There are nine causes of screw tap failure

  1. Poor quality of tap: main materials, cutter design, heat treatment, machining accuracy, coating quality, etc.

For example, if the dimensions at the transition point of the tap cross section are too different or there is no designed transition angle resulting under stress concentration, it is easy to break when used.

The cross section transition to the junction of the handle and blade is too close to the welding mouth, which results in the superposition of complex welding stress and the stress concentration at the cross section transition, resulting in a larger stress concentration, leading to the tap breaking in use.

For example, the heat treatment process is improper.

In the heat treatment of tap, the tap may crack if it is not preheated before quenching, overheated or over-burnt, not tempered in time and cleaned too early.

  1. Improper selection of tap:

High quality screw tap should be used for tapping parts with too high hardness, such as cobalt high speed steel tap, hard alloy tap, coating tap etc. In addition, different tap designs are used in different work situations. For example, the number of chip slots, size, Angle, and so on of the tap affected chip removal performance.

  1. No matching between tap and processed materials:

With the increase in new materials and the difficulty of processing, in order to meet the market demand, the variety of cutter materials is also increasing. This needs to select a suitable tap product before tapping.

  1. Small bore size of bottom hole:

For example, when machining M5 x 0.5 thread of black metal material, the cutting tap should be used to make the bottom hole with a 4.5mm diameter bit. If the 4.2mm diameter bit is misused to make the bottom hole, the cutting part of the tap must be increased when tapping, so that the tap will be broken. It is suggested to choosing the correct bottom hole diameter according to the type of tap and the material of tapping.

  1. Material problem of tapping parts:

The tapping material is not pure, and there are some hard points or pores, causing the tap to lose balance and break.

  1. The machine does not meet the requirements for the accuracy of tap:

Machine tool and clamping body are also very important, especially for high-quality taps, only certain precision machine tool and clamping body can give play to the performance of taps. Common is lack of concentricity. At the beginning of tapping, the tap is incorrectly positioned, that is, the spindle axis is different from the center line of the under hole, and the torque is too large during tapping, which is the main reason for the tap breaking.

  1. Cutting fluid and lubricating oil has poor quality:

The cutting fluid and lubricating oil have problems in quality. The quality of the processed product is prone to defects such as burrs, and the service life is also greatly reduced.

  1. Unreasonable cutting speed and feed amount:

When there are problems in machining, most users will reduce the cutting speed and feed amount, so that the propulsive force of the tap is reduced, and the thread precision of its production is greatly reduced. As a result, the roughness of the thread surface is increased, the thread aperture and thread precision are uncontrollable, and the problems like burrs are inevitable. However, if the feed speed is too fast, too much torque will cause the tap to break. The cutting speed of machine attacked is generally 6-15m/min. The tempered steel or hard steel material is 5-10m/min. Stainless steel is 2-7m/min; Cast iron is 8-10m/min. In the same material, the diameter of the tap is smaller and higher, while the diameter of the tap is larger and lower.

  1. The operator’s skills and skills do not meet the requirements:

Above these problems, need operation personnel to make judgment or feedback to technical personnel. For example, when processing blind hole threads, when the tap is about to contact the bottom of the hole, the operator did not realize that, still press the tapping speed when it did not reach the bottom of the hole, or if the chip removal is not smooth forced feed causes the tap to break. Operators are advised to being responsible.

It can be seen from above that there are various causes of tap fracture, including machine tool, fixture, workpiece, technology, chuck and cutter.

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When the tap wears out, we can use our PG-Y3C screw tap grinder or PG-600 universal tool grinder. But if it breaks, you can only replace it with a new one. In the use of tap, we should try to avoid the above reasons to prevent the tap fracture caused by losses.

Why are so many customers buying universal tool grinding machines now?

The universal tool grinder has been a hot seller in recent years. A large part of the reason is that more and more people have realized its importance and its advantages. Why don’t we take the worn-out tools to a professional organization for grinding and choose to buy the Universal Tool Grinder for grinding?


What kind of tools need grinding?

Most cutting tools require grinding and are designed with future grinding in mind.

The small-diameter taps and most of the indexable blades give up the grinding due to their low price and relatively high grinding cost.

