Family Picnic for Children’s Day – Time Together for the SIM Gdynia Team in Chwaszczyno
On 14 June 2026, the Family Picnic for Children’s Day took place at Toyota Arena Stadium in Chwaszczyno. The event was organized with the idea of spending time together in a family-friendly atmosphere. The programme included many attractions for children and adults, such as animations, competitions, artistic performances, inflatable attractions, family sports activities and a food zone. It is an event that has attracted the local community for years and creates a space for shared celebration, conversations and good fun. We are pleased that this year we once again managed to gather enough participants to prepare a SIM Gdynia zone for our employees and their loved ones. It was a space for spending time together, talking and relaxing with prepared snacks and drinks. Time Together Outside Everyday Work Our zone was a place where we could meet outside the everyday work environment, spend time with our families and simply be together in a less formal atmosphere. It was also an opportunity to share a meal, talk and take a moment to rest during the event. Such initiatives are of great value to us because they help build relationships not only within the team, but also among families and loved ones, who are an important part of our employees’ lives. In the daily pace of work, there is not always space for such meetings, which is why we appreciate even more the opportunity to take part in local events together. Engagement in Local Initiatives For us, it is not only an opportunity for integration, but also a way to support initiatives taking place in our closest surroundings. We are happy to get involved in events that bring people together and create a positive atmosphere around spending time together. The weather was good, and the whole event took place in a friendly and family-oriented atmosphere. It was a good opportunity to spend time together and meet outside everyday professional duties. Thank you to all participants for the time spent together, and see you at the next events!
Technological Training with ISCAR at SIM Gdynia
On 15 May, a technological training session conducted by ISCAR took place at SIM Gdynia. ISCAR is our partner with extensive experience in the field of cutting tools and CNC machining technology. The meeting was an opportunity for our team to expand its knowledge and learn about solutions that may support the further development of production processes carried out at SIM Gdynia. In the CNC machining industry, the development of tool technologies has a direct impact on process stability, production efficiency and the quality of manufactured parts. That is why meetings of this kind have real practical value for us. New Solutions in Cutting Technology During the training, ISCAR representatives presented the new LOGIQUICK tool line, developed for modern cutting and milling processes. Solutions from this series make it possible to better match tools to specific technological applications, which may translate into both greater precision of the processes performed and optimization of machining times. In practice, such solutions are important not only from the perspective of efficiency, but also for the repeatability of production processes, which is crucial in everyday work for the quality of finished components. Exchange of Experience and Competence Development For our team, this was not only a product meeting, but above all an opportunity to exchange experience and discuss practical aspects of cutting technology. Direct contact with technology partners makes it easier to assess the potential of new solutions and look at the production process from the perspective of everyday technological challenges. At SIM Gdynia, development means not only investments in the machine park, but also systematic expansion of the team’s competences and improvement of the processes used. Meetings like this are an important part of this approach because they allow us to combine practical knowledge with technological innovations emerging on the market. We would like to thank ISCAR for the substantive training, valuable discussions and the opportunity to learn more about new technological solutions.
DUAL USE – Business and Security
On 19 May, we had the opportunity to take part in the conference “Dual Use – Cooperation, Challenges, Opportunities and Financing Directions in the Era of Offshore Wind Energy and Nuclear Energy”, which was held at Stacja Kultura in Rumia. The event was organized by the City of Rumia, Rumia Invest Park and Kongsberg. It was dedicated to dual-use technologies and solutions, meaning those that can be applied in both the civilian and defence sectors. The conference brought together representatives of business, industry, the energy sector and companies connected with modern technologies. The discussions focused on the development of offshore wind energy, nuclear energy, infrastructure security and the future of industry in the Pomerania region. Pomerania Facing New Industrial Challenges During the conference, a lot of attention was given to the changes currently taking place in the region. The dynamic development of energy and infrastructure investments is increasing the demand for new technologies, competences and industrial partners capable of carrying out demanding production projects. Dual-use solutions are becoming increasingly important, as they can be applied both in the civilian sector and in areas related to security and the defence industry. For manufacturing companies, this means not only new development opportunities, but also the need to adapt processes to increasingly high technological and quality requirements. Discussions on Technology and Market Development Directions Our participation in the event was an opportunity to discuss the directions of industrial development and the role of manufacturing companies in projects related to energy, the maritime industry and infrastructure security. Meetings of this kind are very valuable because they help us better understand market needs, technology development directions and the challenges that the industrial sector will face in the coming years. During the conference, the topic of cooperation between business, local governments and technology companies was also discussed. The development of large energy projects requires not only infrastructure investments, but also the creation of a stable production and technological base in the region. The Importance of Cooperation and Exchange of Experience For us, participation in such events is not only an opportunity to gain knowledge, but also a chance to exchange experience and talk with representatives of different industrial sectors. Direct contact with technology partners, manufacturers and market experts allows us to look more broadly at the changes taking place in the industry and better assess the development directions of modern industrial production. We would like to thank the organizers for the opportunity to take part in the event and for valuable industry discussions.
