El taladrado es un término que cubre todos los métodos para producir agujeros cilíndricos en una pieza con herramientas de arranque de viruta. Además del taladrado de agujeros cortos y largos, también cubre el trepanado y los mecanizados posteriores tales como escariado, mandrinado, roscado y brochado. La diferencia entre taladrado corto y taladrado profundo es que el taladrado profundo es una técnica específica diferente que se utiliza para mecanizar agujeros donde su longitud es varias veces más larga (8-9) que su diámetro.

Con el desarrollo de brocas modernas el proceso de taladrado ha cambiado de manera drástica, porque con las brocas modernas se consigue que un taladro macizo de diámetro grande se pueda realizar en una sola operación, sin necesidad de un agujero previo, ni de agujero guía, y que la calidad del mecanizado y exactitud del agujero evite la operación posterior de escariado.

Como todo proceso de mecanizado por arranque de viruta la evacuación de la misma se torna crítica cuando el agujero es bastante profundo, por eso el taladrado está restringido según sean las características del mismo. Cuanto mayor sea su profundidad, más importante es el control del proceso y la evacuación de la viruta.[6]​.

Hole production

The main factors that characterize a hole from the point of view of its machining are:.

Almost all of the holes made in the different drills that exist are related to screws in general, that is, the majority of drilled holes serve to embed the different screws that are used to assemble some parts with others of the mechanisms or machines of which they are part.

According to this criterion, there are two different types of holes: those that are through and completely go through the piece and those that are blind and only enter a certain length into the piece without going through it. Both of them can be smooth or they can be threaded.

Regarding the through holes that are used to embed screws in them, there are countersunk entry holes for flat head screws, two-diameter holes for inserting Allen screws, and single-diameter cylindrical holes with the upper face faced to improve the seat of the washer and screw head. The diameter of these holes corresponds to the outer diameter of the screw.

Regarding threaded holes, the diameter of the hole drill must be the one that corresponds to the type of thread used and the nominal diameter of the screw. In blind screws, the drill bit must be deeper than the length of the thread due to the problem of the chip from the tap.

Los parámetros de corte fundamentales que hay que considerar en el proceso de taladrado son los siguientes:.

cutting speed

Cutting speed is defined as the tangential speed of the periphery of the drill bit or other tool used in the drill (Reamer, thread tap, etc.). The cutting speed, which is expressed in meters per minute (m/min), has to be chosen before starting the machining and its appropriate value depends on many factors, especially the quality and type of drill bit used, the hardness and machinability of the material being machined and the feed speed used. The main limitations of the machine are its speed range, the power of the motors and the rigidity of the workpiece and tool fixation.

From the determination of the cutting speed, the revolutions per minute that the milling spindle will have can be determined according to the following formula:

Where V is the cutting speed, n is the rotation speed of the tool and D is the diameter of the tool.

Cutting speed is the main factor that determines tool life. A high cutting speed allows machining to be carried out in less time but accelerates tool wear. Tool manufacturers and machining manuals offer indicative data on the appropriate cutting speed of tools for a given tool duration, for example, 15 minutes. Sometimes it is desirable to adjust the cutting speed for a different tool life, for which the cutting speed values ​​are multiplied by a correction factor. The relationship between this correction factor and the life of the tool in cutting operation is not linear.[7]​.

Excessive cutting speed may result in:.

Cutting speed too low may result in:.

Bit rotation speed

The rotation speed of the drill spindle is usually expressed in revolutions per minute (rpm). In conventional drills there is a limited range of speeds, which depend on the rotation speed of the main motor and the number of speeds of the machine's gearbox. In numerical control drills, this speed is controlled with a feedback system that usually uses a frequency converter and any speed can be selected within a range of speeds, up to a maximum speed.

The rotation speed of the tool is directly proportional to the cutting speed and inversely proportional to the diameter of the tool.

Feed speed

The feed or feed rate in drilling is the relative speed between the piece and the tool, that is, the speed with which the cut progresses. The feed of the cutting tool is a very important factor in the drilling process.

