How to choose abrasive and grinding tools?

With the development of the economy, the use of stone is more and more extensive, especially in various public places. Stone is popular with people for its graceful and luxurious posture. Its use, with the change of time, will appear aging and pollution. Such as the problem, this can be initially solved by means of cleaning, but sometimes it must be refurbished by grinding. The following is an introduction to abrasives and grinding tools, so that everyone has a preliminary understanding.

 

 

 

First, abrasive and grinding tools

 

Abrasives are materials used for grinding. The current classification is general abrasives and superabrasives. Common abrasives mainly include corundum (brown fused alumina, white corundum, etc.). The main chemical composition is Al2O3 (aluminum oxychloride). , silicon carbide (black silicon carbide, green silicon carbide), the main chemical composition of which is SiC (silicon carbide). Their hardness is brown fused alumina, microhardness 2000-2200 kg / mm 2; white corundum, microhardness 2200-2300 kg / mm 2; black silicon carbide, microhardness 3100-3300 kg / mm 2 ; Green silicon carbide, microhardness 3200-3400 kg / mm 2; particle size from 4 # - micro powder W0.5 (even finer), hardness order we can sort out the processing of granite is green silicon carbide, black carbonization Silicon, processing marble is white corundum (soft), black, green silicon carbide (hard); in view of the cost of materials, green silicon carbide, black silicon carbide, white corundum, can be made around these abrasives, inorganic Grinding tools, including diamonds, ceramics, etc.; organic grinding tools, including phenolic, unsaturated resins, and epoxy (also including abrasive cloth sandpaper), these abrasive tools constitute the grinding of ordinary abrasives tool.

 

 

 

Diamond abrasive is a super-hard abrasive. Although its processing history is relatively long, it is a large-scale industrial production in the past 30 years. Its microhardness is 8000-10000 kg/mm2; the hardness is the highest. In the process of processing materials, it is the mechanism of micro-cutting, so it is the preferred cutting tool. In recent years, it has a large-scale increase in production and reduction of industrial cost, high processing efficiency (more than 5 times normal), and good processing effect (may be It is used for polishing highly demanding materials. Therefore, its application is becoming more and more extensive. Diamond grinding tools are mainly metal, resin, ceramic, etc., which are classified according to the type of bonding agent. Metal grinding tools mainly include iron-based, copper-based, and cobalt-based. It determines the processing cost of different types of materials. As a grinding tool, its particle size is from the thickest (20#), often to the fineness of 400#, and it is characterized by long service life, but the cost will be higher. Resin-based grinding tools, due to relatively low manufacturing costs, have relatively large applications. They are now used for rough grinding to polishing, which is the biggest advantage in fine-grained grinding and polishing; ceramic diamond-like grinding tools are recent Among the fastest-growing tools in the year, the processing performance is long, the metal processing is long, the resin processing is short, and the technology has a good advantage. However, due to its cost, it has not been seen in the stone renovation.

 

 

 

Second, the steps of the stone renovation process

 

The refurbishment of the stone floor generally has the following steps. One is to use the coarse-grained grinding tool to “level” the damaged surface, “cut the mouth”, or “flatten” the uneven part that has already been laid. Generally, this process must have a certain amount of removal. When constructing, pay attention to the overall flatness. Second, use a coarser-grained tool to grind the stone to remove the rough lines of the processing. Also maintain the flatness of the construction surface. Third, the fine grinding process, the amount of removal in this process is relatively small, through the 4-5 grain size, the smoothness of the stone can be polished. Finally, it is the polishing process. To achieve the requirements of stone renovation.

 

 

 

Third, the choice of grinding tools in the stone renovation process

 

1. Diamond bitumen grindstone is made of silicon carbide abrasive with magnesium oxide and magnesium chloride. The use of silicon carbide is better with green silicon carbide. Black silicon carbide is relatively cheaper. The granularity is generally from 16#--1200. #, The hardness of the grindstone produced is also from hard to soft. It is characterized by low cost, good self-sharpness, strong processing adaptability, and can process granite, marble, artificial stone, ceramic tile, etc., but the processing efficiency is compared. Low, the production cycle is relatively long, the grinding head needs a large pressure when working, it is a conventional grinding tool. After the grinding stone has a storage period of more than one year, various properties will change, such as self-sharpness, soft Hardness, etc.

