Some manufacturers are troubled by many quality problems in the production process of resin grinding wheels. Today, the editor specially found some common problem analysis and solutions, hoping to exchange and learn with you~

　　1 The particle size and hardness of the material do not match.

　　Strictly calculate the ingredients according to the ingredient list, review is the key procedure

　　2 inclusions

　　Before and during the mixing process, clean up the tooling and equipment. Before batching, check the various raw materials for impurities

　　3 uneven mixing

　　Mixing time according to process requirements. Replace mixer parts that are too worn at any time. The powdered resin material should be sieved according to the screen number and times specified in the process

　　4 Uneven structure, uneven hardness and unbalanced

　　Adjust the dry humidity of the mixture to make it have good formability. Carry out spreading and scraping operations according to process requirements. According to the process requirements, first use the pad iron to maintain the accuracy of the press; when feeding, the material is unevenly spread and scraped, the mixed material is wet, or the material is agglomerated, the material is uneven, the mold is worn, and the leakage is serious, so the mold needs to be replaced

　　5 Formed body cracks

　　If the hot pressing temperature is too high, the product will be cooled and heated rapidly. When the core is removed, the temperature will be too low. The core should be removed in time.

　　The following four crack prevention measures:

　　The plasticity of the mixed material is good with speed regulation, the forming tools and molds must not exceed the specified wear standard, the template and pad iron maintain good flatness, the thickness of the selected pad iron must be consistent, the elasticity of the spring pad iron must be consistent, and the mold should be unloaded in the order specified in the process

　　6 end face crack

　　The plasticity of the molding material is poor, and the method of unloading the mold and taking the blank is improper. The bottom plate of the forming mold is not flat or the backing plate is not parallel too much

　　7 Peripheral cracks

　　The mold sleeve is seriously worn, and when the mold sleeve is removed, it is too deflected

　　8 aperture cracks

　　The strength of the blank is low, the vibration is too large when unloading the mold, the wear of the mandrel is too large or the taper is too small, and the unloading sequence does not conform to the process regulations

　　9 diagonal cracks

　　The selected spring pad iron has inconsistent elastic force, which causes the mold to be deflected and compressed to produce diagonal lines. The pressing speed of the fine material grinding tool is too fast, the pressure maintenance time is short, and the mold fit clearance is too large

　　10 Both ends are not parallel

　　Maintain the precision of the pressing table of the press and operate according to the process regulations

　　11 uneven surface

　　Maintenance of tooling equipment within the required accuracy range

　　12 Forming hardness does not match

　　The first piece of pressing must be inspected, each batch of blanks is not less than 30%, and the weighing unit weight is often checked, and the pressure is often observed for changes

　　13 The bridge is uneven

　　The cooling needs to be uniform; the surface of the part is "warped" and there is no flat plane called bridge flute. This is caused by uneven shrinkage of the workpiece due to uneven cooling or unevenness of the backing plate for the furnace. Most of them come from thin slice grinding wheels and fine-grained thin products. Flake grinding wheels are prone to bridging waste when the cooling rate is too fast

　　14 起泡

　　按产品规范的硬化曲线进行控制温度硬化，对配混料工序进行严格的质量控制;成型温度过高或过低，需要调整温度。固化温度过高，固化炉温度失控。结合剂配错; 超硬磨具局部表面凸起变形或整个表面膨胀，并呈树脂光泽，有的出现龟状裂纹。

　　产生的原因：

　　1升温速度太快或温度波动大，容易使粒度细、硬度高、组织紧的制件起泡和膨胀。因这类产品含结合剂量多或气孔小，若温度控制不准确使升温速度太快，会引起结合剂反应激烈，挥发物量急增，坯体内部气体压力大而使制品起泡和膨胀。

