Part of Metal Cutting Theory, Machines and Tools for Machine Work Study
Toolholders - Introduction
The design and structural properties of toolholders have a strong influence on machining cost, accuracy, and stability.
Cutting tools may either be mounted directly to the spindle/turret, or may be connected through an adapter (arbor or toolholder). The spindle connection for a toolholder (or integral cutting tool) is the foundation that supports the cutting edge in any rotating or stationary tool machining system, and may take a variety of forms. The toolholder is often the weakest link in the machining system, which has even limited full utilization of the potential of advanced cutting tool materials in some applications. This means some effort can be devoted to improve tool holders further.
TOOLHOLDING SYSTEMS
1. IntroductionProperly engineered tool–toolholder and toolholder–spindle interfaces are critical to achieving high
performance and high throughput.
There are many important structural and dynamic characteristics of a tooling structure and its interface with spindle. They are the manufacturing tolerances of tool holding system elements, static and dynamic runout, radial and axial positioning accuracy and repeatability, connection rigidity (static and dynamic stiffness), force transmission capability, momentum and torque characteristics, clamping forces, balance requirements, fatigue life and durability, retention force requirements, safety, locking/unlocking forces, coolant capability, ease of connection and disconnection, chemical and thermal stability, maintenance requirements, sensitivity to contamination, and cost. Other aspects to be addressed include the efficiency of the connection over a long period, tool presetting requirements, and provisions for data storage modules.
The cutting tool body and the tool holder can be made in one solid piece.
Modular systems in which the same tool holder can be used for various tools will provide flexibility with some reduction in inventory.
2. Modular Toolholding Systems
Modular toolholding systems consist of stationary or rotating adapters in a variety of configurations to develop tooling systems of various size that fit various machines with a common toolhoder-spindle coupling. There are several major types of toolholder-spindle connections with respect to centering and locating characteristics. These include different types of cylindrical shafts including single and multiple cylinders, face and nonface contacts, as well as different types of tapers and taper/face contact systems. There are also several designs of connections with respect to torque transmission, such as polygon, straight, and spiral gear designs, the more conventional key and pin drive methods, and mounting bolt patterns or draw bars.
3. Quick-Change Toolholding Systems
This is also a modular system. Quick-change tooling is important for increasing productivity. Reducing tool change time is also important. A quick-change tooling system consists of a tool or holder that can be changed for another as quickly as possible. It allows the correct length tool to be built off line to maintain maximum performance. The presetting capability of quick-change tooling, in conjunction with the repeatability of the coupling between the cutting unit and the toolholder, ensures that the cutting edge is properly positioned in relation to the workpiece.
1. General
There are A to K types described in Stephenson-Agapiou book that have variations in types of cylindrical shafts including single and multiple cylinders, face and nonface contacts, as well as different types of tapers and taper/face contact systems.
2. Conventional Tapered "CAT-V" Connection
3. Face-Contact CAT-V Interface
4. HSK Interface
Kennametal KM
NC5
Sandvik Capto
-------------
Sandvik Coromant Capto Tool Holder
Coromant Capto by Sandvik is a modular system that can be used to create extended-length toolholders. Coromant Capto adapter has a spindle side to put in the machine spindle and then different types of milling cutters, drills or boring heads are mounted on the machining side of the assembly end of the adapter by adding extensions to make it longer and stack them out as far as you need. On the same tool assembly, different diameter extensions can be used, which gives a lot of versatility. You usually would start with a larger diameter at the base and then reduce it to the required diameter in steps or keep it all the same diameter for the entire assembly.
https://www.sandvik.coromant.com/en-gb/products/coromant_capto/pages/default.aspx
2019
https://www.cnctimes.com/editorial/new-connected-driven-tool-holder-solution-maximises-machine-utilisation-sandvik-coromant
https://www.ctemag.com/news/articles/extended-reach-toolholders-remain-requirement
https://www.tradeindia.com/fp4207315/Coromant-Capto-Modular-Tools.html
https://www.grainger.com/product/SANDVIK-COROMANT-Coromant-Capto-Adapter-14L475
https://www.indiamart.com/proddetail/sandvik-coromant-capto-tooling-system-22046925255.html
1998
https://www.americanmachinist.com/cutting-tools/article/21892978/modular-means-more
---------------
5. Quick-change interfaces
6.Turning Tool Holders
7. Evaluation and Comparison of Toolholder/Spindle Interface
The static and dynamic bending stiffness and the torsional stiffness can be measured from a bench test. The reliability can be based on an evaluation matrix using factors such as fracture fatigue, dirt/nick sensitivity, wear/corrosion sensitivity, sticking extra force, torque slippage, temperature sensitivity, maintenance, lubrication, coolant feed, and gauging. The ease of tool change is assessed based on an evaluation matrix with the factors of holder weight, length engagement, surface cleanliness, drawbar force, critical location, and coolant through ease.