Each drill bit can cut adequately at a range of feed rates per revolution of the tool, called feed per revolution (f). This range depends fundamentally on the diameter of the drill bit, the depth of the hole, as well as the type of material of the piece and the quality of the drill bit. This speed range is determined experimentally and is found in drill bit manufacturers' catalogs. Furthermore, this speed is limited by the rigidity of the workpiece and tool clamping and by the power of the machine's feed motor. The maximum chip thickness in mm is the most important limiting indicator for a drill bit. The cutting edge of the tools is tested to have a certain value between a minimum and maximum chip thickness.

The feed rate is the product of the feed per revolution and the rotation speed of the tool.

As with the tool rotation speed, in conventional drills the feed speed is selected from a range of available speeds, while numerically controlled drills can work at any feed speed up to the maximum feed speed of the machine.

Effects of ground speed.

The high forward speed gives rise to:.

Low forward speed results in:.

Machining time

In order to calculate the machining time of a drill, it is necessary to take into account the approach and exit length of the drill bit of the piece being machined. The approach length depends on the diameter of the drill bit.

Specific cutting force

The cutting force is a necessary parameter to be able to calculate the power necessary to carry out a certain machining. This parameter is a function of the feed of the drill, the cutting speed, the machinability of the material, the hardness of the material, the characteristics of the tool and the average thickness of the chip. All these factors are included in a coefficient called K. The specific cutting force is expressed in N/mm².[8]​.

Cutting power

The cutting power P necessary to carry out certain machining is calculated from the value of the chip removal volume, the specific cutting force and the performance of the drill. It is expressed in kilowatts (kW).

This specific cutting force F is a constant that is determined by the type of material being machined, tool geometry, chip thickness, etc.

In order to obtain the correct power value, the value obtained has to be divided by a certain value (ρ) that takes into account the efficiency of the machine. This value is the percentage of the motor power that is available in the tool placed in the spindle.

where.

The massive installation of CNC machining centers in metallurgical industries has been a great revolution in all aspects of traditional machining.

A machining center has united in a single machine and in a single process tasks that were previously carried out in several machines, drills, milling machines, boring machines, etc., and also carries out the different machining operations in minimal times that were previously unthinkable due mainly to the robustness of these machines, the very high rotation speed at which the spindle operates and the extraordinary quality of the different tools used.

So a machining center incorporates a tool store for different operations that can be carried out on the different faces of the cubic pieces, so that with a single fixation and manipulation of the piece, the integral machining of the faces of the pieces is achieved, so the total machining time and precision achieved is very valuable from the point of view of machining costs, by achieving faster speed and fewer defective parts.

When engineers design a machine, equipment or utensil, they do so by coupling a series of components made of different materials that require machining processes to achieve proper operating tolerances.

The sum of the raw material cost of a part, the cost of the machining process, and the cost of defectively manufactured parts constitute the total cost of a part. Technological development has always had the objective of achieving the highest possible quality of the components as well as the lowest possible price for both raw materials and machining costs. To reduce the cost of drilling and machining in general, action has been taken on the following fronts:

To reduce the rate of defective parts, it has been possible to automate the work of the drills as much as possible, drastically reducing manual drilling, and building very sophisticated automatic drills or drills guided by numerical control that execute machining according to a previously established program.

Due to the multiple conditions in which drills are used, they can be classified according to their power source, their function and their support.

Due to their power source there are:

Due to their function there are:

For your support:

Las brocas son las herramientas más comunes que utilizan los taladros, si bien también pueden utilizar machos para roscar a máquina, escariadores para el acabado de agujeros de tolerancias estrechas, avellanadores para chaflanar agujeros, o incluso barras con herramientas de mandrinar.

Las brocas tienen diferente geometría dependiendo de la finalidad con que hayan sido fabricadas. Diseñadas específicamente para quitar material y formar, por lo general, un orificio o una cavidad cilíndrica, la intención en su diseño incluye la velocidad con que el material ha de ser retirado y la dureza del material y demás cualidades características del mismo.

Constituent elements of a drill bit

Among some of the parts and generalities common to most drill bits are:.

Characteristics of carbide drill bits

For high-production drilling machines, solid carbide drills are used for small holes and boring bars with changeable inserts for machining large holes. Its selection is made taking into account the material of the part, the type of application and the machining conditions.

The variety of insert shapes is large and standardized. Likewise, the variety of materials used in modern tools is considerable and is subject to continuous development.[6]​.

