FAQ

Top 10 Surface Finishing For CNC Machined Metal Parts

CNC Machined Parts Finishing

CNC Machined Parts Finishing and surface treatment;While the tool marks left on CNC machined metal parts and components made by another manufacturing process, Those marks are visually appealing to some, in many cases, some additional post-processing may be desired or even required. There are a variety of finishes that one can use to add functionality or aesthetic appeal to parts, Therefore, we list some very common finishing methods below and expect that will help you decide which of them may be a good choice for your machined parts

• Anodizing

Anodizing is mainly applied to aluminum parts. Anodizing is the use of electrochemical principles to generate a layer of Al2O3 (alumina) film on the surface of aluminum and aluminum alloys. This layer of oxide film has special properties such as protection, decoration, insulation and abrasion resistance.

1. Single color or double color on one part, any kinds color or customized color except white.
2. Additional process before anodizing to make the parts different looking. Glossy by polishing; Sandblasting, Brushing.
3. The additional process after anodizing, Lasing engraving for Model notes; marks; company logo; or other design, this will make the parts looking like unique.
4. Nickel-free sealing, to meet the requirements of countries such as Europe and the United States without nickel.
5. Enhance the surface hardness

• Electroplating for metal parts

Electroplating is a technique in which a metal film is attached to the surface of a metal by electrolysis to prevent corrosion, improve abrasion resistance, conductivity, light reflection, and enhance appearance. There are most popular electroplating is Nickel plating, Zinc plating, Chrome plating, Brass plating, .etc.

1. Plating gloss, high-quality metal appearance;
2. Competitive cost then PVD.

• Vacuum Metallizing for plastic parts

Vacuum costing is fast becoming the method of choice for depositing bright, shiny, metallic films on plastic parts.

Vacuum coating Methods that use evaporation or high-rate cathode sputtering processes are the best-known means of metalizing plastic components.

• Powder coating

Powder spraying uses powder spraying equipment (electrostatic spraying machine) to spray the powder coating on the surface of the workpiece. Under the electrostatic action, the powder will be uniformly adsorbed on the surface of the workpiece to form a powder coating; the powder coating is subjected to high temperature drying The baking leveling cures to a final coating with various effects (different types of effects for powder coatings).

1. Rich colors, high gloss or matte optional;
2. lower cost, suitable for construction furniture products and heat sink shell; outdoor or indoor used CNC machined parts, sheet metal stamping or bending housing
3. high utilization, 100% utilization, environmental protection
4. Strong ability to shield defects, such as the parts made of aluminum & Zinc alloy die casting parts like lighting fixtures.

• Spray painting

Spray painting is a painting technique where a device sprays a coating (paint, ink, varnish, etc.) through the air onto a surface.

• Brushing

Brushing finishing process is a kind of surface treatment method that forms a line pattern on the surface of the workpiece by grinding product and plays a decorative effect. According to the different lines after brushing can be divided into straight-line brushing, chaotic pattern brushing, corrugated, swirling pattern.

The brushing process gives the metal surface a non-mirror-like metallic luster, while the brushing process also eliminates the tiny defect on the metal surface.

Brushing is mostly used for stainless steel parts or before anodizing aluminum parts, even for electroplating parts as post-process after plating.

• Shot Blasting

Sandblasting and bead blasting

Sandblasting and bead blasting is powered by compressed air to form a high-speed jet beam to spray the material at high speed onto the surface of the workpiece to be processed so that the appearance or shape of the external surface of the workpiece surface changes, and a certain cleanliness and different roughness are obtained.

1. To achieve different reflective or matte.
2. It can clean the tiny burrs on the surface of the workpiece and make the surface of the workpiece smooth, eliminating the danger of burrs and improving the grade of the workpiece.

3, clear the residue left before the pre-treatment, improve the workpiece finish, the workpiece can expose a uniform metal color so that the appearance of the workpiece looks more beautiful

• Polishing

Polishing is the use of flexible polishing tools and abrasive particles or other polishing media to modify the surface of the workpiece. For different polishing processes: rough polishing (basic polishing process), medium polishing (finishing process) and polishing (glazing process), the use of a suitable polishing wheel can achieve the best polishing effect while improving polishing efficiency. Improve the dimensional accuracy or geometry accuracy of the workpiece to obtain a smooth surface or mirror gloss while eliminating gloss.

• Etching

Etching, also known as photochemical etching, refers to the removal of the protective film of the area to be etched by exposure to the plate, development, exposure to chemical solutions during etching, to achieve dissolution corrosion effect, the formation of uneven or hollow forming effect。

• Heat Treating

There are actually several types of heat treating( case hardened, nitride.etc), but all relate to the heating of metal in different ways and for different lengths of time to alter its properties. The most common types of heat treatment are all result in an increased hardness of the part.

