Contents

Part 1 Overview of tools and methods .............................................4-23

Part 2 Selecting tools and methods ...............................................24-79

Part 3

Application hints ..............................................................80-155

Part 4 Application examples ......................................................156-215

Part 5 Technical information ......................................................216-237

Part 1 – Overview of tools

and methodsContents

Introduction...................................................................................................................................... 4

Selecting hole making methods ...................................................................................................... 4

Hole making parameters ................................................................................................................. 5

Hole making methods with drills ................................................................................................... 7

Selecting drills ................................................................................................................................... 8

The main types of drills – an overview .......................................................................................... 8

Hole making methods with milling tools .................................................................................... 12

Selecting milling tools for hole making ....................................................................................... 14

The main milling cutter types – an overview .............................................................................. 15

Hole making methods with boring tools –rotating tools .......................................................... 17

Selecting boring tools for hole making rotating tools ................................................................ 18

The main boring tool types – an overview of rotating tools ..................................................... 19

Boring with internal turning tools ............................................................................................... 21

Selecting boring bars for internal turning – non rotating .......................................................... 21

The main boring bar types –

an overview of internal turning tools ........................................................................................... 22

Silent Tools – for long tool overhangs ......................................................................................... 23

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IntroductionMost components in the metalworking industry require some type of hole to be produced or there for machining. There are a vast range of holes for different purposes, with different sizes and quality demands, produced in different machines and in different volumes. Most machine shops have to machine holes as competitively as possible and as it is such a frequent opera-tion, meaning that hole making today can be a challenging practice.

Hole machining techniques have come a long way in the last few decades, since the introduction of the indexable insert drill, new tool materials and point technology for drills. This development has accelerated during the past few years, it is ongoing and provides a continuous potential for improve-ments in machine shops.

The aim of this guide is to provide recom-mendations for the various aspects of hole making, presenting the methods available and suitable tool solutions. The intention is to make it easier for machine shops to realise the potential available, related to their com-ponents, through performing hole making in the most suitable way with the best tool.

Selecting hole making methodsThere are several basic ways to make new holes and machine exisiting holes :- drilling- milling- boring- reaming

There are also additional machining methods such as multi-step drilling, chamfering, back-facing, internal grooving, etc. The use of stationary or rotating tool, dependent on the machine tool type can make a difference to the choice of tool and method.

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Hole making parametersThe choice of best method is dependent upon a number of parameters. Productivity, quality and reliability are the main measures of success in the majority of applications and are normally dependent on the following parameters:

1. The hole to be made or machined

This is defined by the diameter and depth and affect the tool selection. For example, small-diameter holes (less than 12 mm and deeper than 5 times the diameter) cannot normally be made by indexable insert drills. The hole quality is determined by the tole-rance and surface finish and also affect the tool selection, cutting data and set-up. For an indexable insert drill to achieve a close tole-rance (down to IT10), it needs to be pre-set in a holder or in the machine so that the cutting edge is located accurately.

The hole configuration – especially connected to the batch size – will affect the solution, where balances between productivity and flexibility will determine the use of dedicated or versatile tools.

2. The component and material

This will affect the tool selection. The stability of the workpiece, set-up and machine has to be assessed and measures taken achieve a good machining process. The material and its hardness affects the choice of tool-material and geometry.

3. The machine tool

Its type and suitability, whether a stationary or rotating tool, CNC facility and coolant supply affect the tool, tool holder and method selection.

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4 4. The machining economics

Of the application should cast its shadow over the whole of the selection process. The cost per hole is a priority when it comes to mass production. The machining of single cavities may require an approach dominated by tool and programming versatility.

Most holes are drilled but modern machine tools provide alternative methods in the form of milling, which can be advantageous, espe-cially when the size of the hole is large and power and torque is limited. Precision holes (IT7 or better) normally require a secondary finishing operation, made by a boring tool or reamer, but also here milling may be an alternative. Using a precision solid-carbide endmill may also be an alternative as these, in the right type of tool holder, provide high precision and finish. Hole diameter and batch size will determine the direction for methods to be considered.

