Understanding Rotary Toolholders

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This is a basic outline of the concepts, designs, and application of Steep Taper and HSK tooling

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  • I LIKE END MILL HOLDERS, WHY SHOULDN'T I USE THEM?* As a general rule most cutting tool (end mill) manufacturers prefer to use single angle (ER/DR style) collet chucks for most tool applications under .500". Why? Runout and uneven chip load. This is primarily for two reasons: The error accumulation on ID tolerance of the end mill holder and the OD shank tolerance of the end mill or drill. The smaller the diameter the more potential for problems.
  • Can you get "Cheap" retention knobs? Yes. But, it's best not to "cheap out" on retention knobs. There are places where you can get retention knobs at 1/3 the price of brand name retention knobs. In many cases they will work fine. The real question ends up being " Do you want to be responsible when a retention knob breaks and sends a toolholder flying out of the spindle at 10,000 RPM?" If you've ever seen this happen you are happier spending and extra $5 - 10 on a brand name retention knob. Do you own a retention knob socket? If not you need to get one. Remember the FAQ on AT3? Steep taper toolholders are generally made from some derivative of 8620 and then case hardened. The widest point of contact.htm needs to be at the Gage line (gage diameter) of the holder. If you over-torque the retention knob, at an AT3 tolerance or greater, you risk the possibility of expanding the smaller diameter of the taper.Retention Knob sockets only cost about $60 depending on the taper. The sockets fit about 99% of all retention knobs on the market. This socket attaches to most torque wrenches and allows you to tighten your retention knobs to the manufacturer's specific torque requirement.
  • Understanding Rotary Toolholders

    1. 1. Understanding Taper Connections
    2. 2. Toolholder Overview <ul><li>Steep Tapers </li></ul><ul><li>Flanges </li></ul><ul><li>Big Plus </li></ul><ul><li>HSK </li></ul><ul><li>Shrink Fit </li></ul><ul><li>Connections (Collets, etc) </li></ul>
    3. 3. Toolholder Identification: Steep Taper
    4. 4. Toolholder Characteristics: CAT <ul><li>American Standard </li></ul><ul><li>V-flange for auto changing </li></ul><ul><li>Dimple in the notch of flange </li></ul><ul><li>Top and bottom of flanges are equal in width </li></ul><ul><li>Drive dog knotches are unequal depth </li></ul><ul><li>CV is often referred to as “CAT” or Caterpillar V-flange tooling as described under ANSI B5.50, and typically has inch threads for the retention knob. Some CV holders have a counter bore for a piloted retention knob. This is typically used in higher spindle speed applications. </li></ul>
    5. 5. Toolholder Characteristics: BT <ul><li>Asian or Japanese standards </li></ul><ul><li>Have round top in drive dog notches-looks like top of the key in BB </li></ul><ul><li>Top of flange is thicker than bottom </li></ul><ul><li>Drive dog notches are equal distances from the center. Better balanced by design </li></ul><ul><li>V-flange for auto changing </li></ul><ul><li>The BT taper is a JIS B6339 specification (Japan Industrial Standard). BT tooling carries a wider flange than a CV or DV tool and contains metric retention knob threads. </li></ul>
    6. 6. Toolholder Characteristics: DIN <ul><li>European standards </li></ul><ul><li>V-flange for auto changing- very similar to CAT except for additional whistle knotch </li></ul><ul><li>Has 3 notches in flange-2 drive dogs and one triangular-whistle knotch </li></ul>
    7. 7. Toolholder Characteristics: ISO <ul><li>Made exclusively for the woodworking industry </li></ul><ul><li>Have no drive dog slots </li></ul><ul><li>Same specs has DIN </li></ul><ul><li>Works on the 2 main woodworking spindles-Colombo and HSD </li></ul><ul><li>Balanced by design due to no drive dogs </li></ul><ul><li>Has wrench flats to hold the chuck from turning when tightening the nut </li></ul><ul><li>Comes in manual changing and quick change </li></ul>