Toolholder–spindle interfaces can be evaluated and compared based on experimental and analytical/finite element results. Bench tests provide a relative comparison between toolholders. The static and dynamic stiffness seen at the tip of the cutting tool also depend on the stiffness of the tool, the spindle geometry and bearings, the housing, and the overall machine structure. Bench tests results that reflect only the stiffness of the toolholder–spindle interface may thus be misleading in applications in which the properties of the spindle and bearings largely determine the structural response.
The characterization of the toolholder/spindle interface is made using the joint stiffness parameters. A methodology for estimating the joint stiffness parameters of a toolholder/spindle interface using one linear spring and one rotational spring has been found to be very effective. The method is based on the FRF of the interface system. It involves FEA and experimental measurements of a bench fixture. The most important assumption is that the behavior of the test system is linear. After the joint stiffness parameters are estimated, they can be used in any machine tool spindle FEM to estimate the static and dynamic characteristic at the tool tip.
The Spindle Analysis program (SPA) from Manufacturing Laborites, Inc. can be used to create a two-dimensional axisymmetric model of a spindle for evaluating the interfaces. The spindle shaft, the housing, and the toolholder structure can be modeled. The SPA program can model a 2-DOF spring to include a linear direction and rotational direction to represent the joint between the spindle and the toolholder. The SPA FEA program simulates both the dynamic and static behavior of a spindle and tooling system. The static bending deflection of the tool can also be defined analytically using the joint stiffness parameters; the bending deflection of the tool includes the elastic deflection of the bar itself.
The material removal rate that a machining center can achieve is strongly dependent upon the static and dynamic characteristics of the machine–tool–workpiece system as seen at the tip of the tool. In the selection of the best spindle–toolholder interface, the stiffness is one of the important parameters to consider in the selection. The static stiffness measures the deflection at the end of the tool in response to a static force. It provides some indication of the ability to create a surface or hole with the tool in the intended location. In milling, drilling, reaming, boring with a relatively low spindle speed, the error in location of the machined surface or hole is related to the static stiffness. The higher the static stiffness, the more accurately the surface or hole will be located with smaller form error. If static stiffness is the performance criterion, then the data show that the face contact connections perform better than the nonface contact connections in a machine tool spindle. Therefore, the static stiffness of the tool should be estimated by consideration of the spindle stiffness in order to properly select an interface style. The static stiffness can be estimated using the FEA or analytically assuming the joint stiffness parameters are available.
In the case of high metal removal rate, accurate surface location at higher spindle speeds, the better selection criterion is dynamic stiffness (or chatter criterion) at the tip of the tool. The dynamic stiffness is a combination of stiffness and damping in a particular mode of vibration (at a particular frequency). The damping is estimated from the FRFs while the natural frequencies and modal stiffness can be estimated using several programs, including commercial FEA solvers and advanced codes, which consider bearing preload and other nonlinear effects. For dynamic cutting performance at the tip of the tool, FEA can be also used assuming the joint parameters are available. There are cases where the bore quality or surface flatness are very critical, in which case the quality of the interface taper and face including the quality of the tool point (runout) with respect to the taper interface are very important. In addition, the static bending stiffness becomes important assuming it is not a high-speed application. Rigid face contact interfaces provide higher static stiffness or normalized bending stiffness at higher moments assuming: (1) the taper quality for the nonface contact interfaces is worse than AT3 tolerance, and (2) the clamping force is high enough to sustain larger bending moments without losing contact between the toolholder and the spindle face.
