What Are the Advantages of aluminum cnc machining service？

Ease with which a metal can be cut

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Machinability is the ease with which a metal can be cut (machined) permitting the removal of the material with a satisfactory finish at low cost.[1] Materials with good machinability (free machining materials) require little power to cut, can be cut quickly, easily obtain a good finish, and do not cause significant wear on the tooling. Factors that typically improve a material's performance often degrade its machinability, presenting a significant engineering challenge.

Machinability can be difficult to predict due to the large number of variables involved in the machining process. Two sets of factors are the condition of work materials and the physical properties of work materials.[2] The condition of the work material includes at least eight factors: microstructure, grain size, heat treatment, chemical composition, fabrication, hardness, yield strength, and tensile strength.[3] Physical properties are those of the individual material groups, such as the modulus of elasticity, thermal conductivity, thermal expansion, and work hardening.[3] Other important factors are operating conditions, cutting tool material and geometry, and the parameters of the specific machining process being performed.[3]

Machinability of steels

Steels are among the most important and commonly used materials in engineering. Free machining steels are alloys that include elements like sulfur and lead that reduce the size of chips produced by the machining process.[4] Free machining steels are more expensive than standard steels, but their cost is offset by savings on manufacturing costs.

Quantifying machinability

There are many factors affecting machinability, but no widely accepted way to quantify it. Instead, machinability is often assessed on a case-by-case basis, and tests are tailored to the needs of a specific manufacturing process. Common metrics for comparison include tool life, surface finish quality, cutting temperature, tool forces, and power consumption.[5][6]

Tool life method

Machinability can be based on the measure of how long a tool lasts. This can be useful when comparing materials that have similar properties and power consumptions, but one is more abrasive and thus decreases the tool life. The major downfall with this approach is that tool life is dependent on more than just the material it is machining; other factors include cutting tool material, cutting tool geometry, machine condition, cutting tool clamping, cutting speed, feed, and depth of cut. Also, the machinability for one tool type cannot be compared to another tool type (i.e. HSS tool to a carbide tool).[6]

Machinability index ( % ) = cutting speed of material for 20 minute tool life cutting speed of free-cutting steel for 20 minute tool life ' 100 {\displaystyle {\text{Machinability index (}}\%{)}={\frac {\text{cutting speed of material for 20 minute tool life}}{\text{cutting speed of free-cutting steel for 20 minute tool life}}}*100}

Tool forces and power consumption method

The forces required for a tool to cut through a material is directly related to the power consumed. Therefore, tool forces are often given in units of specific energy. This leads to a rating method where higher specific energies equal lower machinability. The advantage of this method is that outside factors have little effect on the rating.[6]

Surface finish method

The surface finish is sometimes used to measure the machinability of a material. Soft, ductile materials tend to form a built up edge. Stainless steel and other materials with a high strain hardening ability also want to form a built up edge. Aluminium alloys, cold worked steels, and free machining steels, as well as materials with a high shear zone don't tend to form built up edges, so these materials would rank as more machinable.[7]

The advantage of this method is that it is easily measured with the appropriate equipment. The disadvantage of this criterion is that it is often irrelevant. For instance when making a rough cut, the surface finish is of no importance. Also, finish cuts often require a certain accuracy that naturally achieves a good surface finish. This rating method also doesn't always agree with other methods. For instance titanium alloys would rate well by the surface finish method, low by the tool life method, and intermediate by the power consumption method.[7][8]

Machinability rating

The machinability rating of a material attempts to quantify the machinability of various materials. It is expressed as a percentage or a normalized value. The American Iron and Steel Institute (AISI) determined machinability ratings for a wide variety of materials by running turning tests at 180 surface feet per minute (sfpm).[9] It then arbitrarily assigned 160 Brinell B steel a machinability rating of 100%.[9] The machinability rating is determined by measuring the weighted averages of the normal cutting speed, surface finish, and tool life for each material.[9] Note that a material with a machinability rating less than 100% would be more difficult to machine than B and material with a value more than 100% would be easier.

Machinability Rating= (Speed of Machining the workpiece giving 60min tool life)/( Speed of machining the standard metal)

Machinability ratings can be used in conjunction with the Taylor tool life equation, V T n = C {\displaystyle VT^{n}=C} , in order to determine cutting speeds or tool life. It is known that B has a tool life of 60 minutes at a cutting speed of 100 sfpm. If a material has a machinability rating of 70%, it can be determined, with the above knowns, that in order to maintain the same tool life (60 minutes) the cutting speed must be 70 sfpm (assuming the same tooling is used).[1]

Steels

The carbon content of steel greatly affects its machinability. High-carbon steels are difficult to machine because they are strong and because they may contain carbides that abrade the cutting tool. On the other end of the spectrum, low-carbon steels are troublesome because they are too soft. Low-carbon steels are "gummy" and stick to the cutting tool, resulting in a built up edge that shortens tool life. Therefore, steel has the best machinability with medium amounts of carbon, about 0.20%.[5]

Chromium, molybdenum and other alloying metals are often added to steel to improve its strength. However, most of these metals also decrease machinability.

Inclusions in steel, especially oxides, may abrade the cutting tool. Machinable steel should be free of these oxides.

Additives

There are a variety of chemicals, both metal and non-metal, that can be added to steel to make it easier to cut. These additives may work by lubricating the tool-chip interface, decreasing the shear strength of the material, or increasing the brittleness of the chip. Historically, sulfur and lead have been the most common additives, but bismuth and tin are increasingly popular for environmental reasons.

Lead can improve the machinability of steel because it acts as an internal lubricant in the cutting zone.[10] Since lead has poor shear strength, it allows the chip to slide more freely past the cutting edge. When it is added in small quantities to steel, it can greatly improve its machinability while not significantly affecting the steel's strength.

Sulfur improves the machinability of steel by forming low shear strength inclusions in the cutting zone. These inclusions are stress risers that weaken the steel, allowing it to deform more easily.

Stainless steel

Stainless steels have poor machinability compared to regular carbon steel because they are tougher, gummier and tend to work harden very rapidly.[5] Slightly hardening the steel may decrease its gumminess and make it easier to cut. AISI grades 303 and 416 are easier to machine because of the addition of sulfur and phosphorus.[11]

Aluminium

Aluminium is a much softer metal than steel, and the techniques to improve its machinability usually rely on making it more brittle. Alloys , and have very good machinability.[11]

Other materials

Thermoplastics are difficult to machine because they have poor thermal conductivity.[10] This creates heat that builds up in the cutting zone, which degrades the tool life and locally melts the plastic. Once the plastic melts, it just flows around the cutting edge instead of being removed by it. Machinability can be improved by using high lubricity coolant and keeping the cutting area free of chip build up.

Composites often have the worst machinability because they combine the poor thermal conductivity of a plastic resin with the tough or abrasive qualities of the fiber (glass, carbon etc.) material.

The machinability of rubber and other soft materials improves by using a very low temperature coolant, such as liquid carbon dioxide. The low temperatures chill the material prior to cutting so that it cannot deform or stick to the cutting edge. This means less wear on the tools and easier machining.

See also

Notes

References

• Degarmo, E. Paul; Black, J T.; Kohser, Ronald A. (). Materials and Processes in Manufacturing (9th ed.). Wiley. ISBN 0-471--4.

• Schneider, George Jr (). Cutting Tool Applications

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  . Archived from the original

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For CNC machining projects, aluminum is one of the most popular material choices due to its desirable physical properties. It is strong, which makes it ideal for mechanical parts, and its oxidized outer layer is resistant to corrosion from the elements. These benefits have made aluminum parts common across all industries, though they are particularly favored in the automotive, aerospace, healthcare and consumer electronics spheres.

Aluminum also offers specific advantages that simplify and improve the process of CNC machining. Unlike many other metals with similar material properties, aluminum offers excellent machinability: many of its grades can be effectively penetrated by cutting tools, chipping easily while being relatively easy to shape. Because of this, aluminum can be machined more than three times faster than iron or steel.

