How can you make the cnc machining parts more precise

 

CNC center

What is the cnc machining?

CNC precision machining is a very specific machining process that helps you manufacture the parts you need using computer-controlled machine tools. Traditionally, this process is conducted by skilled machinist operators, but some companies rely on robots to use this process to manufacture parts at high speed.

Ultimately, precision machining boils down to two key aspects. To begin, you’ll need to use the right cutting tools (the more advanced, the better) to remove the material as needed; this allows you to perfectly match the dimensions of the part that your project requires. Next, you’ll need a CNC (or Computer Numerical Control) machine to control the cutting tool as it works.

How do you verify that your parts are precise?

What is the really meaning of “precision”?
Precision and accuracy are often confused and used interchangeably. Both of these are indeed related to quality, but they each have their own distinct meaning.
Accuracy means how close to the targeted values something is; for example, how close the measurement is to the dimension.

Precision is the ability to replicate consistent attributes across a large number of produced units (for example hitting the same dimension when machining 200 parts).

The graphic above is a good representation of the difference between accuracy and precision.

How to verify the parts are precise?

Measurement System

Measurement
The first step is to make sure your measurement system is good enough. Is it measuring your parts accurately over and over again? (Accuracy and precision!) One way to check this is to use gauge parts and calibration to ensure that your measurement system is performing well. Gauge parts are parts that are machined extremely accurately to a known value. You can measure gauge blocks or pins.
Second, factory must Equipped with experienced quality inspectors.

Measurement System Analysis

Conduct systematic analysis and evaluation of measurement system variation to determine whether the measurement system meets the specified requirements and ensure the quality of measurement data
These are a few sources of error that can lead to larger variations in measurement: processes, personnel, equipment, and environment. If you identify that one is causing a significantly larger proportion of the variation, you can address that issue and know that you’re getting good measurements. You want measurements to be repeatable, reproducible, stable, and not include bias. An MSA helps to ensure that your measurements are on the right track

Measuring Repeatability and Reproducibility

Repeatability refers to the ability of the operator to get the same measurement over and over again on the same part. A reproducible measurement is one that can be consistently and accurately measured by multiple people. By identifying the variation within one person’s measurements and from person to person, you can identify the actual part-to-part variation.
Identifying these different sources of variation is critical to increasing the precision of your contract CNC machining process and parts. If you find that most of the error is coming from a lack of reproducibility, for example, you can focus on training operators rather than wasting time and money trying to improve your measurement system.

How to improve the accuracy of cnc machining?

CNC machining parts

Improving the accuracy of CNC machines

If we continue thinking about our hypothetical MSA, there is also the chance that your measurement system isn’t the problem. Maybe you’re actually getting great measurements, but your parts are not as precise as you need them to be. There are many ways to improve precision across your CNC machined parts.
So we can improve in the following ways:

Test cutting

Make it by adjusting the blade extension to the material, using such raw materials as included in the design. We often use it for the production of small batches of single pieces.

Adjustment method

Make it by adjusting the blade extension to the material, using such raw materials as included in the design. We often use it for the production of small batches of single pieces.

Reduce tool wear and deformation

Tool wear cannot be completely avoided, but at least it can be minimized. Adequate water supply is the basic premise to ensure the normal rotation of the tool. Choosing the right tool based on the milling material can also optimize usage and reduce wear.
One of the most effective ways to reduce tool wear is to use and maintain the tool correctly. Here are some suggestions:

Select the right tool material: according to the hardness, chemical composition and cutting conditions of the machining material, select the appropriate tool material, such as high-speed steel, carbide or ceramic tools.

Control of cutting parameters: Appropriate feed speed and cutting depth can effectively reduce tool wear. During the processing, attention should be paid to maintaining the appropriate coolant flow and pressure to avoid excessive heating and hot cracking of the tool.

Use the right tool coating: The right tool coating can improve tool wear resistance and reduce wear. Commonly used coatings are TiN, TiAlN, TiCN, CrN and so on.

Regular inspection and maintenance: check the wear of the tool regularly, replace the tool with serious wear in time, maintain the sharpness of the tool and reduce the wear. In addition, the storage and cleaning of the tool is also very important, should be kept dry and clean, and appropriate lubrication protection.

Use professional tool grinding equipment: For severely worn tools, professional grinding equipment should be used for dressing to avoid improper dressing resulting in shortened tool life.

Pay attention to daily thorough cleaning;

Regular tool inspection, timely detection and response to component wear or damage;

Perform regular maintenance and inspection of sprinkler systems;

Select the milling tool suitable for the working condition.

Regarding the tool deformation, affected by the workpiece cutting process, the tool will produce a series of thermal deformation phenomenon, which is inseparable from its cutting heat, in daily work, the heat of the tool is not particularly much, but subject to certain conditions, if the heat is too concentrated in the workpiece, it will lead to a short time of temperature rise, so as to improve the temperature of the tool body itself. In order to reduce the thermal deformation of the tool, the geometric parameters of the tool should be reasonably selected in use, and the amount of cutting tool should be fully cooled and lubricated to reduce the cutting heat and reduce the temperature of the tool, so as to provide the accuracy of the machined parts

Reduce measurement error

Production

The error can be reduced by improving the measuring method, selecting the measuring tool with high precision and calculating the average value of multiple measurements. Multiple measurements to obtain the average value, the selection of precision measuring tools, improve the measurement method.

Conclusion

Producing quality parts often depends on a complex combination of CNC machines, software, tools and processes, and skilled machinists. By managing these different parameters well, you will be able to deliver quality and consistent machined parts with the right levels of accuracy demanded by your customers.

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