Top 8 Factors of CNC Precise Machining and Manufacturing Deviation

Machining deviation refers to the degree of deviation between the actual geometric parameters (geometry liner, form and position) of the part after machining and the designed geometrical parameters. The degree of coincidence between the actual geometrical parameters and the ideal geometrical parameters after machining the part is the machining accuracy. The smaller the machining deviation, the higher the degree of conformity and the higher the machining accuracy. Machining accuracy and machining deviation are two standards of quality level. Therefore, the size of the machining deviation reflects the level of machining accuracy.

1. CNC machines’ deviations

Spindle rotation deviation, rail deviation and drive chain deviation.

The spindle rotation deviation refers to the variation of the actual rotation axis of the spindle relative to its average rotation axis at each moment, which will directly affect the accuracy of the workpiece being machined. The main causes of the spindle rotation deviation are the spindle’s coaxial error, the bearing’s own error, the coaxiality deviation between the bearings, and the spindle’s winding degree. The guide rail is the reference for determining the relative position of each machine part on the machine tool and is also the reference for the machine tool movement. The manufacturing deviation of the guide rail itself, the uneven wear of the guide rail and the mounting quality are important factors causing the guide rail deviation. Drive chain deviation refers to the deviation of the relative motion between the transmission elements at the end of the drive chain. It is caused by the manufacturing and assembly deviation in the various components of the drive chain and the wearer during use.

2. Tool geometry deviation

Any tool is inevitably subject to wear during the cutting process, and this causes changes in the size and shape of the workpiece. The influence of tool geometry deviation on machining error differs depending on the type of tool: When machining with a fixed-size tool, the manufacturing error of the tool directly affects the machining accuracy of the workpiece, while for general tools (such as turning tools, etc.), the manufacturing error There is no direct effect on machining deviation.

3. Fixture & Jigs geometry deviation

The role of the fixture is to make the workpiece correspond to the correct position of the tool and the machine, so the geometric error of the fixture has a great influence on the machining error (especially the position error)

4. The positioning deviation ofprecise machining and manufacturing

The positioning deviation mainly includes the base misalignment deviation and the positioning inaccurate manufacturing deviation. When machining a workpiece on a machine tool, several geometric elements on the workpiece must be selected as the positioning reference during machining, if the selected positioning reference and design reference (the reference used to determine the dimensions and position of a certain surface on the part drawing) ) If not coincident, there will be benchmark misalignment errors.

The workpiece positioning surface and the jig positioning element together constitute the positioning pair. Since the positioning pair is manufactured inaccurately and the maximum displacement of the workpiece is caused by the matching clearance between the positioning pairs, the positioning pair is called an inaccurate error. Inaccurate errors in positioning and manufacturing are only produced when using the adjustment method and are not produced in the test cutting method.

5. Manufacturing Process deviation due to force-deformation

Workpiece rigidity: If the workpiece stiffness is relatively low in the processing system relative to machine tools, tools, and fixtures, under the action of cutting force, the deformation due to insufficient rigidity of the workpiece has a greater influence on the machining error.

Tool Stiffness: The external turning tool is very rigid in the normal (y) direction of the machining surface, and its deformation is negligible. The smaller diameter borehole, the poor rigidity of the knife bar, the deformation of the knife bar has a great influence on the hole processing accuracy.

Machine tool component stiffness:

The machine tool component consists of many parts. There is no suitable simple calculation method for machine tool component rigidity so far. The main method is to determine the stiffness of the machine tool component by using experimental methods. The factors affecting the rigidity of machine tool components include the influence of contact surface deformation, the influence of friction force, the influence of low-rigidity components, and the influence of clearance.

6. Machining adjustment deviation

In every process of mechanical processing, the ordinarily or every adjustment of the processing system is always performed. Because adjustments cannot be absolutely accurate, adjustment errors occur. In the processing system, the mutual position accuracy of the workpiece and the tool on the machine tool is ensured by adjusting the machine tool, the tool, the fixture, or the workpiece. When the original precision of machine tools, tools, fixtures, and workpiece blanks meets the process requirements without considering dynamic factors, adjustment errors play a decisive role in machining errors.

7. Measurement deviation

When precise machining and manufacturing parts are measured during or after processing, measurement methods, gauge accuracy, and workpiece and subjective and objective factors directly affect the measurement accuracy.

8. The internal stress of workpiece

The stress that exists on the part without external force is called internal stress. Once the internal stress is generated on the workpiece, it will cause the workpiece metal to be in an unstable state with a high energy level. It instinctively transforms to the stable state of the low energy level and is accompanied by deformation, so that the workpiece will lose its original machining accuracy.

Top 7 Main Factors That Affect Custom CNC Machining Parts Cost.