This article explains some of the key advantages of aluminum CNC machining ' reasons why it is one of our most widely requested prototyping and production processes ' but also suggests machining alternatives to aluminum.

Other metals and plastics can provide similar benefits to aluminum, in addition to the unique benefits of their own.

What are the benefits of aluminum CNC machining?

• Machinability

• Corrosion resistance
• Strength-to-weight ratio
• Electrical conductivity
• Anodization potential
• Recyclability

Machinability

One of the main reasons why engineers choose aluminum for their machined parts is because, quite simply, the material is easy to machine. While this would appear to be more of a benefit for the machinist manufacturing the part, it also has significant benefits for the business ordering the part, as well as the end-user that will eventually use it.

Because aluminum chips easily, and because it is easy to shape, it can be cut quickly and accurately with CNC machine tools. This has some important consequences: firstly, the short timeframe of the machining job makes the process cheaper (because less labor is required from the machinist and less operating time is required from the machine itself); secondly, good machinability means less deformation of the part as the cutting tool goes through the workpiece. This can allow the machine to meet tighter tolerances (as low as ±0.025 mm) and leads to higher accuracy and repeatability. For more detailed information, check 7 ways to avoid part deformation in aluminum CNC machining.

Corrosion resistance

Different aluminum grades differ greatly in their resistance to corrosion ' the degree to which they can withstand oxidization and chemical damage. Fortunately, some of the most popular grades for CNC machining are the most resistant. , for example, offers excellent corrosion resistance, as do other alloys on the lower end of the strength spectrum. (Strong aluminum alloys may be less resistant to corrosion due to the presence of alloyed copper.)

Strength-to-weight ratio

Aluminum has desirable physical properties that make it ideal for both mechanical and aspect parts. Two of the most important are the metal's high strength and its lightweight, both of which make the material favorable for critical parts such as those required in the aerospace and automotive industries. Aircraft fittings and automotive shafts are two examples of parts that can be successfully machined with aluminum.

However, different grades of aluminum serve different purposes. Because of their favorable strength-to-weight ratio, general-use grades like can be used for a wide variety of parts, while notably high-strength grades like may be preferred in aerospace and marine applications.

Electrical conductivity

CNC machined aluminum parts can be useful for electrical components due to their electrical conductivity. Though not as conductive as copper, pure aluminum has an electrical conductivity of about 37.7 million siemens per meter at room temperature. Alloys may have lower conductivities, but aluminum materials are significantly more conductive than, for example, stainless steel.

Material

Conductivity (S/m) at room temperature

Copper

59.6 million

Aluminum

37.7 million

Zinc

16.9 million

Iron

10 million

Carbon steel

7 million

Titanium

2.4 million

Stainless steel

1.5 million

Anodization potential

Machined aluminum parts are especially popular in the consumer electronics industry, not just for strength and weight demands, but because of important aesthetic considerations. As well as being receptive to paints and tints, aluminum can be treated with anodization, a surface finishing procedure that thickens the protective and oxidized outer layer of the part.

The anodization process, which generally takes place after machining is completed, involves passing an electric current through the part in an electrolytic acid bath and results in a piece of aluminum that is more resistant to physical impact and corrosion.

Importantly, anodizing makes it easier to add color to a machined aluminum part, since the anodized outer layer is highly porous. Dyes can find their way through the porous sections of the outer layer and are less likely to chip or flake since they are embedded within the tough exterior of the metal part.

Recyclability

Another benefit of aluminum is its high recyclability, which makes it preferable for businesses seeking to minimize their environmental impact or for those who simply want to reduce material wastage and recoup some of their expenditure. Recyclable materials are particularly important in CNC machining, where there is a relatively large amount of waste material in the form of chips from the cutting tool.

Alternatives to aluminum in CNC machining

Businesses may seek alternatives to aluminum for CNC machining for any number of reasons. After all, the metal has a few weaknesses: its oxide coating can damage tooling, and it is generally more expensive than alternatives like steel, partly due to the high energy costs of aluminum production.

