Principles of the Theory of System Constraints (production planning in ERP). Five Focusing (Guiding) Steps Drum Rope

For any production today, the task of fulfilling customer orders in the shortest possible time is especially acute. Despite its apparent simplicity, this task is by no means easy to complete. Today there are many approaches to production management, but they are often too complex, expensive, require a long implementation time, and are therefore ineffective. Is there an alternative?

The world's production management experts, who developed the Theory of Constrains, argue that these techniques may actually work in many enterprises around the world. But, often, they can be replaced with much simpler and understandable solutions based on the tools of the Theory of Constraints.

The key issue in production is drawing up a production program and managing the process for its implementation. For these purposes, Theory of Constraints suggests using the “Buffer-Drum-Rope” tool. It is based on the following idea: the output volume of the entire enterprise depends on the output volume of the least productive section or machine. Excess work in progress or missed deadlines for fulfilling orders is most often due to the fact that other areas are not working in coordination with the limiting resource.

Drum

In this regard, it is necessary to synchronize the work of all sections, focusing efforts on planning the work of the “drum” constraint (the constraint as a drum sets the clock of the entire enterprise). An important difference between this approach is that only for the limitation is a detailed plan and order of work drawn up; the remaining sections work according to the “relay runner” principle: “received a task - do it as quickly as possible.”

The availability of free capacity usually allows these areas to get everything done on time. Orders in the work plan restrictions are placed depending on the deadline. This allows us to produce products within the time required by the client.

Rope

To avoid the accumulation of work in progress in the production chain, it is necessary to release materials from the warehouse on time. It is proposed to use the average time for an order to pass from materials to restrictions as such time. This approach, on the one hand, makes it possible to provide the limiting resource with blanks at the right time, and on the other hand, it does not create excessive inventories. Thus, we, as it were, tied a rope: we correlated the rate of work of the restrictions with the rate of release of materials into production.

Buffer

In real life there is always a place for chance, which is almost impossible to predict, but must be taken into account: a machine broke down, a worker did not show up for work, etc. To combat such accidents, you need to manage the so-called buffer.

When we “tied the rope”, data on the average order completion time were used in the calculation. If this order is given priority, then its completion time will be significantly reduced (practice shows that this time is usually a third of the average order completion time). Therefore, if we divide all the time into three zones: green, yellow, red; and we will track in which zone this or that order is located, we will get an effective management tool.

Let's explain with an example. Let’s say the order time from the launch of materials to the limitation is 9 days. Let's divide this time into three equal zones of three days. Today is the morning of April 1, 2011 - the day raw materials are released into production, so the order is in the green zone. Let us see on the morning of the fourth that the order is in the yellow zone. This means you don't have to worry about this order. If on the seventh we notice that the order has moved into the red zone, then we need to worry about its fulfillment. First of all, it is necessary to determine what operation the order is in and assess the likelihood of completion on time. If it is obvious that the order cannot be completed in time, then it must be given priority.

For a production system, it is enough to create and monitor three types of buffers:

A limit buffer designed to protect the limit from underloading;
. shipment buffer - protects compliance with order deadlines;
. assembly buffer - protects the production flow coming from a resource of limited capacity from stopping due to a lack of components that come from other resources.

Such a system allows you to receive timely information and manage production, focusing efforts where necessary.

Before this, we had never talked about how to implement the plan and increase the productivity of the enterprise. Let us dwell briefly on this issue. If a limiting resource determines the output of the entire enterprise, then all efforts must be concentrated on its maximum use. For this purpose, various tools for combating the loss of working time of this resource may be useful. For example, such lean manufacturing tools (Lean) as:

Quick changeover system (SMED);
. total equipment maintenance (TPM) system;
. Poka Yoke system - protection against personnel errors;
. visualization;
. 5S system, etc.

In this case, the effectiveness of these tools increases significantly and you don’t have to wait years for results.

