CNC machining supports high-value manufacturing in numerous industries. Each relies on accurate measurements down to the micron to ensure product functionality. Without that level of accuracy, CNC machines cannot produce quality goods.

Investing in the accuracy and precision of machining equipment can mitigate the risk of faulty or imperfect products. Operator training, software updates and inspection systems are just a few of the ways you can improve your facility’s manufacturing processes.

In this article, we examine precision and accuracy in CNC machining and discuss the many ways you can enhance them in your machining processes. Â鶹ԼÅÄ offers advanced machining solutions that can significantly improve both precision and accuracy in your CNC operations.

Precision vs. Accuracy in Machining

In machining, precision and accuracy refer to two distinct concepts. Both have a deep impact on the final quality of manufactured products and their compliance with industry standards.

Precision is the consistency of measurements across products. After manufacturing, the entire line of products needs to function in the same way. Spark plugs, for instance, are designed to fit precisely in vehicle engines. If the spark plugs for a given engine vary in size by even centimeters, only some of them will be usable. In this way, there is a direct connection between precision and profit.

Accuracy is the proximity of a given product to the intended design. Where precision focuses on repeatability, accuracy focuses on perfection. If products do not adhere to their design measurements, they will not be able to carry out their intended purpose, even if they are interchangeable with one another.

CNC machining must excel in both precision and accuracy to consistently produce functional, high-quality products.

How Precise Can Machining Be?

CNC machining is extremely precise, capable of fabricating products with measurements that differ by fractions of an inch. The typical CNC machine has a tolerance of about ±0.005 millimeters, whereas high-end machines can push that number as low as ±0.002 millimeters. Some ultra-precision machines that fabricate products for the aerospace and medical industries even yield tolerances as narrow as 1 to 5 microns.

This level of precision is extremely impressive and promotes uniformity across manufacturing processes. However, the CNC machines that produce these results are still not able to achieve ultimate precision.

Factors Affecting Machining Precision and Accuracy

The precision and accuracy of CNC machines are impacted by a range of circumstances and conditions. Some may lead to microscopic and unavoidable imperfections, while others can lead to large defects. These factors include:

• Machine quality, calibration and maintenance: Precision and accuracy vary from machine to machine. A five-axis machine, for instance, provides a level of quality that a three-axis machine cannot. However, each machine must also be calibrated properly. Spindles, ball screws and guides must all be aligned for the job, and each component must be kept clean and functional to perform at a high level.
• Machine age: All machines experience wear and tear over time. This damage can be mitigated by regular inspections and upkeep, but eventually, every CNC machine will reach the end of its life and experience a gradual drop in both precision and accuracy.
• Operator skill and training: While computers play a key role in controlling CNC machining, operators are still required. They program the machines using geometric code, conduct repairs when necessary and ensure the machines are manufacturing products within acceptable tolerances. Their level of skill and training directly impacts the quality of CNC machining.
• Thermal drift: When materials are exposed to the intense heat of CNC machines, they tend to expand slightly. This phenomenon is called thermal drift. Cooling agents are typically used to minimize thermal drift, but it often still .
• Machine vibration: During the cutting process, CNC machines naturally experience intense vibrations. Dampers and rigid designs can mitigate these vibrations, but malfunctions and poor workpiece placement and fixturing can exacerbate them. If your machine regularly experiences excess vibrations, it may be time for maintenance or additional training.