The pull system (including Kanban and just-in-time) is a production management system called suction (PULL). This means that production planning takes place on the basis of orders formulated at each stage of production, with the starting point being actually updated on an ongoing basis the volume of orders placed by customers of final products (S. Singh, 2017, p. 492). The planning procedure begins with the determination of the planning values ensuring the execution of the last stage of production. No one at the top of the stream should produce a part or service until someone at the bottom of the stream asks for it (S. Singh, 2017, p. 492).
The Pull System reduces work in progress inventory by producing in smaller lots and controlled stocks (fixed minimum and maximum stocks). The production plan is delivered for the last process in the value stream (in this case the final assembly), while the production for the previous processes takes place on a supermarket replenishment basis, i.e. on the basis of the following principle: the production of the last process in the value stream (in this case the final assembly), the production for the previous processes takes place on the basis of the replenishment of the supermarket, i.e. the production of the last process in the value stream (in this case the final assembly) (S. Singh, 2017, p. 492-495). The production of the part number that has been extracted by the process is based on the principle of supermarket replenishment, i.e. the production of the part number that has been extracted by the process. higher. The size of the supermarket after each stage of production is determined individually and depends on the specificity of the process (size of the assortment, the number and time of conversions, the length of the production cycle, etc.) (S. Singh, 2017, p. 492-495).
Pull system means nothing less than the collection/pick-up/pick-up/pick-up of products or parts during the day at least once an hour. However, people are tempted to pick up their goods once or twice a day at most, so as not to overburden logistics by accident. By doing so, they are destroying the pulling effect on the line, hardly improving much and, in fact, completely discrediting the idea of the pulling system, which is beginning to appear to people as another corporate program of the month (M. Baudin, 2004, p. 5-6).
An essential element of successful implementation of the Pull system is the creation of a simple manual for operators and effective training. The basic principles that an operator must follow are (M. Baudin, 2004, p. 5-6):
- there is no signal - no PULL card - do not produce,
- don't pass a faulty play on to a client,
- each container/bogie has an identification (PULL card),
- there is always a standard number of pieces in the package/on the trolley,
- after the last piece has been removed from the container/buggy PULL/ card take the trolley/container to a designated place,
- maintenance of the system is the responsibility of both processes and all operators.
When using the PULL system in an organization, each employee should have basic knowledge of the subject. The found PULL card should in any case be returned to the appropriate process (A. Puchkov, 2016, p. 66).
The pull system requirements
The PULL system requires regular audits. Change in demand, frequency of card withdrawals requires recalculation. An issue that is often a point of contention is the situation when one of the processes is stopped e.g. due to failure - what should the next process do?
Theoretically, the answer is simple - there is no signal/no card/empty trolley - we do not produce (A. Puchkov, 2016, p. 66-71). On the other hand, we know that shipping is important and we will have to make up for it at the weekend by setting the overtime work. In many such cases, unfortunately, the decision is to continue production. This causes confusion among workers and is the first a step towards failure in the implementation/maintenance of the PULL system (A. Puchkov, 2016, p. 66-71).
To sum up, the success of PULL implementation requires (A. Puchkov, 2016, p. 66-71):
- continuous flow of materials in the production process;
- standardisation - reducing the structural diversity of products;
- observance of the rule - I buy as many raw materials as is required at a given moment;
- produce according to the demand for a product;
- high quality raw materials;
- deliveries on time;
- increased production flexibility - possibility of quick changeovers (SMED);
- increased machine availability (OEE over 85%, efficient TPM system;
- perfect information flow and communication.
The Pull system is never simple because it always questions the status quo. On the other hand, it makes all employees work to the rhythm of the clock time, which makes the process begin to function smoothly (Balle).
Benefits and risks
The PULL system allows to (M. Baudin, 2004, p. 5-6):
- establishment of one simple standard method of controlling and balancing the flow of resources;
- control of quantities for production and transport of materials;
- transition from large to small production batches;
- visual management of information flow in the production area;
- minimizing the number of stages required in the process;
- elimination of 7 losses (overproduction, waiting, overprocessing, unnecessary transport, repair, supplies, shortages);
- producing only what has been used up;
- producing and dispatching only what is required;
- promoting continuous improvement.
In the process of PULL system implementation many difficulties are encountered. Organizations that implement this system often give up on the first slip - reducing the delivery rate on time. The deterioration of this ratio results from the fact that the PULL system shows all the imperfections.
The risk factors are as follows (A. Puchkov, 2016, p. 75-76):
- material - the greatest difficulty is to deliver materials for production on time, especially in very complicated processes and with a large number of different components;
- machine - low OEE resulting from machine failure or long a change of armor;
- man - one of the critical elements of the efficient operation of the PULL system are people. The most frequently occurring event is a high turnover of employees in positions, lack of proper training and discipline;
- method - observing the production/assembly processes one can see many situations where the operator does not work repetitively due to difficult installation, unclear instructions for use or lack of ergonomics on the machine standpoint.
The PULL system brings many benefits for the organization, provided that it is implemented correctly, the conditions are right for it and it is systematically checked (S. Singh, 2017, p. 495). Training and awareness of not only managers but also employees play an important role here. The PULL system also requires regular reviews, calculations, inventory volumes and appropriate number of cards. Effective functioning of this system depends on many other methods/tools such as TPM, SMED, standardization.
- Baudin M., (2004), Lean Logistics. The Nutsand Bolts of Delivering Materials and Goods, Productivity Press, New York
- Norani N., Risyawati M., I. Rohaizah S., (2014), Lean manufacturing implementation: developing a qualitative research design , Journal of Technology and Operations Management 9(2),
- Puchkov A., et.all, (2016), Balancing Push and Pull Strategies within the Production System, IFAC-PapersOnLine Volume 49, Issue 2
- Singh S., (2017), Study on Push/Pull Strategy Decision Taken by Organizations for Their Products and Services, Universal Journal of Management 5(10)
- Sundara R., Balajib A.N., Satheesh Kumarc R.M., (2014), A Review on Lean Manufacturing Implementation Techniques, Procedia Engineering Volume 97
Author: Sara Pilch