Longsheng

Thread taps is one of the core techniquesin mechanical manufacturing, and its accuracy and reliability directly affect the performance of the equipment. However, in the face of complex working conditions such as deep hole, blind hole and high hardness materials, traditional universal tap can not meet the requirements. Blind hole thread relies onbottom tapsto form deep cavity thread, but screw groove design restricts the ability of deep hole thread to be dedenuded, which can lead to tool wear and even hole diameter deviation due to chip blockage.

In addition, the diversity of material hardness (e.g. HRC 50 or above), thread tolerance (e.g. IT6 level) and processing environment (e.g.dry or wet cutting) further complicates selection. In this paper, different types of taps are studied in detail, which provides engineers with a life-cycle selection strategy based on materials, processes and costs, which can improve the efficiency and reliability ofprecision manufacturing.

What is a thread taps?

Threaded tapis a metal cutting tool used to process internal threads in pre drilled holes. The core feature is the spiral blade design, which converts the rotating motion into linear cutting motion,thus forming a thread structure in the inside of the workpiece that perfectly matches the profile, pitch and angle of the cone. It is usually made ofhigh-hardness alloy steel(e.g.high-speed steel, hard alloy) to ensure abrasion resistance and machining accuracy of the cutting edge and is widely used in mechanical manufacturing,aerospace and other areas requiring precision threaded connections.

What Are the 3 Fundamental Types of Thread Taps?

Taper taps

1.Core parameters

• Main cone: 8-10 teeth (compatible with 60°/55° thread angle).
• Total effective tooth height: ≤ 70% of total thread height.

2.Applicable scenarios:

• Blind hole thread machining(required when depth to diameter ratio greater than 1:1).
• Plastics such asaluminum alloy/low carbon steel.

3.Key Features:

• Gradual taper design: The first 5-7 teeth assume 80% of the guiding effect, reducing the risk of chip breakage at the bottom of blind hole.
• Type R blade geometry: Recommended for ISO M3-M10 coarse thread to optimize shear force distribution.

4.Drilling requirements:

• Aperture=thread main diameter-(1.3 x pitch).
• Depth= full thread length+0.5 x pitch.

Plug Taps

1.Core parameters

• Conical length: 3-5 teeth (taper angle 60°± 5°).
• Excessive cutting: Retain 0.05-0.1mm thread correction amount.

2.Applicable scenarios:

• Punching Machine Threaded Repair (Accuracy Level IT7-IT9).
• Processing oftitanium alloys/ Hyperalloys in aerospace industry.

3.Key Features:

• Revised tooth profile design: 15-20 teeth a radial correction 0.02mm.
• HF coating process:TiAlN coating thicknessis 3-5 μm, compared to uncoated material can improve 300%.

4.Process window:

• Recommended feed rate: 0.08-0.15mm/rev (for hard materials).
• Speed limit: ≤ 800rpm (HSS material).

Bottom Taps

1.Core parameters:

• Ultimate taper: 1.5 teeth (specially designed asymmetric taper).
• Cutting cone length: ≥ 120% of the total thread height.

2.Applicable scenarios:

• Ultimate deep blind hole (hole depth>3 multiply thread diameter).
• Medical implant316L stainless steel processing.

3.Key Breakthroughs (Third Order Cutting System):

• Stage 1: Conical guide rail (3 teeth).
• Stage 2: Parallel cutting (6 teeth).
• Stage 3: Fine-tuning threads (remaining teeth).
• ELID electrolytic grinding technology: Blade R ≤0.08mm, surface roughness Ra ≤0.4 μm.

4.Process specifications:

• Drilling depth=thread length+1.8 multiply pitch (cast iron).
• The coolant flow rate ≥ 15L/min.

Which Tap Type is Best for Thread Starting?

According to the technical principle of thread machining and LS company's engineering practice experience, taper tap is the most suitable type of thread starting,the following is a detailed technical analysis:

Technical advantages of tapered tap

1.A step-by-step approach to design

The taper of a conical tap (usually 8°-10°) allows asegmented cutting toolto cut into the workpiece (cutting depth of the first tooth ≤ 0.1mm to 0.3mm), gradually directing the faucet to the centre and stabilizing the cutting force through the first few threads. This design is particularly suitable forsoft metals (aluminium, copper, low-carbon steel)and significantly reduces the risk of tap breakage or thread fracture due to sudden force.

