CNC Metal Machining Accuracy, Precision, Tolerances and Considerations

DALIAN, China - April 25, 2022 - PRLog -- What Is Accuracy?

Although accuracy and precision seem to be synonymous, they have different meanings when it comes to machining. Therefore, it is important to understand what we mean by the different terms.

In the context of metalworking, accuracy is the degree to which a machine can match the measurements specified in the design.

If a machine can cut at the exact location specified in the design, then it has high accuracy.

If it misses the target occasionally, but hits the right spot on average, then we can say it still has high accuracy.

What Is Machining Repeatability Or Precision?

Machining accuracy refers to the similarity of measurements over multiple attempts or between multiple copies of a part.

In other words, a machine is highly precision if it hits exactly the same point on 100 copies of a part.

This is not the same as accuracy because precision doesn't particularly care if the "point" is the same as specified in the design! A machine can be very precise, even though it always cuts 3mm to the left of the intended mark.

Obviously, it is important to have both accuracy and precision.

Accuracy means you're hitting the coordinates specified in the design, and precision means you're hitting them consistently across multiple units.

What Are Machining Tolerances?

In machining, tolerance refers to the deviation from the value of cutting. So it's about precision, but it's a customer-specified value, not a property of the machine itself.

If a customer requires a feature of a part to be very consistent between elements, they will specify a tight tolerance on that feature to allow for minimal deviation. In practice, this means that the machine has to be operated more slowly and carefully.

If a looser tolerance is specified—for example, on a non-mechanical feature—machining can be done faster.

Although tolerances are defined by the customer, machines typically specify their standard and smallest possible tolerances.

Whole Post at https://www.sansmachining.com/cnc-metal-machining-accurac...