 

 

 

2. A silicon carbide resin grindstone is formed by mixing and solidifying a silicon carbide abrasive and a resin, and is pressed by a phenolic resin, and is mixed with a liquid resin to be poured. Mainly used in fine grinding, the pressing type is characterized by good durability and good wettability during grinding. Especially when processing marble, the grinding luminosity is good and the efficiency is relatively high, but the cost is relatively high, mainly with fine Granularity number, phenolic grindstone is easy to color when grinding light-colored stone, which is the main reason why it cannot be widely used. It is a fine-grained silicon carbide powder and other materials mixed with resin. The grindstone is the main means of applying granite, terrazzo and concrete polishing.

 

3. Ceramic grindstone, which is made of silicon carbide abrasive mixed with vitreous and sintered at high temperature. It is characterized by good durability, but it is easy to block, the phenomenon of grinding and slipping occurs, and the cost is high. Now it is used less.

 

 

 

4. The metal bond grinding disc is made of diamond and metal powder. It is characterized by high processing efficiency and good processing effect. Generally, it starts from 50#, and the coarse grain size is 20#. It should be carefully selected. Otherwise, it will appear thicker. The scratches are difficult to process behind. In addition, the finest particle size used does not exceed 400#. This tool is used to trim rough surfaces and is the most effective tool to process a satisfactory plane. The cost is relatively high. Said, to be higher, but the efficiency of its processing is unmatched by ordinary millstones.

 

 

 

5. Resin bond grinding disc, which is made of diamond single crystal, fine powder and resin. It is characterized by lower cost than metal and high processing efficiency. It is mainly used for fine grinding of stone, to polishing, after grinding of metal grinding disc. , continue grinding and polishing tools. The cost is moderate.

 

 

 

6. Diamond soft-grinding disc is a new type of tool used for ground refurbishment in recent years. Its lightness and unique flexibility make it a good fit for the machined surface. It can provide the granularity from 20#---3000#. And BUFF black, white (polished). This kind of product uses diamond as abrasive material, which is light in weight and can effectively protect the soft part of the stone surface during grinding. The processed product has high gloss; the nylon gluing is used for connection and convenient operation. Its use, as well as a good upside.

 

 

 

Fourth, the choice of grinding tools for different machines during the refurbishment process

 

It is our goal to renovate the stone floor to achieve a good smoothing effect. At the same time, we must also take into account the actual cost. According to the requirements of the engineering party, we must properly configure the grinding tools to meet the expectations of different machines. purpose. First of all, there is an estimate of the cost of the project. If the cost is relatively low, the construction period is allowed, and the work of acceptance is relatively loose, ordinary grinding tools can be considered.

 

 

 

The requirements for the construction period are strict. It is best to use diamond grinding tools and select them according to the conditions of the machine. If the machine is heavy and works at a high speed, you can use a durable tool; if the machine is light and the work speed is low, you can use a sharp tool. In addition, during the grinding process, the processing efficiency can be achieved by the change in the amount of water. Sometimes, when “leveling” the ground, using coarse-grained diamond resin grinding discs (or diamond soft-grinding discs), it will feel that it can't be worn; it can be done by adding less water, increasing the pressure, or improving the machine under the same conditions. The speed is so that the grinding piece can be cut out as soon as possible. The best way is to use metal cutting piece or metal grinding piece to carry out the preliminary work. In order to ensure the flatness of the ground, try to use the flatness of the grinding piece before processing. After processing, it is polished with a diamond soft abrasive sheet, and its good fit can effectively improve the grinding efficiency and achieve good gloss. When polishing, in order to overcome the scratch on the stone, the hardness of the grinding tool should be soft, which is good for glazing. At the same time, in order to improve the gloss, the water volume can be reduced, the rotation speed of the machine can be increased, and the surface can be increased. Temperature also promotes gloss. In short, the polishing of stone is a complex physical and chemical process, both physical micro-plowing and surface purification reactions, depending on the situation, is not the same.

 

 

 

V. New progress in stone renovation technology

 

Wall renovation, many customers abroad, using dry grinding method to achieve; the specific process is to use diamond dry grinding tablets, starting from 50#, without water, sequentially 100#,200#,400#,800#, 1500#, 3000#, BUFF for grinding to achieve the desired finish. Polishing of concrete, diamond grinding disc with metal bond, coarse grinding without water, semi-fine grinding, and then fine grinding and polishing by dry grinding to achieve satisfactory results.