Characteristics and selection of a hacksaw blade for metal

A hacksaw is used to create through cuts on dense materials made of metal, cut slots, trim contour products. The locksmith tool is made of a hacksaw blade and a base machine. One end of the frame is equipped with a static clamping head, a handle for holding the tool, and a shank. The opposite part consists of a movable head and a screw that tightens the cutting insert. The heads of hacksaws for metal are equipped with slots in which the working blade is installed, which is fixed with pins.

The frames are made in two forms: sliding, allowing you to fix the working blade of any length, and solid.

Each type of material has its own cutting blade.

• Saw blade for metal is a narrow metal strip with fine teeth placed on it. Frames are made outwardly similar to the letters C, P. Outdated frame models were equipped with wooden or metal handles, placed parallel to the blade. Modern models are made with a pistol grip.

• Saw blade for working with wood - the most common carpentry version of the product. It is used for processing and cutting plywood, wood building materials of various densities. The design of hand saws is specially equipped with a beveled working surface, teeth are located on the side of the blade.

• For working with concrete the blade has larger teeth on the cutting edge. Equipped with carbide taps. Thanks to this, it becomes possible to saw concrete structures, foam blocks, sand concrete.

• For processing metal products blades with a step width of about 1.6 mm are used, up to 20 teeth are located on a 25 mm long file.

When processing metal products with a different hardness index, files with a certain number of teeth are used:

• angle and other steel - 22 teeth;
• cast iron - 22 teeth;
• hardened material - 19 teeth;
• soft metal - 16 teeth.

In order for the file not to get stuck in the workpiece, it is worthwhile to pre-set the teeth. Let's consider on what principle the wiring is done.

• The width of the cut is greater than the thickness of the working blade.
• Hacksaw saws with a pitch of about 1 mm must be wavy. Each pair of adjacent teeth must be bent in different directions by approximately 0.25-0.5 mm.

• The plate with a pitch of more than 0.8 mm is divorced using the corrugated method. The first few teeth retract to the left, the next few teeth to the right.
• With an average pitch of about 0.5 mm, the first tooth is retracted to the left side, the second is left in place, the third to the right.
• Coarse insert up to 1.6 mm - each tooth retracts in opposite directions. It is necessary that the wiring ends at a distance of no more than 3 cm from the end of the web.

GOST 6645-86 is a standard that establishes requirements for the type, size, quality of saw blades for metal.

It is a thin, not wide plate with holes located at opposite ends, on one side there are cutting elements - teeth.Files are made of steel: Х6ВФ, Р9, У10А, with hardness HRC 61-64.

Depending on the type of work, hacksaw files are divided into machine and manual.

The length of the plate is determined by the distance from the center of one hole to another.The universal hacksaw file for hand tools has the following dimensions: thickness - 0.65-0.8 mm, height - 13-16 mm, length - 25-30 cm.

The standard value for the length of the blade is 30 cm, but there are models with an indicator of 15 cm. Short hacksaws are used when the standard large tool is not suitable for work due to its size, as well as for filigree types of work.

GOST R 53411-2009 establishes the configuration of blades for two types of hacksaws. Saw blades for handheld equipment are available in three sizes.

• Single type 1. The distance between the through holes is 250 ± 2 mm, the length of the file is no more than 265 mm.
• Single type 2. The distance from one hole to another is 300 ± 2 mm, the length of the plate is up to 315 mm.
• Double, the distance is 300 ± 2 mm, the length of the working surface is up to 315 mm.

Single plate thickness - 0.63 mm, double plate - 0.80 mm. The height of a file with a single set of teeth is 12.5 mm, for a double set - 20 mm.

GOST defines the values ​​of the pitch of the teeth, expressed in millimeters, the number of cutting elements:

• for a single plate of the first type - 0.80 / 32;
• single of the second type - 1.00 / 24;
• double - 1.25 / 20.

The number of teeth changes for longer tools - 1.40 / 18 and 1.60 / 16.

For each type of work, the value of the cutter angle can be changed. In the process of processing metal with a sufficient width, rather long cuts are achieved: each saw cutter removes the sawdust filling the chip space until the tip of the tooth comes out completely.

The size of the chip space is determined from the pitch of the tooth, the front angle, the back angle. The rake angle is expressed in negative, positive, zero values. The value depends on the hardness of the workpiece. A saw with a zero rake angle is less efficient than a rake angle greater than 0 degrees.

