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Solve the Problem of Poor Surface Quality of CNC Machined Parts

Feb. 11, 2020

For outsiders who are unfamiliar with the operation of CNC machining workshops, once the chips stop flying away, the CNC Milling Parts is dropped, and another precision machine tool part is launched, they will probably think that the final product is accurate and meets the specifications. Unfortunately, this is not always the case. In any relevant CNC processing workshop, the finished product is not delivered to the customer until the finished product passes the inspection service process. The dimensions of the part must meet the tolerances set by its design, including a thorough inspection of the finish of all machined surfaces. In general, parts may meet specific dimensions, but must be scrapped because the overall appearance and surface finish are not up to standard. Not only does this cause aesthetic issues, but more importantly, it can negatively affect the function of the part.


Most importantly, in the final stages of the milling and machining process, the amount of work that must be sent to the waste bin is less than the desired result. CNC mechanics are inherently attention to detail, proud of their work, and want to see a complete project. Scrap parts due to surface finish issues can also be a real profit killer for machining shops. Poor quality can lead to increased costs, increased downtime, delayed delivery and, in the worst case, lost orders. The question becomes; how do mechanics and shops solve it? What to do when the final result does not reach the expected level? Let's take a quick look with CNC Machined Brass Plain Components Manufacturer to get the best surface finish with a CNC milling machine.


1. Increase cutting tool speed

Faster speeds, measured in surface feet per minute, mean shorter contact time between the material and the cutting tool. This reduces edge buildup, which results in poor surface finish, and also extends the life of the cutting tool. Tool failure is the main cause of damage to precision machined parts. Never estimate or guess the speed required for your work.


2. Always clear / control the chip

Removing excess chips or stacked edges and not allowing them to contact the workpiece during processing is a critical task and the key to producing a high-quality surface finish. Chips and BUE are easy to accumulate, and if not removed, it is easy to damage the surface finish of the cutting tool. Chip breakers, compressed air and the best solution, flooded coolant can be used to remove chips for better control and reduce scraping / damage of parts.

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CNC Precision Machining Service

3. Different tools should be used for roughing and finishing

Do not use the same tools used for roughing to complete the CNC Precision Machining Service. Instead, a small number of roughing tools should be used to remove most of the material, while newer, sharper tools should be retained and used only for finishing passes. When used in conjunction with roughing or finishing tools, the tool blade radius, rake angle, feed rate, and blade material itself can bring higher quality.


For the layperson, once milling and machining are complete and the delivery time is approaching, it only seems necessary to check the aesthetic appearance of the precision machined part. Regardless of the material, a thorough inspection of the work done is a key factor in the function of the part. Especially suitable for aerospace and medical equipment manufacturing industries. Excessive chipping, slower running speeds, and improper use of tools are the main reasons for the decrease in surface finish. Lack of machine maintenance, low coolant volume, poor settings and CNC programming errors are also the reasons for this. The tips we provide are suitable for a variety of machining operations, including milling, turning and grinding, and if used consistently, the surface finish of the problematic job should be greatly improved to obtain a satisfied customer and reuse business.