Comprehensive analysis of resin cutting disc quality
- Inconsistent material granularity and hardness. Measures: Calculate the ingredients strictly according to the ingredient list, and review is the key procedure;
- Inclusions. Before and during the mixing process, clean up the tooling and equipment along with it. Before ingredients, check the various raw materials for impurities;
- Uneven mixing. Mix the materials according to the mixing time required by the process. Replace parts of the mixer that are too worn at any time. The powdered resin material should be sieved according to the screen number and frequency specified in the process;
- Uneven organization and uneven hardness. Adjust the dry humidity of the mixture to make it have good moldability. Spread and scrape materials according to process requirements. According to the process requirements, first use the shim to maintain the accuracy of the press; when feeding, the material is unevenly spread, the mixture is wet, or the material is agglomerated, the material is unevenly fed, the mold is worn, and the material leakage is serious. The mold needs to be replaced;
- Cracks in the forming body. The hot pressing temperature is too high, the product is rapidly cold and hot, the temperature is too low when the core is removed, the core should be removed in time, the raw material is damp and deteriorates, or the compounding is wrong;
5.1 End face cracks. The molding material has poor plasticity, and the method of unloading the mold and taking the blank is improper. The bottom plate of the molding die is not flat or the backing plate is not too parallel.
5.2 Peripheral cracks. The die sleeve is seriously worn, and the die sleeve is too skewed when it is unloaded.
5.3 Aperture cracks. The strength of the blank is low, the vibration is too large when unloading the mold, the core rod is too worn or the taper is too small, and the unloading sequence does not meet the process regulations.
5.4 Diagonal cracks. The selected spring shim has inconsistent elastic force, which makes the die deflection and compression produce diagonal lines. The pressing speed of the fine material abrasive tool is too fast, the pressure maintaining time is short, and the mold fit gap is too large.
5.5 Preventive measures for cracks above: adjust the speed to ensure the plasticity of the mixture, the molding tool must not exceed the specified wear standard, the template and the shim should maintain good flatness, the thickness of the shim should be consistent, and the elasticity of the spring shim should be consistent. Unload the mold in the order specified by the process;
- The two ends are not parallel. Maintain the accuracy of the press table and operate in accordance with the process regulations;
- The surface is not flat. Tooling equipment is maintained within the required accuracy range;
- Inconsistent molding hardness. The first piece of pressing must be inspected, and each batch of blanks shall be inspected not less than 30%. Always check the weighing unit weight and observe whether the pressure changes;
- The bridge is uneven. Cooling needs to be uniform; the surface of the part that is “warped” without a flat surface is called a bridge. This is due to uneven cooling and inconsistent shrinkage of the workpiece or uneven backing plate of the furnace. Mostly come from thin-slice cutting discs and fine-grained thin products. The flake cutting discis easy to produce bridge waste when the cooling speed is too fast;
- Foaming. Control the temperature hardening according to the hardening curve of the product specification, and strictly control the quality of the compounding process; if the molding temperature is too high or too low, the temperature needs to be adjusted. The curing temperature is too high and the curing oven temperature is out of control. The binding agent is mismatched; the surface of super-hard abrasives is locally convex and deformed or the entire surface swells, and shows a resin luster, and some have turtle-shaped cracks. Causes:
10.1 Too fast heating rate or large temperature fluctuations can easily cause foaming and swelling of parts with fine particle size, high hardness and tight organization. Because this type of product contains a large amount of binding agent or small pores, if the temperature control is not accurate and the heating speed is too fast, it will cause the binding agent to react fiercely, the amount of volatile matter will increase sharply, and the high gas pressure inside the blank will cause the product to foam and expand.
10.2. The type material is not uniformly mixed, there is a binding agent in the material or contains a lot of boiling pointLower solvents (such as ethanol, acetone).
10.3 Due to errors in the mixing and molding processes, the combined dosage of the parts increases, the unit weight increases, and the pressure increases.
- Deformation and collapse. The furnace is installed and the temperature is controlled according to the process regulations. The ratio of fillers should be strictly controlled and adjusted, and there is an interaction between fillers. Insufficient pressure will cause deformation when cutting sheets are stacked. The reasons for the deformation and collapse of the super-hard abrasive tool during the hardening process are:
11.1 When the furnace is installed, the blank is exposed outside the hardened backing plate or the blanks are squeezed against each other, and the backing plate is not flat so that the blank is inclined;
