If you don’t have experience machining aluminum alloys but you’d like to expand your capabilities to solicit work from aerospace companies, here are a few points to consider:
Horizontal versus vertical machining centers. Many shops rely on VMCs for a number of basic machining tasks. However a horizontal machining center provides superior chip control, automatic pallet indexing and rotation (B axis) as part of its basic design. Additionally, HMCs typically provide longer tool life, greater process stability and superior part quality. If you plan to machine close-tolerance parts, you’ll want to acquire an HMC that is designed for advanced thermal stability. Otherwise your operators must deal with size fluctuations due to machine warm-up and changes in plant temperature. Thermally stable machine tools will reduce scrap and demand less operator attention.
Spindle power and maximum RPM. Aluminum alloys for the most part are free cutting in comparison to harder materials, however aluminum will consume a surprising amount of horsepower at aggressive speeds and feeds. Therefore the spindle should be capable of speeds in excess of 12,000 RPM with a horsepower rating sufficient to accommodate your production needs. CAT 40 spindles are commonly used with spindle speeds up to 15,000 – 20,000 RPM. CAT 50 spindles are popular for direct drive and geared spindles with higher horsepower and torque ratings, and maximum speeds less than 15,000 RPM. The CAT 50 spindles are also well suited for larger diameter drills, end mills over 1.0” diameter and tooling that generates high axial thrust loads, such as extended length end mills and larger diameter face mills. HSK spindles are used across a wide range of spindle speeds, particularly in high RPM applications greater than 20,000 RPM.
Through spindle coolant. Make sure the coolant delivery components are capable of 1,000 psi. If not, you can’t use the hardware for high-pressure applications. It’s best to equip the machine at the outset with a 1,000 psi through spindle coolant system.
Flood coolant. Consider the addition of a flood coolant system to assist in flushing chips away from the work envelope. In some cases this feature requires additional coolant tank capacity, and the chip conveyor must also have the flow rate capacity to support the additional coolant flow.
Chip conveyor. Not all chip conveyors are created equal. Many can’t handle the types of chips associated with aluminum alloys. Make sure your chip conveyor is capable of managing these kinds of chips. A self-cleaning, filtering chip conveyor is the best solution.
Gosiger’s technical support team can help you get ready to successfully machine aluminum alloys for aerospace and other applications. Contact them today. And for more tips on machining for the aerospace market, download the following white papers: