Precautions for use of high speed steel drill bits

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1. Check whether all parts of the drilling machine are normal before use;
2. The high-speed steel bit and the workpiece must be clamped and tightened, and the workpiece cannot be held by hand, so as to avoid injury accident and equipment damage accident caused by the rotation of the bit;
3, focus on the operation, rocker arm and drag plate must be locked before work. When loading and unloading the drill bit, do not use hammer and other tools or objects to knock, and do not use the spindle up and down to hit the drill bit, should use a special key and wrench to load and unload. A drill chuck cannot be used to hold a bit with a tapered handle;
4, when drilling thin plate need to be padded with wood, and use a small amount of feed. When the dill bit is about to drill through the workpiece, the feed should be appropriately reduced. Gently apply pressure to avoid breaking the drill bit, damaging equipment or causing an accident;
5. It is prohibited to wipe the drilling machine and remove iron scraps with cotton yarn and towel when the high-speed steel drill bit is in operation. After work, the drilling machine must be wiped clean, cut off the power supply, stacking parts and keep the working site neat and tidy;
6. When the cuttings are wound on the workpiece or drill bit, the high speed steel drill bit should be raised to make it cut off, and special tools should be used to remove the cuttings after stopping drilling;
7. The drill must be drilled within the working range of the drilling machine, and the drill bit exceeding the rated diameter cannot be used;
8. When changing the belt speed change position, the power supply must be cut off;
9, in the work of any abnormal circumstances, should stop the machine for processing;
10. Before operation, operators must be familiar with the performance, use and precautions of the machine. Operators who are not familiar with the machine are strictly prohibited to operate the machine alone.

What are the differences between machining center and drilling & tapping center?

Now with the vigorous development of industrial manufacturing industry, various industries are using machining center equipment in abrasive tool processing. Many customers still know machining center better. When someone says drilling and tapping center, many people are not clear. Today, let’s talk about the similarities and differences between machining center and drilling & tapping center.


Same points


Machining center and drilling and tapping center, literally, have the word “center”. It can be seen that they are both metal cutting machine tools and CNC processing equipment. In terms of style and function, machining center and drilling and tapping center are very similar.




  1. Application: Machining center is widely used, mainly for processing plane, surface and other shapes of equipment. Drilling and tapping centers are mainly used for drilling and tapping. Machining center can be used for milling, but machining center can only do slight milling, because the power of drilling and tapping center spindle is not very large, it can not carry out heavy milling.
  2. Shape: drilling and tapping center is smaller than machining center in shape.
  3. Tool library selection: machining center is mainly a hat-type tool library and a disc-type tool library, while drilling and tapping center is mainly a turret-type tool library and a turret-type tool library.
  4. Fast moving speed: drilling and tapping center adopts linear guide rail, which is faster than machining center. The machine tool processing efficiency is obvious.
  5. Price: As far as machinery is concerned, the price of machining center is higher than that of drilling and tapping center.
PURROS Multiaspect Special Purpose Machine

PURROS Multiaspect Special Purpose Machine

Many machinery plants choose to use drilling and tapping centers. Both drilling and tapping centers and machining centers can cause tool damage and wear. In some cases the tool has not been completely damaged, many can be used after repaired with the drill bit grinding machine. For example, worn bits can be repaired with a drill bit sharpener for more than 90% of worn bits. The repaired bit can be reused. We produce a variety of tool grinding machines, you can choose the right tool grinding machine according to your needs to complete the repair work.

What is the reason for the rising price of cutting tools?

Why do the major brands of cutting tools in the same price? It is understood that the rise in the price of raw materials is the main reason for the rise in the price of tools.

In 2017, the price of raw materials for cemented carbides has been rising continuously, leading to a sharp rise in the production cost of enterprises producing cemented carbides. While the annual prices of cemented carbide products have not increased much, carbide tool manufacturers generally face the embarrassing situation of low profits. At present, manufacturers of cemented carbide cutting tools have been unable to bear the soaring cost of raw materials. At the end of the year, many cutting tools manufacturers were forced to raise their prices. Among the rising prices of raw materials, tungsten and cobalt rose the most.

Of course, there are many reasons for the price increase. The increase in raw material costs is only one of the reasons. In recent years, with the trend of consumption upgrading, the public demand is constantly increasing, and high quality products are accompanied by high prices. Therefore, the price increase will come naturally.

PURROS PG-F4N Multi-Purpose Grinder

PURROS PG-F4N Multi-Purpose Grinder

PURROS ‘Multi-Purpose Grinder for mill and drill is largely capable of repairing damaged cutting tools, allowing your tools to be reused at cost savings.

Coating and grinding technology of tools

In the regrinding process of the drill bit or milling cutter, cutting lip should be ground to remove the original coating, so the grinding wheel used must be of sufficient hardness. Regrinding pretreatment of cutting lip is crucial, not only to ensure that the geometric shape of the original cutting lip after regrinding can be fully and accurately retained, but also to require regrinding to be “safe” for PVD coated cutting tools. Therefore, unreasonable grinding techniques must be avoided (e.g., rough or dry grinding that results in tool surface damage due to high temperature).

All existing coatings can be chemically removed before the tool is recoated. Chemical removal methods are commonly used for complex cutting tools (such as roller burnishing tool, rotary broaching tool), repeatedly coated tools, and tools that have problems due to the thickness of the coating. Chemical removal of coatings is usually limited to high speed steel cutters because it can damage the hard alloy matrix. Chemical removal of coatings will remove cobalt from the hard alloy matrix, resulting in loose surface of the matrix, generation of pores and difficulty in recoating.

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At present, the typical recoating process is to remove the original coating by regrinding process.

The most common tool coatings are TiN, TiC, and TiAlN. Other superhard nitrogen/carbide coatings are also available, but not very common. PVD diamond coated tools can also be reground and recoated. The cutter should be “protected” from critical surface damage during recoating.


It is often the case that after the user has purchased an uncoated tool, a coating is applied when the tool needs to be reground, or a different coating is applied on a new tool or reground tool. In many cases, we remove the TiN coating from the cutter and reapply the TiAlN coating. Because users want to improve the production efficiency of tools, TiAlN coating tools are faster and more resistant to high temperature than TiN coating tools. Users often wish to get new coated tools with better performance from tool makers. So ‘tool makers may have to redevelop a new tool with a TiAlN coating’. But compared to redeveloping the new cutter, it takes much less time to remove the TiN coating from the old cutter and apply the TiAlN coating.


Just as a cutting tool can be reground multiple times, cutting lip of a cutting tool can be recoated multiple times. “The key to improve the performance of the tool is to obtain a coating with good adhesion on the surface of the tool that has been reground.” With the exception of cutting lip, the rest of the surface of the cutting tool may not need to be removed or recoated during each trim, depending on the type of cutting tool and the cutting parameters used in machining. Roller burnishing tool and rotary broaching tool are the tools that need to be removed from the original coating for recoating, otherwise the performance of the cutter will be reduced. When recoating without removing the old coating, a thickness is added to the outside diameter of the cutter. In the case of drill bit, that means the drill hole is getting larger. Therefore, the influence of the additional thickness of the coating on the outside diameter of the cutter must be considered.


A drill bit can be recoated 5 to 10 times without removing the old coating, but will face serious errors after that. The coating thickness is not a problem within the error range of 1. However, the effect of coating thickness must be considered when the error is within the range of 0.5-0.1 m. As long as the thickness of the coating does not become a problem, the recoated, reground cutter may well be better than the original performance.

What are the differences between normal wear and abnormal wear of cutting tools?

Tools in the production process will encounter a variety of problems, the master of mechanical processing often asked, “why can’t I use this cutter for so little time?

Under the condition of high temperature, the tool will be gradually worn and damaged by the chip friction of the workpiece. But how can we distinguish the normal wear from the abnormal wear?


Normal wear and tear


Normal wear refers to the wear pattern that gradually expands with the increase of wear over time. There are two aspects that are clearly indicated as normal wear.

  1. Front wear: there is crescent depression wear at the front edge of the blade, which is formed by friction and high-temperature and high-pressure action during chip outflow.
  2. Main rear wear: the main rear wear is divided into three areas. It is assumed that blade tip wear C zone, and wear loss VC is caused by low strength and concentrated temperature near the blade tip. In the intermediate wear area B, except for uniform wear amount VB, the maximum wear amount in the severe wear area is VBmax, which is caused by friction and heat dissipation difference. The boundary wear N zone, where the cutting edge and the surface to be processed wear VN, is caused by high temperature oxidation and surface hardening.


Abnormal wear


Abnormal wear is usually caused by tool damage caused by impact, uneven heating and improper use during cutting.

  1. Crushing: small crushing on the cutting edge is caused by low cutting edge strength, impact and hard points in cutting layer.
  2. Cutting edge: it is easy to crack at the cutting point or cutting point, with brittle cutting material, low cutting strength and heavy cutting load.
  3. Thermal cracking: small cracks in the vertical cutting edge are caused by uneven cutting temperature, discontinuous cutting and uneven pouring of cutting fluid.
  4. Collapse: in the process of cutting, the cutting edge lost its cutting performance under the action of high temperature and high pressure, resulting in the collapse of the front or tip and cutting edge.

