There will be many quality problems in the production process of resinoid grinding wheels. Since the manufacture of resinoid grinding wheels belongs to the multidisciplinary integration of composite materials, there are many complex reasons. The main reasons are analyzed below:
1. Raw material problem:
Resinoid grinding wheel is a complex system composed of a variety of main and auxiliary raw materials. The main materials are abrasives and binders, and the auxiliary materials include fillers, reinforcing materials, and colorants.
(1) Abrasives should pay attention to the problem
At present, the quality of abrasives on the market is uneven, mainly as follows:
◆ The chemical composition of abrasives is often qualified, but the physical properties are poor: the main manifestation is that the bulk density of abrasives still has a gap with foreign countries.
◆ The particle size composition of the abrasive is chaotic, which is quite different from the standard requirements: it is mainly manifested in the difference between the basic particle content of the same particle size abrasive and that of foreign countries.
(2) In terms of binders, mainly phenolic resins:
◆ Resin quality stability issues, especially the level of free phenol content in the resin. Excessive free phenol content will accelerate the resin cracking after heating and hardening of the resinoid grinding wheel and affect the strength of the grinding wheel.
◆ The mixing uniformity of resin powder and urotropine, urotropine is used as the hardener of resin, and the amount of urotropine added is insufficient, the resin hardening is incomplete, and the strength and hardness of the grinding wheel are affected; if the content is too high, excessive urotropine Tropin is not combined with resin, and decomposes and volatilizes during the hardening process, which increases the pores of the grinding wheel and reduces its strength and hardness.
◆ The particle size (fineness) of the binder is too coarse or too fine. It is generally believed that the particle size of the binder should be fine, which is conducive to the uniform distribution of the binder. If the particle size is too coarse, the molding material is not easy to mix evenly, which affects the hardness and strength of the grinding wheel. Even for the coarse-grained resin flake cutting wheel and cymbal-shaped grinding wheel, the particle size of the binder (resin powder) selected should be finer than 320#.
However, if the particle size of the phenolic resin powder is too fine, it will bring difficulties to the mixing, and it is difficult to achieve the uniformity of the mixture, which in turn affects the cutting and grinding performance of the resinoid grinding wheel.
2. Resinoid grinding wheel manufacturing process problems:
Resinoid grinding wheel manufacturing is an industrial product with strong craftsmanship, and there are many problems in compounding, molding, hardening, processing and other processes.
(1) Mixing process: The key to mixing is uniformity. The molding material should achieve: the components are evenly distributed and loose, but there should be no obvious powder leakage. It must be ensured that the material is evenly spread and has good molding performance.
(2) Forming process: At present, most of the domestic rotary feeding mechanisms are used. However, due to the limitations of the rotary feeding mechanisms, the employees of some large manufacturing enterprises are unable to operate, the mixture is unevenly distributed, and the shape and position tolerances and static balance are out of tolerance. .
(3) Hardening process: This is the most critical production process. There are two factors that are likely to cause quality problems. One is that the temperature difference between the curing oven or the firing kiln is too large; the other is the improper method of loading the furnace. The temperature difference of the hardening furnace and kiln is too large, which causes the hardening of the resinoid grinding wheel to deviate from the set hardening specification (hardening curve), so that the curing (hardening) quality of the grinding wheel cannot be fully guaranteed.
(4) Processing process (mainly large diameter and high thickness resinoid grinding wheel): resinoid grinding wheel, especially large diameter and high thickness, or grinding wheel with strict dimensional tolerance, should be processed after hardening to ensure the geometric size and shape and position tolerance of the grinding wheel.
(5) The production formula and process parameters are rigidly copied.
3. Equipment tooling problems:
(1) Equipment problems: Production equipment is an important material condition for grinding wheel production. Some companies have insufficient equipment, such as lack of good mixers, small tonnage specifications of hydraulic presses, etc. At the same time, equipment maintenance is poor, and product quality is not easy to guarantee.
(2) Tooling problem: Some of the small-scale resinoid grinding wheel enterprises have weak tooling management and no good storage places, and they are piled up at the production site.
4. Inspection equipment problems:
(1) Raw material inspection, process inspection, and delivery inspection are important contents for resinoid grinding wheel manufacturers to implement effective inspection and control, but there are few manufacturers that truly implement standardized management and standardized management. The main problems are incomplete system, unimplemented functions, lax management, lack of inspection equipment and lack of control, and poor professional quality of inspection personnel.
(2) The inspection equipment is not fully configured. The inspection equipment is not complete. There are three major pieces of inspection equipment for resinoid grinding wheels: namely, rotary strength testing machine; sandblasting hardness machine (or Rockwell hardness machine) --- except for resin chips and grinding chips; static balancer (Dynamic balancer is also required for diamond grinding wheels), and others should include the end face of thin grinding wheel, radial runout tester, inner diameter gauge, vernier caliper, grinding wheel cutting performance testing machine, etc. The inspection equipment lacks due maintenance and maintenance.
