b'Illuminating Aluminum machine tool designs had to changeparts, and carbide tools usually are so gravity could be used to helpused only when necessary. Machin-evacuate chips. Some vertical lathesing die-cast alloys requires poly-hard-coat anodize to aluminum sur- have been reversed so their chuckscrystalline diamond tools.faces so we could use OD grindersare above the cutting tools, forcingPCD tools are manufactured by on aluminum parts. chips to fall away from parts. brazing industrial-grade diamonds Chip control is another typicalAluminum also has a propensityonto carbide or HSS bodies. These problem with rolled, forged and ex- for chip welding, or adhering to thetools then are lapped to create the truded alloys. In short, forming aedge of a cutting tool. Chip weld- desired geometry. Two significant chip is easy, but it can be difficulting alters tool geometry, which ex- characteristics make PCD ideal for to break the chip, resulting in long,acerbates the welding problem andmachining aluminum. PCD is the stringy ones that wrap around toolscreates a chain reaction that typi- most wear-resistant substance used and parts. Cutting tool geometriescally results in tool failure. A fuzzyfor cutting tool manufacturing and have advanced significantly in recentor melted-looking surface finish isis highly resistant to chip welding. years, but light depths of cut andthe primary indicator of chip weld- Machining high-volume automotive high cutting speeds still can create issues with continuous chip forma- Aluminum is light, clean and easily machined, tion. Eliminating stringy chips may require altering cutting speeds, chipwhich is why machinists enjoy working with it.loads and tool geometries. Continu-ous chips are a substantial hindranceing. Well-formed aluminum chipsparts in autonomous cells demands to achieving optimal cycle times. should be very shiny and smooth onthe use of PCD tools.Development of machine tools,one side and have a frosted appear- As you may guess, PCD tools are cutting tools and machining tech- ance on the other. This indicatesvery expensive and almost always niques specifically for aluminum hasthat chips are sliding across the facecustom-engineered for a specific advanced quickly since the 1990s,of the tool uninhibited. If a chip isapplication. PCD is capable of work-and several machine tool buildersfuzzy and white on both sides, chiping at extremely high speeds. It is have placed machines on the mar- welding likely has occurred. Cor- also the first choice when finishing ket expressly designed for machin- rect cutting speeds, suitable cool- close-tolerance parts because alu-ing aluminum. When paired withant, properly prepared cutting toolsminum does not weld to the cutting advanced cutting tools, the combi- and good process development areedge. Chip welding is the primary nation can create huge volumes ofneeded to combat chip welding. cause of poor surface finish and the aluminum chips. If they are not re- Aluminum automotive parts ofteninability to hold tight tolerances.moved from a work area, bad thingsare made by die casting, and auto- Aluminumcanpresentchal-might happen. Commonly known asmakers use enormous quantities oflenges, but machine tool and cut-re-cutting, chips can be drawn in bydie-cast aluminum. Although it isting tool manufacturers have made a cutting tool and become trappedfast and accurate and creates near- significant advances in the past between the tool and part, causingnet-shape parts, machining is fre- two decades. Becoming efficient poor surface finish, tool breakagequently required to ensure properrequires understanding available and increased tool wear. Manufac- mechanical fitment. The alloyingtechnologies and balancing costs turers have employed high-pressurechemicals used to create die-cast- with production quantities.coolant to blast chips out of the cut- ing alloys make the materials ex- There are amazing videos of ma-ting zone and applied high-volumetremely abrasive and can wreakchining aluminum on the internet. flood systems to wash chips out ofhavoc on cutting tools. The use ofCheck them out, and see how fast the machine. The volume of chipshigh-speed steel is not even a con- a well-designed process can move from these machines is so great thatsideration when machining die-castaluminum.CTEabout the authorctemag.comChristopher Tate isFor more information about machining aluminum, facilities operation direc- view a video presentation at www.ctemag.com by tor at EthosEnergy inscanning the QR code with your smartphone or Houston. Contact him atentering this URL on your web browser: cteplus.chris23tate@gmail.com. delivr.com/27bpa40JUNE 2021 MachiningAluminum.indd 40 5/14/21 3:27 PM'