2.Self-correcting ability

Cone structure of the conical tap can help to adjust the center offset of the hole automatically and reduce the difficulty of manual calibration,especially for blind hole or deep hole processing.

3.Low torque start

When processing soft metal material, the tapered faucet can be gradually cut to disperse the cutting load. If you use a carbide tap (with a recommended speed of speed up to 1500 RPM), you can further improve efficiency without sacrificing stability.

Application guidelines for Bottom Tap in exceptional scenarios

Although conical taps are very versatile, you will need to use a bottom taps:

1.Quenched steel or cast iron

The material is highly brittle, and repeated cutting of the conical tap can lead to localized stress concentration that can cause the blade to break. The straight edge design of the bottom taps can tap directly into the bottom of the hole,reducing the risk of secondary cutting.

2.Precision thread repair

Bottom thread depth control is more accurate and suitable forrepairing pre-drilled threadto avoid excessive cutting, with 98.5% thread qualification rate (IT7 level).

3.High-precision machine tool environment

LS companyis a supplier of high rigidity equipment that can be programmed to precisely control the feed speed ofthe bottom valve to a micrometer level tolerances.

Critical Process Parameters

Tool Type	Material	Rotational speed (rpm)	Feed rate (mm/rev)	Cooling method
Taper taps	Aluminum alloy 6061	1500	0.2	Dry cuttin
Taper taps	Cast iron HT250	800	0.1	Emulsion (5%)
Bottom taps	45# steel	400	0.05	Oil mist cooling
Bottom taps	Ti-6Al-4V	600	0.03	Nitrogen atomization

How to solve the blind hole challenge with bottom taps?

Geometric Structure Innovation: Flat Bottom Design+30° Spiral Angle

LS Company's Bottom Tapsfeatures a unique flat-bottom blade design compared to traditional conical taps:

1.Bottom residue free: The flat bottom structure can be cut directly into the bottom of blind hole, eliminating the bottom residue accumulation problem caused by traditional tap cones.

2.Optimization of chip removal channels: With a30° helix angle design, the chip removal space is expanded. The chip removal efficiency of refractory materials such as titanium alloy can be improved by 60% through internal cooling channels, avoiding the risk of tap rupture due to chip blockage.

High-performance materialadaptation

For high strength materials such astitanium alloys and nickel based superalloys:

1.Cobalt high speed steel material: HC65 high hardness coated tap withTiAlN or AlCrN abrasionresistant coating, high temperature resistance by 30%,high torque and frictional heat from blind hole processing.

2.Gradient hardness design: Handle hardness is HRC30-40 (easy to clip), blade maintains high strength HRC65, balance toughness and abrasion resistance.

3.Increasing abrasion resistance:

• Coating technology:TiAlN (Al 70%-75%, Ti 25%-30%) coating thickness is 3-5 μm, friction coefficient decreases to 0.12.
• Nitrogen treatment: Surface hardness increased to HRC 70 and abrasion resistance increased threefold.

4.Application verification of Information

• Titanium alloy processing:Tool life>500 pieces (M6 × 1 thread, cutting speed 600rpm, feed 0.05mm/rev), surface integrity Ra=0.4 μm, arc centrifugation ≤0.015mm.
• Nickel based superalloys:Cutting force Fc=18-22kN (compared to 35-40kN for HSS cutting) with a main cutting angle of 45° to reduce chip height to less than 0.02mm.

What are the hidden costs of choosing the wrong tap?

Classification and Quantitative Analysis of Hidden Costs

Cost type	Cause of occurrence	Industry Impact Cases	Annual average loss estimation
Cost of tool wear and tear	Conical taps areused for hard materials, resulting in a fracture rate of up to ↑300%.	The M6 faucet is broken at a cost of $50+/time, with an average monthly loss of 200 pieces in the automotive production line.	$10000/month
Thread scrap cost	Incompletetapping of blind holesleads to bolt loosening (recall risk).	A car company is recalling 500 thousand vehicles for thread defects, causing more than $200 million in damage.	A single recall can reach $5 million+
Cost of wasted working hours	Frequent tool changes result in production line downtime ($800+per hour).	Manufacturing companies are losing $3 million a year in downtime because of short life of the tool.	$2.4 million per year (8 hours/day x 365)

How LS company technology avoids these costs

1.Root cause of tool wear and its solution

Root cause of the problem:

• Taper taps in castiron/quenched steelhave a concentration of stress due to multiple squeezing and cutting processes.
• Failure to use coated tap results in increased frictional heat (hardness decreases by 30% when blade temperature exceeds 800 °C).