Reverse Engineering – From a Worn Part to New Documentation and CNC Machining
In many production plants, the problem is not the part failure itself, but the lack of possibility to quickly reproduce it. This applies especially to older machines for which technical documentation is incomplete, unavailable or simply no longer exists. In such situations, replacing the entire machine is often not financially justified, while the availability of original spare parts may be limited. This is where reverse engineering combined with CNC machining becomes useful. This process makes it possible to reproduce a part based on a physical sample, prepare new technical documentation and manufacture a component adapted for further operation within the existing system. When Reverse Engineering and CNC Machining Are an Alternative to Buying New Parts Not every part needs to be recreated from scratch, but in many cases this is the most reasonable solution. This is especially true when machine downtime generates real costs and obtaining the original part turns out to be difficult or unprofitable. This applies in particular to older machines, for which the availability of spare parts is limited or the delivery time does not meet the needs of continuous production. Lack of Technical Documentation and the Need to Reproduce a Component In the case of older machines, technical documentation is often unavailable. This applies both to equipment that has been withdrawn from production and to parts that were designed many years ago without a digital documentation archive. In such situations, the worn part becomes the only reference point. If its condition and preserved geometric features allow for reliable analysis, it is possible to prepare new technical documentation and manufacture a replacement part using CNC machining. Worn or Unavailable Parts in Older Machines The problem concerns not only documentation, but also part availability. In maintenance practice, a frequent challenge is dealing with components that are no longer offered by the manufacturer or whose delivery time is unacceptable from a production perspective. In such cases, reverse engineering can significantly shorten the path from identifying the problem to manufacturing a new part, without the need for costly modernization of the entire machine. What the Reverse Engineering Process Looks Like Before CNC Machining Reproducing a part based on a worn component is not simply about copying its shape. Understanding the function of the subassembly, its geometry and the conditions in which it will continue to operate is essential. The aim of the process is to prepare a solution that can operate again within the existing system, not merely to recreate the appearance of the element. Analysis of the Physical Part and Assessment of Reproduction Possibilities The first stage is the analysis of the available part. Its technical condition, degree of wear and whether its preserved geometric features allow reliable reproduction are assessed. Not every worn part can be directly replicated. In some cases, it is necessary to take operational wear into account and separate the original geometry from changes that occurred during use. Recreating Geometry and Preparing Technical Documentation After the analysis, it is possible to prepare new technical documentation, which becomes the basis for further production. At this stage, the physical part is no longer just a sample, but becomes a source of information needed to reproduce the component. The documentation must include not only dimensions, but also key functional features that will be important during the operation of the component. Selection of Material and Production Assumptions Recreating the geometry does not always mean automatically recreating the entire solution one-to-one. The material, the way the component operates and its service requirements are also important. In some cases, it is necessary to take into account production parameters different from those used in the original solution, especially if the reproduced component is to operate under changed conditions. The Role of the Technologist in Reverse Engineering and CNC Machining Effective reverse engineering requires a combination of measurement, technological and production knowledge. The available part itself does not always provide a complete picture of the parameters needed to reproduce it, which is why proper interpretation of the collected data and assessment of production possibilities are crucial. From a technological perspective, it is important to translate the information obtained from part analysis into documentation that enables the new component to be manufactured using CNC machining. It is equally important to consider the function of the element, how it works with other parts and the operating conditions in which it will continue to be used. This is the area handled by the technologist preparing the production process. We describe what this role looks like in practice in more detail in the article: “From documentation to stable production – the work of a technologist at SIM Gdynia” Which Components Are Most Often Reproduced Through Reverse Engineering and CNC Machining? Reverse engineering is used wherever quick reproduction of a part helps reduce downtime or avoid costly replacement of a larger system. Most often, this concerns parts of production machines, wear components and mechanical parts that deteriorate over time, while replacement with original equivalents is difficult. Most commonly, these include: This is especially important in plants that modernize existing machine parks and want to extend the life of proven equipment without having to fully replace the infrastructure. Summary Reverse engineering makes it possible to reproduce worn or unavailable components based on physical samples and prepare new technical documentation for further production. Combined with CNC machining, it enables the production of spare parts for existing machines without the need to replace entire devices. In many cases, this solution helps reduce downtime and maintain the continuity of machine park operation. At SIM Gdynia, we provide CNC machining of parts for demanding industrial applications, including cases where the starting point is an existing component that needs to be
