Aluminum Turned Parts: A Comprehensive Overview From Start to Finish

As a manufacturer, you understand the importance of precision and quality in your production processes. One critical set of components that requires strict control and expertise is aluminum turned parts. To produce high-quality aluminum turned parts, you need to understand the materials, equipment, and techniques required from start to finish.

Commonly Used Aluminum Alloys for Turned Parts

When producing aluminum turned parts, manufacturers commonly use several grades of aluminum that are well-suited for machining and turning. The most popular options include:

• 6061 aluminum alloy: This is a versatile, heat-treatable grade with medium strength. It has good machinability and corrosion resistance, making it suitable for intricate, complex parts.
• 7075 aluminum alloy: For high-strength needs, 7075 is a good choice. Although more difficult to machine, it produces durable parts for structural applications where lightweight, high-strength properties are required.

To achieve the closest tolerances and best surface finishes, modern CNC turning centers and lathes are typically used. These computer-controlled machines can produce high volumes of parts with exceptional precision and repeatability.

The specific cutting tools and speeds/feeds will depend on the aluminum grade and final part requirements. In general, higher cutting speeds are needed for aluminum compared to steel. Special aluminum cutting lubricants and coolants are also commonly used to prevent overheating, reduce tool wear, and promote chip evacuation.

Post-processing, parts often undergo heat treatment to harden and strengthen the aluminum. They may also need deburring, sanding, and/or surface treatments like anodizing to improve corrosion resistance and wear properties or for esthetic purposes.

Finally, proper packaging is important to prevent surface damage during shipping and transport. Parts are usually separated with dunnage or placed in nesting trays and covered. Shock-absorbing, moisture-resistant packaging materials help ensure parts reach the customer in perfect condition, ready for their intended end use.

With the variety of aluminum grades and processing options available today, manufacturers can produce high-quality turned parts to suit virtually any commercial or industrial need. By following best practices and working closely with experienced suppliers, you can develop lightweight, precision-machined components to meet your most demanding product requirements.

Equipment Used to Machine Aluminum Turned Parts

To machine aluminum turned parts, certain equipment is required. The most commonly used are:

• CNC lathes: Computer numerical control (CNC) lathes are automated lathes that can produce high volumes of precision turned parts. They use programmed commands to control the cutting tool. CNC lathes are used to perform turning, facing, boring, threading, grooving, chamfering and other operations.
• Turret lathes: Turret lathes are manually operated lathes with a rotating turret that holds multiple cutting tools. They are more versatile than engine lathes but less automated than CNC lathes. Turret lathes are ideal for low to medium volume production.
• Chuckers: Chuckers are small CNC lathes designed for high volume production of small diameter parts (typically under 2 inches). They provide quick changeover times and fast machining speeds.

The aluminum grades frequently used for turned parts are 2011, 2024, 6061 and 7075. These provide good machinability and mechanical properties. The parts then often undergo surface treatments like anodizing or powder coating to improve corrosion resistance and esthetics.

Proper packaging is important to prevent damage during shipping and storage. Turned parts are typically packaged in plastic bags, placed in partitioned boxes and surrounded by cushioning material like foam or cardboard. Desiccant packets may be added to control humidity.

With the right equipment, material selection, surface treatments and packaging, high quality aluminum turned parts can be produced efficiently while still maintaining tight tolerances and an attractive final appearance. The possibilities for customization and application are endless.

Surface Treatments and Coatings for Aluminum Turned Parts

Anodizing

Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. The most commonly used anodize treatment for aluminum turned parts is Type II, which produces a clear finish allowing the natural aluminum shine through. Type III hard anodize penetrates deeper into the aluminum for increased durability.

Painting

Aluminum turned parts can be painted for color and additional protection. A conversion coating is first applied, followed by a primer, then a topcoat of paint. Conversion coatings like Alodine help the primer and paint adhere better to the aluminum surface. For the most durable finish, a two-part polyurethane paint should be used. Powder coating, where an electrostatic charge bonds dry powder to the aluminum, also produces an attractive durable finish.