However, a natural question arises. Why not immediately, if we have identified a bottleneck, not invest funds and increase its capacity by “expanding” or “expanding” it? The answer is simple. This usually requires significant financial investments and takes a long time, and not all enterprises can afford it. At the same time, tools that make it possible to make maximum use of the limitation do not require significant financial investments and the effect of their use appears almost instantly. Very often, the use of such tools eliminates the question of investment altogether. This fact is another argument in favor of making maximum use of the limitation, instead of immediate investment.

Let's summarize. What does the Theory of Constraints offer for production?

Significantly simplify the planning process: a detailed production plan is drawn up only for the limiting resource.
. Reduce the amount of work in progress in the system: all production works in harmony (pull instead of push),
. Increase the number of orders completed on time: managing buffers.
. Reduce order fulfillment time: control over order fulfillment time and analyze the reasons for penetration into the red buffer zone.
. Increase the production capacity of the enterprise through maximum use of the limiting resource.

5. DRUM-BUFFER-ROPE (DBR) METHOD

The “Drum-Buffer-Rope” method (DBR-Drum-Buffer-Rope) is one of the original versions of the “push-out” logistics system developed in the TOC (Theory of Constraints). It is very similar to the limited FIFO queue system, except that it does not limit the inventory in individual FIFO queues.

Rice. 9.

Instead, an overall limit is set on the inventory located between the single production scheduling point and the resource that limits the productivity of the entire system, the ROP (in the example shown in Figure 9, the ROP is area 3). Each time the ROP completes one unit of work, the planning point can release another unit of work into production. This is called a “rope” in this logistics scheme. “Rope” is a mechanism for controlling the restriction against overload of the ROP. Essentially, it is a materials issue schedule that prevents work from entering the system at a rate faster than it can be processed in the ROP. The rope concept is used to prevent work in process from occurring at most points in the system (except critical points protected by planning buffers).

Since EPR dictates the rhythm of the entire production system, its work schedule is called “Drum”. In the DBR method, special attention is paid to the resource that limits productivity, since it is this resource that determines the maximum possible output of the entire production system as a whole, since the system cannot produce more than its lowest capacity resource. The inventory limit and the time resource of the equipment (the time of its effective use) are distributed so that the ROP can always start new work on time. This method is called “Buffer” in this method. The “buffer” and “rope” create conditions that prevent the ROP from being underloaded or overloaded.

Note that in the “pull” logistics system DBR, the buffers created before the ROP have temporal rather than material in nature.

A time buffer is a reserve of time provided to protect the scheduled “start of processing” time, taking into account the variability in the arrival at the ROP of a particular job. For example, if the EPR schedule requires that a particular job in Area 3 begin on Tuesday, then material for that job must be issued early enough so that all pre-EPR processing steps (Areas 1 and 2) are completed on Monday (i.e., in one full working day before the required deadline). Buffer time serves to “protect” the most valuable resource from downtime, since the loss of time of this resource is equivalent to a permanent loss in the final result of the entire system. The receipt of materials and production tasks can be carried out on the basis of filling the “Supermarket” cells. The transfer of parts to subsequent stages of processing after they have passed through the ROP is no longer a limited FIFO, because the productivity of the corresponding processes is obviously higher.

Rice. 10. An example of organizing buffers in the DBR method
depending on the position of the ROP

It should be noted that only critical points in the production chain are protected by buffers (see Figure 10). These critical points are:

the resource itself with limited productivity (section 3),

any subsequent process step where the part processed by the limiting resource is assembled with other parts;

shipment of finished products containing parts processed with a limiting resource.

Because the DBR method focuses on the most critical points of the production chain and eliminates it elsewhere, production cycle times can be reduced, sometimes by 50 percent or more, without compromising reliability in meeting customer shipment deadlines.

Rice. eleven. Example of supervisory control
passing orders through the ROP using the DBR method

The DBR algorithm is a generalization of the well-known OPT method, which many experts call the electronic embodiment of the Japanese “Kanban” method, although in fact, between the logistics schemes for replenishing the “Supermarket” cells and the “Drum-Buffer-Rope” method, as we have already seen, there is a significant difference.

