Introducing an Innovative Hybrid CBN Grinding Wheel for Enhanced Tap Threading Production Efficiency

What is a drill tap?

A drill tap is a versatile tool used in metalworking for drilling holes and simultaneously threading them to create a thread. It’s commonly used in applications where precision and speed are crucial, such as in the automotive industry, electronics manufacturing, and aerospace engineering.

Drill tap types

Drill tap bits primarily have three main types: the first type is High Speed Steel (HSS) taps, the second type is Carbide Steel Threading taps, and the third type involves taps with a coating. Tap coatings generally include titanium nitride coating (TiN), titanium carbide nitride coating (TiCN) titanium nitride aluminum and titanium aluminum nitride coating (TiAlN/AlTiN) and so on. Designed to improve the tap’s wear resistance, corrosion resistance, self-lubrication and dimensional stability and other properties, in order to improve its  screw tapping lifetime and  work efficiency.

Threading Taps Production

The tap manufacturing process begins by shaping the raw material into its fundamental form through turning, followed by milling the square edges. Subsequently, the part undergoes hardening and tempering to significantly enhance its mechanical properties through targeted alterations to the microstructure. Hardening involves heating the part, followed by rapid cooling and re-heating during the tempering phase; this step might be iterated multiple times for optimal results.

Following hardening, the focus shifts to hard machining, which includes grinding the flutes on a specialized flute grinding machine, then threading the tap on a thread grinding machine, and finally chamfering it on a dedicated chamfer grinding machine. These subsequent operations are typically executed in a single setup on advanced machine tools to ensure precision and efficiency. The use of modern laser technology allows for marking the final product, providing a clear identification.

The quality of the end product is directly influenced by both the choice of materials and the execution of these manufacturing processes. Using substandard materials, such as tool steel instead of high-speed steel, can lead to inferior products. Additionally, improper hardening and tempering, inadequate grinding techniques, particularly for relief-ground threads, and incorrect rake angles can result in taps that fail to perform effectively or degrade rapidly over time.

What cutting and grinding tools are used in the threading tap production process?

Taps require the use of a variety of tools and abrasive products in the production process, the following is a brief list of some of the main tools:

Cutting tools

Carbide Cutting Tools:  carbide cutting tools or carbide inserts can be used for initial cutting and shaping of taps.

Diamond tools: diamond tools may be required to provide higher cutting efficiency and machining quality.

Abrasive Products

Grinding Wheels: Grinding wheels are the core tool in the tap grinding process, used to grind the threaded portion of the tap and the chip removal groove. Depending on the processing needs, the type, specification and material of the grinding wheel will be different.

Single line grinding wheel: suitable for single line tap grinding machine, can grind high quality tap tooth type.

Multi-Line Grinding Wheel: Suitable for multi-line tap grinding machines, which can improve productivity by working with multiple grinding lines at the same time.

Diamond Pen Dresser: Used to correct the shape and accuracy of the grinding wheel to ensure that the tap tooth pattern ground meets the requirements.

Roller Dresser: In multi-line tap grinding machines, the roller dresser is used to extrude the molded grinding wheel to improve productivity.

Wheel Dressers: Flexible dressing options are available for dressing and adjusting grinding wheels to suit different machining needs.

Innovative Solutions for Tap Drill Threading Production

We now offer hybrid CBN grinding wheels that can replace both cutting tools and grinding wheels, allowing for direct threading and chip flute grinding. These CBN(cubit boron nitride) hybrid wheels excel in grooving high-speed steel taps, providing multiple advantages:

HIgher HSS Taps Production Efficiency

Thanks to their exceptional hardness and wear resistance, CBN hybrid wheels greatly extend the lifespan of grinding tools. This means less frequent replacements, reducing labor intensity for workers and substantially boosting thread taps production efficiency.

Optimized Processing Quality

Utilizing CBN hybrid wheels yields sharper edges on HSS thread taps, leading to superior product quality. This enhancement directly improves market competitiveness, giving businesses a valuable edge.

Enhanced Environmental Benefits

Hybrid CBN grinding wheels produce high-speed steel chips during grinding, which do not contaminate the grinding oil. This allows for easy disposal as general solid waste, significantly lowering environmental handling costs.

Customer Application Showcase of CBN Grinding Wheels in High-Speed Steel Drill Taps Grooving

 

Equipment and Environment

Machine: 5-axis CNC Taps Grooving Machine

Spindle Power: 11 kW

Wheel Specification: 200X75X10X13mm

Cooling Method: Oil cooling, recommended use of high-quality cooling oil

Processing Parameters

Workpiece Size:

Workpiece Size: M24X45 (tap diameter x flute length), four-edges taps

Thread Tap Material: W6Mo5Cr4V2 high-speed steel

Wheel Speed: 2750 RPM (approximately 28 m/s)

Grinding Depth: 1.65 mm, one-pass shaping

Feed Speed: 120 mm/min

Processing Time: Approximately 2 minutes 15 seconds per HSS Tap

Dressing and Maintenance

Dressing Frequency: Dress approximately every 100 taps, adjusting based on processing conditions. Set dressing allowance to 0.015 mm for long-term wheel effectiveness.

Grinding Precautions

Initial Break-In: Newly dressed CBN wheels should grind the first 1-3 tools at reduced speed (50%) to prevent burn.

Grinding Strategy: Employ a deep cut with a slow feed to ensure complete allowance removal in one pass while maintaining a lower feed rate.

Core Diameter Monitoring: Check the core diameter every 10-30 taps and adjust according to tolerance requirements due to potential changes from machine rigidity and grinding pressure.

Wheel Dressing: Use a roller for CBN wheel dressing when shape inconsistencies occur, setting the cutting amount to 0.015 mm.

Adjustable Linear Speed: Wheel linear speed can be flexibly adjusted between 25-30 m/s; lowering speed enhances wheel sharpness and extends dressing intervals, though this may increase wheel wear.

Coolant Selection: Use high-quality grinding oil to enhance processing efficiency, avoiding inferior substitutes like transformer oil.

In summary, the application of hybrid CBN grinding wheels in high-speed steel thread taps grooving effectively resolves many issues associated with traditional white corundum wheels while significantly enhancing processing efficiency, product quality, and environmental performance, marking a crucial technological innovation in modern precision manufacturing.

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