Electroplating

Electroplating involves using an electric current to coat aluminum parts in a thin layer of metal. Common for aluminum hardware are nickel, chrome, zinc, and gold plating. Nickel provides a durable silver finish while chrome produces a shiny metallic finish. Zinc plating protects against corrosion and is often clear coated or dyed. Gold plating is mainly for appearance and protection in electronic applications.

To summarize, the surface treatments and coatings commonly used for aluminum turned parts include:

• Anodizing (Type II clear, Type III hard)
• Painting (conversion coating, primer, polyurethane topcoat)
• Powder coating
• Electroplating (nickel, chrome, zinc, gold)

The specific treatment used depends on the level of protection and desired finish required for the end application. Proper surface preparation like cleaning and degreasing is required for adequate adhesion and the best results.

Heat Treatment of Aluminum Turned Parts

Solution Heat Treatment

Solution heat treatment involves heating aluminum turned parts to a high temperature and then rapidly quenching them in a liquid medium like water or oil. This is done to increase the strength and hardness of certain aluminum alloys by precipitating hardening elements like magnesium and silicon out of solid solution.

The most common grades of aluminum that are solution heat treated are the 2xxx, 6xxx, and 7xxx series alloys. These alloys contain magnesium and silicon as the major alloying elements. By heating these alloys to a high temperature, the magnesium and silicon dissolve into the aluminum matrix. When the part is quenched, the magnesium and silicon precipitate out as fine particles, which hinders dislocation movement and increases strength.

Solution heat treatment requires precise control of both temperature and quench rate in order to achieve maximum strengthening. Parts are typically heated to temperatures between 480 to 520°C for 2xxx alloys and 510 to 550°C for 6xxx and 7xxx alloys. After soaking at the solutionizing temperature to allow for complete solute dissolution, parts are rapidly quenched in water or oil at a rate higher than 80°C per second.

Proper handling and packaging are required after solution heat treatment to avoid part warping. Parts should be cooled to room temperature, then aged at a lower temperature to further increase strength and stability. Additional surface treatments like anodizing can then be performed if desired for a protective oxide coating.

In summary, solution heat treatment of aluminum turned parts involves heating and rapid quenching to precipitate out solute elements, which strengthens and hardens the material. When performed properly on the appropriate aluminum alloys, this process can significantly enhance the mechanical properties and performance of finished parts. Care must be taken to properly handle, age, and finish parts after solution heat treatment.

Post-Machining Operations for Aluminum Turned Parts

Surface Treatments

Once machined, aluminum turned parts often require surface treatments to improve corrosion resistance, adhesion, and esthetic properties. Common surface treatments for aluminum include:

• Anodizing – An electrochemical process that creates a durable, non-conductive aluminum oxide layer. Anodizing improves corrosion resistance and provides an attractive matte finish. Hard anodizing produces a thicker, more durable coating.
• Powder coating – A protective polymer coating applied as a dry powder then cured under heat. Powder coating is highly durable and comes in a wide range of colors and finishes. It provides excellent corrosion protection for aluminum.
• Painting – Liquid paints, like polyurethane or lacquer, are spray-applied then cured to form a protective coating. Painting aluminum requires proper surface preparation to ensure adhesion. Painted finishes can provide an attractive, custom appearance along with good protection.
• Plating – Electroplating involves applying a metal coating, like zinc or chrome, to the aluminum surface. Zinc plating, or galvanization, protects against corrosion. Chrome plating provides a bright, shiny finish that is decorative but offers only moderate protection.
• Conversion coating – Chemical treatments, like chromate conversion coating, produce a protective oxide layer. Conversion coatings are inexpensive but provide only short-term corrosion resistance. They are often used as a pretreatment prior to painting or powder coating.