PURROS there are many sharpening machines. If your tools wear a little bit, you can use our tool grinder. Before you buy a new tool, you can use a grinded tool for a period of time to save manufacturing costs.

If you do not know our products, please feel free to ask. Our products include: 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, portable multi-purpose grinder for mill and drill, saw blade grinding machines, polish grinder vertical belt sanding machines, 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.

Geometric angle of cutting tool

Choosing the appropriate geometric angle of the tool can help reduce the vibration of the tool, and in turn, the workpiece is not easy to collapse.

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1. Land angle

With the decrease of the absolute value of negative land angle, the wear area of the rear tool surface has little change, but the overall trend is decreasing. With the increase of the rake angle, the strength of the tool edge is weakened, which leads to the decrease of the wear area. The flank wear is aggravated. When negative land angle machining is used, the cutting resistance is large and the cutting vibration is increased. When large positive land angle machining is used, the tool wear is serious and the cutting vibration is also large.

2. Lip Relief Angle

If the lip relief angle increases, the strength of the tool edge will decrease, and the worn area of the flank will gradually increase. After cutting tool lip relief angle is too large, cutting vibration is strengthened.

3. Helix angle

When the helix angle is small, the cutting edge which cuts into the graphite workpiece simultaneously on the same cutting edge has the longest cutting edge length, the greatest cutting resistance and the greatest cutting impact force, so the tool wear, milling force and cutting vibration are the greatest. When the helix angle is large, the direction of milling resultant force deviates from the surface of the workpiece to a great extent, and the cutting impact caused by the collapse of graphite material is intensified, so the tool wear, milling force and cutting vibration are also increased. Therefore, the influence of tool angle change on tool wear, milling force and cutting vibration is caused by the combination of land angle, lip relief angle and spiral angle, so more attention must be paid to the selection.

Through a large number of scientific tests on tool grinding, our tool grinding machines optimizes the geometric angle of the relevant tool in the design, thus greatly improving the overall cutting performance of the tool.

Several methods of tool grinding

No matter what kind of cutter, after a certain period of use, it will be somewhat different from the prototype, which is not as smooth and sharp as it was when I bought it. In order to keep the cutter in its original shape, some grinding operations must be done, which can obviously remove the residue on it, make the blade tip sharper and effectively improve the speed of operation. Different methods should be chosen according to different types of cutter.


Tool grinding method:


Hollow Grind: a groove is excavated on both sides of the cutter surface of the shaping cutter and other cutting tools. Because it is easy to process and design, many factories in the market use this grinding method. The advantage is that this grinding will result in a very thin blade, and the thinner the blade the better. Its drawback is “thinner blade is more fragile”.


Chisel Grind: There is only one side to grind. The advantages are as follows: 1. Easy to process: one side grinding only needs half of the other grinding methods, and does not need to be too precise, so it saves time, labor and money. 2. Easy to grind: Only one side is needed unless there is serious damage, and the grinding technique need not be as advanced as other grinding methods. 3. strong blade: only a single edge, so the blade angle is large (about 30-45 degrees), and the blade is thick. 4. Save material: In the early hammering knife era, this kind of grinding method does not need to be like other grinding methods to generally remove excess steel, can save the most steel consumption.

There are three drawbacks: inaccurate cutting: when you cut apples with chisel grinding and other bilateral grinding knives, you will find that the two-sided grinding knife can cut the apple in two, and the chisel grinding knife will go out with the grinding angle. 2. Unable to puncture too deep: chisel grinding on the tip of the knife caused too much inclination, making it puncture on the formation of many obstacles. 3. Grinding surface error: right-handed knife grinding mode is (from the knife back down) the left side of the knife surface is flat, the right side is grinding; left-handed knife just the opposite. However, due to the differences in the traditional display of knife face and the usage of knife, most of the chisels made by Western knife factories are left-handed knives. When the blade is cut outward, the cutting angle of the knife must be increased to be used smoothly.


Flat Grind/V Grind: a grinding method for both sharpness and solidity. The back of the cutter, such as the shaping knife, has been ground to the blade from the beginning, so it has a fairly solid back and blade.


Saber Grind: Similar to the plane grinding method, they are both sides of the knife face without grooves. The difference is that the surface grinding method runs from the back of the knife to the blade, whereas the cavalry grinding method runs from the half. It also has excellent cutting and splitting ability. The early cavalry knife is the form of grinding, so it is called cavalry grinding.


