Sandpaper for polishing metal –

Sandpaper grit

Depending on the abrasive crumb fraction, base material and purpose, the entire range of produced abrasive cloth can be divided into several modifications.

Based on the grain size, the following types of sanding cloths are distinguished: fine-grained and coarse-grained. The table shows the grit values ​​of the most commonly used sandpaper:

https://www.youtube.com/watch? v=bkm-4LzOWWs

Initial sanding, correction of minor surface defects

GOST R 52381-05

GOST 3647-80

Grit size, µm

Scope of application

Coarse

Р22

80-N

800-1000

Pre-stripping

Р24

63-N

630-800

Р36

50-N

500-630

Р40

40-N

400-500

Wood roughing

Р46

32-N

315-400

Р60

25-N

250-315

Р80

20-N

200-250

Initial grinding

Correction of minor surface defects

Р90

16-N

160-200

Р100

12-N

125-160

Р120

10-N

100-125

Р150

8-H

80-100

Treatment of hardwood before final sanding

Sanding soft wood

Removing old paint

Р180

6-H

63-80

Fine sandpaper

Р240

5-H; M63

50-63

Finish sanding of hardwood

Intermediate sanding

Р280

4-H; M50

40-50

Р400

M40; N-3

28-40

Surface polishing

Sanding for painting

Wet grinding

Р600

M28; N-2

20-28

Р1000

M20; N-1

14-20

Grinding of ceramics, plastics and metals

Wet grinding

Р1200

M400

10-14

Polishing, deglazing

Р1500

M10; N-0

7-10

Р2000

M7; N-01

5-7

Р2500

M5; N-00

3-5

As can be seen from the grit table, the range of application of sandpaper is quite wide:

  • Carpentry and furniture industries;
  • Mechanical engineering and industrial production;
  • Manufacturing of non-standard equipment and instrumentation;
  • Car repair and painting;
  • Construction and finishing works;

This is far from a complete list, and the ways of using sandpaper in everyday life cannot be described at all due to its endless variety.

The most common are three forms of produced emery cloths:

As for the release form, the most common are sheet and roll. In addition, there are ready-made ring modifications for scraping and hand grinders, disk pads for electric drills and some other varieties.

Marking of sandpaper depending on its purpose: table

Depending on the specifics of the work, coarse sandpaper is divided into several main groups:

Marking

Types of work

Р22; Р24;Р36

Preparatory work: removing rust

Elimination of large surface defects

80-N; 63-N; 50-N

Р40; P46; Р60

Rough surface treatment

40-N; 32-N; 25-N

Р80; P90; P100; Р120

Pre-grinding

20-N; 16-N; 12-N; 10-N

Р150; Р180

Final grinding and finishing

8-H; 6-H

Fine-grained sandpaper is also marked according to the specific use:

Marking

Types of work

P240; Р280

Sanding hardwood

5-H; M63

Р400; Р600

Polishing surface preparation for painting

M28; M40; 2-H; 3-H

Р1000

Grinding of ceramic surfaces, plastics and metals

M20; 1-H

Р1200; P1500; P2000; Р2500

Polishing and deglazing

M14; M10; M7; M5; N-0;N-00; N-01

When purchasing sandpaper, you may find other symbols on the back side. Each of them carries a certain meaning, for example, the type of abrasive powder, the method of its attachment, the characteristics of the adhesive mixture and the type of base and its mechanical properties. Let’s look at the basic notation.

  1. The name “P” indicates the abrasive structure of the material;
  2. The letter “L” denotes the form of release, in this case – sheet;
  3. The numbers “1” and “2” indicate the purpose of the abrasive cloth: 1 – for grinding soft surfaces, 2 – metal and other hard and especially hard materials;
  4. Resistance to moisture is indicated by the symbols “L1”, “L2” or M;
  5. The designation “P” indicates that exposure to moisture and dampness is extremely undesirable.

In addition to these designations, special attention must be paid to the properties of the abrasive particles themselves.

Sandpaper – types, classification, marking

It often happens that a small and seemingly insignificant thing turns out to be truly irreplaceable, and it is easier to name those areas where its use is not required than to list the opposite. Sandpaper falls into the category of such necessary things, in this article master

plumber

will tell you more about it.

Classification

The principle of sandpaper processing is based on the effect of its abrasive particles on the surface through friction. Abrasives are glued to a base: textile or paper. A paper base is an inexpensive solution. Nulevka and other grains of small fractions are applied precisely to such a base. To produce sandpaper, paper of different densities is used: the larger the grain, the denser the base should be.

The fabric base is more durable and can also be used for wet sanding (waterproof). The following types of fabrics are in demand in the production of emery:

  • Polyester – have a dense base, but stretch slightly when inserted into the grinder; Compared to cotton, more wear-resistant.
  • Synthetic – capable of withstanding heavy loads, which allows them to be used in industry, mainly as sandpaper for machines in furniture production.
  • Cotton – have high elasticity, but are inferior in strength to previous types.