Packaging

Proper packaging is essential to prevent damage to aluminum turned parts during shipping and handling. Parts should be packaged in durable boxes, crates or cartons lined with padding like foam, bubble wrap or packing peanuts. More delicate parts may require custom nesting or compartmentalization within the package to prevent scratches. Desiccant packets can be included to prevent oxidation or water spotting during transit.

Inspection and Quality Control of Aluminum Turned Parts

Inspection of Raw Materials and Components

Upon receiving aluminum round bars, plates or other raw materials, inspect them to ensure they meet the required aluminum grade, dimensions, and surface finish specifications before starting any machining process. Check material certificates to verify the correct grade of aluminum, such as 6061 or 7075, was received. Measure key dimensions using calipers and micrometers to confirm they are within tolerance. Examine the surface for any scratches, dents or other imperfections that could affect final part quality.

Monitoring Machining Processes

Closely monitor all machining processes like turning, milling, drilling and threading to minimize waste and ensure high quality aluminum turned parts. Regularly measure key part features during machining using instruments like calipers, micrometers and pin gages to confirm they comply with the engineering drawings or 3D model. Inspect cutting tools like lathe bits and end mills for any damage or wear and replace as needed to achieve the desired surface finish and dimensional accuracy. Conduct in-process inspections for attributes like surface roughness, parallelism, concentricity and angularity.

Final Inspection and Part Approval

Once the machining of the aluminum turned parts is complete, conduct a final inspection to verify all attributes meet the required specifications before approving the parts for surface treatment or shipment to customers. Check all key dimensions, fits, and cosmetic attributes. Use instruments like optical comparators to check complex geometries. Ensure there are no burrs, scratches or other surface imperfections. Approved parts can then proceed for anodizing, powder coating or other surface treatments based on requirements. Packaging and storage procedures should also protect parts from damage prior to shipment.

Maintaining high quality standards through comprehensive inspection and quality control procedures at every step of the manufacturing process will result in high-quality aluminum turned parts that meet or exceed customer requirements. Thorough inspections and monitoring help minimize wasted materials and rework, reducing overall costs. Satisfied customers will come back for all their precision machined aluminum parts needs.

Packaging Requirements for Aluminum Turned Parts

Protective Packaging

To prevent damage during shipping and handling, aluminum turned parts require protective packaging. Soft, shock-absorbent materials should surround the parts to protect against scratches, dents, and dings.

Moisture-Resistant

As aluminum can corrode when exposed to moisture, a moisture-resistant barrier is essential. Polyethylene bags, polypropylene bags, or coated craft paper all provide an effective moisture barrier. Desiccants or drying agents placed inside the packaging can help absorb excess moisture.

Proper Labeling

Clearly label each package to properly identify the contents. Include details such as part number, quantity, material specifications, and any special handling instructions. This helps to avoid confusion, ensures the parts are used as intended, and aids in quality control.

Securing the Parts

Take measures to secure the parts within the packaging to prevent shifting during transport. Place padding, blocking, or separators between parts. For small parts, a compartmented organizer keeps each piece in place. Taping, strapping or heat-sealing the packaging closed also helps contain the contents.

Consider Part Features

Certain part features may require extra protection or have additional packaging needs:

• Sharp edges: Dull sharp edges or cover/cap them to avoid tearing the packaging.
• Thin sections: Place separators between thin sections to prevent bending or denting.
• Machined surfaces: Use soft, lint-free materials that won’t scratch machined surfaces.
• Anodized/coated finishes: Prevent marring of special finishes; indicate proper handling.
• Irregular shapes: Custom compartmented organizers or form-fitted packaging may be required.

Proper protective packaging is essential for aluminum turned parts to arrive at their destination undamaged and ready for use. Following these guidelines will help ensure your parts make the journey securely.