　　2.型料混合不均匀，料内有结合剂疙瘩或含有较多的沸点较低的溶剂(如乙醇，丙酮)。

　　3混料、成型工序的差错所致，使制件结合剂量增多，单重增大，压强增高等。

　　15 变形和倒塌

　　按工艺规定进行装炉，控温操作。填充料之间的配比要严格控制与调整，填充料之间存在着相互作用。切割片叠装时压力不足会变形。

　　超硬磨具在硬化过程中变形、倒塌的原因有：

　　1装炉时坯体露出硬化垫板外或坯体互相挤靠在一起，以及垫板不平使坯体倾斜。

　　2高厚度制件未按工艺规定进行围纸灌砂。

　　3自然干燥时间短或未经低温干燥而直接进炉硬化。

　　4升温速度太快，结合剂急剧熔化使坯体软化后下塌。

　　16 红心

　　硬化炉排风系统需要畅通，按产品规范的硬化曲线硬化操作，正确控制，液体树脂料的坯件，选用多孔垫板或陶瓷垫板; 超硬磨具中心出现发红现象，造成砂轮硬度不均易破裂。

　　产生原因：

　　1硬化设备排风系统不良，废气排出困难。

　　2硬化曲线不合理，升温速度过慢。

　　3液体树脂坯件的垫板透气性差。

　　4液体树脂料的树脂游离酚含量过高，固体含量过低。

　　17 硬化硬度不符和回转破裂

　　按硬化曲线正确控温操作，粉状树脂料坯件硬化必需要加盖或埋砂，在装，卸搬运过程中，避免坯件受震。超硬磨具在进行检验回转时破裂，这是由于结合强度低或磨具有裂纹造成的。

　　产生原因是：

　　1硬化温度过高，结合剂已部分炭化使磨具强度降低。

　　2 Compounding errors, such as more abrasives, less binders, or poor quality binders and lower strength.

　　3 Violent vibration during mold unloading, transportation, and furnace loading will cause mechanical damage to the workpiece and dark cracks inside.

　　4 The structure of the grinding wheel is uneven, and the number of unbalanced grams is too large.

　　5 The grinding wheel is seriously eccentric or the aperture is too large.

　　18 Cutting discs come off the net during use

　　The quality of the resin powder, resin solution and mesh should be qualified, and the process formula should be reasonable, so that the above-mentioned problems basically do not exist. Some fractures have coarse abrasive grains, loose tissue, and lack of bonding agent, and the mesh cloth will fall off after a little pulling. These defects are all related to improper manufacturing process

　　19 The hardness and strength of the finished product do not match

　　1 The quality of the resin is unstable, and the free phenol content of the resin fluctuates. The so-called free phenol is the phenol remaining in the resin. The molecular formula is C6H5OH. Long-term heating can crack the hardened resin and affect the strength of the grinding wheel.

　　2 The mixing of resin powder and urotropine is uneven. The scientific name of urotropine is hexamethylenetetramine ((CH2)6N4). As a hardener for resin, the amount of urotropine added is insufficient, and the resin hardens incompletely. , affecting the strength and hardness of the grinding wheel; if the content is too high, the excess urotropine will not combine with the resin, and will decompose and volatilize during the hardening process, increasing the pores of the grinding wheel and reducing its strength and hardness.

　　3. The particle size of the binder is too coarse, and the particle size of the binder should be finer, which is conducive to the uniform distribution of the binder and the full contact of the hardener. If the particle size is too coarse, the molding material is not easy to mix evenly, which will affect the hardness and strength of the grinding wheel. Even for resin flake cutting wheels and cymbal-shaped grinding wheels with relatively coarse particle sizes, the particle size of the selected binder (resin powder) should be finer than 320#. To manufacture fine-grained grinding wheel products, the particle size of the bond is required to be several microns.

　　20 Dropped edges and corners

　　Care should be taken after forming until hardening to ensure that the edges of the part are intact and avoid mechanical damage. Dropped edges and corners are mostly caused by careless handling during furnace loading and transportation. For unskilled workers, training should be strengthened to improve their skills. The green body of the resin abrasive tool has low wet strength and should be transferred or picked up by the flip method, and the green body cannot be moved directly by hand.