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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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.

The drill bit grinder developed by PURROS is very popular in the market, and we can accept OEM custom service at the same time!

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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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.

PURROS PG-X3B End Mill Grinder has successfully entered the Republic of South Africa

South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by 2,798 kilometers (1,739 mi) of coastline of Southern Africa stretching along the South Atlantic and Indian Oceans; to the north by the neighboring countries of Namibia, Botswana, and Zimbabwe.

 

PG-X3B End Mill Grinder SDC Grinding Wheel for Carbide Metal (Grinding Stone)

PG-X3B End Mill Grinder SDC Grinding Wheel for Carbide Metal (Grinding Stone)

PG-X3B End Mill Grinder SDC Grinding Wheel for Carbide Metal (Grinding Stone)

PG-X3B End Mill Grinder SDC Grinding Wheel for Carbide Metal (Grinding Stone)

PURROS PG-X3B End Mill Grinder Collet Chucks for 2-flute, 4-flute

PURROS PG-X3B End Mill Grinder Collet Chucks for 2-flute, 4-flute

SPECIFICATION

Model: PG-X3B
Diameter: Φ4-Φ14mm
Power: 220V/160W
Speed: 4400rRPG
Point angle: 3°
Dimension: 35*25*25cm
Weight: 14KG
Standard Model: Grinding wheel :SDC (for carbide)×1
Six collets:  Φ4, Φ6, Φ8, Φ10, Φ12, Φ14
Two collet chucks:2,4 flutes ×1 piece;3,6 flutes×1 piece
Optional Model: Grinding wheel :CBN (for HSS)

Features:

There is a simple operation design, no grinding experience can work quickly, no matter you are small and medium enterprises, family workshop, personal maintenance, can achieve satisfactory grinding effect!

  1. Portable end mill sharpener, can grind 2-flute, 3-flute, 4-flute end mill.
  2. Grinding is accurate and rapid, easy operation to grind.
  3. It can be equipped directly with an accurate angle and long service life.

 

Standard with SDC grinding wheel for the Carbide material, Optional CBN grinding wheel for the HSS material.

End Mill Grinding Machines can grind 2-flute, 3-flute, 4-flute end mill

The use and safety management of drill bit grinder grinding wheel

From the transportation and storage of the grinding wheel, the inspection before use for the installation, dressing of the grinding wheel, and the operation of the grinding machinery, any negligence of any link will bury a hidden danger to the drill bit grinder.

 

  1. Grinding wheel inspection

The grinding wheel with cracks and other defects is absolutely not allowed to use. The grinding wheel must undergo strict inspection before it is used.

(1) Visual inspection is to observe whether there are cracks or damages on the surface of the grinding wheel directly with the naked eye or with the aid of other instruments.

(2) Sound inspection is also known as percussion tests. The inspection method is to beat the grinding wheel with a small wooden hammer. The normal grinding wheel is crisp. If the voice is active and hoarse, it will be problematic.

 

  1. Grinding wheel device

Whether the grinding wheel matches the spindle size.

(1) Check whether the characteristics of the grinding wheel meet the requirements of use.

Do not press hard. The matching gap between the grinding wheel inner diameter and the spindle and chuck is appropriate.

(2) Assemble the grinding wheel freely to the spindle of the grinding wheel. Prevent too large or too small. The matching surface should be clean and free of debris.

(3) The chuck of the grinding wheel should be symmetrical. Abundant contact with the front of the grinding wheel and stable clamping prevented the two sides of the grinding wheel from deformation or even fragmentation due to unbalanced force.

(4) A certain thickness of flexible data lining (such as asbestos rubber board, elastic cardboard or leather) should be inserted into the chuck and the end face of the grinding wheel to make the chuck clamping force evenly distributed.

(5) The tightness of the grinding wheel should be tightened enough to make the grinding wheel do not to slide.

 

  1. Balancing test of grinding wheels

For example, the imbalance of the grinding wheel is due to the fact that the center of gravity of the grinding wheel does not coincide with the axis of rotation. The reasons are the defects of grinding wheel manufacture and installation, uneven density of grinding wheel, non-parallel end face, geometric shape or concentricity error of inner and outer holes, eccentricity of grinding wheel device and so on. When an unbalanced grinding wheel rotates around high speed, the centrifugal force which forces the grinding wheel to deviate from the axis will occur, thus causing the vibration of the grinding wheel. The results not only affect the grinding quality, but also accelerate the wear and tear of the main shaft bearing of the grinding wheel. When the centrifugal force exceeds the allowable range of the grinding wheel strength, the grinding wheel will be broken.

 

  1. Dressing of grinding wheels

To prevent passivation, blockage and distortion of grinding wheel, regular dressing can make grinding wheel adhere to good grinding performance and correct geometry. The usual dressing tool is diamond pen.

 

  1. Storage and transportation of grinding wheels

(1) It can not be subjected to strong vibration and impact. The wheels are in transportation and storage. It is not permitted to move the wheel when handling, so as to avoid cracks and surface  to damage.

(2) Signs of characteristics of wheel and safety speed must not be smeared or damaged at will.

(3) The storage time of grinding wheel should not exceed the validity period of grinding wheel. If the storage time exceeds one year, it must be qualified after the rotation test is used.

(4) Grinding wheel storage site should be kept dry. Prevent mixing with other chemicals. Prevent wheel dampness, low temperature, overheating and harmful chemicals from erosion.

(5) Grinding wheels should be based on specifications, shapes and sizes. Prevent overloading damage or cause improper grinding wheel deformation.

How to solve the problem after the bit is broken?

 

 

Cause Solution
Bending, deformation, sliding Increase the rigidity of tool and machine tool, increase the rigidity of workpiece and jig
Lip Relief Angle is too small Regrinding Lip Relief Angle
High Stock Removal To reduce Stock Removal
Bit wear Use drill bit grinder to grinding
Blocking of chips Re-select the alloy bit (chip groove, helix Angle);

Re-select machining method (adjustment of feed rate, step-step method, etc.)
Poor cutting Increase the rigidity of tools and machine tools

Increase the rigidity of workpiece and jig

Predrilling center hole

The cutting plane is first adjusted or processed into a horizontal plane with a guide sleeve

What are the difficulties in drilling stainless steel?

The difficulties of stainless steel material processing mainly include the following aspects:

  1. High cutting force and high cutting temperature

This type of material has large strength and large plastic deformation during cutting, so the cutting force is large. In addition, due to the poor thermal conductivity of the material, the cutting temperature is increased, and the high temperature is often concentrated in the narrow area near the cutting edge, which accelerates the tool wear.

 

  1. Severe work hardening

Austenite stainless steel and some high temperature alloy stainless steel are Austenite structure. These materials tend to be hardened when machined, often several times as much as plain carbon steel. The cutter is cut in the hardened area to shorten the tool life.

 

  1. Easy to stick the tool

Both Austenite stainless steel and Martensite stainless steel have the characteristics of strong and tough chip and high cutting temperature. When the strong and tough chip flow through the front surface of the cutter, the phenomenon of bonding, welding and other adhesion will occur, affecting the surface roughness of the processed parts.

 

  1. Tool wear is accelerated

The above materials generally contain high melting point elements, large plasticity and high cutting temperature, which make the tool wear faster and the tool wear and change frequently, thus affecting the production efficiency and increasing the tool use cost.

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