Applications of Aluminum Turned Parts

Transportation

Aluminum turned parts are commonly used in the transportation industry for aircraft, automobiles, trucks, and trains. Their lightweight, corrosion-resistant properties make them ideal for various vehicle components like:

• Wheel spacers
• Suspension components
• Brake calipers
• Engine parts (pistons, cylinders, valve covers, oil pans, etc.)
• Transmission components
• Fuel system parts

Industrial Machinery

Turned aluminum parts are also popular for use in industrial machinery and equipment where durability and precision are required, such as:

• Pumps and valves
• Compressors and blowers
• Conveyor components
• Robotics
• Tooling fixtures
• Milling and grinding machines

The strength-to-weight ratio and dimensional stability of certain aluminum grades are beneficial for high-performance machinery operating under stressful conditions.

Medical Equipment

Aluminum turned parts are commonly machined for components in medical devices and equipment like:

• Imaging equipment (MRI, CT scanners, X-ray)
• Dental equipment
• Surgical instruments
• Prosthetics
• Mobility aids (crutches, walkers, wheelchairs)

Aluminum is valued for medical applications because it can be repeatedly sterilized without degradation and does not interfere with imaging or diagnostic equipment. Certain alloys provide the strength required for weight-bearing medical devices.

In summary, aluminum turned parts have a wide range of important applications across industries where lightweight, durable, and corrosion-resistant properties are required. With a variety of aluminum grades and secondary finishing options available, aluminum turned parts can be customized to suit the needs of any application.

Aluminum Turned Parts FAQs: Getting the Answers You Need

What aluminum grades are commonly used for turned parts?

The most commonly used aluminum grades for turned parts are the 6xxx and 7xxx series. These include:

• 6061 – This is a versatile, heat-treatable grade with good corrosion resistance and machining properties. It is used for a wide range of turned parts like fittings, fasteners, and electronic components.
• 7075 – This high-strength grade is ideal for turned parts requiring minimal deformation, like aircraft fittings and gears. It has good fatigue strength and average machinability.

What equipment is typically used to machine aluminum turned parts?

The primary equipment used includes:

1. Lathes – Lathes spin the aluminum stock while cutting tools shape it into a symmetrical part. Lathes can produce turned parts with diameters from a fraction of an inch up to several feet.
2. Automatic lathes – These are lathes that operate automatically once set up, enabling high volume production. They are commonly used to produce turned parts like fasteners, electronic components, and automotive fittings.
3. Swiss-type lathes – These specialized lathes have a guide bushing that supports the workpiece, allowing them to produce small, high precision turned parts with tight tolerances, such as those used in the medical industry.

How are aluminum turned parts surface treated and packaged?

Aluminum turned parts typically receive surface treatments to improve corrosion resistance and durability. The most common methods are:

• Anodizing – An electrolytic process that creates a durable, protective oxide layer. Anodizing is often dyed in different colors for esthetic purposes.
• Painting – Applying a coat of paint, powder coat, or other sealant. This is a more economical surface treatment for aluminum turned parts.

Packaging requirements depend on the part size, quantity, and end use:

• Bulk – Loose parts are packaged in bags, boxes, or drums. Common for small fasteners and electronic components.
• Tray – Parts are secured in molded trays or carriers. Used when organization and part orientation is important.
• Custom – Parts are mounted on boards or in bespoke fixtures to keep them secure during shipping and handling. Often required for precision turned parts.

Proper surface treatment and secure packaging help ensure aluminum turned parts reach customers in pristine, functional condition. With the right aluminum grade and machining process, turned parts can be produced to exacting standards for a wide range of applications.

Conclusion

As you’ve seen, the manufacturing of aluminum turned parts requires a significant amount of work and expertise. From choosing the right aluminum alloy and turning equipment to properly finishing and packaging the parts, each step in the process is crucial to producing high-quality components. By understanding the various grades of aluminum, cutting tools, and surface treatments available, you can determine the optimal combination for your specific application and requirements. While aluminum turned parts may seem simple on the surface, a huge amount of science, technology, and craftsmanship go into creating precision parts that meet the needs of today’s industries. With the right knowledge and skills, aluminum turned parts can be produced efficiently and economically.