Basic knowledge of saw blades

Basic knowledge of saw blades

Carbide saw blades are the most commonly used cutting tools for wood product processing. The quality of carbide saw blades is closely related to the quality of processed products. The correct and reasonable selection of carbide saw blades is of great significance to improving product quality, shortening processing cycles, and reducing processing costs. Carbide saw blades include multiple parameters such as the type of alloy cutter head, material of the matrix, diameter, number of teeth, thickness, tooth shape, angle, aperture, etc. These parameters determine the processing capability and cutting performance of the saw blade. When choosing a saw blade, you must choose the correct saw blade according to the type, thickness, sawing speed, sawing direction, feeding speed, and sawing path width of the material being cut.

(1) Selection of cemented carbide types
Commonly used types of cemented carbide are tungsten-cobalt (code YG) and tungsten-titanium (code YT). Because tungsten-cobalt carbide has better impact resistance, it is more widely used in the wood processing industry. Commonly used models in wood processing are YG8-YG15. The number after YG indicates the percentage of cobalt content. As the cobalt content increases, the impact toughness and bending strength of the alloy increase, but the hardness and wear resistance decrease. It is necessary to Choose according to actual situation.

(2) Selection of matrix
1. 65Mn spring steel has good elasticity and plasticity, economical material, good heat treatment hardenability, low heating temperature and easy deformation, so it can be used for saw blades with low cutting requirements.
2. Carbon tool steel contains high carbon and has high thermal conductivity, but its hardness and wear resistance drop sharply when exposed to temperatures of 200°C-250°C. It suffers from large heat treatment deformation, poor hardenability, and long tempering time and is prone to cracking. Make economical materials for cutting tools such as T8A, T10A, T12A, etc.
3. Compared with carbon tool steel, alloy tool steel has good heat resistance, wear resistance and better processing performance. The heat-resistant deformation temperature is 300℃-400℃, which is suitable for manufacturing high-grade alloy circular saw blades.

(3) Selection of diameter
The diameter of the saw blade is related to the sawing equipment used and the thickness of the workpiece being cut. The diameter of the saw blade is small, and the cutting speed is relatively low; the diameter of the saw blade is high, and the requirements for the saw blade and sawing equipment are high, and the sawing efficiency is also high. The outer diameter of the saw blade should be selected according to different circular saw machine models. Use a saw blade with a consistent diameter.
The diameters of standard parts are: 110MM (4 inches), 150MM (6 inches), 180MM (7 inches), 200MM (8 inches), 230MM (9 inches), 250MM (10 inches), 300MM (12 inches), 350MM ( 14 inches), 400MM (16 inches), 450MM (18 inches), 500MM (20 inches), etc. The bottom groove saw blades of precision panel saws are mostly designed to be 120MM.

(4) Selection of number of teeth
The number of teeth of the saw teeth. Generally speaking, the more teeth there are, the more cutting edges can be cut per unit time and the better the cutting performance. However, more cutting teeth require more carbide and the price of the saw blade will be higher, but the saw teeth are too dense. , the chip capacity between the teeth becomes smaller, which can easily cause the saw blade to heat up; in addition, there are too many saw teeth, and when the feed rate is not matched properly, the amount of cutting per tooth will be very small, which will intensify the friction between the cutting edge and the workpiece, affecting the service life of the blade. . Usually the tooth spacing is 15-25mm, and a reasonable number of teeth should be selected according to the material being sawed.

(5) Choice of thickness
The thickness of the saw blade: In theory, we hope that the saw blade should be as thin as possible. The saw kerf is actually a consumption. The material of the alloy saw blade base and the process of manufacturing the saw blade determine the thickness of the saw blade. If the thickness is too thin, the saw blade will easily shake during operation, affecting the cutting effect. When choosing the thickness of the saw blade, you should consider the stability of the saw blade and the material being cut. Some materials for special purposes also require specific thicknesses and should be used according to equipment requirements, such as grooving saw blades, scribing saw blades, etc.