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Hole making methods with drillsSome drills, in addition to creating a hole from solid material, can perform boring and plunge operations. The CoroDrill 880 index-able insert drill provides versatility in that it can drill, bore during an additional pass and be used for helical interpolation and plunge-drilling. Solid carbide drills, such as the CoroDrill Delta-C, are limited to drilling holes.

The indexable insert drill is an easy-to-use standard tool that covers a large hole-size area and the most frequent hole depths. Moreover, one drill can be adjusted to cover a certain diameter area.

When hole diameters exceed a practical drill size (about 60 - 80 mm) for the application, trepanning could become a more suitable method in that the power and torque requirement is considerably lower.

When multi-diameter holes or chamfered holes are required in larger numbers, coun-terboring or countersinking with step drills in the form of solid carbide drill or indexable insert drills is a suitable method. These tools can be designed to suit the application in question and provides a tool for performing more than one cut in one pass.

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Selecting drillsDrill selection procedure

1. Define hole diameter, depth and quality requirements

2. Define the workpiece material and its machining condition

3. Select the type of drill

4. Choose the drill grade and geometry

5. Select the shank style

6. Define the start values of cutting data

Solid carbide and brazed carbide drills ope-rate at lower cutting speeds/higher feeds in relation to machine and operation while indexable insert drills use higher cutting speeds/low feeds.

The main drill types – an overviewThe solid-carbide drill range of CoroDrill Delta-C covers diameters from 0.3 to 25 mm with drills dedicated to various workpiece materials.

The braze-tip, cemented carbide drill Coromant Delta covers diameters from 9.5 to 30.4 mm. As such it is suitable for larger-diameter holes and when process stability is rather poor, as the steel part of the drill pro-vides toughness.

Achievable hole tolerances for these drills are within IT8-10, while shorter drills can achieve IT6 in some cases. Finishes within Ra 0.5-2 microns are also possible depending on drill length, tool holding, material and conditions. Cemented carbide grade options and geometries are available for various materials.

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CoroDrill® Delta-C

CoroDrill® 805

T-Max UCoroDrill® 880

Coromant Delta®

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10 20 30 �0 �0 �0 �0 �0 110Dc

The indexable insert drill starts at a diameter of 12.7 mm and provides high machining productivity, versatility and long, reliable tool-life. Todays drills are not just for roughing drills. They are capable of drilling holes even more rapidly than the first gene-rations of these tools and are also capable of finishing holes to a better level and keeping within closer tolerances than previously - not just during the solid drilling operation, but also in boring passes.

The indexable insert drills CoroDrill 880, Coromant U-drill, T-Max U and T-Max (including the trepanning tool version) cover the diameter range 12.7 to 110 mm as standard. Hole depths are up to 5 times the diameter.

The achievable hole tolerances with the new CoroDrill 880 drill have been reduced to plus 0.25 mm (IT 10 when pre-set and plus/minus 0.05 mm when used as a stationary boring-tool). A surface finish of about Ra 1-2 micron is normal with a high feed and down to Ra 0.5 micron with a moderate feed - thanks to the Wiper peripheral insert.

The indexable insert drills can also provide high levels of productivity when making cavities by plunge drilling.

Diameter and hole depthDrilling tools that can be used in conventional machines*

Trepanning

*) Machining centres, NC-lathes, Multi-Task machines etc.

Gun Drill

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Deeper holes

There is a distinction between short holesand deep holes, with the latter includingholes as deep as 150 times the diameter whileshort holes normally have depths of up to 5times the diameter. Deep hole drilling needsspecialized technology and equipment and isusually performed on dedicated machines.

However, modern drilling tool technology offer possibilities to produce deep holes in conventional machines.

Thanks to the drill geometry and close manu-facturing tolerances the CoroDrill Delta-C is capable of hole depths up to 15 times the diameter and the CoroDrill 805 indexable insert drill provides the possibility to drill holes of depths to 13 times the diameter in machining centres, multi-task machines, CNC-lathes, etc. without special deep-hole-drilling equipment.

