What are the problems that cause the quality of resin bond diamond grinding wheels to be unstable?

There are many quality problems in the production of resin bond diamond grinding wheels. Since the manufacturing of resin bond diamond grinding wheels is a multidisciplinary synthesis of composite materials, the causes are complex and numerous.

One, the problem of raw materials

Resin bond diamond grinding wheel is composed of a variety of main and auxiliary materials. The main material is abrasive and bonding agent, the auxiliary materials include fillers, reinforcing materials, colorants, etc.

1. Issues that should be paid attention to in abrasives

At present, the quality of abrasives on the market is uneven, mainly as follows:

 (1) The chemical composition of abrasives is often qualified, but the physical properties are poor; it is mainly manifested in the bulk density of abrasives.

(2) The particle size composition of abrasives is chaotic, which is quite different from the standard. It is mainly manifested in the basic particle content of the same size abrasive.

2. In terms of bonding agent, mainly phenolic resin:

(1) The stability of resin quality, especially the content of free phenol in the resin. Too high free phenol content will accelerate the cracking of the resin after the resin bond diamond grinding wheel is heated and hardened, and affect the strength of the grinding wheel;

(2) The uniformity of the mixing of resin powder and urotropine. Urotropine is used as the hardener of the resin. Insufficient addition of urotropine and incomplete resin hardening will affect the strength and hardness of the grinding wheel. If the content is too high, the excess urotropine does not combine with the resin, and decomposes and volatilizes during the hardening process, which increases the pores of the grinding wheel and reduces its strength and hardness.

(3) The particle size of the binder is too coarse or too fine:

It is generally believed that the particle size of the bonding agent is preferably fine, which is conducive to uniform distribution of the bonding agent. If the particle size is too coarse, the molding material is not easy to mix uniformly, which affects the hardness and strength of the grinding wheel. Even for super thin resin bond cutting wheels with coarser particle size, the selected binder (resin powder) particle size should be finer than 320#.

However, if the particle size of the phenolic resin powder is too fine, the mixing process is very difficult. And it will be difficult to achieve the uniformity of the mixture, which will affect the cutting and grinding performance of the resin bond diamond grinding wheel.

Second, the manufacturing process of resin bond diamond grinding wheel. 

Resin bond diamond grinding wheel manufacturing is an industrial product with strong technology, and there are many problems in the process of compounding, forming, hardening, and processing.

(1) Mixing process: The key to mixing is uniformity. The molding material should achieve: uniform distribution of the ingredients, maintaining looseness, but not obvious powder leakage; must ensure that the material is evenly spread and has good molding properties. 

(2) Molding process: At present, most of the rotating materials mechanism, but due to the limitations of the rotating material mechanism, some of manufacturing companies are unable to operate correctly so that the mixture is unevenly distributed, the position tolerance and the static The balance is out of tolerance.

(3) Hardening process: This is the most critical production process. There are two factors that easily cause quality problems. One is that the temperature difference of the curing oven or the firing kiln is too large; the other is the improper way of installing the furnace. The temperature difference of the hardening furnace is too large, causing the hardening of the resin bond diamond grinding wheel  to deviate from the set hardening specification (hardening curve), so that the curing (hardening) quality of the grinding wheel cannot be fully stable.

(4) Processing procedures (mainly large diameter and bigger thickness of resin bond diamond grinding wheels): resin bond diamond grinding wheels, especially large diameter and bigger thickness, or grinding wheels with strict dimensional tolerances, must be processed after hardening to ensure the geometric size, shape of the grinding wheel and position tolerance.

(5) The production formula and process parameters are mechanically copied.

Three, equipment tooling problem

(1) Equipment problems: production equipment is an important condition for the production of grinding wheels. Some companies have insufficient equipment, such as lack of good mixers, small tonnage specifications, etc.; at the same time, equipment maintenance is poor, and it is not easy to guarantee product quality.

(2) Tooling problem: Some of the smaller enterprises have weak tooling management, and there is no good storage place.

Inspection equipment problem

(1) Raw material inspection, process inspection, and factory inspection are important content for resin bond diamond grinding wheel manufacturers, but there are fewer manufacturers that truly achieve standardized management. The main problems are incomplete systems, unimplemented functions, lax management, short and lack of control of inspection equipment, and poor professional quality of inspection personnel.

(2) Incomplete inspection equipment

The inspection equipment is not complete. There are three major pieces of inspection equipment for resin bond diamond grinding wheel s: rotary strength tester; sandblasting hardness machine (or Rockwell hardness machine); static balancer (for diamond grinding wheels, a dynamic balancer is required), and there should also be a end face machine, a radial runout tester, an inner diameter gauge, a vernier caliper, a grinding wheel cutting performance tester, etc.

Fourth, the inspection equipment lacks maintenance.

JR Company has strictly quality control, basing on ISO9001.