基礎から分かるシリーズハンドタップ 超硬タップ編

Transcription

1 Understanding the basics of Hand taps Understanding the Basics of Hand Taps and Carbide Taps July 2017 基礎から分かるシリーズハンドタップ 超硬タップ編

2 Understanding the basics of Hand taps Understanding the Basics of Hand Taps and Carbide Taps What is a Hand taps? Hand taps and Serial hand taps Cutting torque of taps What is a carbide tap? The relationship between an internal thread, a tap and a gauge. Yamawa s offering of Hand taps. Yamawa s offering of carbide taps. Taps for cast irons. Carbide Taps for high hardness steels Selecting hand taps/carbide taps based on workpiece materials being cut. Introduction of RE-HT Introduction of UH-CT/EH-CT 2

3 Understanding the basics of Hand taps What is a Hand taps? A hand tap is used for general tapping work. The same diameter is offered in three types of cutting chamfer lengths for manual tapping. The first is a taper chamfer, the second is a plug chamfer and the last is a bottoming chamfer. These are sold as a set for general tapping. In succession, these are used with the starter taper chamfer tap cutting first, depending on the work piece condition. Yamawa currently produces the plug and bottoming chamfer taps. Plug type: 5 thread chamfer <Fine chips are created with hand taps> Bottoming type : 1.5 threads chamfer The serial hand tap is explained on next page. <The classification of a tap s cutting action is based on the geometry of the taps, the chip direction and the hole shape> Chip ejec on Hand Taps Chip ejec on Spiral Fluted Taps Chip ejec on Spiral Pointed Taps The characteristic of hand taps are summarized as below. 1) High cutting edge strength. 2) Suitable for tool wear prone materials like high hardness materials and cast irons. 3) The cutting chamfer length can be selected. 3

4 Understanding the basics of Hand taps Hand taps and Serial hand taps Hand taps(used in many other countries besides Japan) Hand taps have two or more taps with the same thread diameter and a different number of threads in the cutting chamfer section. There are three lengths of cutting chamfers offered in the same diameter tap. Yamawa sells plug and bottoming taps as standard products. Serial taps(mainly used in Europe market) Serial hand taps are made to have two or more taps that remove an increasing amount of thread material. These taps are offered as one set. After the first V starter tap is used, each additional middle M and Finishing F tap of the same diameter removes more of the read diameter. First the tapping is done with V with the lowest thread form, then M F is processed. Yamawa product catalog on Products for Europe page Product catalog HT page 4

5 Understanding the basics of Hand taps Cutting torque of taps The charts below show torque diagram comparisons of hand taps, spiral fluted taps and spiral pointed taps with their torque values. Selecting the same processing conditions and in the same material and hardness while using the same diameter and pitch tap with the same chamfer the tapping torque for each style is shown above. The tapping torque can change depending on the type of cutting fluid and chip effect. Spiral pointed taps are less affected by chips when compared with other taps. The tapping torque appears low in the charts above. Spiral fluted taps discharge the chip back toward the shank inside the flutes. The taping torque for spiral fluted taps will become slightly larger compared that tapping torque of a spiral pointed taps. While using hand taps, the chips accumulate in the flutes, so the tapping torque increases due to the influence of the chip storage. 5