Some of the machined cutting tools of the groove can not be sharpened because the diameter should be reduced after grinding.


Why do tools need sharpening?

Tool grinding is a low carbon activity to reduce production cost and resource consumption.


Key points of tool grinding

Sharpen the dull and worn original blade, and grind the new blade on a better matrix.

The wear of the guide part must be taken into account comprehensively for hole cutting tools.

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If you are interested in our products or want to be agent of our tool grinding machines, please contact us. We’ll give you the best price.

How to deal with tool wear?

Tools is arguably the most commonly used key component, and it’s also easy to wear out. How to reduce the tool wear is very important.

Common causes of tool wear:

All components of the cutter will be worn by milling and shaping materials. If one of the components of the cutter is damaged, such as the blade tip, steel body, gasket or snap spring, the entire cutter should be replaced to prevent damage to the relatively expensive tool holder system. Moreover, the replacement of the cutter holder system is more complicated. Therefore, how to reduce the tool wear is very important.

How to deal with tool wear with drill bit grinder

Common tool wear includes the following reasons:

  1. Incorrect installation;
  2. Use components from different manufacturers;
  3. Choose the wrong type of cutter (different type of cutter should be selected for different types of machine);
  4. Milling planer materials are bonded and continuously accumulated on the cutter, which is generally caused by incomplete cleaning;
  5. Insufficient water supply in the sprinkler system inside the casing of milling plane.

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How to reduce tool wear?

Tool wear is unavoidable, but can at least be minimized. Adequate water supply is the basic premise to ensure normal rotation of cutter. According to the material selection of milling cutter, can also optimize the use and reduce wear.

  1. Select the suitable working condition milling tool;
  2. Pay attention to daily thorough cleaning;
  3. Regularly check the cutter, and timely find and deal with the wear or damage of components;
  4. Regular maintenance and inspection of sprinkler system;


Only through proper maintenance can the wear of key parts be minimized, thus greatly saving cost and ensuring efficient operation of the machine. If the cutter is only slightly worn, a cutter grinder can completely repair the wear. The use of universal tool grinder can reduce the waste of many tools, saving cost and time.

Introduction to the hole cutting tools which commonly used in NC machining

Hole cutting tools used in NC machining are:

  • High speed rake angle oil hole twist drill;
  • Helical groove Centre Drill;
  • 3 – flute Solid Carbide Drill;
  • S-type carbide drill bit;
  • Indexable carbide bit;
  • Carbide double edge boring tool;
  • Carbide single edge fine boring tool

In addition, some special industries of NC machining have their own often used hole tool. Such as the printed circuit board industry micro-cemented carbide integrated drill, refrigerator compressor industry integrated cemented carbide precision reamer and step twist drill.

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Compared with the tools used in ordinary machine tools, CNC tools have many different requirements, mainly with the following characteristics:

(1) good rigidity (especially rough tool), high precision, low seismic and thermal deformation; Good interchangeability, easy to change tools quickly;

(2) high life, stable and reliable cutting performance;

(3) the size of the tool is easy to adjust, so as to reduce the adjustment time of tool changing;

(4) the tool should be able to reliably break the scrap or roll the scrap, so as to facilitate the scrap removal;

(5) serialization and standardization to facilitate programming and tool management.


When your tool is blunt, choosing to use a tool grinder can be very useful. Our drill bit grinder can repair all kinds of tools (drill bit re-sharpener, end mill re-sharpener, screw tap re-sharpener, lathe tool grinder, saw blade sharpener, universal(all-purpose) cutter grinder, universal(all-purpose) tool grinder, chamfer, air tapping machine, gear chamfering machine, universal(all-purpose) head, rotary table, etc. ). If you want to buy our products, please send us your requirements and cutter parameters first. We will help you choose the corresponding model.

Glad Tidings: PURROS’s Universal Tool Grinder successfully entered the Kuwaiti market

Kuwait, officially the State of Kuwait is a country in Western Asia. Situated in the northern edge of Eastern Arabia at the tip of the Persian Gulf, it shares borders with Iraq and Saudi Arabia.