    8. 8. Toolholder Characteristics: HSK <ul><li>Hollow Shank Taper (Kegel) </li></ul><ul><li>Comes in manual changing and quick change </li></ul><ul><li>Taper is short and non tapered to eliminate the problems associated with tapered spindles in milling applications </li></ul><ul><li>Gives both Radial and axial contact.htm to the spindle </li></ul><ul><li>Used in high speed applications (HSK-63A is most common in metalworking) associated with soft material machining-wood, aluminum and plastics </li></ul><ul><li>Six styles of HSK (known as a &quot;FORM&quot; A-F; e.g. HSK63, Form A) depending on manual or quick change, ultra high speeds and coolant through </li></ul>
    9. 9. Understanding Tapers <ul><li>16 Degree Included Angle </li></ul>CV, DV and BT tapers are all identical and known as 7/24 tapers. These tapers are commonly referred to as a “self-releasing” or “fast tapers.” The primary differences between the toolholders are the flange design and retention knob threads . Socket Shank Perfect Taper <ul><li>Allowable </li></ul><ul><li>Socket </li></ul><ul><ul><li>Tolerance </li></ul></ul>Allowable Shank Tolerance
    10. 10. AT3
    11. 11. Fretting <ul><li>STD’s on a machine </li></ul><ul><li>Causes are unknown </li></ul><ul><li>Form or corrosion </li></ul><ul><li>Friction welding </li></ul>
    12. 12. Flanges <ul><li>BT 40 </li></ul><ul><li>CAT 40 </li></ul>Note the differences between the Flange: The Taper is the same but how the toolchanger fingers engage the holder is different
    13. 13. DIN-B Coolant <ul><li>Din B tool holders have coolant through the flange.. DIN B style coolant can be a requirement on either a CAT or a BT Holder. DIN B designates &quot;through the flange&quot; </li></ul>
    14. 14. Steep Taper Problems <ul><li>Only taper contact </li></ul><ul><li>Changes in Z </li></ul><ul><li>Outside grippers </li></ul><ul><li>Good to 10-18,000 RPM </li></ul>
    15. 15. Big Plus Advantage
    16. 16. Big Plus More contact
    17. 17. LyndexNikken 3Lock <ul><li>When a 3Lock Holder is inserted into a 3Lock Spindle (before clamping), the gap between the spindle flange and the tool flange is 0.2mm for a 40 taper, or 0.5mm for a 50 taper.When the tool is clamped, the taper cone preloaded by the disc springs deforms radially and slides axially to create contact between the spindle face and the tool flange. </li></ul>
    18. 18. 3Lock after clamping <ul><li>When the tool is clamped, the taper cone preloaded by the disc springs deforms radially and slides axially to create contact between the spindle face and the tool flange . </li></ul>
    19. 19. LyndexNikken 3Lock <ul><li>Flange contact is good </li></ul><ul><li>Taper contact is good </li></ul><ul><li>Renention Knobs? </li></ul>
    20. 20. Wait a second! <ul><li>None of these solutions address the centrifugal forces affecting the retention knob grippers </li></ul>
    21. 21. HSK <ul><li>Hollow Shank Kegel </li></ul><ul><li>Dual Contact </li></ul><ul><li>Grippers internal </li></ul><ul><li>Expanding taper </li></ul><ul><li>Left side: clamped </li></ul><ul><li>Right Side unclamped </li></ul>
    22. 22. Toolholder Identification: HSK
    23. 23. HSK Forms <ul><li>Hollow Shank Kegel </li></ul><ul><li>6 forms </li></ul>
    24. 24. HSK-A & HSK-C <ul><li>HSK-A for automatic tool changing </li></ul><ul><li>HSK-C for manual tool changing </li></ul>Moderate Torque; Moderate- high spindle speeds; drive slot
    25. 25. HSK-B & HSK-D <ul><li>HSK-B for automatic tool changing </li></ul><ul><li>HSK-D for Manual tool changing </li></ul>High Torque; Moderate to high spindle speeds; drive slot
    26. 26. HSK-E & HSK-F Low Torque; Very High spindle speeds; Automatic tool change
    27. 27. Torsional Rigidity <ul><li>CAT40 = 670 Nm/mm </li></ul><ul><li>HSK63 = 3,600 Nm/mm </li></ul><ul><li>CAT50 = 2,400 Nm/mm </li></ul><ul><li>HSK100 = 17,000 Nm/mm </li></ul>