The diameter range of Corodrill 805 is 25 to 65 mm and the hole depth possibility changes progressively from 13 to 7 times the diameter. The hole tolerance and surface finish achievable with the 805-drill is similar to the CoroDrill 800 drill, normally IT10 and a surface finish ranging from Ra 0.5 (oil) to 2 microns (emulsion) depending upon feed values, coolant and conditions.

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Gun drilling is a complement to CoroDrill 805, the indexable insert drill, and CoroDrill Delta-C, the solid carbide drill, for smaller diameters and deeper holes.

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Hole making methods with milling toolsVarious methods of milling holes and closed cavities :

1. Circular interpolation – the rotating cutting tool performs internal machining of an existing hole following a circular tool-path. In this way the hole is opened up and, in some cases, finished.

Suitable tools are, in addition to CoroDrill 880, CoroMill 390 endmill and long-edge mill, CoroMill 300 round insert cutter and CoroMill Plura solid carbide endmills. Various applications may be suitable for this method. One way would be to drill a hole to be opened up through a milling operation. An accurate machine with radius compensa-tion, equipped with a CoroMill Plura cutter, can achieve tolerances within IT6.

Circular interpolation can also be used for chamfering operations with turning tools, for example the CoroTurn XS.

2. Helical interpolation – the rotating tool makes a hole by following a circular tool-path while simultaneously being fed axially (also called tornado milling). The method can also be used to machine existing holes. This is a circular ramping operation where a tool, normally about half the diameter of the hole, is used at a ramping angle recommended for the tool in question. The operation can be performed with a rotating tool and as internal turn-milling with a stationary tool and rotating workpiece. Suitable tools are, in addition to the CoroDrill 880, the CoroMill 390 endmill, CoroMill 300 round insert cutter and CoroMill Plura solid carbide endmill as well as any cutter with ramping ability.

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3. Plunge milling/drilling – is making a deeper hole or cavity through repeated axial cuts with a drill or milling cutter at a recom-mended step-over. It is especially suitable for rough machining, the method is advan-tageous in that it is power-efficient, produc-tive and spares the machine tool spindle as the main cutting forces are directed axially along the spindle. Internal plunge milling is started off by drilling a hole for the plunging tool to enter. Suitable tools are the Coromant Plunge drill, CoroDrill 880, and CoroMill 390 endmill as well as the CoroMill 210 high feed cutter and round insert cutter CoroMill 300.

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Selecting milling tools for hole making

Milling cutter selection procedure :

1. Define the hole/cavity parameters

2. Define the workpiece material and its condition

3. Identify the most suitable milling operation

4. Select the type, size, pitch and mounting of cutter

5. Select the insert size, geometry and grade

6. Define the start values for cutting data.

The hole size determines the type of tool suitable - solid carbide endmills with index-able insert tools being the first choice when hole size allows. The type of indexable insert milling cutter is then determined by the method and how large the hole is.

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CoroMill® Plura CoroMill® 300 CoroMill® 390

The main milling cutter types – an overviewThe solid carbide range of endmills: CoroMill Plura, provides sharp cutting edges, long tool-lives and minimized tool deflection during machining. They cover diameters from 0.4 to 25 mm in different styles suitable for various applications and materials, including high speed machining and hard materials. These are modern, preci-sion endmills with various geometries which can perform roughing to super-finishing. High productivity in finishing is facilitated through many teeth and short to long reach options. CoroMill Plura cutters can gener-ate close-tolerance holes through circular and helical interpolation or boring. Max hole depth is approx. 2xD.

Diameter and hole depthMilling tools

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Indexable insert endmills, type CoroMill 390, can make holes through helical interpolation, linear ramping and plunge milling. The long- edge CoroMill 390 cutters can machine exisiting holes through circular interpola-tion. The endmill programme starts at 16 mm diameters and long-edge at 32 mm. Large depths of cut can be taken with the 90 degree entering-angle endmills, with steep ramping possibilities and minimized mismatch at repeated passes to make holes and cavities. Good finishing possibilities even at high feeds and precision ground inserts for high accuracy. Max hole depth is approx. 4xD.

