This process utilizes computerized instructions to remove excess material, leaving a finished shape or part. The capabilities of cutting, milling, and turning allow for its diverse application using various raw materials, although it is typically used for metal. The greatest beauty of CNC machine tools is their precision. Since it is computers, not people, who perform the cutting, these machines can achieve a much higher level of accuracy. The ability to meet rigorous specifications makes it worthwhile to use the CNC machining method for high-precision industries, such as aviation and medical device manufacturing. Of course, it is also perfectly suited for general production, providing very accurate cuts. Although CNC machines are very precise, they use tolerances to determine how much a part can deviate from traditional standards. Some products, such as the applications we mentioned, may require tighter tolerances than toy or children's furniture manufacturers.
Improving the accuracy of CNC machines
Probably the most important reason for such improvement is the project time saving. Minor cuts can avoid the need for rework. In addition, the automation of many aspects of machining, such as tool setting, allows for reducing the time required to perform each task. If you use machined parts, more efficient operations will speed up the process needed to complete the project.
Accurate measurement of machined parts can also save valuable time. Differences can affect the initial accuracy of the parts and the ability to replicate them, so changing the equipment to reduce these variables will allow for repeatable and desired results. In striving to improve the accuracy of the machine, you will need to limit human input. By automating the process, you reduce the risk of error, resulting in a more accurate copy of each machined part. Since the number of errors is finite, you can bring the equipment to a state of highest precision, controlling potential errors and eliminating them. Although you do not have to measure every part, you should still use laser measurement and control to continuously verify the accuracy of the process. Information from these measurements can help you better predict when your machines will require maintenance or adjustment to improve performance.
Benefits of Improving CNC Machine Positioning Accuracy
By upgrading your equipment, you gain many things. The exact benefits that your company will derive from these changes will depend on current loads and updates of existing devices. Thanks to modernizations, you won't fall behind, as both technology and demand drive the development of more precise parts.
Key Criteria for Precise CNC Machining
- Programming skills
CNC programming is the most fundamental task associated with machining. An experienced programmer can skillfully use the internal program, reducing accumulated system errors, while ensuring full flexibility within the main program and subroutine. In the process of complex CNC operations, we generally apply multi-part form machining. If there are several identical shapes, the relationship between the main program and the subroutine should be applied, where the latter should be used multiple times in the base program until the processing is completed, thus ensuring the consistency of processing size and improving its efficiency. Incremental calculations, also known as delta calculations, are a software function that, by recalculating only those results that depend on changing data, tries to save time with each such change. Many programs use such calculations, ensuring stable machine operation.
- Test Cut
Perform it by adjusting the blade protrusion to the material, using the raw materials included in the project. We often use it for the production of small series of single pieces.
- Adjustment Method
The size can be determined by adjusting the relative positions of the machine tool, the holder, the workpiece, and the tool. This method is often used for mass production.
- Reduce measurement error
Choose from precise roller bearings, rich in oil for wedge bearings and hydrostatic bearings, to increase the accuracy of bearing rotation.
- Improve the precision of bearing parts
Improve the accuracy of machining the hole supporting the box and the spindle pin. Measure and adjust the range of radial beating of related parts to reduce errors.
- Reduce tool wear
Sharpen tools to extend their lifespan. Use special cutting oil to ensure proper lubrication. Choose the right lathe tool for the appropriate machining.
- Reduce thermal distortions of the process system
The thermal error of the machine tool depends on the cutting speed, feed, machining time, and ambient temperature.
Assembly process
When preparing the machine for work, use the tool controller to make the work more precise. These add-ons measure the accuracy of tool placement in less than a minute. In turn, setting up fifteen tools for a project with probes takes a mechanic over an hour. The use of locators also improves accuracy, as the system can more precisely determine the position of the tool for finer cuts. Thanks to tool positioning, work will not be hindered by errors during manual setting. Although the initial tool preparation is just a concept for larger operations, any workplace where tools are frequently changed can save time with such applications. In addition to precise tooling, it is also necessary to ensure that the workpiece does not fall or slip during machining. The workpiece holder prevents accidents, and if you have a piece of metal, you can use durable electromagnets for this purpose. American processors have been using these devices for almost 25 years since their introduction to the market and they remain a popular choice to this day. Using electroactive magnets to hold metal parts is a clever idea for thin parts that may move or bend during cutting or milling. Thanks to the holder, this activity becomes more precise, as the elements do not move during machining. Ordinary clamps can also be used for this purpose. It is important to note that any workpiece holder that improves the stability of the part is better than none, especially for smaller parts that have a greater tendency to shift during machining.
