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Sibai specializes in manufacturing precision machined parts for the medical, automotive, machines, research, and other industries. With over 20 years knowledge and experience, our team is able to produce parts that require innovative tooling and fixturing in a timely manner. We approach each job with the intention of minimizing the number of operations & run-time, therefore increasing accuracy & efficiency, and decreasing cost. We are capable of holding tight tolerances in difficult to machine materials such as copper, stainless steel, titanium, etc. CNC Machining uses a modern CAM system and highly precised machining and measuring equipment to ensure the highest quality products and to realise customer satisfaction.

Custom CNC Machining Service

CNC Machining Materials

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    Stainless steel

    1. Stainless steel classification

    The classification of stainless steel is often divided into: martensitic steel, ferritic steel, austenitic steel, etc. In addition, it can be divided into: chromium stainless steel, chromium-nickel stainless steel and chromium-manganese-nitrogen stainless steel according to the composition.

    A. Ferritic stainless steel: 12% to 30% chromium. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and its resistance to chloride stress corrosion is better than other types of stainless steel.

    Belonging to this category are Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on. Because of the high chromium content, ferritic stainless steel has good corrosion resistance and oxidation resistance, but poor mechanical properties and process performance. This kind of steel can resist the corrosion of the atmosphere, nitric acid and brine solution, and has the characteristics of good high temperature oxidation resistance and small thermal expansion coefficient. .

    B. Austenitic stainless steel: It contains more than 18% chromium, and also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements.

    It has good comprehensive performance and is resistant to corrosion by various media. The commonly used grades of austenitic stainless steel are 1Cr18Ni9, 0Cr19Ni9, etc. The C content of 0Cr19Ni9 steel is less than 0.08%, which is marked as "0" in the steel number. This type of steel contains a large amount of Ni and Cr, which makes the steel in an austenitic state at room temperature. This type of steel has good plasticity, toughness, weldability and corrosion resistance, and has good corrosion resistance in oxidizing and reducing media. It is used to make acid-resistant equipment, such as corrosion-resistant containers and equipment linings, transportation pipelines, Equipment parts for nitric acid, etc. Austenitic stainless steel is generally solution treated, that is, heating the steel to 1050-1150 °C, and then water-cooling to obtain a single-phase austenite structure.

    C. Austenitic-ferritic duplex stainless steel: It combines the advantages of both austenitic and ferritic stainless steels and has superplasticity.

    Austenitic and ferritic structures each account for about half of stainless steel. In the case of low C content, the Cr content is 18%~28%, and the Ni content is 3%~10%. Some steels also contain alloying elements such as Mo, Cu, Si, Nb, Ti, and N. This type of steel has the characteristics of both austenitic and ferritic stainless steels. Compared with ferrite, it has higher plasticity and toughness, no room temperature brittleness, and significantly improved intergranular corrosion resistance and welding performance. The 475 ℃ brittleness and high thermal conductivity of element stainless steel have the characteristics of superplasticity. Compared with austenitic stainless steel, it has high strength and significantly improved resistance to intergranular corrosion and chloride stress corrosion. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.

    D. Martensitic stainless steel: high strength, but poor plasticity and weldability.

    The commonly used grades of martensitic stainless steel are 1Cr13, 3Cr13, etc. Due to the high carbon content, it has high strength, hardness and wear resistance, but the corrosion resistance is slightly worse, and it is used for high mechanical properties and corrosion resistance. Some general parts are required, such as springs, turbine blades, hydraulic valves, etc. This type of steel is used after quenching and tempering.

    2. Grouping of stainless steel grades

    Precipitation hardening stainless steel. It has good formability and good weldability, and can be used as an ultra-high-strength material in the nuclear industry, aviation and aerospace industries.

    According to the composition, it can be divided into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni (200 series) and precipitation hardening series (600 series).

    200--Series--Chromium-Manganese Nitrogen Austenitic Stainless Steels

    300--Series--Chromium-Nickel Austenitic Stainless Steels

    301--Good ductility, used for molded products. It can also be hardened by mechanical processing. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel.

    302--corrosion resistance is the same as 304, because the carbon content is relatively high, so the strength is better.

    303--It is easier to cut than 304 by adding a small amount of sulfur and phosphorus.

