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Drilling is a machining process that uses rotary cutting movements superimposed by a translatory feed movement in the direction of the rotational axis of the tool. Both movements are usually assigned to the tool, but they can also be executed by the tool. An example would be creating central, axial holes in turned parts on a lathe.
The results normally achieved by drilling processes are round-shaped through- or blind holes. Deviations from a cylindrical form are normally undesired, but can be created if needed by certain products/applications.
The spindle position in drill machines is usually vertical and it is used for five different forms of machining: drilling with a spiral drill, or drilling rod, countersinking, grinding, and tapping (creating threads) using a tapping machine. Drilling and milling also have other very close similarities and some drilling tasks can be performed on milling machines (and vice versa). Thread tapping requires an automated feed that is synchronised with the rotary motion, which can be achieved on drilling machines using guide nuts or thread-cutting heads.
Drilling is one of the oldest production techniques despite it being a difficult task to perform by hand due to the rotary force required. This soon resulted in simple, hand-operated drills that made the job easier. The key milestone in the journey to the modern CNC industrial drill came in the form of the coordinate-controlled jig boring machine, created by the Geneva -based firm SIP in 1921.
There are a range of specialist and multi-functional machine tools available for the metal drilling sector. As mentioned, some of these production processes can also (partly) be performed on mills and lathes. For example, creating axial holes on turned parts on a lathe, where the workpiece turns and tools remains stationary. On a drill, the process would be the other way around.
When it comes to assembly and repair tasks, hand-held machines are ideal, especially those which are independent of the mains supply and use batteries. For work on magnetisable steels, however, magnetic drilling machines are the primary choice. They are a form of the column/pillar drill and use magnetic force to hold the workpiece in place, which provides benefits in terms of alignment precision and reliable drill tool guidance, as well as the option to use it in different locations with ease.
Major manufacturers of hand-held and magnetic drills include AEG, BDS, FEIN, MAB and MAGTRON.
The multi-spindle drilling machine reduces machining times in serial production by enabling several bore holes to be created simultaneously on one workpiece by means of hole patterns.
Manufacturers of multi-spindle drilling machines include ERLMANN and KALTENBACH. Heinrich Metz GmbH from Aschaffenburg, Germany is a specialist in multi-spindle heads.
Particularly large or weighty metallic parts that are too heavy for column/pillar drills are often machined using a radial drilling machine. In these machines, the drill head can be adjusted both in terms of height and radial alignment, which is not possible on column/pillar drills.
Turret drilling machines facilitate automatic tool-changing thanks to computerised numerical control (CNC) and mark the transition between conventional drills and CNC drilling machines.
The classic types of machines used for drilling are pillar and column drilling machines. They are true all-rounders for small series or amateur carpentry. Pillar and column drills are primarily found in workshops and can also be used to cut thread into material.
In these devices, the drill machine head is operated by a motor, gears and drilling spindle and is linked to a single pillar (either cylindrical or a stand with a prismatic cross-section) which supports it. This results in a C-shaped frame that can be used as a table-top device or free-standing.
The work table can be adjusted on the support and pillar drilling machines can also be pivoted laterally for better access and machining options.
They are produced by companies such as ALZMETALL, EPPLE and GILLARDON.
Bore holes whose depth is more than ten times greater than its diameter are created using deep hole drilling machines. This form of machining can be problematic in terms of chip removal and tool cooling, which is why these drill machines use special drilling tools, such as those which apply coolant directly to the cutting location.
Recommended manufacturers of high-quality deep hole drilling machines include DEGEN, IXION, SIG and WOHLENBERG.
There are also many core drills for sale on the market, which work by removing a cylinder of material (the core) from a given item which is then left within the drill bit for later removal. When used on metal, core drills are generally called annular cutters.
Buying used drill machines for sale is generally an easy task. If maintained properly, a used drilling machine can be expected to provide many years of trouble-free operation.
Cooling and lubrication for the tool are significant factors when it comes to drilling metal and help by reducing tool wear and increasing drilling performance. This means that when buying metalworking drilling machines, close attention should be paid to the cooling unit/equipment.
Other criteria to look out for vary depending on the intended application, but numerical controls, for example, are highly useful if the drill is to be integrated into a production line.
So, you would like to buy a used drilling machine? Then Surplex, the used machinery portal for metal- and woodworking is the place to be. We regularly hold industrial auctions in which you have the chance to acquire high-quality second-hand drilling machines at attractive prices. Our range of machinery includes simple hand-held machines, conventional industrial drills, through to automated CNC drilling systems.