The disadvantage of the “Drum-Buffer-Rope” (DBR) method is the requirement for the existence of a ROP localized at a given planning horizon (at the interval of calculating the schedule for the work being performed), which is only possible in the conditions of serial and large-scale production. However, for small-scale and individual production, it is generally not possible to localize EPR over a sufficiently long period of time, which significantly limits the applicability of the considered logistics scheme for this case.

6. LIMIT OF WORK IN PRODUCTION (WIP)

A pull logistics system with a work in process (WIP) limit is similar to the DBR method. The difference is that temporary buffers are not created here, but a certain fixed limit of material inventories is set, which is distributed to all processes of the system, and does not end only at the ROP. The diagram is shown in Figure 12.

Rice. 12.

This approach to building a “pull” management system is much simpler than the logistics schemes discussed above, is easier to implement, and in a number of cases is more effective. As in the “pull” logistics systems discussed above, there is a single planning point here - this is section 1 in Figure 12.

A logistics system with a WIP limit has some advantages compared to the DBR method and the FIFO limited queue system:

malfunctions, fluctuations in the rhythm of production and other problems of processes with a margin of productivity will not lead to a shutdown of production due to lack of work for the EPR, and will not reduce the overall throughput of the system;

only one process must obey scheduling rules;

there is no need to fix (localize) the position of the ROP;

It is easy to locate the current EPR site. In addition, such a system gives fewer “false signals” compared to limited FIFO queues.

The considered system works well for rhythmic production with a stable range of products, streamlined and unchangeable technological processes, which corresponds to mass, large-scale and serial production. In single-piece and small-scale production, where new orders with original manufacturing technology are constantly being put into production, where product release times are dictated by the consumer and can, generally speaking, change directly during the manufacturing process of products, then many organizational problems arise at the level of production management. Relying only on the FIFO rule in the transfer of semi-finished products from site to site, the logistics system with a work in progress limit in such cases loses its effectiveness.

An important feature of the “push” logistics systems 1-4 discussed above is the ability to calculate the release time (processing cycle) of products using the well-known Little formula:

Release time = WIP/Rhythm,

where WIP is the volume of work in progress, Rhythm is the number of products produced per unit of time.

However, for small-scale and individual production, the concept of production rhythm becomes very vague, since this type of production cannot be called rhythmic. Moreover, statistics show that, on average, the entire machine system in such industries remains half underutilized, which occurs due to constant overloads of one equipment and simultaneous downtime of another in anticipation of work related to products lying in line at previous stages of processing. Moreover, downtime and overloading of machines constantly migrate from site to site, which does not allow them to be localized and to apply any of the above logistics pull schemes. Another feature of small-scale and individual production is the need to fulfill orders in the form of a whole set of parts and assembly units by a fixed deadline. This greatly complicates the task of production management, because The parts included in this set (order) can be technologically subjected to different processing processes, and each of the areas can represent an ROP for some orders without causing problems when processing other orders. Thus, in the industries under consideration, the effect of the so-called “virtual bottleneck” arises: the entire machine system on average remains underloaded, and its throughput is low. For such cases, the most effective “pull” logistics system is the Calculated Priority Method.

7. COMPUTABLE PRIORITIES METHOD

The method of calculated priorities is a kind of generalization of the two “push” logistics systems discussed above: the “Supermarket” replenishment system and the FIFO system with limited queues. The difference is that in this system, not all empty cells in the “Supermarket” are replenished without fail, and production tasks, once in a limited queue, are moved from site to site not according to the FIFO rules (i.e. mandatory discipline is not observed “ in the order received"), and according to other calculated priorities. The rules for calculating these priorities are assigned at a single production planning point - in the example shown in Figure 13, this is the second production site, immediately following the first “Supermarket”. Each subsequent production site has its own executive production system (MES - Manufacturing Execution System), the task of which is to ensure timely processing of incoming tasks taking into account their current priority, optimize internal material flow and timely show emerging problems associated with this process ,. A significant deviation in the processing of a particular job in one of the sites can affect the calculated value of its priority.