Tightness and Surface Smoothness in CNC Machining of Hydraulic Power Components
Hydraulic power is an area where even minor quality deviations can affect the operation of the entire system. Component tightness, stability of operating parameters and durability of cooperating elements depend not only on the design, but also on the quality of each manufactured part. That is why CNC machining of hydraulic power components requires high precision, control of process parameters and repeatable quality. Dimensional accuracy, surface quality and the compatibility of cooperating elements are particularly important here, as they are responsible for maintaining pressure and ensuring proper seal operation in the finished system. Why CNC Machining of Hydraulic Power Components Requires High Precision In hydraulic systems, tightness is not only a feature of a single component. It is the result of many elements working together, all of which must maintain the right dimensional and surface parameters. Even small deviations can affect the operation of the entire system. In hydraulic power systems, maintaining the correct working pressure is crucial for performance and operational safety. Leaks may lead to pressure drops, reduced efficiency and faster component wear. For this reason, CNC machining of hydraulic components requires a high level of manufacturing accuracy. This applies both to sealing surfaces and to cooperating elements that must maintain geometric compatibility within the entire system. We discuss manufacturing accuracy and tolerance classes in more detail in the article: “Dimensional and fit tolerances – how to optimise IT classes in CNC machining to avoid overpaying?” Surface Smoothness in CNC Machining and Seal Effectiveness One of the key quality parameters in hydraulic components is the condition of the surface after CNC machining. The effectiveness of cooperation with seals and the long-term durability of the system largely depend on this parameter. Surface quality affects not only tightness, but also the stability of cooperating elements and the rate of wear during operation. How Surface Roughness After CNC Machining Affects Seal Performance Excessive surface roughness may lead to faster seal wear. Irregularities increase friction and place greater stress on sealing elements during operation. In the long term, this may result in loss of tightness, reduced system efficiency and the need for earlier replacement of wear components. Surface quality requirements depend on the function of a specific component and its operating conditions. Different parameters will be important for static components, while others will matter for elements operating in continuous motion. Is an Extremely Smooth Surface After CNC Machining Always Beneficial? High surface quality is important, but oversimplifying this issue can lead to incorrect assumptions. An extremely smooth surface does not always mean better operating conditions. In some applications, a specific surface structure helps maintain proper lubrication conditions and stable cooperation with seals. Required surface parameters are selected depending on the component’s function and operating conditions. Tolerances and Quality Control in CNC Machining of Hydraulic Components The tightness of a hydraulic system results from the compatibility of many parameters. Surface quality alone is not enough if the elements do not maintain the required dimensional accuracy. In components operating under pressure, even minor deviations can affect the fit of cooperating parts and the stability of the entire system. Fits and Manufacturing Accuracy in CNC Machining In hydraulic components, fits and dimensional compatibility of cooperating elements are highly important. Dimensional deviations may affect the tightness of connections or the operation of moving mechanisms. Problems of this type often appear only at the assembly or operating stage, when individual elements begin to work together under load. Measurement and Surface Control After CNC Machining Quality control in the production of hydraulic components includes both dimensional measurements and the assessment of surface parameters. Verification of the part geometry makes it possible to confirm compliance with technical documentation, while surface quality control directly affects the functionality of the finished component. We discuss methods of measuring and inspecting parts in more detail in the article: “How to measure workpieces in CNC machining? Measurement methods and their applications” For elements responsible for tightness, what matters is not only a single measurement result, but also repeatable quality across successive parts. Repeatability of the CNC Machining Process and Component Tightness The production of hydraulic components requires a stable process. Even a correctly manufactured part does not guarantee the quality of the entire series if process parameters are not kept under control. Repeatability is particularly important wherever components operate under pressure and must maintain identical functional properties regardless of the production batch size. Which Hydraulic Power Components Require the Highest CNC Machining Precision? Not all hydraulic system