When cutting the hardest surfaces, saws with teeth are used, which are sharpened at a large angle. For soft products, the indicator may be below average. The hacksaw blades with the sharper teeth are the most wear-resistant.

The saw type is classified into professional and household tools. The first option has a rigid structure and allows work at angles of 55-90 degrees.

The second criterion for choosing a blade for a hacksaw is the material from which the product is made.

Used steel grades: Х6ВФ, В2Ф, Р6М5, Р12, Р18. Domestic products are made only from these types of material, but diamond-coated products are found in specialized stores. The surface of the file is sprayed from various refractory metals, titanium nitride. These files differ in appearance in color. Standard steel blades are light and dark gray, diamond and other coatings - from orange to dark blue. The tungsten carbide coating is characterized by the extreme sensitivity of the blade to bending, which affects the short life of the blade.

Diamond-coated tools are used to cut abrasive and brittle materials: ceramics, porcelain and others.

The strength of the file is ensured by the hot heat treatment procedure. The saw blade is divided into two hardening zones - the cutting part is processed at a temperature of 64 to 84 degrees, the free zone is exposed to 46 degrees.

The difference in hardness affects the sensitivity of the product to the bending of the blade during the execution of work or the installation of the file in the tool.To solve this problem, a standard was adopted that regulates the indicators of the forces applied to handheld equipment. The force on the tool should not exceed 60 kg when using a file with a tooth pitch of less than 14 mm, 10 kg is calculated for a cutting product with a tooth pitch of more than 14 mm.

Saws made of carbon steel, marked with the HCS mark, are used for working with soft materials, do not differ in durability, and quickly become unusable.

Metal cutting tools made of alloy steel HM are more technological, like blades made of alloyed chrome, tungsten, vanadium. In terms of their properties and service life, they occupy an intermediate place between carbon and high-speed steel saws.

High speed products are marked with the letters HSS, are fragile, high price, but more resistant to wear of cutting elements. Today, HSS blades are being replaced by bimetallic saws.

Bimetallic products are designated by the abbreviation BIM. Made of cold-rolled and high-speed steel by electron beam welding. Welding is used to instantly connect two types of metal while maintaining the hardness of the working teeth.

When choosing a cutting product, they are guided, among other things, by the type of tool.

Hand saws are, on average, equipped with type 1 single blades marked HCS, HM. The length of the file depends on the length of the tool frame, the average is in the region of 250-300 mm.

For a mechanical tool, files with any marking are selected depending on the surface to be treated. The length of the cutting double blade is from 300 mm and more. Mechanical equipment is used when processing a large number of workpieces with a length of 100 mm.

Mini hacksaws work with blades no more than 150 mm. They are mainly designed for convenient and quick cutting of wooden materials and metal products of small diameter, work with blanks, in a curve.

Before using the tool, it is worthwhile to properly install the blade into the equipment.

The installation method depends on the design of the fastening system of the tool. If the heads are equipped with slots, then the blade is inserted directly into them, stretched a little if necessary, and fixed with a pin.

The installation of the cutting product in a lever-type hacksaw is carried out by extending the lever, putting on the blade, returning the tool frame to its original position.

Correctly stretched blade, when the fingers click on the surface of the file, emits a slight ringing and small vibrations. It is strictly forbidden to use pliers or a vice while tensioning the file. Slight misalignment or bending will damage the saw blade or break it completely.

Installation of single-sided blades requires utmost care due to the direction of the cutting elements. You need to attach the file so that the teeth look towards the handle of the equipment. Progressive movements when cutting products are performed from oneself. It is not recommended to set the saw blades with the teeth in the opposite direction from the handle, this will not allow the planned work to be carried out and will lead to the saw sticking in the material or blade breakage.

During the metal processing process with a hand hacksaw, you need to stand behind the workpiece clamped in a vice. The body is half-turned, the left leg is put forward, the jogging leg is left behind to take a stable position.

The cutting blade is placed strictly on the cutting line.The angle of inclination should be in the range of 30-40 degrees; it is not recommended to cut straight in a vertical position. The tilted position of the body allows for a straight cut with minimal vibration and noise.

The first impact on the material is made with little effort. The blade must cut into the product so that the file does not slip and there is no risk of tool breakage. The process of cutting the material is carried out in an inclined position, the free hand is placed on the product, the worker makes pushing movements of the hacksaw forward and backward.

You can get acquainted with the intricacies of choosing a hacksaw for metal in the next video.