    28. 28. Balance & “G” <ul><li>&quot;U&quot; is the allowable unbalance in g.mm). </li></ul><ul><li>&quot;G&quot; is the standard for balance quality of rotating rigid bodies. (For machine tool drives it is G 2.5). </li></ul><ul><li>&quot;W&quot; is tool holder assembly weight in (kg). Our example chuck has a weight of 2.75 kg. </li></ul><ul><li>&quot;9549&quot; is a constant. </li></ul><ul><li>&quot;RPM&quot; is our rotational speed </li></ul>
    29. 29. Sources of Imbalance <ul><li>Controllable (Fixed) Sources </li></ul><ul><ul><li>Unground Diameters </li></ul></ul><ul><ul><li>Drive Slot Depth </li></ul></ul><ul><ul><li>Centerline deviations </li></ul></ul><ul><ul><li>AT tolerance </li></ul></ul><ul><li>Uncontrollable (Variable) forces </li></ul><ul><ul><li>Cutting Tool Shank Tolerance </li></ul></ul><ul><ul><li>Non-Symetric tools (boring bars) </li></ul></ul><ul><ul><li>End Mill Flats </li></ul></ul><ul><ul><li>Different length/depth of flutes </li></ul></ul>
    30. 30. Single Plane Balance <ul><li>Single plane </li></ul><ul><li>balancing applies to toolholders which: </li></ul><ul><ul><li>Have operating speeds less than 18,000 RPM </li></ul></ul><ul><ul><li>Have been pre-balanced by the manufacturer </li></ul></ul><ul><ul><li>Have a length less than two times the diameter at the gage line </li></ul></ul>
    31. 31. Parameters for Duel Plane Balance <ul><li>Dual Plane </li></ul><ul><li>balancing should be considered for Toolholders which: </li></ul><ul><ul><li>Have operating speeds in excess of 18,000 RPM </li></ul></ul><ul><ul><li>Have a length more than two times the diameter at the gage line </li></ul></ul>
    32. 32. Toolholder Balance
    33. 33. Which is best <ul><li>Cat 40 up to 15,000 RPM </li></ul><ul><li>BT40 up to 18,000 RPM </li></ul><ul><li>CAT50 up to 15,000 RPM </li></ul><ul><li>BT50 up to 18,000 RPM </li></ul>
    34. 34. End Mill Holders & TIR
    35. 35. Bore & Shank Tolerance <ul><li>For every 0.0001&quot; improvement T.I.R. </li></ul><ul><li>You Gain 10% Tool Life </li></ul>Min Dim Max Dim H5 H6 H7 H8 - .118&quot; -.00015&quot; -.00039&quot; -.00055&quot; .118&quot; .236&quot; -.00019&quot; -.00047&quot; -.00070&quot; .236&quot; .394&quot; -.00023&quot; -.00035&quot; -.00059&quot; -.00086&quot; .394&quot; .709&quot; -.00031&quot; -.00043&quot; -.00070&quot; -.001&quot; .709&quot; 1.181&quot; -.00035&quot; -.00051&quot; -.00082&quot; -.0012&quot; 1.181&quot; 1.968&quot; -.00063&quot;
    36. 36. Toolholder Manufacturing <ul><li>All Steep taper toolholders are made from some derivative of 8620 </li></ul><ul><li>They are case hardened </li></ul><ul><li>Remember AT3 on the holder; AT2 on the spindle </li></ul>
    37. 37. Retention Knob Torque <ul><li>30 Taper = 40 ft/lbs </li></ul><ul><li>35 Taper = 40 ft/lbs </li></ul><ul><li>40 Taper = 85 ft/lbs </li></ul><ul><li>45 Taper = 100ft/lbs </li></ul><ul><li>50 Taper = 110 ft/lbs. </li></ul>MAS Style ANSI Style
    38. 38. Controlling TIR <ul><li>Leads to </li></ul><ul><li>Better Tool Life </li></ul><ul><li>Better Finish </li></ul><ul><li>More parts </li></ul><ul><li>More $$$$ </li></ul>
    39. 39. Best methods <ul><li>The best toolholding method for most standard shop operation is a collet. </li></ul><ul><li>But which one? </li></ul>
    40. 40. DA (RDA) Collets <ul><li>8 Slots </li></ul><ul><li>4 Point engagement </li></ul><ul><li>“ bunch up” at smaller diameter </li></ul><ul><li>Ok for Drilling </li></ul><ul><li>Bad for Milling </li></ul>
    41. 41. TG(RTG) Collets <ul><li>16 Slots </li></ul><ul><li>.0004” TIR </li></ul><ul><li>1/64” increments </li></ul><ul><li>Better holding power </li></ul><ul><li>Good for ranges 1.0” - 1.5” dia. </li></ul><ul><li>Large head diameter </li></ul>
    42. 42. ER Collets <ul><li>16 slots </li></ul><ul><li>.0004” TIR standard </li></ul><ul><li>.0002” TIR UltraPrecsion </li></ul><ul><li>Smaller nose dia </li></ul><ul><li>.039” range </li></ul><ul><li>16 degree angle </li></ul><ul><li>Most Versatile </li></ul><ul><li>Most common </li></ul><ul><li>Most readily available </li></ul><ul><li>DIN Standard 6499 -1993 </li></ul><ul><li>Fritz Weber </li></ul>