components are equally demanding. The highest precision is required where even small manufacturing differences may affect tightness, fluid flow or the stable operation of the entire system. The most demanding components include: In their case, not only dimensional accuracy matters, but also surface quality and manufacturing repeatability. Valve bodies are particularly demanding, as their manufacturing quality directly affects fluid flow and the functionality of the entire system. Both the geometry of the part and the surface quality of flow channels and cooperating surfaces are important here. A similar situation applies to sleeves and pistons operating in motion, where even small deviations can increase friction, accelerate seal wear or affect component stability. Summary Hydraulic power is an area where CNC machining requires particularly strict quality control. System tightness depends on many factors – from dimensional accuracy and surface quality to the stability of the entire production process. In the case of components operating under pressure, even minor manufacturing differences can affect the durability and reliability of the finished solution. That is why repeatability of parameters and high manufacturing quality are crucial in the production of such elements. At SIM Gdynia, we provide CNC machining of components for demanding industrial applications, where tightness, accuracy and manufacturing repeatability are of key importance.
Mechanical Assembly of Subassemblies – Why It’s Worth Outsourcing Complete Modules to a CNC Machining Supplier
Mechanical assembly in modern industry is increasingly becoming integrated with the manufacturing process instead of functioning as a separate stage. More and more companies are asking whether it is better to coordinate multiple suppliers or outsource the production of a complete module to a single partner. From our experience, combining CNC machining and assembly helps reduce fitting issues between components and simplifies production management. Is It Worth Combining CNC Machining and Assembly in One Place? In the traditional production model, individual components are manufactured by different suppliers. Only after delivery are they assembled and completed at the customer’s facility. This model requires coordination of multiple orders, shipments, and quality control stages. Each of these elements increases the risk of errors and makes it harder to maintain control over the entire process. As a result, the likelihood of delays and inconsistencies between suppliers grows. Reducing Organizational Costs Outsourcing the production of a complete module simplifies production management. Instead of handling multiple ERP entries and coordinating several purchase orders, you work with one consistent production order. It also reduces the number of administrative operations related to order processing and delivery control. This is especially important in projects involving a large number of components that require coordination between multiple suppliers. Shorter Lead Times in CNC Machining and Assembly Processes In an integrated model, the process runs more smoothly because components move directly from one production stage to the next without the need to organize transportation between suppliers. This eliminates downtime and reduces waiting times for subsequent operations, resulting in faster project completion. Reducing lead times is important not only operationally but also from a business perspective. It allows products to be introduced to the market faster and helps minimize costs associated with production downtime or project delays. Fits and Tolerances in CNC Machining – One Supplier, One Responsibility Most assembly problems occur where components produced by different suppliers must fit together. Even small differences in tolerances can prevent proper assembly of a subassembly. In such cases, the issue is not caused by a single mistake, but by the accumulation of minor deviations that only become visible during final assembly. We discuss the topic of tolerances and component fitting in more detail in the article: “Dimensional Tolerances and Fits – How to Optimize IT Classes in CNC Machining to avoid Overpaying?” Eliminating Assembly Issues When an entire module is handled by a single supplier, tolerances are adjusted already at the production stage, and any deviations can be corrected immediately. Components are verified as a complete system, which helps avoid assembly problems later on. This is especially important in serial production, where assembly repeatability directly affects production time and costs. Quality Control of the Entire Subassembly Quality control for a finished subassembly includes not only checking individual dimensions but also verifying overall functionality. Fits, movement resistance, and — if required by the project — sealing performance are tested. Thanks to this, the completed module can be used directly in further production stages. We describe quality control and measurement methods in more detail in the article: “How to measure workpieces in CNC machining? Measurement methods and their applications.” How Production and Assembly Integration Impacts the Project Combining CNC machining and assembly allows for a broader perspective on the entire production process. In practice, this means the possibility of simplifying the design or selecting technologies more effectively. Integration of CNC Machining and Assembly Processes In the integrated model, one supplier is responsible for the entire process — from CNC machining and finishing operations to part preparation and final assembly. This approach makes production planning easier and reduces unnecessary operations. As a result, subsequent production stages are