Round insert milling cutters, type CoroMill 300 start at 40 mm diameters and can make holes through helical interpolation, linear ramping and plunge milling. Light cutting forces, high feed rates and good roughing and finshing capabilities make this cutter a versatile hole making tool also for weaker machines and unstable setups in most materials. Pitch and precision insert options combine for a broad range of operations. Max hole depth is approx. 5xD.

Indexable insert multifunctional tooling, type CoroPlex MT, can make holes through circu-lar interpolation and perform boring opera-tions. Especially developed for multi-task machines, these tools are both milling and turning tools, starting at 32 mm diameters, with a performance comparable to dedicated indexable insert endmills and internal turning tools using CoroMill 390 inserts and CoroTurn 107 inserts, respectively. It is used in both rotating and stationary applications in most materials.

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Hole making methods with boring tools – rotating toolsHole making with boring tools is limited to machining exisiting holes and divided into :Single edge boring: usually applied for finishing operations and for roughing and finishing in materials where chip control is demanding. A single-edge boring tool may also be a solution when machine power is a limiting factor.

Multi-edge boring: involves two or three cutting edges and is employed for roughing operations where metal removal rate is the first priority. High productivity levels can be maintained by letting two or three inserts, set at the same axial height and diameters, each machine at the recommended feed per tooth. This results in a high feed per revolution through the hole.

Step-boring: performed in roughing by a boring tool having the inserts set at different axial heights and diameters. This also improves chip control by dividing the total radial depth of cut into smaller cuts, providing smaller chips.

Reaming: a light finishing operation per-formed with a multi-edge reamer giving high-precision holes. Very good surface finish and close dimensional tolerance are achieved at high penetration rates. The pre-machined hole needs to be within close limits and the radial depth of cut is small.

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Selecting boring tools for hole making – rotating tools

Boring tool selection procedure :

1. Define the boring diameter and hole requirments

2. Define the type of operation most suitable for the hole

3. Define the workpiece material and its condition

4. Select the type of boring tool

5. Choose the entering angle

6. Select an adaptor

7. Select inserts for the tool

8. Define the starting values of cutting data.

The choice of tool for single-edge, multi-edge or step-boring operations is very much down to machine capability and hole-condition and requirements. Roughing tools are primarily multi-edge and finishing are single-edge tools.

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Duobore®

CoroBore® 820

The main boring tool types – an overview of rotating toolsRoughing

Mainly for rough boring, CoroBore 820 is the first choice, providing high metal removal capability through boring with three inserts in medium to high powered machines. Providing high stability, the boring range is 35 to 260 mm diameter. Power requirement is higher with several cutting edges engaged. All three inserts are set to the same diameter and height for high-productivity boring while for step-boring, the inserts are set at different diameters and heights. When single- edge boring is performed with CoroBore – particularily for finishing or when materials with demanding chip control are involved - only one insert-slide is used.

Also mainly for rough boring, Duobore has two inserts and needs less power. The boring-diameter range is 25 to 270 mm. For high-productive rough step boring, the two inserts are set to the same diameter and height in the tool providing a penetration rate based on double the recommended feed per tooth. For step-boring the tool setting principle is the same as for CoroBore 820. This is a short, rigid and compact boring tool. The heavy duty boring tools for rough machining, (R391.B..-R) primarily for larger diameters, are also capable of all three opera-tion types and has a diameter range of up to 550 mm. The tool design resembles the boring tools for the smaller diameter range but with mounting dimensions for the standard milling arbour. Approximate settings are made by moving sides across the adaptor or bar followed by fine setting on the cartridge.

Rough boring tools Diameters and hole depth

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CoroBore® 825

Finishing

CoroBore 825 is the first choice for general finish boring within the diameter range of 23 to 265 mm. This stable boring tool has a single cartridge and is easily adjustable radially to within 2 microns, to achieve IT6 tolerances and surface finishes within Ra 1 micron.