Machining Process
There are several ways to improve machining processes. First, think about your employees. If there is disorganization among them when operating the machine, they may lose time or make mistakes. When updating software, make sure all employees are fully trained in its operation. Failure to input information into the system will result in further machine errors due to incorrect data. The advantages of CNC machining certainly include high precision, low production costs (with the right personnel and equipment), and the ability to create products from plastics or metals. Almost every type of material can be machined. However, the accuracy of machining can also be indicated by a properly set program.
Appropriate software
Updating software and hardware to adapt to higher levels of precision will also improve this process. Upgrading to new software enhances the machine's ability to look further than before, and since the computer can predict where the tool will need to be placed in the future, it becomes more efficient and accurate throughout the machining process.
Navigation System
Another way to improve equipment for greater accuracy is to replace the navigation system. The accuracy of the drive system depends on how well it mitigates tilts, inclinations, and deviations — movements around the X, Y, and Z axes respectively. Precision guidance systems with narrow height, width, and parallelism tolerances will cost more as the tolerances decrease. However, the lower it is, the greater the precision of the device. If your budget does not allow for an ultra-precision guidance system for your equipment, consider outsourcing this task to external entities.
Appropriate support
The quality of the machine bed support will also affect the accuracy of precision CNC machining equipment. The bed supports the moving parts of the machine and ensures CNC accuracy, so you need a flat, thermally stable, and rigid base that absorbs vibrations. To achieve these properties, it may be necessary to grind the surface on which the hardware rails are mounted. The interaction between the bed and the foundation affects the accuracy of the equipment. If your machine has a surface area of one square meter and a very solid bed, you only need three connection points. Placing the bed frame at the connection point is crucial to reducing distortions. Even the toughest bed can imperceptibly sag between points. To achieve the ideal setting, the spacing of the bed legs should be about 60% of its length. These are Airy points - support points that help minimize bed sagging. Place the third support between the remaining two. Reduced bed sagging ensures precision during machining.
Reducing tool wear and deformation
When your tools are in perfect condition, they become more durable and efficient. Blunt or worn out tools often need to be replaced, which takes time when implementing projects. There are several ways to reduce wear and avoid unexpected failures of CNC machining tools.
Over forty percent of downtime cases were caused by equipment failure. Unplanned downtime is 10 times more expensive than planned maintenance downtime. Keeping up with the repair and improvement of equipment can prevent many of these problems. First, if possible, opt for preventive maintenance. Unlike planned maintenance, it uses data to determine when is the best time to perform maintenance tasks. Predicting when CNC machining equipment will require them reduces unnecessary actions, while preventing unplanned downtime caused by machine failure. If you do not have available data to predict the best time to service equipment, at least follow the manufacturer's guidelines for preventive maintenance schedule. During planned maintenance, the condition of tools, filters, and spindle should be checked. If you use the device frequently, these parts may require frequent replacement. Ensuring that your machine has high-quality parts will help you fully utilize its capabilities. Another way is to use harder tools during the machining of your part. Frequent use of less durable material often accelerates its wear and tear.
While the most durable tools have comparable prices, you will achieve more precise machining solutions, maintaining sharpness. No matter how precisely you set your machine, dull, worn-out tools cannot achieve high precision.
Finally, if you have a specific project that requires an exceptionally durable tool that you don't want to invest in, consider outsourcing the work. You don't have to choose an external mechanical workshop for all tasks, but in the case of very delicate parts or parts requiring special equipment, having the work done by someone else can help prevent wear and tear on your facility's equipment. CNC machining (Computerized Numerical Control) is a widely used manufacturing process related to this.