better aligned, and the number of intermediate operations is minimized. This has a direct impact on overall process efficiency. Management of Standard Components As part of the module production process, procurement of standard components is also handled, including: This allows the entire subassembly to be produced as one cohesive order. It reduces the risk of using incorrect components and simplifies quality control of the complete assembly. Where Errors Occur in CNC Machining and Assembly Projects In demanding industries such as energy or heavy machinery, failure of a single component can lead to serious consequences. In more complex assemblies, even small errors may result in operational issues or the need for modifications during assembly. Most often, these problems arise from discrepancies between documentation and the actual execution of parts by different suppliers. The Importance of Process Control In the integrated model, assembly takes place in controlled conditions, reducing the risk of contamination and enabling material verification at different stages of the process. As a result, finished subassemblies are more repeatable and less prone to operational errors. Why the Price of a Single Part Is Not the Total Project Cost The cost of an individual component is only part of the overall project cost. Storage costs, assembly organization, team working time, and the risk of errors and rework are equally important. Only by considering all these factors can the actual total production cost be properly evaluated. For this reason, cost analysis should include the entire project lifecycle, not just the price of a single component. Summary Outsourcing mechanical assembly together with CNC machining helps simplify production organization, shorten lead times, and reduce the risk of errors at component interfaces. This results in greater process predictability and improved quality control of the finished subassembly. For more complex assemblies, consistency throughout the entire process — from CNC machining to final assembly — is essential. At SIM Gdynia, we provide production and assembly of components, ensuring proper fit, repeatability, and compliance with project requirements.
CNC Machining in the Medical Industry – Surface Quality Requirements
CNC machining in the medical industry is one of the most demanding areas of manufacturing. In this context, build quality and process repeatability are of critical importance, as the components are used in demanding technical applications. Parameters such as surface roughness and process cleanliness are of key importance here, as they directly affect the safety of the parts’ use. Why is CNC machining in the medical field so demanding? Manufacturing for the medical sector differs from standard industrial production primarily in terms of the level of responsibility. Components such as surgical instruments or implant parts must be completely safe when in contact with the human body. It is not just about the material, but also its finish. Even minor surface imperfections can affect the durability and safety of the component. The importance of surface quality in CNC machining for the medical industry It is precisely at the surface finishing stage that the difference between standard machining and production for the medical industry is most often evident. The greatest challenge is not the fabrication of the part itself, but achieving the appropriate surface quality. Every scratch, microcrack, or irregularity can: This means a higher risk of operational issues and difficulties in maintaining the required cleanliness of the part during use. That is why medical manufacturing strives for a surface that is as smooth as possible and easy to clean. Surface roughness in CNC machining Surface roughness determines how much a given surface deviates from being perfectly smooth. The Ra parameter, which describes the average surface roughness, most commonly appears in documentation. Which values matter In standard industrial manufacturing, Ra values of approximately 1.25 µm are considered acceptable. In the medical industry, requirements are significantly higher—often below 0.4 µm, and even lower for certain components. For the end user, this means: This translates to greater safety of use and better control over the operation of the tool or implant. Sterilization and surface quality after CNC machining Excessive roughness can hinder effective sterilization. Contaminants can remain in microscopic irregularities, which are difficult to remove even in high-pressure processes. Therefore, additional finishing processes are used, such as: The selection of the appropriate finishing process depends on the requirements of the specific component and its application. Material Challenges in CNC Machining for the Medical Industry Materials used in the medical industry, such as stainless steels, titanium, or certain engineering plastics, are among the most difficult to machine. Their machining requires greater temperature control, stable cutting parameters, and the appropriate selection of tools. A lack of control over these factors can lead to a deterioration in surface quality and instability of the entire process. We discuss the topic of machining difficult materials in more detail in the article: “CNC Machining of stainless and acid-resistant steel – technological challenges in demanding conditions”. Temperature control and process stability in CNC machining During machining, some materials heat up faster than standard structural steels. If the process is unstable, this can lead to a deterioration in surface quality or changes in the material’s structure. Therefore, proper cooling, control of cutting parameters, and process repeatability are particularly important. Only