Here’s How to Improve Quality Control in CNC Machining

Computer numerical control (CNC) machines have become a standard in the machining industry. Their accuracy, speed, and ease of use make them indispensable tools. But despite these advantages, they’re still not perfect. Quality control remains an essential step to catch and prevent defects, yet many facilities have sub-par CNC quality control systems.


While errors are far less likely with CNC machines than manual processes, they can still happen. When they do, they can create bottlenecks, lead to waste and, if not caught, hamper client-customer relationships through poor-quality products. Conversely, an effective quality control program improves the entire machining process by stopping these errors.


With that in mind, here’s how manufacturers can improve their CNC quality control.


Check Raw Materials Before Machining

Many people often think of quality checks as the final step in the production process. While final checks are necessary, quality control should start early on, too. Identifying errors after machining means it’s too late to recover costs, but early checks can prevent waste.


One of the most crucial steps in ensuring quality from the beginning is checking material quality. CNC machines can virtually eliminate human error, but if they’re working with low-quality or defective materials, that won’t matter. Even a highly accurate system will produce a poor-quality product if the materials it uses aren’t up to par.


To prevent these mistakes, employees must check the quality of their raw materials before working with them. Sourcing from trusted suppliers will help reduce many material-related issues, but machinists can’t afford to take any risks here. By looking for any cracks, weak points, or other defects in their materials, workers can ensure they use their CNC machines to their full potential.


Use the Appropriate Type of Machine

Not all CNC machines are created equal, and manufacturers should consider this when addressing CNC quality control. Using the wrong machine for a given task can result in more errors, so facilities must be selective about which orders go through which machines. The more complex a product or part is, the more advanced its CNC machine should be.


A three-axis CNC machine, the most common type for mechanical components, is sufficient for simpler designs, but not much beyond that. For more complicated parts or products, workers should use a four- or five-axis machine. More axes give machines more precision, enabling them to perform more complex work without error.


This is not to say that facilities should only use four- or five-axis machines. Balancing work between different machines can help reduce bottlenecks and keep the overall operation efficient. As companies go about this balancing, though, they should send more complicated designs to higher-axis machines.


Employ On-Machine Inspection

Machining operations can also include quality control steps during the CNC machining process itself. Devices called machine tool probing systems attach to CNC machines and inspect quality as they work. This on-machine inspection lets facilities address and correct problems as they arise, preventing errors in the final product.


Probing routines don’t interrupt or interfere with the machining process, so adding them won’t hinder efficiency. What they will do is automatically redirect machines to correct issues they detect in real-time. By catching and correcting errors early, they prevent substantial mistakes, reducing the number of defective or poor-quality parts down the line.


In addition to reducing scrap, on-machine inspection reduces quality control bottlenecks. Since machining time is the primary cost driver for the field, ensuring efficiency in these operations is essential. Tool probing systems prevent rework, reduce total machining time, and produce more consistent quality by minimizing disruptions from end-of-line quality checks.


Use Multiple Quality Control Methods

Just as CNC machining itself isn’t perfect, every quality check method has unique strengths and weaknesses. No one process can catch every error that might arise. To account for this, facilities should use multiple CNC quality control methods, ensuring mistakes missed by one process won’t pass further down the line.


The order of quality control methods is as critical as including multiple options, too. More specifically, human inspections should always be the last stop, as should be the case with all automation-reliant processes. Automated checks are often highly effective, but technical issues can arise and hinder their accuracy. Placing manual checks last can catch these potential mistakes.


One thing to keep in mind here is that too many different methods can create bottlenecks. Facilities don’t need to implement every quality control method possible, but they should use more than one. Generally speaking, one material check before machining, one on-machine inspection process, and one human-driven post-machining check should be sufficient.


If Outsourcing, Look for Vendors With Proper Certification

Not all facilities perform their own CNC machining in-house, but CNC quality control is still relevant. To ensure high-quality outsourced CNC operations, companies should look for vendors with the right certifications. These will vary by industry, but all vendors should at least comply with ISO 9001, a general quality management certification.


Manufacturers in some industries should look for additional certification as well. ISO 13485, for example, demonstrates compliance for medical-grade products, making it essential for those in the health care sector. Similarly, ISO 16949 applies to automotive parts, so manufacturers in the transportation industry should look for vendors that comply with it.


These certifications don’t mean vendors will prevent 100% of possible errors, but they reduce the risk. Obtaining these certifications requires rigorous standards, so it’s a reliable guideline for quality production partners. As such, any facility that outsources CNC processes should understand relevant standards.


Reliable CNC Quality Control Is Essential

An improved CNC quality control system will minimize waste and produce better products. As a result, companies will save money and establish a better reputation among their clientele. Poor quality management can have the opposite effect, making this area a crucial point of focus for any CNC operation.


By following these steps, machining processes can ensure their CNC quality control is as accurate and efficient as possible. They can then take full advantage of these remarkable machines and stand out from their competitors. CNC machining can be an excellent resource, but only if the companies using it abide by high quality control standards.