The suitability of the different types of inserts used in carbide drills, whether welded or changeable, are adapted to the characteristics of the material to be machined and are indicated below and are classified according to an ISO/ANSI Standard to indicate the applications in relation to the resistance and toughness they have.

Los taladros utilizan como accesorios principales:.

drill chuck

The drill chuck is the device used to fix the drill bit in the drill when the drill bits have a cylindrical handle. The chuck is attached to the machine with a Morse taper handle") depending on the size of the chuck.

The chucks are opened and closed manually, although there are some that have a small device that can be tightened with a special key. The most common chucks can hold drill bits up to 13 mm in diameter. Larger diameter drill bits have a Morse taper handle and clamp directly onto the drill.

Jaw

In drills it is very common to use clamps or other clamping systems to hold the pieces while they are drilled. When holding the pieces, the pressure and the clamping area must be well controlled so that they do not deteriorate.

Conical clamping pliers

When multi-spindle heads or high-production drills are used, instead of drill chucks, whose tightening is weak, screwed conical collets are used that take up less space and give a more rigid tightening to the tool.

Garnet

A hand tool that has the shape of a tempered steel pointer sharpened at one end with a tip of approximately 60° is called a punch that is used to mark the exact place that has been previously drawn on a piece where a hole needs to be made, when a suitable template is not available.

Drilling templates

When machining parts in series, the holes are not marked with punches but rather templates are manufactured that are incorporated into the fixation system of the duly referenced part. The templates have guide bushings incorporated so that the drill bit can face the holes exactly without deviations of the drill tip. In operations that incorporate reaming or subsequent threading, the guide bushings are removable and are changed when the hole is reamed or threaded.

Drill bit sharpener

In metalworking industries that do a lot of drilling, special sharpening machines are available to sharpen drill bits when the cutting edge has deteriorated. Sharpening can be done on a grinder that has a fine-grained stone, but the quality of this manual sharpening is usually very poor because you have to be quite an expert to achieve the appropriate cutting angles. The best option is to have drill bit sharpeners").

These two factors are very important in the drilling process. The generation of appropriate chip shapes and sizes, as well as their evacuation, is vital to correctly perform any drilling operation. If the process is not correct, any drill bit will stop cutting after a short time because the chip will get stuck in the hole. With modern drill bits, drilling speeds are very high, but this has only been possible thanks to the efficient evacuation of the chip by the cutting fluid.

All twist drills have channels to evacuate the chip. During machining, cutting fluid is injected into the tip of the drill bit to lubricate it and to evacuate the chip through the channels.

Chip formation is determined by the material of the part, the geometry of the tool, the cutting speed and to some extent by the type of lubricant used. The shape and length of the chip are acceptable as long as they allow for reliable evacuation.

When working on a drill, you must observe a series of requirements to ensure that you do not have any accident that could cause any piece to be thrown off the table or the chip to be thrown off if it is not cut properly. For this it is essential that the pieces are well secured. But also of utmost importance is preventing being caught by the rotational movement of the machine, for example by clothing or long hair. Caution is essential, since being accidentally caught can be fatal.[9]​[10]​.

There is no specialized technical profession for handling drills, because they are simple machines to handle, but technicians who use numerical control drills are trained, especially programmers who know the factors involved in machining, such as the performance of the machine and tools, the clamping of parts, the material and the number of parts to be machined, etc.

You must also know the technological parameters of drilling, such as cutting speed, machining feed, etc. In addition, you must know how to interpret the plans of the pieces and know the programming technique according to the drill.[11]​.

don't go barefoot.

Contenido

En el Paleolítico Superior los humanos taladraban conchas de moluscos con fines ornamentales. Se han hallado conchas perforadas de entre 70.000 y 120.000 años de antigüedad en África y Oriente Próximo, atribuidas al Homo sapiens. En Europa unos restos similares datados de hace 50.000 años muestran que también el Hombre de Neandertal conocía la técnica del taladrado.[3]​.

Taladrar requiere imprimir un movimiento de rotación a la herramienta. El procedimiento más antiguo que se conoce para ello es el denominado "arco de violín", que proporciona una rotación alternativa.[4]​ Un bajorrelieve egipcio del año 2700 a. C. muestra una herramienta para taladrar piedra accionada de otra manera, mediante un mango.[5]​.