the combination of these elements allows for maintaining stable part quality in mass production. We describe quality control and measurement methods in more detail in the article: “How to measure workpieces in CNC machining? Measurement methods and their applications”. Surface finish CNC machining itself is only part of the process. Finishing operations, such as deburring and edge smoothing, are also of great importance. In medical components, even very small imperfections can pose a risk, which is why the final surface quality is just as important as dimensional accuracy. Process cleanliness in CNC machining Part cleanliness is not limited to the absence of visible contaminants. It is also crucial to remove residues from the machining process, such as oils, coolants, or material particles. In medical manufacturing, special technological measures are employed, the cleaning process is controlled, and the material is verified as early as the production intake stage. Material inspection To ensure the quality of the part, material inspection is also crucial. This involves verifying its composition and compliance with requirements even before production begins. Process cleanliness and material inspection are crucial for ensuring the quality and safety of medical components. Summary The production of components for the medical industry requires a combination of precise CNC machining, quality control, and appropriate finishing processes. High requirements regarding surface roughness and cleanliness stem directly from the need to ensure the safe use of parts. Projects for the medical industry require special surface quality control and process stability. At SIM Gdynia, we manufacture parts where precise CNC machining and finish quality are critical to the safety and reliability of the components.
STOM 2026 Trade Fair – SIM Gdynia at the Industrial Spring in Kielce
STOM 2026 is behind us. Several days filled with intensive meetings and discussions with machine manufacturers, tooling suppliers, and partners from the CNC machining industry. From March 24–27, 2026, Targi Kielce once again became a meeting place for the industrial sector during the Industrial Spring event cycle, covering areas such as metalworking, automation, robotics, and manufacturing technologies. Meetings and Observations from the Trade Fair Participation in the event was primarily an opportunity for direct contact with technology suppliers and for evaluating solutions presented at the exhibition stands. Such meetings make it possible to: This is particularly important in an industry where technological decisions directly affect process stability and component quality. Development Trends in CNC Machining We returned from the trade fair with new tools to test and new ideas for further development. The key trends we observed include: In CNC machining, there is an increasingly visible shift toward solutions focused on production predictability rather than only individual technological parameters. The Importance of Industry Events Industry trade fairs remain one of the most valuable sources of knowledge about technological development trends. Direct contact with manufacturers and the opportunity to see machines and tools in operation make it easier to evaluate their application in real production environments. Such meetings are highly valuable because they allow solutions to be compared with practical experience and current market requirements. We would like to thank all organizers and participants for the valuable conversations and exchange of experience.
SIM Gdynia’s participation in the drone trade fair – the development of UAV technology in the defence sector
We took part in a drone trade fair to gain a first-hand insight into the development of unmanned aerial vehicle (UAV) technology, with a particular focus on its applications in the defence sector. We focused on analysing solutions, talking to market participants and identifying key technological trends. For us, events of this kind are a vital source of knowledge about the industry’s real needs. This is particularly important in the context of SIM Gdynia’s development in the defence sector, which, following the granting of a licence in 2025, has become one of our strategic priorities. The role of drones and directions for technological development Drones are used in reconnaissance, logistics and operational activities, and their development focuses on increasing autonomy, operational precision and efficiency in diverse environmental conditions. From the perspective of mechanical component manufacturing, this means increasing demands in terms of quality, repeatability and design optimisation with regard to weight and strength. Increasing emphasis is being placed on advanced materials and precision manufacturing technologies, including CNC machining, which plays a key role in ensuring the stability and reliability of entire systems. The trade fair also showed us how dynamically the approach to design is changing – functional integration, miniaturisation and the ability to rapidly implement new solutions are becoming increasingly important. Summary Participating in the drone trade fair was a valuable experience for us, enabling us to better understand current trends in technological development and market needs. Direct contact with the industry has provided us with inspiration and is an important element in building our expertise in the field of demanding applications. We will closely follow future events and the further development of UAV technology, treating them as a natural source of knowledge supporting the development of our production and technological processes.
Dimensional and fit tolerances – how to optimise IT classes in CNC machining to avoid overpaying?
