Some production enterprises are plagued by many quality problems generated in the production process of resin grinding wheels, and today Xiaobian deliberately found some common problem analysis and solutions, hoping to exchange and learn with mill friends
serial number
issue
Cause/Resolution
1
The grain size of the material does not match, the hardness does not match.
Ingredients are calculated strictly according to the ingredient list, and review is a key procedure
2
inclusion
Before mixing and during the mixing process, the tooling equipment is cleaned with the advance. Before batching, check the various raw materials for impurities
3
Uneven mixing
Mixing time according to process requirements. Replace mixer parts that wear too much at any time. The powdered resin material shall be screened according to the screen number and frequency specified in the process
4
Uneven organization, uneven hardness and unbalanced
Adjust the dry humidity of the mixture so that it has good formability. Spreading and scraping operations according to process requirements. According to the process requirements, the horn is used first to maintain the accuracy of the press; When feeding, the scraping of the spreading material is uneven, the mixture is wet, or the material is clumped, the feeding is uneven, the mold is worn, the leakage is serious, and the mold needs to be replaced
5
Cracks in the molded blank
The hot pressing temperature is too high, the product is hot and cold, the temperature is too low when the core type is removed, the core type should be removed in time, the raw material is subject to moisture deterioration, or the mixture is wrong. The following four crack prevention measures: the plasticity of the mixture is regulated, the molding mold shall not exceed the specified wear standard, the template and the horn shall maintain a good flatness, the thickness of the horn selected should be consistent, the elasticity of the spring horn should be consistent, and the mold should be unloaded in accordance with the process regulations
6
End face cracks
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 molding mold is uneven or the parallelism of the pad plate is too large
7
Peripheral cracks
The mold sleeve wears heavily, and when the mold sleeve is unloaded, 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 order of mold unloading does not conform to the process regulations
9
Diagonal cracks
The spring horn selected, the elastic force is inconsistent and the mold is deflected and pressurized to produce diagonal grain. The fine material degree abrasive pressing speed is too fast, the pressure maintenance time is short, and the mold fit gap is too large
10
The two end faces are not parallel
Maintain the accuracy of the press press table and operate according to the process regulations
11
Uneven surface
Tooling equipment is maintained within the required precision range
12
The molding hardness does not match
Pressing the first piece must be inspected, each batch of sampling blanks is not less than 30%, often check the weighing weight, often observe whether there is any change in pressure
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 the bridge deck. This is caused by uneven cooling and inconsistent contraction of the parts or uneven pads for loading the furnace. Mostly from flake grinding wheels and fine-grained thin products. Flake grinding wheels are prone to bridge deck scrap when the cooling rate is too fast
14
bubble
According to the hardening curve of the product specification, the temperature hardening is controlled, and the compounding process is strictly quality controlled; The molding temperature is too high or too low, and the temperature needs to be adjusted. The curing temperature is too high, and the temperature of the curing oven is out of control. Conjugate mismatch; The local surface of the superhard abrasive is convex and deformed or the entire surface is expanded, and it has a resinous luster, and some turtle-like cracks appear. Causes: 1 The heating rate is too fast or the temperature fluctuation is large, which is easy to foam and expand the parts with fine particle size, high hardness and tight organization. Because such products contain many binding doses or small stomatals, if the temperature control is not accurate to make the heating rate too fast, it will cause the binding agent to react fiercely, the amount of volatiles increases sharply, and the gas pressure inside the body is large and the products foam and expand. 2. The mixture of the type material is uneven, and there are binder knots in the material or solvents with a lower boiling point (such as ethanol, acetone). 3 Caused by errors in the mixing and molding processes, the combined dose of the parts increases, the single weight increases, and the pressure increases.
15
Deformation and collapse
According to the process regulations, the furnace is loaded and the temperature is controlled. The ratio between fillers should be strictly controlled and adjusted, and there is an interaction between fillers. Insufficient pressure when the cutting pieces are stacked will deform. The reasons for the deformation and collapse of the superhard abrasive during the hardening process are: 1. When the furnace is installed, the blank is exposed outside the hardened pad or the blanks are squeezed together, and the pad is uneven and tilts the billet. 2 High thickness parts are not grappling with paper in accordance with the process regulations. 3 The natural drying time is short or it is directly hardened into the furnace without low temperature drying. 4 The heating rate is too fast, and the binder melts sharply to soften the blank and collapse.