While you had a custom CNC machining parts, Whether you make it at your own working shop or sourcing outside at contracted factory, First of all, how much the cost of custom machined components? Secondly, the designed parts can be machined with effective cost way, easy to machining or not? What is the best material would be used or has a kind of replaceable material with low cost and easy machining? These issues would be settled before going ahead with mass production.

If you want to know exactly the real cost of Custom CNC machining parts, you obviously need to know what influences CNC Machining cost. Then, How to reduce CNC machining parts costs? After all, the reasonable cost and best solutions would help your project finishing in good quality and a short lead time.

No.01. Material selection;

As with any type of manufacturing, the material of CNC machined parts you are using affects the manufacturing costs. Some kinds of materials are more difficult to process than others, for example, carbon steel is hard than aluminum alloy Since steel are processed at a much slower rate than aluminum alloys, even as modern tools and advanced mechanical technology. Some high hardness materials like steel or tungsten carbide can wear away the expensive consumable cutting tools. If you ask the CNC machining services factory to handle potentially hazardous materials that require additional safety precautions, the overall costs may increase significantly. Therefore, even prior to component design, To choose the suitable materials for your CNC machined component is the most important things to be considered.

No.02. Parts’ Dimensions and design;

Of course, The CNC machining Parts’ Dimensions and geometry design are important factors in CNC machining. Obviously, the bigger part, the more material it will need to make it. The more complex the geometric design, the higher the cost of machining. Very tight tolerances are required, long tooling reach, better surface finishing or roughness, or parts that are difficult to form in geometric shapes will cost more than simpler parts. It is surprisingly easy to design components that cannot be manufactured at all or to be extremely expensive when manufacturing. It is always wise to consult a skilled CNC machining manufacturer during the design phase of the component. This knowledge can help you design a fully functional, highly productive part. At JINGXIN precision machinery limited, our team always provides the custom CNC machining manufacturing solutions with the most effective cost to our customers. if you have parts made by CNC machine, please send through CAD files to get a project review, to see what our CNC engineering team can help your project.

No.03.What kind of CNC machines would be used?

The machine needed to make the part can greatly affect the cost. Can a CNC machining center use a multi-axis machine to complete, or does it require multiple machines? How many different machines and operations are needed? What is size machine needed? Modern processing and manufacturing equipment is very expensive, randomizer types, brand, quality, size And the ability is different. Each of these factors must be considered in determining the exact cost of a CNC machining parts.

No.04. Number of parts to be produced;

One of the most important cost-influencing factors is the Number of parts to be produced. some CNC machining parts require multiple operations and manufacturing process to complete. Each of these operations must be set up and processed. From a basic manual finishing operation, you must put the necessary tools and consumables together to perform very complex machining operations with many tools that can be loaded, dialed in, and adjusted to produce the specified tolerances. The operation settings may be completed in minutes, days, or even weeks. If all the necessary settings are required to run the prototype sample – all relevant costs must be assigned to the sample and it can be very expensive. If you perform the same setup to run 10,000 sheets, you can assign the same setup costs to 10,000 pieces, which greatly reduces the cost per piece of cost. The frequency of these operations can also play a role. If a customer needs 10+ or 50 pieces parts, it’s cost would be a little bit less than 200 pieces. Therefore, providing a guarantee of the machine’s repetitive work and an accurate estimate of demand can often be used to reduce the cost of components. So it means for the same custom CNC machined parts, big quantity parts machining cost is much cheaper than low volume order.

No.05.Additional processing

Many CNC machining parts require additional processing such as heat treatment, special processing operations, surface treatments, and specialty coatings. All of these requirements will increase the cost of the basic product and should be evaluated for its necessity and cost that would be involved.

More complex machined parts require more specialized and skilled machinist. The skills and experience of talented machinists are not without cost Regardless of any formal training program, nothing can replace on-the-job experience and on-the-job training. However, many modern machinists have relevant formal education and on-the-job training. Even if there is a lifetime of processing experience and the industry changes and develops so quickly, the machinist must be a lifelong learner to keep his/her skills at the forefront. The competitive precision machining manufacturer offers continuous training and cross-training opportunities. As the complexity and difficulty of the components increase, the machinist’s experience, and capabilities are also running, so you can see that the cost will increase accordingly

What kind of tolerance standard is adopted? It is also a cost of the CNC machining parts for CNC machining services factory. High level of inspection and very tighter tolerance would cost higher than lower standard. Therefore, when considering the cost of processing components, it should always give a clear quality requirement for the appropriate level of inspection.

Of cause, there are some other effectors to CNC machined parts cost, such as Material price volatility, local labor cost level, and payment terms.

CNC machine manufacturing involves almost every aspect of modern society since it has many advantages than traditional manufacturing. Production efficiency, the custom CNC machined parts are widely used on construction equipment components; oil & gas equipment parts; High precision safety device components; Power generation components; Custom Automotive parts; House appliance products enclosure; Medical equipment shell and components.