SPF is applicable for processes and facilitates elimination of the seven deadly wastes (as described in the Lean Manufacturing Systems).


SPF brings with it a string of benefits like:


Builds in Quality in the product: (as every worker is also an inspector, a Do-Check person. Each piece is looked at by the next process, as it happens, so defects that are passed on are caught before too many more are made).


Reduces inventory cost:  Cash is freed up when inventory/WIP is reduced. The money to move, store, and manage is saved.  Also the fewer inventories you have, the less obsolescence you have, the less unnoticed defects there are.


Improves productivity.  Many non value-activities associated with batch production go away with one-piece flow.  Multi-process handling becomes possible when cycle times are balanced to takt time. The major advantage being consistency, complete involvement of the associates and overall substantial throughput reduction, i.e. lead time dramatically reduces.


Frees up floor space.   One-piece flow gets rid of work in process and the space used for storage is opened up.  Flow requires processes to be connected and space between equipment to be reduced.


Simplifies material replenishment. One-piece flow paced at takt time allows material replenishment to be done by milk runs, timed deliveries or set quantity deliveries.  Continuous flow and line balancing make the material usage rate (line speed) more reliable and material delivery easier.


Improves flexibility. One-piece flow reduces the time through the process. So you can wait longer to schedule the order and still deliver on time.  This lets you respond to last minute changes easier.


Improves scalability.  One-piece flow equipment can be designed smaller, slower (paced to takt time), and generally at lower costs.  Rather than making a process fast as technically possible, often resulting in local optimization and batch processing, very simple processes can be used.


Improves safety.   According to industrial engineering studies the number one cause of workplace injuries/fatigue/pain is overexertion.  Lifting in bulk, sorting/handling multiple pieces continuously is reduced when lot sizes are one-piece.


Improves morale.  Associates can see the effect of the work they do when they perform balanced rhythmic operations/sewing, finishing in one-piece flow.  Associates have the opportunity to learn new skills when they are cross trained.  People work as a team when departmental barriers are removed.  Associates can see problems right away and are given the authority to call for help or stop the line.  Problems-actual facts or sources for variation are solved sooner and the culture shifts from one of finding who to blame to how can we find solutions.  This gives them a sense of fulfillment.


Makes kaizen take root.   One-piece flow and kaizen go hand in hand.  If you do not solve problems and make process improvements, one-piece flow will not work.  You will be forced to go back to batching and hiding problems with inventory. More than one piece between processes is inventory and WIP... a waste or Muda.


SPF can be achieved by:


  1. Abolishing planning centered production and incorporating pull
  2. Abandoning the idea that batch production is the most efficient production method
  3. Designing balanced Work-cells or cutting, sewing , finishing lines
  4. Efficient Supporting Supply Chain Management system
  5. Following lean principles
  6. Following the PSAP process with FMEA and PDCA



Evaluation parameters

1+1 piece as optimal

1+ many, say 3 or 4 pieces




Permits the associate to focus on the job in hand and that any deviation will disturb line balance and rhythm. Easy to carry out a do- check function. Can reduce alteration to 1 in 1000 levels and eventually ppm levels.

More than 1 pc distracts and if there is a problem of quality it gets hidden and uncovered much later. Practically very difficult to bring in quality perspective when there is inventory, needs a lot of supervisory effort.


1 +1 piece is the Lean and World Class Standard to achieve quality in any industry for processes other than bulk operations like dyeing, washing etc., .where the process is capable automation.

2. Types of Muda’s or wastes

Permits each associate to properly place the processed garment in a mode ready for the next process. It can help reduce waste in motion for the next process. Help in increasing needle time ratio.

The pieces will get jumbled up and it is not associate friendly to keep pieces neatly in a right manner for the next operation. FIFO cannot be followed and can lead to start...stop...start kind of operations which will not be rhythmic.  


There will two types of waste or Muda’s that will emanate when there is more than one piece-motion waste leading to more time in the next operation and waiting waste, plus clutter at the work station as 5 pieces cannot practically be kept neatly.


Permits the associate to ensure there is pacing and convergence to the process before and after. It is like a tug of war- everyone pulls simultaneously, so the entire line works on a smooth desired manner to reach the set norms.

Each associate works to their pace and the inventory hides the orientation of the next process being an immediate customer. There will be imbalance in terms of the flow. Does not permit problems to be highlighted as it occurs.


1 +1 piece is the Lean and World Class Standard to achieve productivity in any industry and drastically reduces lead time. It facilitates the ANDON function for effective team work and instant responsiveness to solve bottlenecks or constraints. More ownership from all team members

4. Opportunity for improvements

Uncovers continuously deficiencies in the processes for on- line improvements. Everyone related to the line is committed to methods and systematic improvement.

The preventive steps using FMEA helps a lot to ensure problems are anticipated and resolved in a PDCA cycle.

Gives rise to time cushions to solve problems and can lead to breaking the flow and involvement of the operators in owning the line.

With time cushions, there is that much more difficulty in catering to a psychological need for job enrichment and belonging.


One of the major benefits is the owning of the line by the associates and the pride for ensuring takt time or pitch time with quality. They belong so therefore they will perform. Improvements are self directed.

5. Morale and absenteeism

The importance that everyone has to be present and contribute to line performance is a key factor for both enhancing morale and imparting a consciousness to being present on a day to day as the performance does get appreciated. There is the importance given that each and every piece is IMPORTANT and hence their skills and ability is precious for optimal performance. This sense of being valued not only enhances morale but also makes the associates conscious of being present and thus reduces absenteeism




Though even in this scenario there could be an environment that can motivate and enhance morale, but the work place by itself does not give the IMPORTANCE to each and every piece.  It slowly becomes a push model and not a pull model and violates the principle of SPF. Also with more than one piece between processes the workplace becomes a clutter and becomes de-motivating after a time. A 35 machine line will have WIP of 175 pieces at any time as against 35 pieces. This cannot be organized neatly, if done then in itself it will be a NON VALUE adding activity. It is well established that whenever the entire workforce are actively engaged with empowerment to enhance their work place and work practice and are aware of their role in meeting the customer requirements, the norms are NOT ONLY MET but EXCEEDED.


In summary a Single Piece Flow (1 +1) would need a cross functional team (CFT) effort leading to consistent and fun filled work environment. It has the power to bind diversity, collaborate all functional efforts to meet Market, Business, Employee and Technology (of Delivery and quality) needs. The activities by different functions are elucidated in the table below:

Process Engineers Quality Assurance Maintenance Production HR PPC

Establish methods and cycle time-Pictorial work instructions

All pre-production activities to establish quality and productivity

Ensure right method for checking defects and control plan for process adherence and then product control Establish high machine uptime and OEE. Respond to any breakdowns or slowness in output very quickly Ensure that standard works is followed and motivate and encourage associates. Ensure work place discipline and be methods and system oriented. Pull production and not push production. Initiate activities to enhance work life and reduce attrition and absenteeism along with production.  

Work to the plan and be alert in real time to variations/

deviations and respond fast to ensure quality supplies on time.


The success of SPF will be the synergistic working of the above CFT.