16
Hearts
The hardening grate exhaust system needs to be unobstructed, according to the hardening curve of the product specification, correct control, the blank of the liquid resin material, the selection of porous pads or ceramic pads; The center of the superhard abrasive has a redness phenomenon, resulting in uneven hardness of the grinding wheel and easy to crack. Causes: 1 Hardening equipment exhaust system is poor, exhaust gas discharge is difficult. 2 The hardening curve is unreasonable, and the heating rate is too slow. 3 The gas plate of the liquid resin blank is poorly breathable. 4 The resin free phenol content of the liquid resin material is too high, and the solids content is too low.
17
The hardening hardness does not match and the rotation breaks
According to the hardening curve of the correct temperature control operation, the hardening of the powder resin blank must be covered or buried with sand, and the blank is avoided from being shaken during loading and unloading. The super-hard abrasive cracks during the test rotation, which is caused by low bond strength or cracks in the grinding. The reasons for this are: 1The hardening temperature is too high, and the binder has been partially charred to reduce the strength of the abrasive. 2 Mismatch in the compound, such as more abrasives, less binders, or poor quality of the binder itself the strength is reduced. 3 When unloading, transporting and loading the furnace, it vibrates violently, causing mechanical damage to the parts and dark cracks inside. 4 The grinding wheel is unevenly organized and the unbalanced grams are too large. 5 The grinding wheel is seriously eccentric or the aperture is too large.
18
During use, the cutting sheet is off the net
The quality of resin powder resin liquid and mesh should be qualified, the process formula should be reasonable, and there are basically no above problems. Some fractures are coarsely abrasive, loosely organized, missing binders, and the mesh cloth will be detached if it is slightly pulled, and the occurrence of these defects is related to improper manufacturing process
19
The hardness and strength of the finished product do not match
1 resin quality is unstable, resin free phenol content is high and low, the so-called free phenol is the phenol remaining in the resin, the molecular formula is C6H5OH, long-term heating can make the hardened resin crack, affecting the strength of the grinding wheel. 2 resin powder and ulotite mixed unevenly, the scientific name of ulotox product is hexamethylenetetramine ((CH2) 6N4), as a hardener of the resin, the amount of ulotox product added is insufficient, the resin hardening is not complete, affecting the strength and hardness of the grinding wheel; the content is too high, the excess of ulotox product is not combined with the resin, decomposed and volatilized during the hardening process, so that the pores of the grinding wheel increase, reducing its strength and hardness. 3. The binding agent particles are too coarse, and the particle size of the binding agent is fine, which is conducive to the uniform distribution of the binding agent and the full contact of the hardener. If the grain is too coarse, the molding material is not easy to mix evenly, which affects the hardness and strength of the grinding wheel. Even for resin flake cutting wheels and cymbal grinding wheels with coarse particle sizes, the particle size of the selected binder (resin powder) should be less than 320#. For the manufacture of fine-grained grinding wheel products, the particle size of the binder is required to be several microns.
20
Drop edges and corners
Careful handling should be taken after molding until after hardening to ensure that the edges of the part are intact and mechanical damage is avoided. The falling edges and corners are mostly caused by the loading of the furnace and the careless removal and placement during transportation. Workers who are not skilled in operation should be trained and skills upgraded. The low wet strength of the resin abrasive body should be transferred or placed by the flap method, and the blank cannot be directly moved by hand.
Disclaimer: This article is compiled from the Internet, its originality and the views and judgments expressed in the text do not represent the purpose of disseminating knowledge, beneficial learning and research for the purpose of extracting, only for the reference and exchange of readers, if there is any objection from the copyright owner or publisher, it will be deleted immediately. If you have any questions about the reprinting of the article, please tell us so that we can correct it in time.
If you have technical problems that you want to discuss with your friends, if you have products that need to be bought or sold, if you want to grasp the industry information for the first time, if you have industry news that you want to share with everyone, then hurry up and hook up with Xiao Rui (Xiao Rui WeChat: airuikefu)! Note "cut and polish exchange", let Xiao Rui pull you into the company, let's hi together~