Convex Grind: Also known as Moran Grind, Bill Moran is the best western master at developing this Grind. This grinding method is different from the above four grinding methods. The other grinding method is to form an inclined surface or groove on both sides of the knife, while the circular grinding method is to form a pair of convex arcs above the blade (also known as the blade in Japan because of its length like a hard clam). This type of grinding is as hard as flat grinding and as sharp as concave grinding. For a very difficult way of grinding. The downside is that if you don’t have a flat-belt Grinder, it can be hard to grind on your own when the blade is blunt.

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Universal Cutting Tool Grinder, Universal Scoring Blade Sharpening Machine, Universal Grooving Cutter Sharpening Machine, Universal Cutter Grinder Manufacturer, Cheap Universal Cutter Grinder, PG-600F Universal Tool Grinder

Most cutting tools can be sharpened with PURROS Universal Tool Grinder. Welcome to consult related products.

What properties should good tool material have?

Tool material is the fundamental factor that determines the cutting performance of a tool. When carbon tool steel is used as tool material, the cutting speed is only about 10m/min. In the early 20th century, high-speed steel tool material emerged, cutting speed increased to tens of meters per minute; In the 1930s, cemented carbide appeared and the cutting speed was increased to more than 100 meters to several hundred meters per minute. At present, the appearance of ceramic cutting tools and super hard cutting tools increases the cutting speed to over one kilometer per minute. The development of processed materials has greatly promoted the development of cutter materials.

What are the properties of good cutter materials?


Cutting tool material with excellent performance is the basic condition to ensure efficient working of cutting tools. The cutting part of the tool works under strong friction, high pressure and high temperature and should have the following basic requirements.


High hardness and wear resistance

The hardness of cutter material must be higher than that of processed material to cut metal, which is the basic requirement of cutting tool material. The current tool material hardness is above 60HRC. The harder the tool material, the better its wear resistance.


Sufficient strength and impact toughness

Strength refers to the ability to resist the cutting force without breaking the blade or breaking the blade. It is usually indicated by bending strength. Impact toughness refers to the ability of cutter materials to ensure that the blade does not collapse under discontinuous cutting or impactful working conditions. Generally, the higher the hardness, the lower the impact toughness, the brittle materials. Hardness and toughness are a pair of contradictions and also a key to overcome the material of cutter.


High heat resistance

Heat resistance is the main index of tool material performance. It is a comprehensive reflection of the tool material under the high temperature to maintain hardness, wear resistance, strength, oxidation resistance, adhesion and diffusion.


Good workmanship and economy

In order to facilitate manufacturing, tool materials should have good technological properties, such as forging, heat treatment and grinding. Of course, economic considerations should be taken into account when manufacturing and selection. The cost of superhard materials and coated tool materials is now more expensive, but the service life is very long, and in mass production, the cost of each part is reduced. Therefore, the selection must be comprehensive consideration.

Standard of tool dressing

Whether or not you have a good set of standard is the standard to measure whether a center is professional. Standard of grinding, the general rules for different Cutting tool in Cutting different materials when the Cutting edge of technology parameters, including the blade Angle, Cutting Lip Angle, rake Angle, Lip Clearance Angle, blade, chamfering etc parameters (in the carbide drill, make the blade passivation process is called “blade”, pour the width of the blade and the Cutting material, generally between 0.03-0.25 Mm. The process of chamfering on the edge (tip) is called chamfering. Each professional company has its own years of review and repair standards.

The use and safety management of drill bit grinder grinding wheel

The use and safety management of drill bit grinder grinding wheel

Differences between HM drill and HSS drill:

HSS drill bit: Cutting Lip Angle is usually 118 degrees, sometimes greater than 130 degrees; The blade is sharp; The precision (edge elevation, symmetry, circumferential pulse) is relatively low. There are many ways to mend a chisel edge.

HM drill bit: Cutting Lip Angle generally 140 degrees; Straight slot drills are usually 130 degrees and three-edge drills are generally 150 degrees. The blade and tip (edge) are not sharp and are often passivated, or referred to as chamfering and chamfering; High demand for accuracy. The chisel edge is often cut into an s-shape for cutting.

Lip Clearance Angle:

The Lip Clearance Angle of the blade is very important for cutting tools. Lip Clearance Angle is too big, the blade is flabby and easy to tie up. Lip Clearance Angle is too small, then friction is too large, cutting disadvantage.

The Lip Clearance Angle of the cutter varies with the cutting material, type and diameter of the cutter. Generally speaking, the Lip Clearance Angle decreases as the cutter diameter increases. In addition, if the cut material is hard, the Lip Clearance Angle is smaller, otherwise, the Lip Clearance Angle is larger.

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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.