6 Understanding the basics of Hand taps What is a carbide tap? In recent years, taps are being used on machines that are dedicated, like automated machines, CNC machines, machining centers, etc. Yamawa has promptly responded to these times and recommends a carbide tap that is popular for mass production and that offers greater cost reduction. If applied properly, it is more than 50 times more durable than the general HSS tap. Features: 1)Yamawa uses ultrafine particle cemented carbide that has a high resistance to breakage and it exhibits high toughness. The Yamawa carbide taps have the same hardness as that of conventional cemented carbide. 2)Because it is hard and has high toughness it offers better abrasion resistance and longer life. 3)Depending on the application, it is also possible to thread difficult to cut materials. Usage notes: 1)Machines used: Carbide taps develop chipped cutting edges if the vibration is large. Carbide taps have a low bending strength and can break if too much side stress is generated. 2)Mounting and holding tool: Misalignment prevention to the minor diameter hole is vital. Mounting tap in accurate holders is critical. (Carbide taps are easy to break due to bending stress. )When attaching the tap to the holding tool is inaccurate, the holding tool will float or move, throwing the balance of the tapping operation off and it can easily develop into chipping and breaking. 3)Threading holes: Threading where the hole is bending or misalignment will cause a bending stress and breakage. Pay attention to the depth of the hole and the length of the screw thread. Pay particular attention to chip clogging and crash into the bottom. 4)Lubrication: Use mainly tapping lubrication. (It helps prevent the development of chip welding to flute. Higher tapping torque can develop from the chip welding and cause breakage. 5)Wok material: The toughness of a carbide tap is lower than that of a HSS material so the range of the work material is limited. About work material Cemented carbide does not have the toughness of HSS taps, so cutting edge chipping and tap breaking Example of chip can easily occur. It is best to limit the work material to those where the metal chips are divided finely as shown in the picture on the right. Typical examples of these materials are cast iron and aluminum die casting. Recently, carbide taps have also been used for ultra high hardness materials exceeding 60HRC. About the main tap types For cast irons N-CT FC For light alloys N-CT LA For high hard materials (hardness: 45HRC~55HRC) EH-CT For ultra hard materials (hardness: 55HRC~63HRC) UH-CT For ultra fast tapping speed HFACT HFICT 6

7 The relationship between an internal thread, a tap and a gauge. Hand taps have larger thread class because they tend to cut closer to tap size. We recommend using oversized taps for the following conditions. 1). When the material has a tendency to shrink after tapping due to the shape of the work piece. 2). If a plating is applied to the internal screw thread after tapping. (The tap diameter needs to be approximately four times of the plating thickness.) 3). When the work piece material does not expand but the tap experiences rapid wear. 4). When tapping on machines with a rigid tapping mechanism. If there is no expansion in the axial direction of the holder, we suggested the use of a tap with a class as high as possible. 5). Choose a tap that has as large of a thread class as possible. Comparison graph of tolerance zone for Pitch Diameter of a internal thread, a gage and tap thread class for M10X1.5 Size: M10X1.5 (μmm) 200 Pitch diameter tolerance zone of JIS 2nd class internal thread Position of Plug gauge JIS 2nd Pitch diameter tolerance zone 6H internal thread Position of Plug gauge class 2 Position of Yamawa P class Cutting Taps. Position of Yamawa G class Roll Taps. Maximum figure of pitch diameter of 6H internal thread for M10X1.5 : 9.206mm NP 160 Maximum figure of pitch diameter of JIS 2nd class internal thread for M10X1.5 : 9.166mm JIS 2nd class internal thread IP 6H internal thread P4 P3 (PO, HT) P2 (SP) G8 G7 Standard thread classes of each tap for M10X1.5 and the figure of pitch diameter. (Roll tap: Recommended tap thread class) SP P2 M10X1.5 P2=+20~+40μm PO P3 M10X1.5 P3=+40~+60μm HT P3 M10X1.5 P3=+40~+60μm N-RZ G7 M10X1.5 G7=+76~+89μm Basic Pitch Diameter: 9.026mm 10 0 GP GP 7