    304--that is, 18/8 stainless steel. GB grade is 0Cr18Ni9.

    309--has better temperature resistance than 304.

    316--After 304, the second most widely used steel grade, mainly used in the food industry, pharmaceutical industry and surgical equipment, adding molybdenum element to obtain a special structure that is resistant to corrosion. Because of its better resistance to chloride corrosion than 304, it is also used as "marine steel". SS316 is usually used in nuclear fuel recovery units. Grade 18/10 stainless steels generally also meet this application level. 

    321--Similar to 304 except that the risk of corrosion in material welds is reduced due to the addition of titanium.

    400--Series--ferritic and martensitic stainless steels.

    408--Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.

    409--The cheapest model (British and American), usually used as a car exhaust pipe, is a ferritic stainless steel (chrome steel).

    410--martensite (high-strength chromium steel), with good wear resistance and poor corrosion resistance.

    416--The addition of sulfur improves the processing properties of the material.

    420--"cutting tool grade" martensitic steel, the earliest stainless steel similar to Brinell high chromium steel. Also used in surgical knives, can do very bright.

    430--ferritic stainless steel, used for decoration, such as for car accessories. Good formability, but poor temperature and corrosion resistance.

    440--High-strength cutting tool steel, with slightly higher carbon content, can obtain higher yield strength after proper heat treatment, and the hardness can reach 58HRC, which is one of the hardest stainless steels. The most common application example is "razor blades". There are three commonly used models: 440A, 440B, 440C, and 440F (easy to process).

    500-- Series--Heat-resistant chromium alloy steel.

    600--Series--Martensitic precipitation hardening stainless steels.

    630--The most commonly used type of precipitation hardening stainless steel, usually also called 17-4; 17%Cr, 4%Ni.

    Sibai does various kinds of stainless steel machining. Stainless steel is the most common steel we did. We use material analyser to test the compositions of stainless steel when we purchased. That is, we ensure the right stainless and good quality before machining, which lower the risk of uncorrect material.

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    Machined PTFE

    Teflon is another name for polytetrafluoroethylene, and the English abbreviation is PTFE. The products of PTFE are generally referred to as "non-stick coatings". It is a synthetic polymer material that uses fluorine to replace all hydrogen atoms in polyethylene. PTFE can resistant of acid, alkali and various organic solvents. It is almost insoluble in all solvents. PTFE can also resistant high temperature resistance. Its friction coefficient is extremely low, so it can be used for lubrication. It also becomes an ideal coating for non-stick pans and the inner layer of water pipes.

    Some of medical customers ask SiBai to use PTFE raw material to provide some medical parts. SiBai use black PTFE material to provide many kinds of brackets to medical customers. These brackets are used for medical equipments. So, these black PTFE material must to meet the FDA requirement. SiBai use Spectrum Analyser to test the raw material PTFE composition. We also ask the 3rd party testing agency to do the raw material test and then they can give the FDA certificate report. In this way, we can ensure the PTFE with good quality. We use the PTFE plate material do these brakets. The dimension of these PTFE plate are 300mm*300mm*8mm.It can resistant high temperature over 134℃. Because these medical customers will do high temperature sterilization several times one day during they use these brackets. To be honest, the process of these PTFE brackets are not complete and difficult. But the key is to find the right and good PTFE raw material. The right and good PTFE raw material means good PTFE brackets. SiBai buys imported PTFE raw material to ensure the quality of these bracket quality. We can also provide parts with PTFE by bar and tube according to customers’ need. SiBai do 100% inspection before delivery. So, there are almost no complaints from medical customers about these parts SiBai made.

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    Machining Titanium Alloy

    Titanium alloy refers to a variety of alloyed metals made of titanium and other metals. Titanium is an important structural metal. Titanium alloys have high strength, good corrosion resistance and high heat resistance. It mainly develops high-temperature titanium alloys for aero-engines and structural titanium alloys for airframes.

    Titanium is a new type of metal. The performance of titanium is related to the content of impurities such as carbon, nitrogen, hydrogen, and oxygen. The purest titanium iodide has an impurity content of no more than 0.1%, but it has low strength and high plasticity. The properties of 99.5% industrial pure titanium are: density ρ=4.5g/cm3, melting point 1725℃, thermal conductivity λ=15.24W/(m.K), tensile strength σb=539MPa, elongation δ=25%, section shrinkage Rate ψ=25%, elastic modulus E=1.078×105MPa, hardness HB195. 

