Precise hole making is complicated especially when the constituent materials have dissimilar properties. Machining a precise hole in custom CNC aluminium affects surface quality, accuracy, and component structure. Both material and machine-related factors affect the outcome of hole precision.
Here we discuss three processes that can be used for machining a precise hole in custom aluminium parts – peck drilling, wire electrical discharge machining, and laser cutting. These processes along with other high precision machining techniques utilize appropriate machining forces and temperature to ensure the hole has the right structure, size, and roughness.
Peck Drilling
Drilling deep and precise holes in custom-machined aluminium parts requires stable drilling tools and an effective chip removal process. The process involves drilling a hole with intermittent feed after tool immersion in the aluminium. Both chip evacuation and drilling occur simultaneously helping improve the quality of the drilled surface.
Achieving high productivity with peck drilling requires that the drill is retracted within and below 0.3mm from the bottom of the hole. Periodical stops during drill rotation are also important for ensuring that productivity is optimal.
Additionally, peck drilling ensures optimal chip evacuation through the retraction of the tool from the drilled hole. This step makes it easy to prevent the chip from sticking to the flute of the drill. With optimal chip evacuation and intermittent tool movement, peck drilling ensures that there is a better penetration rate, which directly contributes to better surface quality and hole precision on the custom machine aluminium parts.
Other factors that make peck drilling effective for precise hole machining in aluminium include high cutting speed and the length of the chip. High cutting speed contributes to the accuracy of the material, while the length of the chip affects the stability and effectiveness of the tool in achieving high-precision hole cuts in aluminium.
Wire Electrical Discharge Machining (EDM)
In wire EDM, electrical charges derived from thermal energy sources are used to erode aluminium during the manufacture of custom CNC aluminium parts. Without the need for mechanical forces or tool input, wire EDM ensures manufacturers achieve the desired precise hole shapes through electrical discharges. In the actual process, rapid current discharges send voltages through a dielectric fluid to remove materials and form a hole in the workpiece. Aluminium being a conductor of electricity is suited to wire EDM.
The mechanism by which wire EDM ensures precise hole CNC machining involves using the electrical discharge to heat the aluminium, melting away the target parts, and creating a precise hole in the material. Concurrently, the process involves running a dielectric liquid through the melted hole to help with the additional removal of material and cooling of the process. In wire EDM brass or copper wire is used to cut to drill through the aluminium to create the hole. The ability of the wire to pass through the material enables the process to produce intricate and complex hole shapes in custom-made aluminium parts.
Other EDM processes that can be used in creating precision holes in aluminium include sinker and hole EDM. Hole drilling EDM can be effective for creating precise holes due to the tubular nature of the electrodes used in the process.
Wire EDM adds precision to hole machining in aluminium because of its flexibility in creating different hole depths. It also enhances the quality of the material surface. Apart from hole drilling, the process has become popular in injection moulding, and die casting.
Laser Cutting
Laser cutting employs laser beams to generate high-intensity thermal energy to cut holes through aluminium and aluminium alloys. During CNC machining a horizontal laser beam is transformed through a 450 mirror that reflects to create a vertical downward laser. The laser beam generates heat of up to 10, 000 C0, which can melt and vaporize the aluminium to create a precise hole around the intended spot.
Consequently, a cutting gas jet passes through the created hole to blow off the cut materials, prevent accumulation, and enhance the quality and precision of the hole. For instance, 600W laser power combined with 16 bars of cutting gas pressure is sufficient to create custom machined aluminium parts holes with a diameter range of 200 micro m to 330 micro m precisely and with high quality.
Compared with its alloys, aluminium has a lower melting point and laser absorption abilities. It is, therefore, recommendable to increase the laser energy intensity for more precise and quality outcomes when working with custom aluminium parts. Generally, during the laser cutting process, the CNC machining tool creates and connects several tiny holes to form the shape of the intended bigger hole on the aluminium workpiece.
Laser cutting has several advantages that make it a suitable process for precise hole cutting in aluminium. Laser beams have a thin cutting seam (0.1mm to 0.2mm) minimizing structural damage to the hole, and ensuring a smooth cut without any slag.
Similarly, the thin and high-energy slits in a laser beam ensure that minimal heat is transferred to the aluminium work piece, thereby reducing the chances of thermal damage to the material and the hole. Also, the process is cost effective because it can be integrated with CNC machining to ensure cut complicated holes’ types accurately.
Conclusion
In conclusion, machining a precise hole in aluminium requires the use of fast cutting, high penetration, and great productivity in CNC machining processes. Precise hole machining in custom-made aluminium parts is essential and can be ensured by one or a combination of laser cutting, peck drilling, and wire electrical discharge machining. These processes are suited for precise hole machining because they are linked to fast speeds, optimal tool functioning, and rapid penetration rates.