8 Yamawa s offering of Hand taps Product Symbol Product Features Size range IHT I series Hand taps for General Purpose Application The IHT taps are for drilling machines or for hand tapping. It is suitable for small volume tapping on work piece materials like SPC and SS400. We recommend tapping speeds less than 5m/min. M3~M10 HT Hand Taps The HT are widely used for general-purpose tapping applications. We recommend tapping speeds of 5 to 10m/min. M1~M48 U W SM HT LH The HT LH hand taps are for left hand threads. M1~M30 Hand Taps for Left Hand Threads LS-HT Long Shank Hand Taps The LS-HT taps have a longer shank than conventional taps. These taps are applicable for use where the tapping length can not be reached with a standard length tap. M2~M30 LS-HT V Long Shank Hand Taps, Coated The LS-HT V is a thin film coated longer shank that is longer than a conventional tap. These taps coating improves wear resistance and welding resistance. The LS-HT V are for use where the tapping length can not be reached by a standard length tap. M3~M12 SU-HT Hand Taps for Stainless Steels The SU-HT is the hand tap suitable for sticky work hardening stainless steels, chrome steel and molybdenum steels. M2~M30 U W FC-HT Hand Taps for Cast Irons The FC-HT taps are suitable for hard and brittle materials like cast iron. The FC-HT is slightly oversize to allow for faster wear in hard materials. M3~M24 LA-HT Hand Taps for die casting The LA-HT is an oversized tap that corresponds to materials that end to contract when tapping internal threads like aluminum alloy die castings (ADC) and zinc die castings (ZDC). M1.4~M24 8

9 Product Symbol Product Features Size range AXE-HT AXE Straight Fluted Taps The AXE-HT is ideal for machining aluminum alloy castings and zinc alloy castings. Powder HSS (characterized by high wear resistance and heat resistance) with a special coating. When combined with the correct tooling, the tool life of the AXE-HT is increased five times over conventional taps designed for aluminum. With less flute damage, the dimensional change of the internal threads is improved plus there is an improvement in the surface finish. Suitable from medium speed to high speed with an optimum combination of negative rake angle and eccentric relief. M6~M12 EH-HT Hand Taps for Hard-to-Machine Materials The EH-HT is a hand tap suitable for tapping of high hardness steel range from 35 to 45HRC. It works best in high carbon steels, alloy steel forging, tempering material, mold material, etc. M3~M30 PL-1 Hand Taps for Plastics The PL1 is a tap for a thermosetting resin. This material can be difficult to create a screw thread in, especially the synthetic resin. M2~M8 MG-HT Hand Taps with Short Chamfer for Magnesium Alloy Castings The number of the cutting chamfer threads is set to 1 thread or less. The MG-HT is optimum when the requirement is a full thread at the bottom of a hole. M1.4~M3 MC-HT Hand Taps with Internal Coolant hole The MC-HT is a coolant through tap with side ports for through hole tapping applications. The internal coolant supply improves the surface finish and tool life. M6~M30 New RE-HT Joint type taps for thread repair and cleaning Main usage of RE-HT is for correcting thread flaws, and cleaning out burrs, paint, rust and residual spatters from welding. M50~M80 9

10 Yamawa s offering of carbide taps Product symbol Product name Features Size range N-CT LA Carbide hand taps for light alloy The N-CT LA is suitable for mass production of aluminum castings (AC), aluminum die casting (ADC), zinc die casting (ZDC) and other mass production products. M1.4~M20 N-CT FC Carbide hand taps for cast iron The N-CT FC is suitable for screw thread tapping of mass-produced products that are hard and brittle material like cast iron. M1.4~M24 No.4~3/4 N-CT PO Spiral Pointed Carbide Taps The N-CT PO is carbide tap for a through hole tapping of screw threads in mass production in hard and brittle materials such as cast iron. M3~M12 EH-CT Carbide hand tap for high hardness steel Ideal for high hardness steel tapping from 45 to 55HRC in steels for hot dies like SKS3, SKD11) The EH-CT is an ultrafine particle cemented carbide superior in abrasion resistance and impact resistance. Recommended for bored hole of 6H internal thread diameters should be the maximum value. M3~M12 UH-CT Carbide hand tap for Ultra Hard Materials The UH-CT is for SKD materials prehardened steels 55 to 60 HRC (Max63HRC). Ultrafine particle cemented carbide superior in abrasion resistance and impact resistance. Screw thread length is set to 1.5D or less. Taking life into consideration, the cutting chamfer is 5 threads long. For the diameter of the bored hole 6H internal thread diameters should be the maximum value recommended. M2~M20 10

