A blade for a hacksaw for metal is one of the most short-lived elements from the entire assortment of consumables for tools. Of course, a lot depends on the technology of working with metal and the skills of using a hacksaw, but first of all, you need to be able to make the right choice of blade. Today, we will talk about the choice and types, and also learn how to easily change the hacksaw blade.
Types of hacksaw blades
GOST R 53411-2009 "Hacksaw blades for metal" establishes two types of such a tool. for machine and manual cutting. We will not touch the first ones, and the second ones are produced in three main standard sizes:
- Single, with a distance between mounting holes of 250 ± 2 mm, with a total web length of not more than 265 mm;
- Single, with a distance between mounting holes of 300 ± 2 mm, with a total web length of not more than 315 mm;
- Double, with a distance between mounting holes of 300 ± 2 mm, with a total web length of not more than 315 mm.
The thickness of the canvas s single execution. 0.63 mm, double. 0.80 mm The height with a single row of teeth is 12.5 mm, and with a double. 20 mm.
GOST also regulates the values of tooth pitch P, mm and their number z, which for the first type of blades are 0.80 / 32, 1.00 / 24 and 1.25 / 20, respectively. Owners of “longer” hacksaws, in addition to the above, can also use hacksaw blades with parameters 1.40 / 18 and 1.60 / 16.
According to the grade of material used for the manufacture of hacksaw blades for metal, produced from tool steels:
- Stamps X6VF.
- Brands B2F.
- High-speed, grades P6M5, P12 or P18.
Video: Hacksaw Installation
The assortment of hacksaw blades of domestic production is exhausted by this, however, so-called diamond blades with surface spraying with titanium nitrides or other refractory metals are widespread in specialized retail chains. Similar canvases can be easily distinguished by color: ordinary steel canvases are dark gray, and sprayed can have a different color. from bright orange to blue (depending on the manufacturer).
There are also paintings with the so-called tungsten carbide spraying, but they are extremely sensitive to bending stresses at very high hardness. Therefore, when cutting metal, their durability is negligible.
The high strength of the blades for hacksaws for metal is ensured by appropriate heat treatment. On the surface of the blade, two zones with different hardness values are distinguished: directly at the teeth it ranges from НРС 64. 67 for alloyed tool steels to НРС 73. 78. for high-speed steels (for diamond blades this parameter reaches НРА 82. 84), and the rest zone. НРС 44. 46. A significant difference in hardness confirms the high sensitivity of the product to bending stresses, so the maximum force exerted on the hacksaw is also limited by the standard. It should not exceed 60 kg when working with canvases with tooth pitch less than 1.4 mm, and 10 kg for canvases with tooth pitch more than 1.4 mm.
The principles of choosing the canvas
The selection criteria are:
- Type of hand saw for metal, more precisely. the distance between the mounting holes. It is better if it is variable, then a hacksaw blade of any size is suitable for work.
- Strength of cut metal. If the tool is supposed to be used for the separation of soft, ductile metals. copper, aluminum, etc., it is advisable to have a hacksaw blade with the smallest hardness. Material can be adopted steel X6VF; imported paintings on the side plane have the designation HCS. For cutting more durable metals, blades made of high-speed steels are suitable (corresponding import marking. HSS).
- The thickness of the cut metal and the quality of the separation surface. Foreign practice recommends using the PPI parameter as the selection criterion. the number of tooth vertices per inch of blade length. So, for thin metals, where a very smooth cutting surface is required, the PPI value is considered correct>24. If for the user the main factor of productivity, than quality, then there should be PPI