(6) Selection of tooth shape
Commonly used tooth shapes include left and right teeth (alternating teeth), flat teeth, trapezoidal teeth (high and low teeth), inverted trapezoidal teeth (inverted conical teeth), dovetail teeth (hump teeth), and the rare industrial-grade triangular teeth. Left and right, left and right, left and right flat teeth, etc.
1. The left and right teeth are the most widely used, with fast cutting speed and relatively simple grinding. It is suitable for cutting and cross sawing various soft and hard solid wood profiles and density boards, multi-layer boards, particle boards, etc. The left and right teeth equipped with anti-rebound protection teeth are dovetail teeth, which are suitable for longitudinal cutting of various boards with tree knots.
The left and right tooth saw blades with negative rake angles are usually used for sawing veneer panels due to their sharp teeth and good sawing quality.
2. The flat-tooth saw edge is rough and the cutting speed is slow, so it is the easiest to grind. It is mainly used for sawing ordinary wood with low cost. It is mostly used for aluminum saw blades with smaller diameters to reduce adhesion during cutting, or for grooving saw blades to keep the groove bottom flat.
3. The trapezoidal teeth are a combination of trapezoidal teeth and flat teeth. The grinding is more complicated. It can reduce the cracking of the veneer during sawing. It is suitable for sawing various single and double veneer artificial boards and fireproof boards. Aluminum saw blades often use trapezoidal saw blades with a larger number of teeth to prevent adhesion.
4. Inverted ladder teeth are often used in the bottom groove saw blade of panel saws. When sawing double-veneered artificial boards, the groove saw adjusts the thickness to complete the groove processing of the bottom surface, and then the main saw completes the sawing process of the board. Prevent edge chipping at the saw edge.
To sum up, when sawing solid wood, particleboard, or medium-density board, you should choose left and right teeth, which can sharply cut off the wood fiber tissue and make the cut smooth; in order to keep the groove bottom flat, use flat teeth or left and right teeth. Combination teeth; when cutting veneer panels and fireproof boards, trapezoidal teeth are generally used. Due to the high cutting rate, the computer cutting saw uses an alloy saw blade with a relatively large diameter and thickness, with a diameter of about 350-450mm and a thickness of 4.0-4.8 mm, most use stepped flat teeth to reduce edge chipping and saw marks.

(7) Selection of sawtooth angle
The angle parameters of the sawtooth part are relatively complex and the most professional, and the correct selection of the angle parameters of the saw blade is the key to determining the quality of sawing. The most important angle parameters are rake angle, back angle and wedge angle.
The rake angle mainly affects the force consumed in sawing wood chips. The larger the rake angle, the better the cutting sharpness of the saw teeth, the lighter the sawing, and the easier it is to push the material. Generally, when the material to be processed is soft, choose a larger rake angle, otherwise choose a smaller rake angle.
The angle of the saw teeth is the position of the saw teeth when cutting. The angle of the saw teeth affects cutting performance. The factors that have the greatest impact on cutting are rake angle γ, clearance angle α, and wedge angle β. The rake angle γ is the cutting angle of the saw teeth. The larger the rake angle, the faster the cutting. The rake angle is generally between 10-15°C. The relief angle is the angle between the saw teeth and the processed surface. Its function is to prevent friction between the saw teeth and the processed surface. The larger the relief angle, the smaller the friction and the smoother the processed product. The clearance angle of carbide saw blades is generally 15°C. Wedge angle is derived from rake angle and back angle. However, the wedge angle cannot be too small. It plays a role in maintaining the strength, heat dissipation and durability of the tooth. The sum of rake angle γ, relief angle α, and wedge angle β is equal to 90°C.

(8) Selection of aperture
The aperture is a relatively simple parameter, which is mainly selected according to the requirements of the equipment. However, in order to maintain the stability of the saw blade, it is best to use equipment with a larger aperture for saw blades above 250MM. At present, the apertures of standard parts designed in China are mostly 20MM holes with diameters of 120MM and below, 25.4MM holes with diameters of 120-230MM, and 30mm holes with diameters above 250. Some imported equipment also has 15.875MM holes. The mechanical aperture of multi-blade saws is relatively complex. , many are equipped with keyways to ensure stability. Regardless of the size of the hole, it can be modified through a lathe or wire cutting machine. The lathe can turn washers into the large hole, and the wire cutting machine can expand the hole to meet the requirements of the equipment.
A series of parameters such as the type of alloy cutter head, the material of the base body, diameter, number of teeth, thickness, tooth shape, angle, aperture, etc. are combined to form the entire carbide saw blade. It must be reasonably selected and matched to better utilize its advantages.

2. The correct way to use alloy saw blades back to catalog
(1) Basic requirements:
1. Select the appropriate saw blade according to the design requirements of the equipment.
2. The equipment should be equipped with safety protection devices, such as protective covers, power-off brakes, overload protection, etc.
3. Have professional operators install and use it, and wear work clothes, protective glasses, earmuffs, etc.
4. Operators must not wear gloves, put long hair in a work cap, and pay attention to ties and cuffs to prevent danger.
5. Keep away from fire sources and humid environments.

