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Deep processing of aluminum profiles

Aluminum profiles need to be machined for various reasons. To save cost, some of the fabrication processes that need to done after the customer has received their shipment may be done during or immediately after the extrusion process. This is usually referred to as deep processing of the aluminum profile. Some of the machining processes that can be carried out during deep processing include: drilling, tapping or threading, sawing, milling, deburring, and turning.

Drilling of holes in the aluminum can done at a high speed with drilling bits. These bits are properly sharpened to decrease the amount of pressure needed for the drilling and to give more accurate results. In addition to standard bits, special bits are used when drilling soft alloys and deep holes. To reduce the adverse effect of the heat generated during drilling, a coolant is applied to the profile and the bit to prevent the hole from contracting due to heat.

A hole is classified as deep hole when its depth to diameter ratio is more than 10:1. Deep hole drilling offers  better straightness, tighter diameter control and excellent surface finish. Special tools are employed during the deep hole drilling process to ensure that the coolant is efficiently delivered, the chips are easily evacuated, and the correct depth to diameter ratio is achieved.

Deep hole drilling is usually carried out on dedicated deep hole drilling equipment. These machines are specially designed to deliver optimum efficiency during the drilling process and keep the hole straight. Some CNC machining centers equipped with newly designed components can be used to drill deep holes up to a limited depth to diameter ratio.

Gun-drilling is utilized for holes that have a diameter between 1 and 50 mm. The coolant is normally introduced via the spindle and in the middle of the gun-drill. Aluminum metal chips can be discharged through the V-shape in the groove incorporated into the tool. To achieve the desired straightness, tolerance and surface finish, the gun-drill tips are ground before the drilling starts.

To drill holes that have a diameter between 20 and 200 mm, BTA deep hole drilling is used. The coolant comes in  through the pressure head assembly and pours the coolant around the tool. Aluminum chips are discharged via the center of the tool through the machine spindle and drill tube. This kind of drilling is capable of 5-7 times faster drilling than the gun-drilling but it requires more power. In addition to drilling of holes, it is possible to do counter boring operations on the BTA drilling machine.

After the drilling of the profiles, internal or external threads may be added with different machining methods. For small diameters, which are 6mm or less, a steel tap may be used. But special taps need to be used for bigger diameters. Internal threading is usually done in a series of taps or with a single tap.