    The most widely used titanium alloys are Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (TA7) and industrial pure titanium (TA1, TA2 and TA3).

    There are many methods of machining titanium alloys, including: turning, milling, boring, drilling, grinding, tapping, sawing, EDM, etc. For continuous cutting, mass production or cutting with a large amount of metal removal, carbide tools are generally used. When forming cutting, grooving or cutting, it is suitable to use adjusting steel tools or cermet tools. A short and sharp drill bit and a low-speed forced feed should be adopted for Titanium alloy drilling. And the support brackets should be tightened and repeatedly adequate cooled, especially for deep hole drilling.

    During the drilling process, the drill bit should keep the drilling state in the hole and not allow idling in the hole, and should maintain a low and constant drilling speed. Tapping of titanium alloys is probably the most difficult machining operation. Blind holes or too long through holes should be avoided as much as possible to prevent internal thread surface to become rougher from or taper breaking inside.

    Sibai has a lot of experience on producing some parts made from titanium alloy, and has suitable machines to produce titanium alloy parts. 

    If you have titanium alloy parts need to be manufactured, you may send us an inquiry.

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    Machined Aluminium

    Aluminium is the most common and common material in the machining industry. It is light in weight, high in strength, good in stability, easy to process and widely used. Its surface is silver-white, which can form an oxide film in humid air to prevent metal corrosion. The relative density of Aluminium is 2.7g/cm³, the melting point is 660℃, and the boiling point is 2327℃. It has the advantages of light weight, good electrical and thermal conductivity, high reflectivity and oxidation resistance.

    Machined Aluminium includes 1060, 2A11, 2A12, 2017, 2024, 5052, 6061, 6063, 6082, 7075, etc.; some of these grades need to be differentiated -T6/-T651. The first digit of these grades indicates the series of Aluminium alloys, the second digit indicates the modification of the original Aluminium alloy, and the last two digits indicate the purity of the Aluminium alloy in the same group.

    Here are some of the machined Aluminiums that we use frequently:

    1. AW5052: Including round bar with diameter 6-500mm, length 0.5-3000mm; tube outer diameter 6-530mm, wall thickness 0.5-50mm, length 1-12000mm; plate thickness 0.5-80mm, length 1-6000mm, width 0.5-3000mm. AW5052 is the most representative alloy of medium strength, with good corrosion, weldability and formability, especially high tensile strength and good seawater resistance. It can be used to manufacture oil tanks, oil pipes, and sheet metal parts of transportation vehicles and ships, Instruments, street lamp brackets and rivets, hardware products, etc.

    2. AW6061: Common states include bar, tube, and sheet, including T6 and T651. Plate thickness 0.3-500mm, bar diameter 3.0-500mm.

    The heat-treated corrosion-resistant alloy will have very high endurance value after T6 treatment, but the strength of the welded joint is low, so it is suitable for high-temperature corrosion-resistant Aluminium boxes, screws, ships, vehicles and land structures. 6061-T651 is the main alloy of the 6-series alloy, which is a high-quality Aluminium alloy product that has undergone heat treatment and pre-stretching process.

    3. AW6063: Common forms are rod/plate/tube/discharge. The thickness of the plate is 0.3-350mm, the diameter of the bar is 3.0-500mm, the outer diameter of the pipe is 6-560mm, and the wall thickness is 0.5*90 mm. As a representative alloy for extrusion, AW6063 has lower strength than 6061, good extrudability, and can be used for profiles with complex cross-sectional shapes. It has good corrosion resistance and surface treatment, and is suitable for electronic semiconductor Aluminium material boxes, construction highway guardrails, vehicles, furniture, home appliances, and decorations.

    4. AW7075: One of the alloys with the highest strength among Aluminium alloys, but with poor corrosion resistance and slightly higher cost, suitable for aircraft, ski poles, and thick plate forgings.

    Commonly used Aluminium grades can be selected according to the different needs of the product. The suggestions are as follows:

    - The product requirements are relatively hard, the surface treatment is coarse wire drawing or coarse sand surface, 5000 series Aluminium alloy is selected, and the commonly used grade is AW5052.