11 Product symbol Product name Features Size range HFACT-P Carbide Taps for Ultra Fast Tapping, Through Hole Use, for Aluminum The HFACT-P is a carbide tap capable of ultra high speed tapping. The tap has an internal hole with side ports for lubrication or mist in through hole tapping. It is suitable for tapping aluminum casting or aluminum die casting. M6~M12 HFACT-B Carbide Taps for Ultra Fast Tapping, Blind Hole Use, for Aluminum The HFACT-B is a carbide tap for super high speed tapping. The tap has a straight internal coolant hole for lubrication or mist in blind hole tapping of aluminum casting and aluminum die casting. M6~M12 HFICT-P Carbide Taps for Ultra Fast Tapping, Through Hole Use, for Cast Irons The HFICT-P is a carbide tap capable for ultra high speed tapping. The tap has an internal coolant hole with side ports for lubrication or mist in through hole tapping in cast irons. M6~M12 HFICT-B Carbide Taps for Ultra Fast Tapping, Blind Hole Use, for Cast Irons The HFICT-B is a carbide tap for super high speed tapping. The tap has a straight internal coolant hole for lubrication or mist in blind hole tapping of cast irons. M6~M12 ACHSP Spiral Fluted taps for tapping Cored Holes in Aluminum Direct cored hole tapping result in a reduction of processing time. The shank diameter is the same as the thread diameter of the tap which improves rigidity and makes the product more resistant to deflection and the cutting side pressure caused from misalignment. (M6, M8: 0.3mm max, M10: 0.6mm max) A thin film coating offers improvements in wear resistance and a reduction of cutting edge chipping. M6, M8, M10X1.5 M10X

12 Understanding the basics of Hand taps Taps for cast irons Cast irons is a widely used material for mechanical parts. It contains up to 6.7% carbon (C) and has a hardness around HB. Since cast irons are abrasive Because the chips are very fine, there are few flute chipping problems from the metal chips wrapping around the tap. Cast irons is relatively easy to process. Yamawa recommends the FC-HT hand tap for cast irons. <Features of FC-HT> 1Recommend cutting speed:less than 10m/min. 2Machine: A wide array of machines can be used to tap cast iron from CNC machining centers to drill machines. 3Material: The FC-HT tool material is high speed tool steel (HSS). 4Surface treatment: When a nitride surface treatment is applied the surface hardness of the tap becomes 1,000 to 1,300HV and the wear resistance very high. 5Rake angle: The cutting edge shape has a rake angle with high rigidity. 6The problem of a thread gauge measuring tight is compensated for by making the FC-HT slightly oversize. The following table compares the number of the holes tapped until the thread gauge measured tight from performing tapping tests on FC250 material with a standard HT and a FC-HT. It was possible to tap about 2,700 holes with the FC-HT compared to 720 with a standard HT. The FC-HT achieved more than three times the number of holes tapped with a standard HT. <Comparison test of HT and FC-HT M8X1.25> Product HT, FC-HT P3 M8X1.25 5P Work piece material FC250 Tapping length, Hole shape 12mm (for through hole) Bored hole size φ6.8 Machine Machining center (Fully synchronous) Tapping speed 12m/min Lubrication Water soluble (*20 Dilution ratio) HT FC- HT Number of tapped holes 12