---------------
Toolholder types other than modular toolholders
https://www.engineering.com/AdvancedManufacturing/ArticleID/11710/Toolholding-101-Top-Tips-for-High-Productivity-Machining.aspx
VDI and BMT Turrets
https://www.mylascnc.com/en/tech/tech_detail-2.htm
--------------
1. Milling cutter drives
2. Side-Lock-Type Chucks
3. Collet chucks
4. Hydraulic Chucks
5. Milling Chucks
6. Shrink-Fit Chucks
7. Proprietary Chcuks
8. Tapping Attachments
9. Reaming Attachments
10. Comparison of Cutting Tool Clamping Systems
Fundamentals of balancing - Good description
https://www.haimer-usa.com/products/balancing-technology/knowledge/fundamentals-of-balancing.html
_____________
MTD CNC
_____________
2020
February 13, 2020: HAIMER at GrindTec 2020: hall 2, booth 2113 - Fine balancing increases productivity during the grinding process
https://www.haimer-usa.com/news/news/news-article/item/haimer-at-grindtec-2020-hall-2-booth-2113-fine-balancing-increases-productivity-during-the-grind-1.html
2014
https://www.ctemag.com/news/articles/balanced-equations-toolholder-vibration-makes-miserable-machining-balancing-can-help
2008
https://www.americanmachinist.com/archive/features/article/21892676/toolholder-balancing-101
1/1/2017
Toolholding for Heavy-Duty Machining
Heller Machine Tools needed to improve metal removal rates during roughing and heavy-duty machining. Haimer's Safe-Lock system enabled high-feed slotting of up to 2 times diameter in difficult materials.
Haimer Safe-Lock system with HSK-A100
https://www.mmsonline.com/articles/toolholding-for-heavy-duty-machining
December 2019
Tool Holder Essentials - Haas
_______________________
_______________________
Toolholder-Spindle Connection Methods
1. General
There are A to K types described in Stephenson-Agapiou book that have variations in types of cylindrical shafts including single and multiple cylinders, face and nonface contacts, as well as different types of tapers and taper/face contact systems.
2. Conventional Tapered "CAT-V" Connection
3. Face-Contact CAT-V Interface
4. HSK Interface
Kennametal KM
NC5
Sandvik Capto
-------------
Sandvik Coromant Capto Tool Holder
Coromant Capto by Sandvik is a modular system that can be used to create extended-length toolholders. Coromant Capto adapter has a spindle side to put in the machine spindle and then different types of milling cutters, drills or boring heads are mounted on the machining side of the assembly end of the adapter by adding extensions to make it longer and stack them out as far as you need. On the same tool assembly, different diameter extensions can be used, which gives a lot of versatility. You usually would start with a larger diameter at the base and then reduce it to the required diameter in steps or keep it all the same diameter for the entire assembly.
https://www.sandvik.coromant.com/en-gb/products/coromant_capto/pages/default.aspx
2019
https://www.cnctimes.com/editorial/new-connected-driven-tool-holder-solution-maximises-machine-utilisation-sandvik-coromant
https://www.ctemag.com/news/articles/extended-reach-toolholders-remain-requirement
https://www.tradeindia.com/fp4207315/Coromant-Capto-Modular-Tools.html
https://www.grainger.com/product/SANDVIK-COROMANT-Coromant-Capto-Adapter-14L475
https://www.indiamart.com/proddetail/sandvik-coromant-capto-tooling-system-22046925255.html
1998
https://www.americanmachinist.com/cutting-tools/article/21892978/modular-means-more
---------------
5. Quick-change interfaces
6.Turning Tool Holders
7. Evaluation and Comparison of Toolholder/Spindle Interface
The static and dynamic bending stiffness and the torsional stiffness can be measured from a bench test. The reliability can be based on an evaluation matrix using factors such as fracture fatigue, dirt/nick sensitivity, wear/corrosion sensitivity, sticking extra force, torque slippage, temperature sensitivity, maintenance, lubrication, coolant feed, and gauging. The ease of tool change is assessed based on an evaluation matrix with the factors of holder weight, length engagement, surface cleanliness, drawbar force, critical location, and coolant through ease.
Toolholder–spindle interfaces can be evaluated and compared based on experimental and analytical/finite element results. Bench tests provide a relative comparison between toolholders. The static and dynamic stiffness seen at the tip of the cutting tool also depend on the stiffness of the tool, the spindle geometry and bearings, the housing, and the overall machine structure. Bench tests results that reflect only the stiffness of the toolholder–spindle interface may thus be misleading in applications in which the properties of the spindle and bearings largely determine the structural response.
The characterization of the toolholder/spindle interface is made using the joint stiffness parameters. A methodology for estimating the joint stiffness parameters of a toolholder/spindle interface using one linear spring and one rotational spring has been found to be very effective. The method is based on the FRF of the interface system. It involves FEA and experimental measurements of a bench fixture. The most important assumption is that the behavior of the test system is linear. After the joint stiffness parameters are estimated, they can be used in any machine tool spindle FEM to estimate the static and dynamic characteristic at the tool tip.