LS technical countermeasures:

• Bottom Taps:Flat bottom designcuts directly into the bottom of blind hole to eliminate stress mutations and reduce fracture rates by 90%.
• TiAlN/DLC coating: Friction coefficient ≤ 0.2, 40% reduction in cutting temperature, 5-fold increase in lifetime (e.g. M10 tap HRC58 steel life from 200 to 1000 pieces).

2.Threaded end-of-life technology control

Root cause of the problem:

• Traditional tapers have incomplete threads at the bottom of blind hole (not up to effective engagement length) due to poor chip removal.
• Software compensation error not calibrated (e.g. cumulative pitch error>0.05mm).

LS technical countermeasures:

• 30° Spiral angle + internal cooling channel:Increases chip removal efficiency by 60% to ensure integrity of the thread at the bottom of the blind hole.
• Laser calibration system: 100% detection of pitch error (≤± 0.01mm) prior to production, with real-time closed-loop compensation function forCNC machine tools.

3.Optimizing paths to waste time at work

Root cause of the problem:

• Failure to adjust speed/feed parameters according to material, resulting in accelerated tool wear.
• In the process of dry cutting,a large number of chip blockage will occur, especially aluminum materials.

LS technical countermeasures:

• Intelligent parameter recommendation engine: Automatic speed/feed matching after input/aperture (e.g. cast iron M8 tapping parameter: N=500 RPM,F=0.15mm/rev).
• High-voltage cooling (MQL) system: Instant atomization chip, chip cleaning downtime reduced by 70%.

4.Industry validation and economic benefits

Car industry case studies:

• Pain spot: Blind hole machining in gearbox housing costs $1.2 million a year due to a 15% threaded scrap rate.
• LS solution: With bottom taps+TiAlN coating, waste rate reduced to 2%, saving $1.18 million annually.

Aerospace case studies:

• Pain: Titanium alloy blind hole tapping wire production line due to tool breakage outage of 12 hours/month.
• LS scheme: Cobalt basedhigh speed steel bottom taps (HRC 65)+internal cooling design,continuous processing of 800 holes without fault.
• Efficiency improvement: Production capacity increased from 150 to 220 units pershift.

How to match the type of tap with the hardness of the material?

Dynamic relationship between material hardness and cutting force

According to the ISO 6336 shearing force formula, for every 10HRC increase in material hardness, the shearing force increases by approximately 25%. This directly affects tap selection strategies:

• HRC ≤ 20 (soft metal): cutting force F=50-80N mm
• 30 ≤ HRC ≤ 45 (medium hard steel): F=150-300 N mm
• HRC ≥ 50 (hard alloy): F=500-1200 N mm

Hierarchical matching technology scheme

Soft metal processing (aluminum/brass HRC 8-15)

1.chip removal Advantage ofSpiral Slot Tap

• Spiral angle design: Inclination angle of 30°-45° allows the chip to be emitted along the spiral line, with a 60% improvement in chip discharge efficiency compared to straight grooves.
• Vibration suppression characteristics: Groove structure effectively disperses cutting force, axial vibration reduced by 40%.

2.Practical parameters:

• Speed: 1200-2,000rpm (aluminum alloy).
• Feed rate: 0.05-0.1mm/rev (brass).

3.Application of special coatings

• Diamond coating reduces friction coefficient to 0.08-0.12.
• A3C product processingcase: 35% increase in processing efficiency and reduction ofsurface roughnessRa from 3.2 μm to 0.8 μm.

Medium Hard Steel Processing (HRC 30-45)

1.rigidity advantage of straight groove tapers: The radial stiffness of straight groove tapers is 3 times that of spiral groove in perforation processing, eliminating axial tension deviation caused by spiral groove.

2.coating technology

• TiAlN (titanium aluminum nitride) coating: Hardness 18-22GPa, temperature resistance 800 °C.
• MoS2 coating: Friction coefficient<0.05, especially fordry cutting conditions.

3.process optimization points

• Segmental percussion: HSS (HRC 60-62) for the first percussion and TiN coated tap percussion for the second.
• It is suggested to use the tap design with an axial groove fordeep hole machining.

Ultra-hard alloy processing (HRC 50-65)

1.Geometric innovation for bottom taps

• Bifurcation design: 3-5° front cone angle, 15-20° helix angle in cutting area.
• Case in point: Blade breakage decreased from 12% to 2.5% during WC Co carbide processing.

