Pull system, also known as the Kanban system (signalling card system), is a critical enabler of Lean manufacturing referred in Toyota Production system (TPS) and developed by Taichi Ohno, four decades ago. It triggers the commencement of production only when there is a consumption or a customer need generated. It facilitates the famous JIT (Just in time) process of TPS. It is a scheduling process for batch production. The specific item, in exact (small) quantity is pulled in the production process based on the Takt time (customer demanded rate). It controls the flow of material based on actual customer requirement. The Pull system, thereby, facilitates value flow in small quantities, reduces work-in-process inventory, cuts down the throughput time to customer and enhances the inventory turn ratio. This system has been effectively applied and benefits realized for decades in manufacturing shop floors. The famous Supermarket system functions on periodic replenishment of goods in the shelf, only after the actual buying by customer. This is also a Pull system synchronizing the supply and demand in the Supermarket. The Pull system is a process of deliberate decision making on what to produce, what quantity to produce and when to produce, to ensure resource efficiency and system effectiveness. Therefore, the Pull system is superior to the Push system which may produce goods when not needed with potential quality issues.
It is often said, eat the right quantity and the right quality of food at a time when you feel hungry (human body’s signal). Drink the right quantity of good quality water, gradually, at the time when you feel thirsty. This is a typical Pull system of the human body based on the signalling by nature. Similarly, the traditional chalk and talk type of teaching-learning process using the blackboard, in a class of students, has always been believed to be more effective to the learners because of better retention, superior connect, more interesting, simpler and controlled learning flow etc. Is it not close to the Pull system? The modern day’s teaching through the Power point presentation (PPT) is believed to have weak alignment between teaching-flow and student’s learning-process, large quantum of intellectual content is thrust in short time, which is definitely closer to Push system?
In an office environment, the flow of work loaded emails keep pouring in the system, oblivious of the queue length of work load at office worker’s end. Almost always, one starts the day’s work by seeing the new tasks arrived through emails, even before the old tasks are completed. This LIFO (Last in first out) feeding of work is more likely to distract the office worker and adversely impact the pending work inventory. Such work flow through emails is definitely a Push and not a Pull system. On exactly similar lines, in business offices, the documents / information are pushed off the desk / computer system to the next desk, across functional boundaries, without being aware of the availability, capacity and priority of the next desk owner in the flow. In case of critical documents processing, the flow is often hampered and delays take place leading to longer lead times, reduced throughput and inferior quality. Such situations often lead to creating a Push system (snarling faces, shouts at time, intervention by superiors, inferior quality etc) to meet the customer demand. This creates unproductive office culture with wastes. Office related common business processes like; Request for quote by customer, Contract formulation and approval, Annual budget preparation, Capital investment approval, New employee recruitment, New product launch, Technical design change and many more, often take more than desired time and quality is not right the first time, highlighting low office efficiency and effectiveness with dissatisfied customers.
Based on the varied examples it can be inferred that Pull system is also needed in the business office environment to structure and control the flow of value documents and information through resources (office equipment, systems and manpower) to ensure a Lean culture. Creating a system of a seamless flow on what to work on, what is the quantum, when to work and who to work to respond to the customer need, is the Pull system in the office. Queue length of work at a work desk is an indicator of capacity constraint of the desk or a weak work flow design. In such situations it is not recommended to Push further the office work load downstream, till the debottlenecking is complete, as done in any lean production line.
This lead to identifying the operating characteristics of an Office Pull system – assessing the work capacity of the desk, setting the work priority, initiating the work processing only when needed, defining the schedule to meet the customer need, facilitating a continuous and seamless work flow, making the queue length visible, debottlenecking when queue length exceeds limits, preventing reverse flow due to rework (not right first time!), standardizing the work elements and conformance to systems in the office. The heterogeneity, low visibility of the office product/service, lack of clear expectations, varied skill levels and varied processing times at work desks of the office work processing are always going to be challenging. However, the process can still be streamlined through the Pull system in a Lean office.
Owing to the controlled office work flow in a Pull system, work management becomes easier, improving the output predictability manifold. It crashes down the lead time. These ultimately enhance the consistency in output and provide delight to customer. The Office Pull system which focusses on flow and schedule, enhances cross-training in terms of skill, improves flexibility and thereby provides a competitive advantage to the organization. This improves the Overall Professional Effectiveness (OPE) of the office driven business process, quite similar to concept of OEE in manufacturing processes.
In summary, the Pull system in office processes add to the Lean culture by ensuring a continuous value flow, preventing waste of waiting, delivering exactly what the next customer wants, providing value when it is wanted and finally, ensuring quality of being right the first time.
(Dr Ravindra Ojha is Professor – Operations at Great Lakes Institute of Management, Gurgaon)