11.2 The high-thickness parts have not been filled with paper and sand in accordance with the process regulations.
11.3 The natural drying time is short or directly into the furnace for hardening without low-temperature drying.
11.4 The heating rate is too fast, and the binder melts sharply to make the body soften and then collapse.
- Red hearts. The exhaust system of the hardening furnace needs to be unblocked, and the hardening operation according to the hardening curve of the product specification should be properly controlled. The blank of the liquid resin material should be selected from the porous pad or the ceramic pad; the center of the super-hard abrasive has redness, which causes the hardness of the cutting discto be weak. All are easy to break. cause:
12.1 The exhaust system of the hardening equipment is poor and the exhaust gas is difficult to discharge.
12.2 The hardening curve is unreasonable and the heating rate is too slow.
12.3 The backing plate of the liquid resin blank has poor air permeability.
12.4 The resin free phenol content of the liquid resin material is too high and the solid content is too low.
- Inconsistent hardening hardness and rotating fracture. According to the correct temperature control operation of the hardening curve, the powdery resin blank must be covered or buried in the hardening. During the loading, unloading and handling process, the blank is prevented from being shocked. The super-hard abrasive tool is broken during inspection rotation, which is caused by low bonding strength or cracks in the grinding. The reasons are:
13.1 The hardening temperature is too high, and the bonding agent has been partially carbonized to reduce the strength of the abrasive.
13.2 Compounding errors, such as too much abrasives, less binding agent, or poor quality of the binding agent itself reduces its strength.
13.3 Severe vibration during mold unloading, transportation and furnace loading will cause mechanical damage to the parts and dark cracks inside.
13.4 The organization of the cutting disc is uneven, and the unbalanced grams is too large.
13.5 The cutting disc is severely eccentric or the hole diameter is too large.
- The cutting piece is off the net during use. The quality of the resin powder, the resin liquid and the mesh sheet should be qualified, and the process formula should be reasonable, and the above-mentioned problems basically do not exist. In some fractures, the abrasive grains are coarse, the structure is loose, and the bonding agent is missing, and the mesh cloth will be detached after a little pull. The occurrence of these defects is related to the improper manufacturing process.
- The hardness and strength of the finished product are inconsistent.
15.1 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 cutting disc.
15.2 The resin powder and urotropine are not uniformly mixed. The scientific name of urotropine is hexamethylene tetramine ((CH2) 6N4). As the hardener of the resin, the amount of hexamethylene tetramine (CH2) 6N4 is insufficient, and the resin hardening is not complete. , It affects the strength and hardness of the cutting disc; if the content is too high, the excess urotropine will not be combined with the resin, and will decompose and volatilize during the hardening process, which will increase the pores of the cutting disc and reduce its strength and hardness.
15.3. The particle size of the bonding agent is too coarse, and the particle size of the bonding agent is preferably fine, which is conducive to uniform distribution of the bonding agent and full contact of the hardener. If the particle size is too coarse, the molding material is not easy to mix uniformly, which affects the hardness and strength of the cutting disc. Even for resin flake cutting wheels and cymbal-shaped wheels with coarser particle size, the selected binder (resin powder) particle size should be finer than 320#. To manufacture fine-grained cutting disc products, the particle size of the bonding agent is required to be several microns.
- The edges and corners should be carefully operated after forming and hardening to ensure that the edges of the parts are intact and avoid mechanical damage. Falling edges and corners are mostly caused by careless handling during furnace installation and transportation. Workers who are unskilled in operation should be trained to improve their skills. The resin mold body has a low wet strength and should be transferred or taken and placed by the flip method, and the body cannot be directly moved by hand.
In summary, strict quality management is the root of stable quality. Organic abrasive tools change at any time due to environmental changes such as temperature and humidity, so raw materials such as bonding agents should be used in time, so it is not scientific to import organic abrasive tool bonding agents from abroad. In addition, we must pay attention to the technical indicators and quantity of the filler when producing the cutting disc, and pay more attention to the relevant ratio, otherwise it is likely to be the opposite.
Abrasives have always been regarded as a good name for industrial teeth, and they play a role in cutting, grinding, polishing, etc. in the machining process. But the current product quality in the industry is also uneven. Many of my country’s abrasives companies started from home workshops. As market competition continues to intensify,
In the past, neither the technical level nor the management level could meet the needs of the increasingly rapid development of new forms. Whether the product quality can meet the ever-increasing individual needs of customers is the standard for testing the technical and management levels of abrasive manufacturers. For a professional manufacturer dedicated to abrasives for many years, how do we control and improve the quality of our products?