Rice. 13.

The “pull” procedure is carried out due to the fact that each subsequent section can begin to perform only those tasks that have the highest possible priority, which is expressed in the priority filling at the “Supermarket” level not of all available cells, but only those that correspond to priority tasks. Subsequent section 2, although it is the only planning point that determines the work of all other production units, is itself forced to carry out only these highest priority tasks. Numerical values ​​of task priorities are obtained by calculating the values ​​of the criterion common to all in each section. The type of this criterion is set by the main planning unit (section 2), and each production section independently calculates its values ​​for its tasks, either queued for processing, or located in the filled cells of the “Supermarket” at the previous stage.

For the first time, this method of replenishing “Supermarket” cells began to be used at Japanese enterprises of the Toyota company and was called “Production Leveling Procedures” or “Heijunka”. Nowadays, the process of filling the “Heijunka Box” is one of the key elements of the “pull” planning system used in the TPS (Toyota Production System), when the priorities of incoming tasks are assigned or calculated outside the production areas executing them against the backdrop of the existing “pull” replenishment system of the “Supermarket”. (Kanban). An example of assigning one of the directive priorities to an executing order (emergency, urgent, planned, moving, etc.) is shown in Figure 14.

Rice. 14. Example of assigning a directive
priority to fulfilled orders

Another option for transferring tasks from one site to another in this “pull” logistics system is the so-called “calculated rule” of priorities.

Rice. 15. Sequence of executed orders
in the calculated priority method

The queue of production tasks transferred from section 2 to section 3 (Figure 13) is limited (limited), but unlike the case shown in Figure 4, the tasks themselves can change places in this queue, i.e. change the sequence of their arrival depending on their current (calculated) priority. In fact, this means that the performer himself cannot choose which task to start working on, but if the priority of tasks changes, he may have to, having not completed the current task (turning it into the current WIP), switch to completing the highest priority one. Of course, in such a situation, with a significant number of tasks and a large number of machines on the production site, it is necessary to use MES, i.e. carry out local optimization of material flows passing through the site (optimize the execution of tasks already being processed). As a result, for the equipment of each site that is not the only planning point, a local operational production schedule is drawn up, which is subject to correction every time the priority of the tasks being executed changes. To solve internal optimization problems, we use our own criteria, called “Equipment Loading Criteria”. Jobs awaiting processing between sites not connected by the “Supermarket” are ordered according to “Queue Selection Rules” (Figure 15), which, in turn, can also change over time.

If the Rules for calculating priorities for tasks are assigned “externally” in relation to each production site (Process), then the Site Equipment Loading Criteria determine the nature of the internal material flows. These criteria are associated with the use of optimization MES procedures on the site, intended exclusively for “internal” use. They are selected directly by the site manager in real time, Figure 15.

Rules for selection from the queue are assigned based on the priority values ​​of the tasks being executed, as well as taking into account the actual speed of their execution at a specific production site (section 3, Figure 15).

The site manager can, taking into account the current state of production, independently change the priorities of individual technological operations and, using the MES system, adjust the internal production schedule. An example of a dialog for changing the current priority of an operation is shown in Fig. 16.

Rice. 16.

To calculate the priority value of a specific job being processed or awaiting processing at a specific site, a preliminary grouping of jobs (parts included in a specific order) is carried out according to a number of criteria:

Number of the assembly drawing of the product (order);

Part designation according to the drawing;

Order number;

The complexity of processing the part on site equipment;

The duration of passage of parts of a given order through the machine system of the site (the difference between the start time of processing of the first part and the end of processing of the last part of this order).

The total complexity of operations performed on parts included in this order.

Equipment changeover time;

A sign that the processed parts are provided with technological equipment.

Percentage of part readiness (number of completed technological operations);

The number of parts from a given order that have already been processed at this site;

The total number of parts included in the order.