(2) Installation requirements:
1. The equipment is in good condition, the spindle has no deformation, no radial jump, the installation is firm and fixed, and there is no vibration, etc.
2. Check whether the saw blade is damaged, whether the tooth profile is complete, whether the saw plate is smooth and smooth, and whether there are any other abnormalities to ensure safe use.
3. When assembling, make sure the arrow direction of the saw blade is consistent with the rotation direction of the equipment spindle.
4. When installing the saw blade, keep the axis, chuck and flange clean. The inner diameter of the flange should be consistent with the inner diameter of the saw blade. Ensure that the flange and the saw blade are tightly combined. Install the positioning pin and tighten the nut. The size of the flange should be appropriate, and the outer diameter should be no less than 1/3 of the diameter of the saw blade.
5. Before starting the equipment, ensure that it is safe and there is a single person operating the equipment and idling. Check whether the equipment is in the correct direction and whether there is any vibration. After the saw blade is installed, it should be idling for a few minutes. If there is no slipping, swinging or jumping, it will be normal. Work.

(3) Usage requirements:
1. When working, the workpiece should be fixed and the profile positioning should be in line with the cutting direction to avoid abnormal cutting. Do not apply lateral pressure or make curved cuts. The cutting should be steady to avoid impact contact with the workpiece by the blade, which may cause damage to the saw blade or damage to the saw blade. The workpiece flies out and an accident occurs.
2. When working, if you find abnormal sound or vibration, rough cutting surface, or odor, you must stop the operation immediately, check in time, and troubleshoot to avoid accidents.
3. When starting and stopping cutting, do not feed the tool too fast to avoid tooth breakage and damage.
4. If cutting aluminum alloy or other metals, use special cooling lubricant to prevent the saw blade from overheating, causing paste, and other damage, which affects the cutting quality.
5. The chip discharge chute and slag suction device of the equipment must be kept clear to prevent slag from accumulating into blocks and affecting production and safety.
6. When dry cutting, please do not cut continuously for a long time to avoid affecting the service life and cutting effect of the saw blade; when cutting wet sheets, water should be added to prevent leakage.

(4) Saw blade maintenance:
1. If the saw blade is not used immediately, it should be laid flat or hung up by using the inner hole. Do not stack other objects or step on the flat saw blade, and pay attention to moisture and rust.
2. When the saw blade is no longer sharp and the cutting surface is rough, it must be regrinded in time. Grinding cannot change the original angle and destroy the dynamic balance.
3. The inner diameter correction of the saw blade and the processing of positioning holes must be carried out by the factory. If the processing is poor, it will affect the product's use effect and may cause danger. In principle, the hole expansion should not exceed the original hole diameter by 20mm to avoid affecting the stress balance.
4. Selection of alloy grinding wheels.
1) The bonding strength of resin bonded diamond grinding wheels is weak, so they can have good self-sharpening properties during grinding, are not easy to block, have high grinding efficiency, low grinding force, and low grinding temperature. The disadvantages are poor wear resistance and abrasive tool loss. Large, not suitable for heavy duty grinding.
2) The wear resistance and bonding ability of ceramic bonded diamond grinding wheels are better than those of resin bonded ones. They have sharp cutting, high grinding efficiency, less heat and clogging, less thermal expansion, easy to control accuracy, but have the disadvantages of rough grinding surface and higher cost. .
3) Metal bond diamond grinding wheels have high bonding strength, good wear resistance, low wear, long life, low grinding cost, and can withstand large loads, but have poor sharpness and are prone to clogging.
4) The particle size of the abrasive has a certain impact on the clogging and cutting amount of the grinding wheel. Compared with fine sand, coarse sand will increase the cutting edge wear of the abrasive when the cutting depth is large, and conversely, the grinding wheel will be easily clogged.
5) The hardness of the grinding wheel has a greater impact on clogging. A high hardness grinding wheel has a high thermal conductivity, which is not conducive to surface heat dissipation, but is beneficial to improving processing accuracy and durability.
6) The selection of grinding wheel concentration is an important characteristic. It has a great impact on grinding efficiency and processing cost. Too low a concentration affects efficiency. On the contrary, the abrasive grains are easy to fall off, but the optimal binder concentration range is also the best.