The Spindle Analysis program (SPA) from Manufacturing Laborites, Inc. can be used to create a two-dimensional axisymmetric model of a spindle for evaluating the interfaces. The spindle shaft, the housing, and the toolholder structure can be modeled. The SPA program can model a 2-DOF spring to include a linear direction and rotational direction to represent the joint between the spindle and the toolholder. The SPA FEA program simulates both the dynamic and static behavior of a spindle and tooling system. The static bending deflection of the tool can also be defined analytically using the joint stiffness parameters; the bending deflection of the tool includes the elastic deflection of the bar itself.
The material removal rate that a machining center can achieve is strongly dependent upon the static and dynamic characteristics of the machine–tool–workpiece system as seen at the tip of the tool. In the selection of the best spindle–toolholder interface, the stiffness is one of the important parameters to consider in the selection. The static stiffness measures the deflection at the end of the tool in response to a static force. It provides some indication of the ability to create a surface or hole with the tool in the intended location. In milling, drilling, reaming, boring with a relatively low spindle speed, the error in location of the machined surface or hole is related to the static stiffness. The higher the static stiffness, the more accurately the surface or hole will be located with smaller form error. If static stiffness is the performance criterion, then the data show that the face contact connections perform better than the nonface contact connections in a machine tool spindle. Therefore, the static stiffness of the tool should be estimated by consideration of the spindle stiffness in order to properly select an interface style. The static stiffness can be estimated using the FEA or analytically assuming the joint stiffness parameters are available.
In the case of high metal removal rate, accurate surface location at higher spindle speeds, the better selection criterion is dynamic stiffness (or chatter criterion) at the tip of the tool. The dynamic stiffness is a combination of stiffness and damping in a particular mode of vibration (at a particular frequency). The damping is estimated from the FRFs while the natural frequencies and modal stiffness can be estimated using several programs, including commercial FEA solvers and advanced codes, which consider bearing preload and other nonlinear effects. For dynamic cutting performance at the tip of the tool, FEA can be also used assuming the joint parameters are available. There are cases where the bore quality or surface flatness are very critical, in which case the quality of the interface taper and face including the quality of the tool point (runout) with respect to the taper interface are very important. In addition, the static bending stiffness becomes important assuming it is not a high-speed application. Rigid face contact interfaces provide higher static stiffness or normalized bending stiffness at higher moments assuming: (1) the taper quality for the nonface contact interfaces is worse than AT3 tolerance, and (2) the clamping force is high enough to sustain larger bending moments without losing contact between the toolholder and the spindle face.
---------------
Toolholder types other than modular toolholders
https://www.engineering.com/AdvancedManufacturing/ArticleID/11710/Toolholding-101-Top-Tips-for-High-Productivity-Machining.aspx
VDI and BMT Turrets
https://www.mylascnc.com/en/tech/tech_detail-2.htm
--------------
Cutting Tool Clamping Systems - Tool Holders
1. Milling cutter drives
2. Side-Lock-Type Chucks
3. Collet chucks
4. Hydraulic Chucks
5. Milling Chucks
6. Shrink-Fit Chucks
7. Proprietary Chcuks
8. Tapping Attachments
9. Reaming Attachments
10. Comparison of Cutting Tool Clamping Systems
Balancing Toolholders
Fundamentals of balancing - Good description
https://www.haimer-usa.com/products/balancing-technology/knowledge/fundamentals-of-balancing.html
_____________
MTD CNC
_____________
2020
February 13, 2020: HAIMER at GrindTec 2020: hall 2, booth 2113 - Fine balancing increases productivity during the grinding process
https://www.haimer-usa.com/news/news/news-article/item/haimer-at-grindtec-2020-hall-2-booth-2113-fine-balancing-increases-productivity-during-the-grind-1.html
2014
https://www.ctemag.com/news/articles/balanced-equations-toolholder-vibration-makes-miserable-machining-balancing-can-help
2008
https://www.americanmachinist.com/archive/features/article/21892676/toolholder-balancing-101
1/1/2017
Toolholding for Heavy-Duty Machining
Heller Machine Tools needed to improve metal removal rates during roughing and heavy-duty machining. Haimer's Safe-Lock system enabled high-feed slotting of up to 2 times diameter in difficult materials.
Haimer Safe-Lock system with HSK-A100
https://www.mmsonline.com/articles/toolholding-for-heavy-duty-machining
December 2019
Tool Holder Essentials - Haas
_______________________
_______________________
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ReplyDeleteHere You can visit for CNC Tool Holder
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