Grit

Sandpaper numbers (grit) are a specific indicator characterizing the number of abrasive particles per square inch. In accordance with this, the skin is usually divided into:

  • Coarse-grained for cleaning surfaces from old coatings (varnish, paint) and initial processing. The abrasive in it is coarse and of a large fraction, together with the removal of the top layer, it leaves grooves and scratches on the material, therefore, further processing will be required. Thus, the coarsest-grained sandpaper is most often used when there is a need not to smooth, but rather to grind off the top layer (for example, on wood to give the desired shape to the workpiece). Numbers 12-80;
  • Medium-grained is required at intermediate stages of grinding and is suitable just for leveling the surfaces of their cleaning, and so on, so that the multi-layer processing is smooth and of high quality. It, of course, smoothes and levels the surface, but still leaves behind traces, although not as obvious as specimens with large grains. Numbers 80-160;
  • Fine-grained removes defects from previous polishing, making the surface ready for final processing (for example, applying paint). This also includes zero grade sandpaper. Numbers 160-4000.

To summarize, we note that the procedure for working with various materials is the same in all cases. They start by using sandpaper with very coarse particles. This includes wood processing, removal of old paints and varnishes, and removal of rust on metal products. Gradually, the transition is made to paper with a finer abrasive, and final polishing is performed.

Type of abrasive

Gradation is also carried out according to the type of abrasive substances included in its composition. The following can be used as abrasives:

  • Carborundum is the most common abrasive. It is well suited for working with plastic, metal, and fiberglass surfaces.
  • Aluminum oxide is a higher quality and more durable material, but products based on it, all other things being equal, are more expensive.
  • Garnet is a natural abrasive ideal for wood. This paper is soft and seals wood fibers well, allowing paint and varnishes to apply more evenly to the wood.
  • Diamond sandpaper is the most durable and wear-resistant. Due to its high cost, it is used mainly in industry and professional activities.
  • Ceramics – rough types are made from it. It has proven itself excellent in leveling wood and in metal processing.
  • Alloyed electrocorundum – has titanium additives, which provides it with excellent strength. This type of grinding is recommended for surfaces that are difficult to machine.

Release forms

As for the release form, two main types can be noted: sheet and sandpaper in rolls. But besides them, other various configurations are also produced:

  • Fiber sandpaper. It is a non-woven material made of mesh impregnated with abrasive materials, fixed to the base using special resins. It is needed for matting surfaces. The elastic base allows you to achieve the desired effect even in hard-to-reach places. In this way, an optimal basis for subsequent priming or painting is achieved.
  • The abrasive mesh is a patented material for dust-free sanding. The structure of this material is a polyester mesh with fixed abrasive grain. This mesh structure ensures excellent dust removal through the entire surface of the abrasive material, which does not clog and is protected from the formation of lumps. The strength of the mesh guarantees its long service life, which results in less consumption of grinding equipment.
  • Abrasive wheels. Micro-fine polishing varieties, thanks to the use of advanced technologies, make it possible to smooth out minor defects in the paintwork. They are used in conjunction with substrates that provide a tight fit to surfaces with complex contours (for example, on cars). Quick removal of small scratches significantly reduces processing time, making it more uniform and of higher quality. Cleaning specimens have a strong cutting edge and have an aggressive abrasive structure. They are designed to heat up less and not become greasy. Unlike wire brushes, they last much longer. Designed for cleaning metal surfaces.
  • Strip abrasive paper has high cutting ability and long service life. Can be produced with special technological holes for dust removal.
  • Waterproof sandpaper is needed for initial or final wet processing of various surfaces.
  • Rolled skin. Produced on different bases for a wide variety of applications and with different technical characteristics, suitable even for highly specialized work (for example, in the production or repair of shoes).
  • The foam-based sandpaper has an anti-clogging treatment and is not intended for wet sanding. It is used for processing primed and varnished coatings, finishing contours and edges. Suitable for both profile and smooth surfaces, because the foam promotes uniform distribution of the abrasive when pressed. The same condition guarantees no slippage.
  • Sandpaper for grinding machines. Available in certain sizes with an adhesive backing, making it easy to attach and quickly change.
  • Abrasive sponges are needed for processing surfaces with complex textures, for shaping, and grinding edges. Well suited for hand polishing in hard-to-reach areas. They are used to prepare the surface for painting. Available in various abrasive grain sizes from ultra and super fine to medium.
  • Abrasive flowers are used to remove small defects. The unusual shape is aimed at ensuring that there are no risks during work. Can be used on both new and repainted surfaces.
  • Sanding belts, due to their design features, are threaded into machines or sanding machines.