2.Coating system

• TiAlN multilayer membrane (3-5 μm): Temperature resistance 1200 °C, 5-fold increase in 5 resistance.
• CrN/TiN composite coating:300% longer service life under dry cutting conditions.

3.Special processing parameters

• Speed: 500-800rpm (to avoid cutting heat accumulation).
• Feed speed: 0.02-0.03mm/rev (minimal lubrication).
• Cooling method: High pressure gas cooling (pressure 6-10MPa).

How can LS company extend the lifespan of tap by 200%?

1.Updating cutting media

Nanoscale Extreme Pressure Additives:Leading the lubrication performance improvement industry, suitable for stainless steel processing usingspecial chlorine-containing cutting fluid, with a three-fold increase in tool life (e.g. from 80 to 240 bolt holes in an automotive company).

Intelligent oil supply system: LS platform monitors cutting fluid concentration (accuracy ± 0.1%), temperature (± 1 °C), pH value, adapts to optimal conditions and reduces friction loss online.

2.Wear dynamic monitoring

Optical 3D detection+intelligent warning: real-time monitoring of tap wear (accuracy 0.01mm), triggering alarm when exceeding 0.1mm:

• Main wear (0.02-0.05mm): Automatic optimization speed (15%-20% reduction) and feed speed (10% reduction).
• Critical wear (≥ 0.1mm):Initiate grinder repair processto restore edge to μ level accuracy.
• The implementation of dynamic monitoring resulted in a 45% decrease in annual procurement cost and a 70% decrease in downtime, according to LS platform data.

3.Optimizing storage

High speed steel (HSS) taps are prone to hydrogen embrittlement fracture in humid environments, leading to sudden failures. LS company long-term stability of materials through vacuum packaging technology and constant temperature storage:

1.Vacuum packaging process:

• Residual moisture to adsorbed by molecular sieve and oxygen content was controlled at<1ppm.
• Laser coding and QR code tracing ensure 80% warehouse traceability efficiency.

2.Constant humidity storage: 20 ± 0.5°C Constant warehouse + RH <40% humidity control to avoid material phase transformation (martensitic transformation temperature Ms=250°C).

3.Lifetime verification: After 3 months, the tensile strength of vacuum-free HSS taps in hot and humid conditions decreased by 18% andLS standard storage was extended from 12 months to 36 months.

Summary

In precision machining, the key to guarantee thread quality and machining efficiency is to choose the appropriate thread cone. Threaded taps are divided into three main types: Taper Tap, Plug Tap and Bottom Taps. Among them, the bottom taps is designed to be the core tool of blind hole machining (such asaerospace fasteners,automobile gearbox housing thread, etc.) with its unique flat rail structure and 30 spiral lead angle.

LS company relies on intelligent selection system andCNC processing technologytoprovide customers with customized taps solutionsto reduce the cost of trial and error. In addition, LS's process database integrates more than 2000+ industry cases from around the world, allowing real-time optimization of cutting parameters such as speed and feed rate, ensuring a 30% improvement in processing efficiency while achieving IT7 level thread accuracy. Whether it's mass production of standard parts or customization of irregular holes, LS'technical integration capabilityprovide customers with a full chain of technologies from design to delivery.

Disclaimer

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FAQs

1.Can I use a bottom tap without a guide hole?

In most cases, guide hole can be omitted, but must be ≥ M6 in aperture and aspect ratio ≤ 15:1. For small holes (45), the hole must be pre-drilled.

2.Why is the price of spiral taps three times higher?

Spiral Tap are complex to manufacture and require five axis CNC grinding (approximately 45 minutes/piece) to match specialized coatings (e.g. TiAlN), while Straight Tap require only three-axis machining (8 minutes/piece).

3.How to identify counterfeit HSS taps?

Genuine high-speed steel (HSS) taps show crimson splinter sparks in spark testing, while counterfeit products (such as carbon steel) usually have bright yellow splinter sparks, the original surface grinding textures is fine.

4.What type of tap is recommended for processing aluminum materials?

Recommended straight groove tap+dry cutting,aluminium is highly plastic and prone to long strips. The large rake angle (25-30°) of the straight slot tapers will reduce cutting resistance. In dry cutting conditions, the chip is expelled directly to avoid entanglement (due to chip discharge discharge, spiral groove tapers can easily create scratches the workpiece surface).

Resources

Machine taper

Unified Thread Standard

Threading (manufacturing)