The accuracy of prototypes and end parts is a very important parameter in metal processing. Precision means that the closer the mechanical function is to the designed performance, the lower the probability of mechanical failure.
Thanks to the rise of CNC machine tools , metal processing is more precise than ever. Machinists can use computers to program the cutting tool's trajectory in microns. It eliminates inaccuracies that are essentially due to human error. If the CNC machine is set up correctly, metal parts need to be cut with high precision.
However, there are many factors that affect the accuracy of metal processing. Machine quality, material selection, and even some customers who can perform all functions at room temperature may have very different accuracy requirements than others.
What is accurate?
Accuracy and precision seem to be synonyms, but they have different meanings when it comes to processing. Therefore, it is important to understand what we mean by the different terms.
In the context of metalworking, precision allows a machine to match the measurements specified in the design. If a machine can cut at the precise location specified in the design, it will have high accuracy. If you occasionally hit the wrong target, but hit the right spot on average, it can still be said to be highly accurate.
Machining reproducibility or accuracy
Machining accuracy refers to the measured similarity between multiple attempts or multiple copies of a part. In other words, if you hit the exact same spot on 100 parts of a part, the machine is very accurate. If the "point" is the same as specified in the design, then this is the same thing as accuracy, because accuracy doesn't matter! The machine can be very accurate even though it always cuts 3mm to the left of the expected mark.
Obviously, it's important to have both accuracy and accuracy. Accuracy means you're hitting the coordinates specified in the design, and accuracy means you're hitting them consistently across multiple units.
What is the machining tolerance
In machining, tolerance refers to the deviation from the cutting value. So it's about accuracy, but it's a customer-specified value. If a customer requires a feature of a part that is very consistent between elements, they will specify a tight tolerance for that feature to allow for minimum deviation. In practice, this means you need to operate the machine more slowly and carefully.
For example, if a slow tolerance is specified, machining can be performed faster relative to non-mechanical features. Tolerances are defined by the customer, but machines often specify standards and minimum acceptable tolerances.
What contributes to the accuracy of CNC machine tools
The accuracy of CNC machine tools depends on several factors. Some of these are determined by the CNC machine manufacturer. In order to achieve precision metal processing, the following factors need to be considered.
Machine Quality:
Well-built machines with high-quality components typically produce more accurate parts than lower-quality machines.
Machine Condition:
CNC machines contain countless components, so proper maintenance is important to maintain their accuracy.
Tool Conditions
Dull worn tools showing signs of flank wear, crater wear, etc. will reduce the accuracy of CNC machine tools, so they need to be kept in good condition. Blunt tools also increase cutting temperatures , which is another factor that reduces accuracy.
Board Check
Feedback tools, such as the onboard probe, can tell you exactly if your machine is disconnected while working. These tools can also be used to correct biases in real time, improving accuracy.
Temperature and humidity
The processing environment affects the processing accuracy. The machine can cut parts in warm conditions, but thermal integrity must be maintained to avoid deviation.
Calibration
Machine tools should be calibrated regularly to maintain accuracy.
What are the best metals for precision metal processing?
Precision machining is best done using materials suitable for CNC machining.
Even the most difficult-to-machine metals and alloys can be precision machined, but certain machine materials can negatively affect machine accuracy.
The machinability of a metal is the ease with which a cutting tool can cut it. Instantly cut through very workable metals using a low cutter to produce a high quality finish on a sharp knife without significant wear.
For highly machinable metals
Aluminum 6061
Aluminum 7075
Aluminum 2024
Stainless steel 303
Stainless steel 304
Brass C 35300
In theory, Given better time and power consumption, a good CNC machine should still be able to cut metal into metal.
However, these hard mechanical metals can have an indirect negative impact on accuracy.
Unmachined metal can significantly increase tool wear, while dull tools can reduce machine accuracy and accuracy.
Furthermore, most customers want to find a good balance between speed and accuracy. If precise metal machining requires very low cutting speeds, the project may not be worth the trouble because the metal is difficult to mechanize.
When does
require precision machining?
Accurate metalworking is important for several reasons to ensure the mechanical functionality of a part and ensure customer satisfaction.
For projects that require high precision
Metal prototypes pitched by investors are clearly inaccurate and can leave a negative impression on senior professionals.
Mechanical parts that interact with other parts Proper functionality can be controlled by specifying appropriate tolerances, but good accuracy is still required to ensure compatibility between parts.
It provides potential opportunities for long-term partners. When you work with a new customer, you increase your chances of building a long-term partnership by providing them with precision machined parts from the start. In some cases, customers will accept orders that guarantee a certain level of accuracy.