A finales de la Edad Media está documentado el uso de taladros manuales llamadas berbiquís.[4]​.

19th century

Main milestones:

20th century

The technologies developed during the Industrial Revolution were applied to drills, which in this way became electrically powered and increasingly precise thanks to metrology and more productive thanks to new materials such as silicon carbide or tungsten carbide.

The appearance of numerical control starting in the 1950s and especially computer numerical control starting in the 1970s revolutionized machine tools in general and drills in particular. Microelectronics made it possible to integrate drills with other machine tools such as lathes or boring machines to form multipurpose "machining centers" managed by computers.[4]​.

El taladrado es un término que cubre todos los métodos para producir agujeros cilíndricos en una pieza con herramientas de arranque de viruta. Además del taladrado de agujeros cortos y largos, también cubre el trepanado y los mecanizados posteriores tales como escariado, mandrinado, roscado y brochado. La diferencia entre taladrado corto y taladrado profundo es que el taladrado profundo es una técnica específica diferente que se utiliza para mecanizar agujeros donde su longitud es varias veces más larga (8-9) que su diámetro.

Con el desarrollo de brocas modernas el proceso de taladrado ha cambiado de manera drástica, porque con las brocas modernas se consigue que un taladro macizo de diámetro grande se pueda realizar en una sola operación, sin necesidad de un agujero previo, ni de agujero guía, y que la calidad del mecanizado y exactitud del agujero evite la operación posterior de escariado.

Como todo proceso de mecanizado por arranque de viruta la evacuación de la misma se torna crítica cuando el agujero es bastante profundo, por eso el taladrado está restringido según sean las características del mismo. Cuanto mayor sea su profundidad, más importante es el control del proceso y la evacuación de la viruta.[6]​.

Hole production

The main factors that characterize a hole from the point of view of its machining are:.

Almost all of the holes made in the different drills that exist are related to screws in general, that is, the majority of drilled holes serve to embed the different screws that are used to assemble some parts with others of the mechanisms or machines of which they are part.

According to this criterion, there are two different types of holes: those that are through and completely go through the piece and those that are blind and only enter a certain length into the piece without going through it. Both of them can be smooth or they can be threaded.

Regarding the through holes that are used to embed screws in them, there are countersunk entry holes for flat head screws, two-diameter holes for inserting Allen screws, and single-diameter cylindrical holes with the upper face faced to improve the seat of the washer and screw head. The diameter of these holes corresponds to the outer diameter of the screw.

Regarding threaded holes, the diameter of the hole drill must be the one that corresponds to the type of thread used and the nominal diameter of the screw. In blind screws, the drill bit must be deeper than the length of the thread due to the problem of the chip from the tap.

Los parámetros de corte fundamentales que hay que considerar en el proceso de taladrado son los siguientes:.

cutting speed

Cutting speed is defined as the tangential speed of the periphery of the drill bit or other tool used in the drill (Reamer, thread tap, etc.). The cutting speed, which is expressed in meters per minute (m/min), has to be chosen before starting the machining and its appropriate value depends on many factors, especially the quality and type of drill bit used, the hardness and machinability of the material being machined and the feed speed used. The main limitations of the machine are its speed range, the power of the motors and the rigidity of the workpiece and tool fixation.

From the determination of the cutting speed, the revolutions per minute that the milling spindle will have can be determined according to the following formula:

Where V is the cutting speed, n is the rotation speed of the tool and D is the diameter of the tool.

Cutting speed is the main factor that determines tool life. A high cutting speed allows machining to be carried out in less time but accelerates tool wear. Tool manufacturers and machining manuals offer indicative data on the appropriate cutting speed of tools for a given tool duration, for example, 15 minutes. Sometimes it is desirable to adjust the cutting speed for a different tool life, for which the cutting speed values ​​are multiplied by a correction factor. The relationship between this correction factor and the life of the tool in cutting operation is not linear.[7]​.

Excessive cutting speed may result in:.

Cutting speed too low may result in:.

Bit rotation speed

The rotation speed of the drill spindle is usually expressed in revolutions per minute (rpm). In conventional drills there is a limited range of speeds, which depend on the rotation speed of the main motor and the number of speeds of the machine's gearbox. In numerical control drills, this speed is controlled with a feedback system that usually uses a frequency converter and any speed can be selected within a range of speeds, up to a maximum speed.