- The construction of quality culture:
The quality control process will be affected by factors such as man, machine, material, law, environment, etc., but in this process, it is the man who plays the leading role. Only in-depth establishment of human quality awareness culture can establish corporate quality culture. Because the corporate quality culture is a combination of values, beliefs, consensus and norms shared by all employees of the company in terms of quality, employees are the key factor in determining the quality of the company’s products. Therefore, we continue to carry out various quality culture publicity activities and quality training activities, so that all employees can actively participate in the construction of the company’s quality culture activities, and establish the concept of “quality is closely related to me. At the same time, we can recruit all employees to participate in the project. Feedback and suggestions from the activity, and provide material encouragement to employees who have put forward constructive opinions and are adopted, so as to enhance the enthusiasm of all employees to participate. Deepen the awareness of product quality in the hearts of every employee and improve the career of every employee.
Level of business, especially front-line production workers and grassroots management staff. The improvement of their quality awareness and business level is a key factor to ensure the stability of product quality.
- Quality control of the production process:
There are many quality control points for the production of resin cutting discs, and the production process can be controlled in three steps: mixing-forming-hardening.
The mixing is the source of the entire cutting disc production control. The quality of the mixing is closely related to the size of the mixing equipment, the temperature and humidity of the mixing workshop, and the raw materials used, especially the quality of the resin.
At present, our company adopts the mixing method of 500 kilograms per pot. Compared with the previous 100 kilograms per pot, it not only meets the needs of batch standard production lines, but also reduces process errors and stabilizes the quality of mass production. One of the main factors. Because of the small pot mix used in the past, the molding material of each pot is different. If there are six to seven hundred pots a day, the materials of each pot will be different, and the error of the product is relatively small, and currently we use this This method can effectively reduce the probability of such unstable factors.
The temperature and humidity in the mixing workshop are the key to directly affecting the quality of the molding materials. The weather in the north is cold and the humidity is high, and the molding materials are not easy to agglomerate during the mixing process. Like in the south, the weather is relatively hot all year round and the humidity is high. Therefore, we use the central air-conditioning to control the temperature and humidity of the workshop within a certain range to avoid the molding material from changing with the temperature and humidity changes to affect the product. the quality of.
For the production of resin cutting discs, we not only need to use high-quality materials, we also need to have stable and high-quality suppliers. The materials used in the cutting disc are mainly resin and abrasive. The stability of these two materials directly affects the stability of product quality. The production of resin and abrasive is also produced in one kettle or one furnace, and the batch size will also affect the product. The smaller the batch, the higher the frequency, and the higher the probability of large quality instability. Therefore, when we purchase materials, we must not only evaluate the technical capabilities of suppliers, but also evaluate their production capabilities. The unified procurement of bulk materials can effectively control the instability of the products due to the instability of the main raw materials.
There are several aspects to control the molding process:
The control of the molding process is different from the control of the mixing process. The mixing process is a special quality control point for the production of cutting discs. The quality control of the molding process is basically the same as the quality control of the production process of other products. The following must be done:
On-the-job training of personnel: It is an indisputable fact for the entire manufacturing industry to face labor tensions. Due to labor shortages, many companies involuntarily reduce the quality requirements of their personnel and neglect the pre-job skills training for their personnel. Due to inadequate quality level and skill training, the frequency of product quality accidents will increase. Therefore, no matter how tight the production is, the skill training for new and old employees is a work that cannot be ignored.
Improvement of engineering technology: Due to the increasing shortage of first-line production workers, we not only need to continuously purchase new advanced equipment to meet the needs of production,
We also need to continuously improve our existing equipment to make the equipment more user-friendly, reduce or reduce labor, improve automation capabilities, save production costs, and improve production efficiency.
Process supervision: The production process must undergo a combination of first inspection confirmation, periodic process random inspection, and process supervision and random inspection to control process production and ensure the quality of process production.
Hardening process control
The control of the hardening process is mainly the control of temperature stability, accuracy and curve continuity. The box-type square furnace hardening used in the past is a hardening method adopted for production enterprises with insufficient or low production capacity. The limitations of this method are low production capacity, large temperature difference in the furnace, unstable temperature in the furnace, and continuous operation. Therefore, the box-type square furnace in the past has a greater impact on the hardening quality of the product. We have always adopted the intelligent tunnel kiln control method. This method can not only increase our production capacity, but more importantly, it can solve the problems of the box oven and fully ensure the stability of product quality. Three. Improvement of process technology:
Developing new products and improving old products is the fundamental way for an enterprise to continue to grow and grow, and it is also an important means for an enterprise to improve its economic efficiency and competitiveness. Although cutting disc products do not have a certain market life cycle like other products, the problem of homogenization has become more and more obvious. Therefore, we have established a technical process department. In addition to perfecting and standardizing our existing production processes to correctly guide production, ensuring that products are produced in accordance with standardization, and stably improving product quality, we must also continue to introduce new ones to meet customer needs and strengthen our company’s The core competitiveness in the industry.