Sandpaper – marking

Marking is an alphanumeric code that contains all information about the product. It stands for:

  • 1 letter indicates the material of the abrasive particles: K – corundum, C – carborundum, G – zirconium electrocorundum, S – ceramics, V – aluminum oxide, A – alloyed electrocorundum.
  • 2nd letter – base material: K – cotton, X – polyester, Y – synthetic fabric, J – elastic cotton fabric, JJ and F – high-strength cotton fabric, P – paper-based.
  • The number following the letters indicates which glue is used to attach the abrasive particles to the base: 1 – two layers of bakelite resin, 2 – single-layer application of glue, 3 – two-layer coating of glue and resin, 4 – varnish, 5 – resin.
  • Method of application: 1 – open, 3 – stearate, 4 – closed.
  • Properties of the base: display the density of the paper (in Latin letters from A to G) or the flexibility of the fabric (flexible – J, very flexible – F, especially flexible – E, T – rigid-flexible, U – polystyrene segment tapes, X – hard).
  • Grain (for explanation see table below).

Sanding with sandpaper

It has already been noted that the described material is required in many fields of activity:

  • Construction and finishing: processing putty surfaces in order to level them and get rid of small grooves from a spatula or sagging, stripping various materials (metal, wood, PVC) from old coating;
  • Car repair: performing various types of body work (removing traces of corrosion, treating the base before puttying and its subsequent leveling, sanding before painting, applying varnish, matting the surface before priming and other types of work);
  • Woodworking: sanding wood, obtaining a uniform surface, work on processing water-based paints and varnishes;
  • Painting work: treating bases before and after applying paint, smoothing out smudges;
  • Furniture repair and production.

Different paper numbers are used for different jobs. In this case, for wood it is better to use sandpaper with an open application method. Such a skin will not clog, which means it will not have to be changed often. But emery for a car must have a closed method of applying abrasives. In addition, metal processing will require harsher abrasives: it is best to use titanium, alloy, ceramic or zirconium electrocorundum. Sanding sandpaper for glass and stone must be waterproof, since it is recommended to process these surfaces with water.

Video

In the story – What types of sandpaper exist and how does sandpaper on a fabric basis differ from sandpaper on a paper or combined basis

In the story – Considered abrasive materials used in the manufacture of sandpaper

In the story – The structure of sandpaper is examined in detail
and their properties

In the story – How sandpaper is made

Continuing the topic, also check out our review How to clean safety glasses from scratches

Source

https://santekhnik-moskva.blogspot.com/2021/03/Nazhdachnaya-bumaga.html

Tool school » markings and sandpaper grit

Sandpaper markings indicate the fraction and concentration of the abrasive.

Domestic GOST 3647-80
determines the number of grains of different sizes per 1 square unit, but this classification is considered outdated. Today, sanding paper complies with international ISO standards; this designation can be found on the back of the product. It should be noted that the data of the old GOST and the values ​​of international standards overlap with each other. Their correspondence can be seen in the table.

P600

20-28

Grinding of metal, plastics, ceramics, wet grinding

  • M20N-1

    P1000

    14-20

  • Even finer grinding, polishing

    M14

    P1200

    10-14

    M10/N-0

    P1500

    7-10


    М7Н-01

    P2000

    5-7


    М5Н-00

    P2500

    3-5

  • Appointment Marking according to GOST 3647-80 ISO-6344 marking Grain size, microns
    Coarse
    Very rough work 80-N P22 800-1000
    63-NP24 630-800
    50-N P36 500-630
    Rough work
    40-N P40 400-500
    32-N P46 315-400
    25-N P60 250-315
    Primary grinding 20-NP80 200-250
    16-NP90 160-200
    12-H P100 125-160
    10-H P120 100-125
    Final sanding of soft wood, old paint for painting 8-H P150 80-100
    6-HP180 63-80
    Fine-grained
    Final sanding of hardwood, sanding between coats 5-Н,М63P240 50-63
    4-Н,М50P280 40-50
    Final polishing, sanding between coats, wet sanding M40N-3 P400 28-40
    М28Н-2
  • The main difference between the old and new standards is the different movement of numbers in the markings:
  • V

    GOST 3647-80

    the values ​​of grain size and density decrease, which is quite logical;

    In the new standard

    ISO 6344 (GOST 52318-2005)

      The product number increases as the value in the marking decreases.

  • Grit description
  • Letter
  • “Р”
  • in the designation indicates the grain size. The larger the value behind the letter, the finer the skin fraction.

  • Р400

  • – a known zero.

    Р600…Р2500

    They have small fractions and an almost smooth surface; their grain size is not so noticeable to the touch. This type of sandpaper is used for final polishing in industry.

  • In the old GOST, things were different. Using 10-N as an example: the first number means that an abrasive of a size corresponding to a sieve with a mesh of 100 microns is applied to the surface of the product. The lower the indicator, the smaller the screening size.

    Other designations

      Types of sandpaper differ in the composition of the base and the properties of the grains. This information is also reflected in the product labeling.

    Letter

    “L”

  • indicates the sheet form of the product. Rolled is not indicated in any way.

  • Letter

    “M”

  • stands for waterproof sandpaper.

  • Product marked

    “P”

    Designed for sanding dry products without contact with moisture.

    “1”

    – abrasive for soft surfaces,

    “2”

    – for the hard ones.