13 Understanding the basics of Hand taps Next, the introduction of the N-CT FC carbide taps for cast irons. The N-CT FC is a tap made from an ultrafine carbide(hf) with a cutting angle specification based on the FC-HT tap to greatly increase wear resistance. The figures below show the comparison of the number of tapped holes and the wear width on the chamfer. The chart below shows a comparison of tap tool life using the N-CT FC to that of the same size HT M8X1.25 tap. The HT tool life was about 2,000 holes and the abrasion of the chamfer was large. It became difficult to continue tapping while holding size. The N-CT FC had a tool life of 20 times more with less abrasion on the chamfer even after tapping 50,000 holes. Comparison graph of abrasion amount at chamfer portion between N-CT FC and HT tap. <Abrasion of chamfer portion> <Number of tapped hole (pcs/hole) <Test condition> Product, Size N-CT FC P4 M8X1.25 3P HT P4 M8X1.25 3P Workpiece material FC250 Hole shape 12mm (for through hole) Bored hole size φ6.8 Machine Machining center (Fully synchronous) Tapping speed 12m/min Lubrication Water soluble (*20 Dilution ratio) To use the N-CT FC taps properly without having problems, it is important to improve the processing environment. The hardness of the N-CT FC is much harder than HSS. Carbide toughness is lower than HSS, so flute chipping and breakage problems are likely to occur if not applied properly. When using the N-CT FC, be careful of any deviation of processing axis, curvature of pilot hole and positional deviation. Tap FC-HT N-CT FC Tapping effectiveness in FC-HT and N-CT FC Product Size Chamfer length Workpiece material Hole shape Tapping length (mm) Tapping speed (m/min) Tapping condition Machine Feed mechanizm Lubrication Number of tapped hole (hole/pc) M5X P FC250 Blind MC Synchronized Water soluble 2,100 M8X P FC250 Blind 18 8 Special-purpose machine Asynchronized Water soluble 2,400 M10X P FC250 Blind Special-purpose machine Asynchronized Non water soluble 2,500 M10X P FC250 Blind Tapping machine Master screw Non water soluble 3,000 M10X1 1.5P FC250 Blind MC Synchronized Non water soluble 5,000 M12X P FC250 Through Special-purpose machine Asynchronized Non water soluble 4,300 M6X1 3P FC250 Through 15 7 Transfer machine Asynchronized Mist 30,000 M6X1 3P FC250 Through MC Synchronized Water soluble 70,000 M7X1 1.5P FC250 Blind 8 15 MC Synchronized Water soluble 50,000 M8X P FC300 Blind MC Synchronized Water soluble 64,000 M10X1.25 3P FC250 Through Tapping machine Asynchronized Dry 16,000 M10X1 1.5P FC250 Blind 8 8 Special-purpose machine Asynchronized Water soluble 40,000 13

14 Carbide taps for high hardness steels There are many types of mold available in the industry depending on the application. Typically, these are divided into two categories, molds (Mold) used for casting and resin molding and a press die (Die Molds) used for press working of metal. For the die mold, a precipitation hardening system is applied which heat treats (tempering ) to hardness of about 40HRC. Steels used for plastic or resin material molds are stainless steels with excellent corrosion resistance. For press dies, it is important to have wear resistance, so there is a common use of alloy tool steels (SKD11, SKS93, etc.) that have been heat treated to harder than 50HRC. The general use of taps made from high speed tool steel (HSS) means the hardness of the tap is about 64HRC and it is difficult to process a mold material with hardness exceeding 45HRC. Therefore, YAMAWA has create a lineup of cemented carbide taps EH-CT for high hardness steel and a carbide taps UH-CT for ultrahigh hardness steel for tapping high hardness steel 45HRC or more. EH-CT:Suitable for high hardness tapping 45~55HRC such as steels for hot mold(sks3, SKD11, etc) UH-CT: SKD material, pre-hardened steel etc. Ideal for tapping 55-60HRC. Precautions on Processing 1Make the hole diameter as large as possible within an allowable range and work. If the bored hole is made larger, the processing load is reduced, so more stable tapping becomes possible. 2Make the depth of the prepared hole as deep as possible within an allowable range. If the tap cuts the chips that accumulated a the bottom of the bored holes, this will create a flute chipping problem. Since the length with chamfer is 5 threads, set the depth of bored hole and take into consideration the length with chamfer. If it is not possible to deepen the bored hole, we suggest that once you have tapped about half of the thread length, remove the tap once, remove the chip continue tapping to the bottom of the hole. 3Pay attention to vibration while tapping, tap bending, the cutting speed and process it. 14 Hole depth Threading length Hole dia.