The fine boring tools for larger diameters consists of two different designs: one for single or twin-edge boring of internal dia-meters 250 to 575 mm and external of 138 to 447 mm and one for internal boring of 250 to 975 mm. Common for both are fine bor-ing heads and cartridges.

Fine boring heads hold dedicated boring bars for diameters of 12 to 25 mm and car-bide bars of 16 mm, to enable production of closer tolerances (IT6) at high spindle speeds (7000 rpm). A diameter range of 3 to 44 mm for hole-depths of 13.5 to 128 respectively, these super-finishing boring tools machine at small depths of cut and small feeds.

The Reamer 830 standard program covers the diameter range 10 to 31.75 mm with varying hole depths, hole toterances of IT 7 are achieved along with high concentricity. Easily exchangeable heads are secured by front clamping. The heads accommodate 4 to 8 carbide brazed blades depending upon diameter. Effective chip evacuation is secured by cutting fluid directed to each cutting edge. There is high concentricity and repeatability with a precision coupling. The combination of multiple cutting edges capable of high cutting speeds result in very high penetration rates. In additon to the standard programme, there is a wide choice of special options for further optimization.

Hole making using tools that are non- rotating is mainly carried out in lathes where the non-rotating tool is used to machine a rotating workpiece. This internal turning is usually carried out with various types of boring bars where again the hole diameter and hole depth are the dominant factors.

Fine boring and reamer tools Diameters and hole depth

Reamer�30

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Boring with internal turning tools

Selecting boring bars for internal turning – non-rotating toolsBoring tool selection procedure :

1. Define the type of operation required in relation to hole parameters

2. Define the workpiece material and its condition

3. Define the boring bar type, size and bar-holding

4. Select the most suitable indexable insert

5. Establish the start values of cutting data.

Tool overhang and tool clamping are issues that always determine the outcome of any boring operation. A conventional steel boring bar is only sufficient up to about four times the overhang and a poor bar-holder in the machine will result in deflection, vibrations and poor results.

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The main boring bar types – an overview of internal turning toolsT-Max P and CoroTurn RC boring bars with indexable inserts are suitable for large hole diameters, from 20 mm, and short tool over-hangs with stable machining conditions. Using negative inserts, these tools can be used for internal turning, facing and profiling.

CoroTurn 107 and CoroTurn 111 boring bars with indexable inserts are internal turning alternatives for boring of small to medium sized holes, from a diameter of 8 mm. These have positive inserts which generate minimal cutting forces and vibra-tion tendencies. CoroTurn 107 (seven degree rake angle) is first choice generally with CoroTurn 111 (eleven degree rake angle) as a backup for optimization.

CoroCut MB mini bar tools are designed for internal precision-machining of holes with a minimum hole diameter of 10 mm. The end-mounted inserts on the bars are available for grooving and threading and can perform various turning operations such as profiling and back boring.

CoroTurn XS boring bars in solid carbide for machining small holes, starting at 0.3 mm diameter. Intended mainly for small part machining, this boring bar programme also accomodates grooving and threading.

Back chamfering is performed with CoroTurn XS as rotating tools in hole with diameters down to 7 mm. The chamfering operation is completed in one step operation with no manual deburring needed. One tool can back chamfer a large range of hole sizes.

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Silent Tools – for long tool overhangsWhen deeper holes are to be machined – generally when the tool overhang is 4 times the shank diameter or more – conventional solid steel tooling is not the most productive solution. More suitable tools, in the form of solid carbide or carbide-reinforced, are needed for internal turning up to overhangs of 6 times the diameter. Beyond this, and for boring with rotating tools and milling with overhangs generally of more than 4 times the shank diameter, vibration-damped tool solutions are needed. This is our Silent Tools range. There are various tools and adaptors available in this design for the different cut-ting tool ranges as well as a wide options for engineered solutions.

The latest in the range of Silent Tools is the CoroBore 825, a one-edge damped boring tool for finishing with high productivity in holes with depths of up to 6 x D.