Based on the given characteristics and calculating a number of specific indicators such as tension (the ratio of indicator 6 to indicator 5), comparing the values ​​of 7 and 4, analyzing the ratios of indicators 9, 10 and 11, the local MES system calculates the current priority for all parts found in one group.

Note that parts from the same order, but located in different areas, may have different calculated priority values.

The logistics scheme of the Calculated Priority Method is used mainly in multi-item production of small-scale and single types. Featuring a "pull" scheduling system and using local MES to ensure high-speed orders flow through individual production areas, this logistics design uses decentralized computing resources to maintain process efficiency in the face of changing job priorities.

Rice. 17. Example of a detailed production schedule
for workplace in MES

A distinctive feature of this method is that the MES system allows you to draw up detailed schedules of work performed within the production area. Despite some complexity in implementation, the method of calculated priorities has significant advantages:

current deviations that arise during production are compensated by local MES based on the changing priorities of the tasks being performed, which significantly increases the throughput of the entire system as a whole.

there is no need to fix (localize) the position of the ROP and limit the work in progress;

it is possible to quickly monitor serious failures (for example, equipment breakdown) at each site and recalculate the optimal sequence of processing parts included in various orders.

The presence of local production schedules in certain areas allows for operational functional and cost analysis of production.

In conclusion, we note that the types of “pull” logistics systems discussed in this article have common characteristic features, these are:

Preservation in the entire system as a whole of a limited volume of stable reserves (current reserves) with regulation of their volume at each stage of production, regardless of current factors.

An order processing plan drawn up for one site (a single planning point) determines (automatically “pulls out”) the work plans of other production departments of the enterprise.

Promotion of orders (production tasks) occurs both from the next section in the technological chain to the previous one using the material resources consumed in the production process (“Supermarket”), and from the previous section to the next one according to FIFO rules or calculated priorities.

E.B. Frolov, Moscow State Technological University "STANKIN"

According to the theory of constraints proposed by E. Goldratt, in each production a relatively small list of work centers can be identified, which are bottlenecks, the productivity of which limits the productivity of the entire production as a whole. To achieve maximum production productivity, these bottlenecks must be expanded as much as possible and used as efficiently as possible.

Method "Drum-buffer-rope" Theories of limitation of TOS systems by E. Goldratt in: General description

Specific steps to optimize production while taking into account production bottlenecks are combined into a technique known as “Drum-Buffer-Rope” or DBR (Drum-Buffer-Rope). Basic steps for using the technique:

• work centers that are bottlenecks. The technique calls these bottlenecks drums;
• ensure the most efficient loading of drums. To do this, you should accurately plan their work, draw up a schedule for the operation of these drums, eliminating downtime;
• subordinate the work on other work centers to the work of the drum. Production time at work centers located in front of the drum during the production process, the technique is called buffer. Work in the buffers must begin in advance, a specified time before the scheduled start time of the drum. The duration of the buffer must be chosen in such a way that work in it must be completed before the operating time of the drum. Thus, the buffer must protect the drum from downtime.

To support the “drum-buffer-rope” (hereinafter referred to as BBV) methodology, the production management functionality offers the following operating procedure:

• All production is divided into stages. The selection of stages is not a consequence of the BBB technique, but it may be necessary for other purposes, for example, the selection of parts of production carried out in different territories;
• stands out at each stage key work center of this stage is his drum. The drum is given precise information about its performance. For all work performed before and after it, a generalized execution time is specified, during which they are guaranteed to be completed - buffer;
• Production schedule planning is carried out on the basis of information from production stages. Thus, for production planning, detailed information about the productivity of all work centers is not required: it is enough to know the productivity of key work centers and the operating time in buffers; During production, the status of work in buffers in front of key work centers is monitored.

Tips for using the Drum-Buffer-Rope technique

• One of the most effective approaches to finding bottlenecks is to look at which work centers have workpieces piling up waiting to be processed.
• It may be advisable to place quality control in front of the “drum”. In this case, the bottleneck will only process workpieces that are known to be of high quality, and its inefficient operation will be eliminated.
• It is necessary to constantly monitor production and control changes in the composition of its bottlenecks. New bottlenecks can be identified by optimizing the loading of previously identified bottlenecks.
• All possible measures must be taken to ensure that the “drum” does not stand idle and works efficiently.
• If possible, the productivity of the “drum” should be increased, because this increases the performance of the entire system.