The rotation speed of the tool is directly proportional to the cutting speed and inversely proportional to the diameter of the tool.

Feed speed

The feed or feed rate in drilling is the relative speed between the piece and the tool, that is, the speed with which the cut progresses. The feed of the cutting tool is a very important factor in the drilling process.

Each drill bit can cut adequately at a range of feed rates per revolution of the tool, called feed per revolution (f). This range depends fundamentally on the diameter of the drill bit, the depth of the hole, as well as the type of material of the piece and the quality of the drill bit. This speed range is determined experimentally and is found in drill bit manufacturers' catalogs. Furthermore, this speed is limited by the rigidity of the workpiece and tool clamping and by the power of the machine's feed motor. The maximum chip thickness in mm is the most important limiting indicator for a drill bit. The cutting edge of the tools is tested to have a certain value between a minimum and maximum chip thickness.

The feed rate is the product of the feed per revolution and the rotation speed of the tool.

As with the tool rotation speed, in conventional drills the feed speed is selected from a range of available speeds, while numerically controlled drills can work at any feed speed up to the maximum feed speed of the machine.

Effects of ground speed.

The high forward speed gives rise to:.

Low forward speed results in:.

Machining time

In order to calculate the machining time of a drill, it is necessary to take into account the approach and exit length of the drill bit of the piece being machined. The approach length depends on the diameter of the drill bit.

Specific cutting force

The cutting force is a necessary parameter to be able to calculate the power necessary to carry out a certain machining. This parameter is a function of the feed of the drill, the cutting speed, the machinability of the material, the hardness of the material, the characteristics of the tool and the average thickness of the chip. All these factors are included in a coefficient called K. The specific cutting force is expressed in N/mm².[8]​.

Cutting power

The cutting power P necessary to carry out certain machining is calculated from the value of the chip removal volume, the specific cutting force and the performance of the drill. It is expressed in kilowatts (kW).

This specific cutting force F is a constant that is determined by the type of material being machined, tool geometry, chip thickness, etc.

In order to obtain the correct power value, the value obtained has to be divided by a certain value (ρ) that takes into account the efficiency of the machine. This value is the percentage of the motor power that is available in the tool placed in the spindle.

where.

The massive installation of CNC machining centers in metallurgical industries has been a great revolution in all aspects of traditional machining.

A machining center has united in a single machine and in a single process tasks that were previously carried out in several machines, drills, milling machines, boring machines, etc., and also carries out the different machining operations in minimal times that were previously unthinkable due mainly to the robustness of these machines, the very high rotation speed at which the spindle operates and the extraordinary quality of the different tools used.

So a machining center incorporates a tool store for different operations that can be carried out on the different faces of the cubic pieces, so that with a single fixation and manipulation of the piece, the integral machining of the faces of the pieces is achieved, so the total machining time and precision achieved is very valuable from the point of view of machining costs, by achieving faster speed and fewer defective parts.

When engineers design a machine, equipment or utensil, they do so by coupling a series of components made of different materials that require machining processes to achieve proper operating tolerances.

The sum of the raw material cost of a part, the cost of the machining process, and the cost of defectively manufactured parts constitute the total cost of a part. Technological development has always had the objective of achieving the highest possible quality of the components as well as the lowest possible price for both raw materials and machining costs. To reduce the cost of drilling and machining in general, action has been taken on the following fronts:

To reduce the rate of defective parts, it has been possible to automate the work of the drills as much as possible, drastically reducing manual drilling, and building very sophisticated automatic drills or drills guided by numerical control that execute machining according to a previously established program.

Due to the multiple conditions in which drills are used, they can be classified according to their power source, their function and their support.

Due to their power source there are:

Due to their function there are:

For your support:

Las brocas son las herramientas más comunes que utilizan los taladros, si bien también pueden utilizar machos para roscar a máquina, escariadores para el acabado de agujeros de tolerancias estrechas, avellanadores para chaflanar agujeros, o incluso barras con herramientas de mandrinar.