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PURROS’s Universal Tool Grinder 600F

Congratulations to PURROS Machinery Co., Ltd. that PG-600F Universal Tool Grinder to successfully enter the Kuwaiti market.
The success in Kuwait market, fully reflect powerful competitiveness of PURROS drill grinding machine in drill grinding industry of Kuwait, at the same time, it has also enhanced our brand awareness in the throughout Middle East.
Pursue higher quality to build more perfect products and continue to explore overseas markets, which is the responsibility and goals of the PURROS Machinery Co., Ltd. We will continuously improve product quality and better serve global customers. Thank you!

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PURROS One-stop supplier of drills and grinders

One-stop supplier of drills and grinders.
We provide you with a professional and complete solution of grinding drill bits.

Our products: drill bit re-sharpener, end mill re-sharpener, screw tap re-sharpener, lathe tool grinder, saw blade sharpener, universal(all-purpose) cutter grinder, universal(all-purpose) tool grinder, chamfer, air tapping machine, gear chamfering machine, universal(all-purpose) head, rotary table, etc. Continuously invent, improve in our management, provide professional and high quality products to satisfy and serve our globe customers’ needs.

Everything you need to know about Drill Bit Grinders

What is Drill Bit Grinder?

Drill bit grinder is a handy machine that is used to sharpen drill bit, so that makes you easily bore holes in a huge number of materials. Whether the drill bit is made by HSS or Carbide Steel, the drill bit grinder can do the job because of it has two types of grinding wheel of options: CBN and SD, CBN for HSS drill bit; and SD for Carbide Steel drill bit. Cutting-edge technology is used for the manufacturing of drill bit grinding machine as it ensures precision and accuracy when you use drill bits to bore holes in any materials whether items are metals or hardwoods.

Who can use a Drill Bit Grinder?

Any person, whether a pro at grinding or a novice. You can use this machine to sharpen drill bit in any situation and anywhere. It doesn’t require expertise or any particular skill set. Only the basic learning of functions and instructions of this machine is required for its operation.

Types of Drill Bit Grinders

There are numerous types of drill bit grinders available in the market. Each type has its own set of features and specifications. The accuracy and precision depend on the type. With the wide range of drill bit grinders available, you can easily find a type that is according to your needs. The most popular drill bit grinders are portable drill bit grinders as they can be easily carried from one place to another.Continue reading

How to bring dull drill bit back to live?

Everything on a drilling rig directly or indirectly assists the bit in crushing or cutting through objects. Although there are almost limitless ways a drill bit can be used, which can either be for grinding a rock, puncturing a hole through irons or drilling through aluminum, all this are only possible when the bit is new and sharp. Most bits work by scraping or crushing through objects, or even both, while some bits known as hammer bits’ pound’s object vertically in much the same fashion as a construction site air hammer, and that is possible because of its general rotational motion.

Most drill bits used in making jewelry becomes dull with normal usage, and the worn cutting edges often make tasks even more difficult, resources consuming and can cause expensive accidents, which includes damage to jewelry and gemstones or even an injury to the body.

When a bit becomes excessively dull or stops making progress; the recommended thing to do is to change it, but what if there is no replacement at the moment or there is a limited supply of drill bit? The next thing to do is sharpen it.

Proper maintenance of a drill bit includes keeping it clean, sharp, and consistent usage at the bench.

Follow the outlined steps below carefully, and learn how to sharpen drill bits by hand. By the end of this article, you will inevitably turn your used, dull, and useless drill bit back into a hole blasting instrument at its prime.Continue reading

Exactly what is the tool and cutter grinder?

A tool and cutter grinder is utilized to develop milling cutters and also device little bits together with a host of various other reducing devices.

It is an exceptionally flexible device made use of to execute a range of grinding procedures: surface area, round, or facility forms. Nevertheless extremely automated Computer Numerical Control (CNC) equipments are ending up being progressively typical as a result of the intricacies associated with the procedure.

The table relocates longitudinally as well as side to side, the head could pivot along with being flexible in the straight airplane, as noticeable in the picture. This versatility in the head permits the vital clearance angles demand by the different cutters to be attained.Continue reading