Literature on the methodology of TOC Theory of system limitations.

One of the most difficult tasks in production is planning the production process and providing operational management based on it. There are several different approaches. In this article, we will focus on the essence and advantages of the approach developed by the “Drum-Buffer-Rope” constraint theory.

The essence of the method is to simplify the problem as much as possible: planning production tasks for only one resource, which is a limitation, and ensuring synchronous operation of all other areas. It is clear that the output of the entire plant depends on the volume of output of this limiting resource, so there is no need to ensure optimal loading of all other centers and plan their work.

The term “drum” in the LBC refers to the production schedule of the internal resource of limited capacity (ROM), which determines the productivity of the enterprise as a whole. Thus, the limitation sets the pace or rhythm of the work of the entire company, protecting against overproduction and overload in the unrestricted. This allows for flexibility and a high degree of system responsiveness.

The “buffer” in BBK is a protective mechanism that allows you to make maximum use of the capacity of the limiting resource (eliminate possible downtime) and fulfill customer orders on time. However, these are not objects, but time. The buffer is designed to ensure that work in progress arrives a certain time before the scheduled start of processing. At the same time, a mechanism is provided to control the consumption of the buffer and the progress of the workpiece, part, assembly or product along the production chain.

“Rope” is a means of communication that allows you to ensure the synchronization of the release of materials and the speed of the restriction. This mechanism allows you to avoid excess materials in the production system, speed up production, reduce inventory and lead time. In fact, this is a plan for the release of materials from the warehouse, which is adjusted depending on the operating modes of the restriction.

This planning mechanism allows you to:

• Monitor and manage the execution of orders on time.
• Reduce production cycle time.
• Reduce the amount of work in progress in the system.

Another advantage of this method is its flexibility: BBK can be used both in order production and in warehouse production.

Unlike other systems, BBK aims to generate income rather than reduce inventory. At the same time, the use of this method allows you to see bottlenecks in production and take focused measures to solve problems that arise. Moreover, the effect of such measures will be immediate and tangible. So, applying the changeover method (SMED) from lean manufacturing to a limited capacity resource (SCR) will instantly increase the output of the entire enterprise. Thus, the approaches of the Theory of Constraints do not contradict, but complement existing techniques, significantly enhancing the effect of their application.

Theory of Constraints is a popular methodology for managing systems in various activities, developed in the 1980s by Eliyahu Goldratt and based on finding and managing the key limitation of the system, which determines the success and efficiency of the entire system as a whole. The main feature of the methodology is that by making efforts to control a very small number of aspects of the system, an effect is achieved that is much greater than the result of simultaneous impact on all or most of the problem areas of the system at once or one by one.

The theory of constraints approach is based on identifying this limitation and managing it to increase the efficiency of achieving the set goal (for business, accelerating and increasing profit generation). Where efficiency is the speed of achieving a goal with the lowest possible costs and without cutting the goal in content. Methodologically, the theory of constraints includes a number of logical tools that allow you to find a limitation, identify the management contradiction behind it, prepare a solution and implement it taking into account the interests of all stakeholders. Focus on the final result allows you to achieve extremely fast results (for business 2-3 months), focus on mutually beneficial solutions allows you to increase the level of interaction and motivation of staff. Eliyahu Goldratt has developed and published Theory of Constraints applications for operations and production management, financial management and performance management, project management (new product development, construction), logistics and the entire supply chain, marketing, all types of sales, personnel management, tactics and system development strategies.

Among the methods proposed by the theory of constraints are a set of rules for checking the logic of statements [⇨] about the work of an organization and the cause-and-effect relationships between them, algorithms for constructing cause-and-effect diagrams, the “drum-buffer-rope” method, as well as the critical chain method for project management.