Las brocas tienen diferente geometría dependiendo de la finalidad con que hayan sido fabricadas. Diseñadas específicamente para quitar material y formar, por lo general, un orificio o una cavidad cilíndrica, la intención en su diseño incluye la velocidad con que el material ha de ser retirado y la dureza del material y demás cualidades características del mismo.

Constituent elements of a drill bit

Among some of the parts and generalities common to most drill bits are:.

Characteristics of carbide drill bits

For high-production drilling machines, solid carbide drills are used for small holes and boring bars with changeable inserts for machining large holes. Its selection is made taking into account the material of the part, the type of application and the machining conditions.

The variety of insert shapes is large and standardized. Likewise, the variety of materials used in modern tools is considerable and is subject to continuous development.[6]​.

The suitability of the different types of inserts used in carbide drills, whether welded or changeable, are adapted to the characteristics of the material to be machined and are indicated below and are classified according to an ISO/ANSI Standard to indicate the applications in relation to the resistance and toughness they have.

Los taladros utilizan como accesorios principales:.

drill chuck

The drill chuck is the device used to fix the drill bit in the drill when the drill bits have a cylindrical handle. The chuck is attached to the machine with a Morse taper handle") depending on the size of the chuck.

The chucks are opened and closed manually, although there are some that have a small device that can be tightened with a special key. The most common chucks can hold drill bits up to 13 mm in diameter. Larger diameter drill bits have a Morse taper handle and clamp directly onto the drill.

Jaw

In drills it is very common to use clamps or other clamping systems to hold the pieces while they are drilled. When holding the pieces, the pressure and the clamping area must be well controlled so that they do not deteriorate.

Conical clamping pliers

When multi-spindle heads or high-production drills are used, instead of drill chucks, whose tightening is weak, screwed conical collets are used that take up less space and give a more rigid tightening to the tool.

Garnet

A hand tool that has the shape of a tempered steel pointer sharpened at one end with a tip of approximately 60° is called a punch that is used to mark the exact place that has been previously drawn on a piece where a hole needs to be made, when a suitable template is not available.

Drilling templates

When machining parts in series, the holes are not marked with punches but rather templates are manufactured that are incorporated into the fixation system of the duly referenced part. The templates have guide bushings incorporated so that the drill bit can face the holes exactly without deviations of the drill tip. In operations that incorporate reaming or subsequent threading, the guide bushings are removable and are changed when the hole is reamed or threaded.

Drill bit sharpener

In metalworking industries that do a lot of drilling, special sharpening machines are available to sharpen drill bits when the cutting edge has deteriorated. Sharpening can be done on a grinder that has a fine-grained stone, but the quality of this manual sharpening is usually very poor because you have to be quite an expert to achieve the appropriate cutting angles. The best option is to have drill bit sharpeners").

These two factors are very important in the drilling process. The generation of appropriate chip shapes and sizes, as well as their evacuation, is vital to correctly perform any drilling operation. If the process is not correct, any drill bit will stop cutting after a short time because the chip will get stuck in the hole. With modern drill bits, drilling speeds are very high, but this has only been possible thanks to the efficient evacuation of the chip by the cutting fluid.

All twist drills have channels to evacuate the chip. During machining, cutting fluid is injected into the tip of the drill bit to lubricate it and to evacuate the chip through the channels.

Chip formation is determined by the material of the part, the geometry of the tool, the cutting speed and to some extent by the type of lubricant used. The shape and length of the chip are acceptable as long as they allow for reliable evacuation.

When working on a drill, you must observe a series of requirements to ensure that you do not have any accident that could cause any piece to be thrown off the table or the chip to be thrown off if it is not cut properly. For this it is essential that the pieces are well secured. But also of utmost importance is preventing being caught by the rotational movement of the machine, for example by clothing or long hair. Caution is essential, since being accidentally caught can be fatal.[9]​[10]​.

There is no specialized technical profession for handling drills, because they are simple machines to handle, but technicians who use numerical control drills are trained, especially programmers who know the factors involved in machining, such as the performance of the machine and tools, the clamping of parts, the material and the number of parts to be machined, etc.

You must also know the technological parameters of drilling, such as cutting speed, machining feed, etc. In addition, you must know how to interpret the plans of the pieces and know the programming technique according to the drill.[11]​.

don't go barefoot.