15 Selecting hand taps/carbide taps based on work piece materials being cut. Material Low Carbon steels Middle carbon steels Features of material These materials have a high machinability rating but can often material welding on the tap when cutting internal thread. These steels are widely used in all industries and have a high machinability rating. This material is easily tapped with a general purpose tap. Red colored taps: Taps for fully synchronized feed Yellow colored taps: Carbide taps Recommendation by YAMA- WA IHT HT HT LH Purpose/Spec. For drilling/ by hand General purpose For left hand threads Surface treatment OX Recommended speed (m/min) ~5-5~10-5~10 LS-HT Long shank - 5~10 LS-HT LH Long shank tap for left hand threads - 5~10 MC-HT Tap with coolant hole - 5~10 High carbon steels Thermal refined Steels Heat treated steels Stainless steels These materials can become harder as the carbon content increased. This increased hardness results in rapid tap wear. If you have heat-treated thermal refined materials, then select a tap designed for thermal refined steels. This is a material whose hardness has increased through heat treating and tapping has becomes more difficult. Steels that are heat-treated to a hardness over 40HRC may not thread well with a general purpose tap and you may have difficulties with tool life or tap breakage. In the case of volume tapping of this type of material, special purpose taps for thermal refined steels should be selected. When tapping stainless steels, problems may occur like torn threads or material welding over the tap. Chips are rather hard and tended to be extended in length. This can cause chip ejection problems. LS-HT V Coating Coating 10~20 EH-HT EH-CT UH-CT Hard-to- Machine material Hard material (45~55HRC) Ultra hard material (55~60HRC) - ~5 Coating Coating ~5 ~5 SU-HT Stainless steels OX ~5 15

16 Material Features of material Recommendation by YAMA- WA Purpose/Spec. Surface treatment Recommended speed (m/min) Cast irons Wrought Aluminum, Aluminum diecastings The tap is prone to wear when cutting cast iron. Chip welding problems occur and the NG screw thread gauge problems tend to be an issue from tool wear. Cast iron produces powdery chips, while ductile iron has a tendency to produce longer chips. These materials have a melting point that easily causes chip welding problems on taps. They are soft and sticky materials. Unless you use the tap with high cutting performance and high geometry, you may easily create torn threads in your internal threads. Materials shrinkage problems occur easily in internal threads. FC-HT For cast irons NI N-CT FC HFICT-B HFICT-P LA-HT Carbide taps for cast irons Ultra fast tapping, blind hole use Ultra fast tapping, through hole use For Aluminum diecasting - 5~15 Coating Coating NI 20~50 20~50 5~15 AXE-HT AXE Coating 10~20 HFACT-B HFACT-P Carbide taps having coolant hole For blind hole use Carbide taps having coolant hole For through hole use Coating Coating 30~100 30~100 Coppers Brass The free machinability of this material is relatively good, but it is soft and flows freely so it is easy for internal threads to be created. Tap welding problems and internal thread shrinkage problems tend to occur easily. N-CT FC Carbide taps for cast irons - 5~15 Thermosetting Plastic It is easy to melt this material even at low temperatures because it is soft. It is necessary to use a tap with good cutting geometry. Internal threads have a high shrink ability. PL1 For thermosetting plastics NI 5~10 Magnesium Alloy Castings The material is easy to cut but fine chips can ignite. Pay attention to the heat of the chips. These materials are inferior in cold processing, so we do not recommend roll tapping. MG-HT For Magnesium - 5~15 16

17 Introduction of RE-HT 17

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20 Introduction of UH-CT/EH-CT Bag full of wisdom when you are in trouble 20

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23 Understanding the basics of series Hand taps and Carbide taps How to refer YAMAWA product catalog Please confirm the details from below link. Bag full of wisdom when you are in trouble YAMAWA introduces important tips about YAMAWA products while answering frequently asked questions by many of our customers. After reading these topics, we are sure you will find how easy and understandable the technique are. Please check the link below. 23

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