Method "drum - buffer - rope"

One of the methods of the theory of constraints, widely used in the field of production, is the “drum-buffer-rope” method, which sets the following principles:

• “drum” - production must work according to a certain rhythm;
• “buffer” - in front of the restriction there must be some buffer of material reserves that protects the restriction from downtime;
• “rope” - materials should be supplied to production only when stocks before the limitation have reached a certain minimum, not earlier, so as not to overload production.

The drum-buffer-rope method is based on the analysis of inventory turnover and its relationship with the turnover of receivables and payables.

The drum is a figurative expression. A symbol that indicates that it is necessary to maintain a certain rhythm of production, one with the rhythm of receiving money from customers and paying suppliers; In essence, we are talking about managing the duration of the financial cycle.

A buffer is also a figurative expression, the essence of which is the need to ration stocks, calculate the amount of deficit and surplus for each item;

The rope is another symbol, the essence of which is to visualize and mark deviations from the norm, generate signals and alerts when such deviations occur.

Inventory management using the drum-buffer-rope method is easy to implement in Excel using financial models.

Thought processes

The theory of constraints also offers a more general systems approach to finding and removing constraints, which can be applied not only in production, but also in other, very diverse systems. This approach consists of the sequential construction of analytical schemes of the following types:

• Current Reality Tree(SDT, similar to the current state diagram used by many organizations) - to identify cause-and-effect relationships between adverse events and the root cause of most of these adverse events.
• Conflict Resolution Diagram(DRC) - to eliminate contradictions in the system, which often cause an undesirable situation in the system. The method of eliminating contradictions is usually called injection.
• Future Reality Tree(DBR) - when certain methods (injections) are selected to eliminate the root causes of problems or conflict identified using DTR in the conflict resolution diagram, a tree is built showing the future state of the system. This is necessary to identify the negative consequences of the selected injections ( negative branches) and choosing ways to deal with them.
• Transition tree- to identify possible obstacles to transformation and eliminate them.
• Transformation plan- to develop specific instructions for performers to implement planned changes.

This approach is described in artistic form in the book “Goal-2. It's not a matter of luck." In more formal academic language - in the book by W. Detmer “Goldratt's Theory of Constraints”.

Criteria for checking logical constructions

Goldratt's method of thought processes, unlike many similar information visualization techniques (for example, Ishikawa diagrams, mental maps), offers a set of rules that allow you to check the presence of cause-and-effect relationships and their reliability. Such rules are called criteria for checking logical constructions(CPLP, Categories of Legitimate Reservation) are eight provisions with which you can check, prove or refute the correctness of the established cause-and-effect relationships:

1. Clarity- everyone clearly understands the statements used in the diagram.
2. Availability of approval- the statement contains a complete thought.
3. Presence of cause-and-effect relationships- Does the named cause really cause the indicated effect?
4. Sufficiency of the reason given- the named cause is sufficient to cause the specified effect, in the given context.
5. Checking for an Alternative Cause- Couldn't the reason mentioned be just one of the possible ones?
6. Inadmissibility of replacing cause with effect- cause and effect are confused.
7. Search for a verification consequence- if the named cause takes place, then it must have not only the indicated consequence, but also some other, side effects (which do not necessarily have to be indicated in a specific diagram).
8. No tautology- the effect is offered as a justification for the existence of the cause.

Notes

Literature

• Eli Schragenheim. Theory of Constraints in Action: A Systematic Approach to Improving Company Efficiency = Management Dilemmas. - M.: Alpina Publisher, 2014. - 286 p. - ISBN 978-5-9614-4727-9.
• Eliyahu M. Goldratt, Jeff Cox. Target. Continuous Improvement Process = English The Goal: A Process of Ongoing Improvement. - Minsk: Potpourri, 2009. - 496 p. - 7000 copies. - ISBN 978-985-15-0641-1.
• Eliyahu M. Goldratt, Jeff Cox. Target. Continuous improvement process. Goal-2. It's not about luck =