    43. 43. DNA Collets <ul><li>Best Solution under 6mm in diameter </li></ul><ul><li>.0002” TIR </li></ul><ul><li>Fits in an ER Pocket </li></ul><ul><li>40% less projection out of collet pocket </li></ul>
    44. 44. Collet Accuracy <ul><li>L = DX4 </li></ul><ul><li>Runout at the end of the tool should be within .0002&quot; or less </li></ul><ul><li>Tool Shank engagement: Minimum engagement should be 2/3 of the collet bore length. 3/4 of the collet bore length is preferred. </li></ul>
    45. 45. Collet Recommendations <ul><li>Use ER style collets </li></ul><ul><li>Use the largest bore diameter in the smallest envelope </li></ul><ul><li>Use shank sizes that are equal to the nominal collet bore. In other words, use a 3/8 collet (.375&quot; max opening) for a 3/8&quot; shank tool, no the equivalent 9-10mm metric collet (.394&quot; max opening) </li></ul>
    46. 46. Collet Nuts-Solutions
    47. 47. Torque Specs ER Collets <ul><li>ER11 = 20 ft/lbs </li></ul><ul><li>ER16 = 50 ft/lbs </li></ul><ul><li>ER20 = 75 ft/lbs </li></ul><ul><li>ER25 = 95 ft/lbs </li></ul><ul><li>ER32 = 125 ft/lbs </li></ul><ul><li>ER40 = 140 ft/lbs </li></ul><ul><li>ER50 = 200 ft/lbs </li></ul>*Recommended torque range is 80-90% of maximum torque
    48. 48. Shrink Fit <ul><li>Made from H13 in US </li></ul><ul><li>Made from H11 in EU </li></ul><ul><li>Tempered to 1050 ºF in US </li></ul><ul><li>.0001” TIR </li></ul><ul><li>Most Rigid </li></ul><ul><li>Better Balance </li></ul><ul><li>10,000 lbs Holding Power </li></ul><ul><li>1 Piece holder </li></ul><ul><li>Slim Design </li></ul><ul><li>G2.5 @ 24,000 RPM </li></ul><ul><li>Extends tool life up to 700% </li></ul>
    49. 49. Shrink Fit - Expansion <ul><li>Safe, controlled induction heat from the shrink fit machine expands the inside diameter of the tool holder bore so the tool shank can be inserted. </li></ul>
    50. 50. Shrink Fit - Contraction <ul><li>Automatic air cooling contracts the bore to hold the tool with up to 10,000 lbs of holding power creating an extremely rigid connection between the spindle and the cutting tool. </li></ul>
    51. 51. Shrink Fit - Pull Out Force
    52. 52. Shrink Fit - Radial Torque
    53. 53. Shrink Fit vs. ER <ul><li>CAT40 </li></ul><ul><li>4140 prehard; 30-32R/c </li></ul><ul><li>3 flute uncoated end mill </li></ul><ul><li>4 passes </li></ul><ul><li>.125” DOC </li></ul>
    54. 54. Shrink Fit vs. ER <ul><li>ER Collet </li></ul>Shrink Fit
    55. 55. Tool Removal Temperatures Removal Temperature is based on carbide shanks at mean dimensions. Increase heat 100-250ºF for High Speed & Steel .
    56. 56. Tool Removal Temperatures Smaller Diameters are where the problems can happen
    57. 57. Shrink Fit - Limitations <ul><li>Thermal Expansion properties of End Mills </li></ul><ul><li>HSS and Cobalt cannot be used </li></ul><ul><li>Can get the tool IN but not OUT </li></ul>
    58. 58. Shrink Fit - Limitations <ul><li>.010”, .015”, .020” end mills all made on 1/8 Shank </li></ul><ul><li>Diameters typically held to -0.0001”/-0.0002” shank </li></ul><ul><li>10% -14% cobalt </li></ul><ul><li>Cobalt measured by WEIGHT NOT VOLUME </li></ul><ul><li>BY VOLUME Cobalt content up to 28% </li></ul>
    59. 59. Best type: Price? Rigidity? <ul><li>1. Accuracy value of 10 defined as 3 microns, 1 is .015&quot; TIR </li></ul><ul><li>2. 10 is the lowest price, 1 is the highest price. </li></ul><ul><li>3. 10 defined as widely available </li></ul>End mill holder = greatest holding power Collet chuck = greatest versatility
    60. 60. Best Practices <ul><li>Best ways to maintain accuracy of your toolholder </li></ul><ul><li>1. Minimize Runout </li></ul><ul><li>2. Grip the cutting tool well </li></ul><ul><li>3. Make sure the cutting tool shank is accurate </li></ul>

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