How to Improve CNC Machining Surface Finish On Your Precision Parts?

How to Improve CNC Machining Surface Finish On Your Precision Parts?

For most case, surface quality is very important for mechanical components. For most mechanical processing workshops, the use of the correct machining process has a great help in improving the surface quality of CNC machining.

Surface finish can be affected by many things, including chip load, step over, tool geometry and inclination of the tool. The benefit of high speed machining is that higher machining rates can be achieved with lower cutting forces and lower chip loads—both of which will improve surface roughness.

In some applications, a single scratch may render a part unacceptable from a design-engineering point of view, regardless of how fine its average roughness value. These same considerations apply to the multiple parameters for waviness and total profile.

When a design engineer specifies a surface finish parameter and value, therefore, he must do so with an understanding of how they will affect the part's performance. Selecting the ideal parameter(s) for a given application is somewhat complicated by the great number of parameters in existence, but most of these have limited applications. The majority of applications can be successfully specified using a few well-known parameters.

Smoother, of course, is not always better. There are obvious economic benefits to machining parts as quickly as possible, and to minimizing the amount of secondary work performed. Additionally, there are applications in which a certain degree of roughness enhances functionality, and specifications may specify minimum as well as maximum roughness values. Having some definite roughness to the surface, for example, often enhances adhesion of paint or other coatings.

Some parts that perform multiple functions require complex surfaces to perform optimally. Engine cylinder walls, for example, must be smooth enough to provide a good sealing surface for the piston rings, to promote compression and prevent blow-by. At the same time, they must have "pockets" of sufficient size, number, and distribution, to hold lubricating oil. The Rk family of parameters was developed to describe such complex, multifunctional surfaces. This is an example of the parameters that were developed as design, rather than inspection, tools.

Once a surface has been defined and specified, the manufacturing engineer must determine how to produce it reliably and cost-effectively. In the case of surfaces specified only by the Ra parameter, this is usually quite easy, because the actual shape of the surface can vary considerably and still meet a given Ra value. Finer Ra values can be achieved by many alternate approaches, including slowing the speeds or feeds, making shallower cuts, or following the primary cutting process with a secondary process such as fine-grinding, honing, lapping, and so on. If Ra is the only parameter specified, the manufacturing engineer can choose whichever approach he determines is the most economical and efficient.

Here are our 5 ways that you can address on the machine to make poor surface finish go away:

1. Rational design cut-in and out route

When processing parts with CNC machine, the cut-in and out route should be designed to optimize the cutting angle of the machine tool. In order to reduce the effect of cutter marks and ensure the quality of the surface is not affected, it is necessary to plan the cutting route of the tool. The cut-in point of the tool is mainly started from the periphery of the part to ensure the smooth contoured surface. Choose a smaller feed rate to cut into the tool, so that it is maintained at a slow speed cutting, the smooth transition of the cutting, thus ensuring cutting quality.

2. Choose correct cutting method

In processing parts with CNC milling machine, there are two methods of clockwise milling and anticlockwise milling. Clockwise milling has a better surface effect than anticlockwise milling. Therefore, as far as conditions permit we choose clockwise milling process to improve the surface quality of the parts. In the turning of shaft parts, try to use the same tool to machining different shaft neck, that can better reduce the traces caused by the tool.

3. Use new efficient tools

The efficiency and performance of CNC machine tools are inextricably linked with the tool. For the processing of parts with high precision, it is necessary not only to focus on the perfect process, but also to select and use new and efficient tools. Today’s tool optimization designs can use new tool concepts to solve the problems of mechanical machining safety, precision, surface roughness, high-speed cutting, and the ability to optimize the cutting path.

4. Using the best CNC machining program

Optimizing CNC machining programs to provide the best CNC data for machining that can improve quality. Compared with ordinary machine tools, CNC machine tools not only require the operator to have a higher level of operation in the processing, but also have a higher level of programming and process analysis. In order to ensure the accuracy of the processing, it is necessary to optimize the procedure to increase the production efficiency.

That’s what you’re looking for to know how you can achieve a great finish. If you need to do better, for your custom precision machined parts, contact us now.