Here are some potential machining alternatives to aluminum, with an emphasis on their differences and similarities to the popular silver-gray metal.

Metals

Steel & stainless steel

Better than aluminum for:

• Strength

• Temperature resistance

  The company is the world’s best aluminum cnc machining service supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Worse than aluminum for:

• Machinability

• Weight

Steels and stainless steels are widely used materials in CNC machining. Because of their high strength, steels tend to be favored for high-stress applications and those that require strong welds. Steels are resistant to very high temperatures, and stainless steels can be heat treated to enhance their corrosion resistance.

However, while machining steels are engineered for improved machinability, aluminum remains the more machinable of the two materials. Steels are also heavier and have a higher hardness than aluminum, which may or may not be desirable depending on the application.

If temperature resistance is a key consideration and weight is not, steel may be an ideal alternative to aluminum.

Titanium

Better than aluminum for:

• Strength-to-weight ratio

Worse than aluminum for:

• Cost

Titanium may be used as a like-for-like replacement for aluminum since its primary advantage is an exceptional strength-to-weight ratio ' also one of the main benefits of aluminum. Titanium has a similar weight to aluminum but is almost twice as strong. Like aluminum, it is also highly resistant to corrosion.

These advantages are reflected in the higher price point of titanium. Though the material is an excellent choice for parts like aircraft components and medical devices, its cost can be prohibitive.

Machining titanium is a suitable alternative to aluminum when lightweight is a primary concern and, importantly, when the manufacturing budget has some flexibility.

Magnesium

Better than aluminum for:

• Machinability

• Weight

Worse than aluminum for:

• Machining safety

• Corrosion resistance

Although not the most common machining material, the lightweight metal magnesium offers many of the benefits of common aluminum alloys. In fact, magnesium is one of the most machinable metals out there, making the machining process fast and efficient.

One potential downside for machine shops? Magnesium chips are extremely flammable and are aggravated further by water, which means machinists must take caution while clearing debris.

Brass

Better than aluminum for:

• Some aesthetic applications

Worse than aluminum for:

• Cost

A metal with a golden appearance, brass is a highly machinable metal available at a slightly higher price point than aluminum. It is commonly seen on parts such as valves and nozzles, as well as structural components, while its high machinability makes it suitable for high-volume orders.

Copper

Better than aluminum for:

• Electrical conductivity

Worse than aluminum for:

• Machinability

Copper shares several material properties with aluminum. However, the superior electrical conductivity of copper can make it preferable for various electrical applications. While pure copper is difficult to machine, many copper alloys offer similar machinability to popular aluminum grades.

Engineering thermoplastics

POM (Delrin)

Better than aluminum for:

• Electrical insulation

• Low friction

Worse than aluminum for:

• Strength

• Heat resistance

CNC machining projects need not be limited to metals. In fact, several engineering thermoplastics can match or exceed some of the benefits of aluminum, depending on the application.

Since aluminum is often favored for its excellent machinability, one viable plastic alternative is POM (Delrin), which is, like aluminum, highly suited to the machining process. POM has a low melting point but impressively high strength for a plastic.

POM is an electrical insulator, making it suitable for parts like electronic enclosures. It is also suitable for mechanical parts. However, given its radically different insulating behavior compared to aluminum, it should only be used as a like-for-like replacement in situations where thermal and electrical conductivity is of negligible importance.

PTFE (Teflon)

Better than aluminum for:

• Electrical insulation

• Very low friction

Worse than aluminum for:

• Strength

Like POM, PTFE (Teflon) is a highly machinable thermoplastic which is an excellent electrical insulator. Unlike POM, however, PTFE is also resistant to high temperatures (up to 260°C), making it a viable aluminum alternative for high-temperature applications.

Also, its high chemical resistance makes PTFE (Teflon) a popular machining material for parts that will be used in the food industry.

PEEK

Better than aluminum for:

• Medical use

Worse than aluminum for:

• Machinability

• Cost

Though PEEK is harder to machine than the previous two thermoplastics, its high strength and thermal stability (resistant to temperatures up to 260°C) make it a genuine like-for-like alternative to aluminum. PEEK's popularity for machining parts like valves, bearings, pumps, and nozzles testifies to its metal-like abilities.