Modern CNC machining allows for very high precision in the manufacture of parts. However, in production reality, the most important question is not: how precisely can we manufacture a part, but what level of precision its function actually requires. In practice, many designs include tolerances that are far stricter than necessary. Every tightening of the accuracy class affects the production technology, cycle time and unit cost of the part. In many industrial applications, CNC machining uses IT7–IT8 classes, which ensure adequate accuracy whilst maintaining process stability. Moving into the IT6 range or higher usually involves increased technological requirements and can lead to higher production costs, particularly for more complex parts. IT tolerance classes in CNC machining – the basis for communication between designer and manufacturer IT (International Tolerance) tolerance classes define the permissible range of deviation from the nominal dimension. The lower the IT class number, the narrower the tolerance range and the greater the demands on the manufacturing process. What is the IT accuracy class in CNC machining practice In accordance with ISO 286, classes IT01 to IT5 are mainly used in measuring instruments and reference elements. In machine design, the IT6–IT11 range is most commonly used. For example:for a shaft with a diameter of 50 mm, IT7 denotes a tolerance of approximately 0.025 mm. By way of comparison, the diameter of a human hair is approximately 0.05–0.08 mm. Such minute dimensional differences demonstrate the high level of stability required in the CNC machining process at high accuracy grades. Thermal expansion of the material One of the factors affecting the maintenance of tolerances is the temperature of the material. Maintaining IT6 class for larger components can be challenging, particularly with materials that have high thermal expansion, such as aluminium. Temperature variations between the production and measurement environments can affect the measurement result and the maintenance of the required tolerance. For this reason, temperature stabilisation is often employed in precision CNC machining prior to final quality control. How tolerances affect production costs in CNC machining The relationship between tolerance class and production cost is not linear. Each successive level of accuracy results in a significant increase in process complexity. Cycle time and number of operations Moving from IT9 to IT6 very often means a change in production technology. Instead of a single finishing operation, the following may be required: Each of these stages extends production time and increases the unit cost of the component. Approximate impact of the IT class on the cost of the workpiece IT class Process complexity Estimated production cost IT11 – IT13 Rough machining Base level IT8 – IT9 Standard CNC machining +20–40% IT7 Precision finishing +60–100% IT6 and above Grinding / controlled conditions +200% and above These figures are indicative, as the actual cost depends on the material, the part’s geometry and the size of the production run. Tools and tooling Higher accuracy also requires more precise tooling. In CNC machining, the following are used, among others: Importantly, the tools may still cut the material correctly, but they no longer maintain the required accuracy class. In practice, this means they need to be replaced sooner. The higher the accuracy class, the more complex and costly the production process becomes. Therefore, optimising tolerances is one of the key elements in the design of parts intended for CNC machining. Fits in mechanical assembly Tolerance classes are directly linked to the selection of fits between components. Three basic types of fits are used in mechanical assembly: Loose fit There is always clearance between components. This is used in moving components, e.g. in plain bearings. Mixed fit Depending on the actual dimensions of the components, there may be clearance or interference. Press fit Joining the components requires the application of considerable force or a temperature difference, for example by heating one component or cooling the other. With large industrial components, incorrect selection of tolerances can cause serious problems as early as the assembly stage. The selection of the appropriate fit has a direct impact on the functioning of mechanical joints. Incorrectly selected tolerances can lead to assembly problems or excessive wear of components. Quality control and measurement of parts in CNC machining Precision CNC machining requires equally precise quality control methods. The measuring system must be more accurate than the tolerance we wish to verify. Depending on the geometry of the workpiece, the following are used: In the case of complex geometries, it is precisely coordinate measurements that allow both linear dimensions and geometric tolerances to be controlled. We discuss this topic in more detail in our article on part measurement methods and the role of the measurement room in CNC machining. Summary Optimising tolerance classes is one of the most effective ways to reduce production costs without compromising the functionality of the part. In many cases, applying a more stringent IT class does not improve the product’s performance, but merely increases its manufacturing cost. Therefore, it is worth analysing what level of accuracy is actually required as early as the design stage. At SIM Gdynia, when carrying out projects, we not only manufacture parts in accordance with the documentation, but also support our clients in selecting tolerances and CNC machining technologies to maintain a balance between precision and production economy.Does your project require specific fits or non-standard tolerance classes? Consult our technical department – we will help you select the parameters to strike a balance between precision and production economy.