    - For products with high surface treatment requirements, there should be no sand holes or material traces. 6000 series Aluminium alloy is selected, and the commonly used grade is AW6061/AW6063.

    - The product has high strength and high hardness and needs to be used for load-bearing structure. The 7000 series Aluminium alloy is selected, and the commonly used grade is AW7075.

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CNC Machining Finishes

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    1. Metal passivation is widely used in various fields such as machining, auto parts, freighters, etc. It is a common surface treatment process, mainly suitable for stainless steel, aluminum, copper, zinc alloy and other metal materials.

    2. The function of the passivation process is to form a passivation film on the metal surface, which effectively hinders the contact between the metal surface and the air, thereby enhancing the corrosion resistance and rust resistance of the metal surface, and increasing the salt zero for more than 72-100 hours. The passivation process is chromate passivation, which can be used for natural passivation or lightly colored passivation. After passivation, a complex passivation film will be formed on the surface of the metal workpiece, which can effectively protect the metal surface and self-repair. When the microscopic part is destroyed, the various ions fixed inside the passivation film will react with the metal surface again, forming a new passivation layer. Because chromate passivation has the advantages of good effect, self-healing, corrosion resistance, wear resistance, salt spray resistance, etc., it is widely used in metal passivation process.

    3. The flow of the passivation process is as follows: 

    First, cleaning, oil removal and rust removal are performed, which is equivalent to pretreatment, which can effectively remove impurities and oxides on the metal surface. 

    Second, put it into a chromate passivation solution for passivation. The pH value of chromate in the passivation solution is an important parameter that needs attention and control. Only by controlling the pH value within the range can the best passivation effect be achieved. 

    Finally, wash and dry.

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CNC Machining Tolerances

CNC Machining Tolerances

Tolerance grade refers to the grade for dimensional accuracy. Sibai often makes according to the F and M level of DIN ISO 2768.

The Chinese standard specifies 20 grades, ranging from IT01, IT0, IT1, IT2 to IT18. The larger the number, the lower the tolerance grade. And the allowable range of size variation (tolerance value) the larger it is, the less difficult it is to produce.

It includes:

  • Limit deviation value of linear dimension;

  • The value of the limit deviation on radius and chamfer;

  • Limit deviation value of unspecified tolerance for linear measurements and angles.

Sibai can make 

  • CNC turning: grade IT8 - IT7, and Ra 1.6 um.

  • CNC milling: grade IT8 - IT7, and Ra 3.2 um.

  • Grinding: Semi-finishing and finishing, the precision can reach IT8 - IT5, surface roughness Ra1.25 - Ra0.16.

  • Drilling: It is hole processing, the precision can reach IT10, and the surface roughness is Ra12.5 - 6.3um (reaming is commonly used for semi-finishing and finishing)

  • Boring: The boring accuracy of steel materials can generally reach IT9 - IT7, and the surface roughness is Ra2.5 - 0.16um. 

Sibai is a f-grade and ultra-precision machining enterprise. The main precision testing equipment includes Zeiss 3D, Hexagon 3D, and 2D projectors. the precision is controlled with CPK value.

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Custom CNC Machining FAQ

How fast does Sibai provide samples?

Generally Sibai needs 3-6 work days to finish samples, from the order confirmation to delivery. If the material, cutting tools, and clamping tools and inspection tools are all ready, it needs only a half day or at most 3 days to finish samples.

What types of threading options in Sibai are available?

Sibai makes threads by the ways of thread lathe cutting, thread forming, dilling and tapping, thread rolling, thread die holder forming.

What is the maximum part size for Sibai CNC machining?

Sibai's CNC machines can make the maximum size, 1500 x 800x 800mm.

Sibai's CNC Lathes can make the maximum size Ø300 mm. 

What is the most precise tolerance Sibai can make?

Sibai make the most precise tolerance +-0.001 mm. 

How fast oceanshipping from Shenzhen China to Europe and the USA?

Generally it takes 7-10 days from goods picked up from Sibai's warehouse to vessel despatch. It takes 28 days from Shenzhen port to Hamburg, and 35 days from Shenzhen to USA port. 

Contact with Us
No. 2, Dantang Road, Daping, Tangxia Town, Dongguan, China.

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