One stumbling block is price. As a high-performance polymer, PEEK is one of the more expensive machinable thermoplastics, making it suitable only for machining projects where ubiquitous materials like aluminum are unusable.

ABS

Better than aluminum for:

• Thermal shock resistance

Worse than aluminum for:

• Strength

ABS is commonly used as an injection molding material and, as of recent years, a 3D printing filament. But while ABS has very little in common with aluminum, it remains a versatile and lightweight material for CNC machining, offering above-average impact strength.

More

Other machinable plastics, most of which are highly dissimilar to aluminum, include PC, ABS+PC, PP, PS, PMMA (Acrylic), PAGF30, PCGF30, DHPE, HDPE, and PPS.

Alternatives to specific aluminum grades

Application

Aluminum

Alternative

General

Mild steel

Aerospace

Stainless steel 303

Marine

Stainless steel 304

Stainless steel 316

Construction

Mild steel A36

Food

PTFE

PC

Combining CNC machining with other processes

If aluminum remains the preferred material choice for a project, there are ways to combine CNC machining with other manufacturing processes in order to create more complex, higher-performing aluminum parts. Doing so can maximize the functionality of aluminum while reaping the benefits of multiple production processes.

In addition to being an all-in-one manufacturing process, CNC machining can be used to refine or modify parts made using other machinery. Extrusion, casting and forging processes can each be complemented with the machining process to make better aluminum components.

Aluminum extrusion + CNC machining

Extrusion is the process of forcing molten material through an aperture in in a die, producing an elongated component with a continuous profile. While aluminum extrusion is an effective way of producing functional components with quality surface finishes and complex cross-sections, it is limited in scope, since those cross-sections must be consistent across the part.

Unless, of course, the part is modified after extrusion. Because aluminum extrusion tends to involve malleable, ductile and machinable aluminum grades like & , the extruded parts can then be post-machined ' cut in various ways using a CNC machining center.

Combining aluminum extrusion and CNC machining is a great way to produce resilient parts with complex cross-sections and irregular geometries.

Die casting + CNC machining

Die casting is a manufacturing process in which molten metal is forced into a mold cavity with high pressure. It is generally used when making parts in larger quantities since the required tool steel dies are expensive to make.

Along with steel, magnesium, and zinc, aluminum is one of the more popular metals for pressure die casting, and die-cast aluminum parts generally have an excellent surface finish and dimensional consistency.

These advantages can be combined with the advantages of CNC machining. By die casting aluminum components then adding further cuts using a machining center, it is possible to create parts with an exceptional finish and more complex geometries that would be possible using either process on its own.

Gravity dies casting can be used instead of pressure die casting if reducing cost is more important than ensuring high precision or creating thin walls.

Investment casting + CNC machining

Investment casting is a metal casting process that uses wax patterns to create metal parts. Like other casting processes, it produces parts with an excellent surface finish and high dimensional accuracy.

The process also produces unique advantages: it can be used to create more intricate parts than would be possible with die casting, and parts emerge with no parting lines.

Aluminum alloys are a common material used for investment casting, and the cast aluminum parts can be post-machined for refinement.

Forging + CNC machining

Many machinable aluminum alloys are also suited to the age-old process of forging, which involves shaping metal through compressive force. (This often involves hitting the metal with a hammer.)

Aluminum , for example, is suited to hot forging with a closed die ' a process commonly used to produce automotive and industrial components.

The forged pieces of aluminum can be post-machined with a CNC machining center. This can be beneficial compared to machining alone since forged parts are generally stronger than fully cast or fully machined equivalents. However, post-machining allows for the creation of more complex geometries without wholly compromising the integrity of the part.

To learn more about aluminum CNC machining services and custom parts, contact 3ERP. 

Our experience with CNC machining and fine detailing means we can produce a wide range of aluminum machined parts, from small and simple to large and complex.

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