Quality problems and solutions are common in the production of resin grinding wheel

20 kinds of quality problems and solutions are common in the production of resin grinding wheel

Num	question	Reason and solutions
1	Material size and hardness are inconsistent	The ingredients are calculated strictly according to the ingredient list, and the review is the key procedure
2	inclusion	Before and during the mixing process, cleaning tools will be provided. Check all raw materials for impurities before adding ingredients
3	Mixing unevenly	Mix according to process requirement. Replace the parts of the mixer which wear too much at any time. The powder resin material shall be screened according to the number and times specified in the process
4	Uneven tissue, uneven hardness and imbalance	Adjust the dry humidity of the mixture to make it have good molding. According to the process requirements to carry out the operation of stripping and scraping. According to the process requirements, first use the pad iron to maintain the precision of the press; Uneven striping, wet mix, or aggregate, uneven feeding, wear of the die, serious leakage, need to replace the die
5	Forming body crack	Hot-pressing temperature is too high, the product thermal shock, when to take off the core temperature is too low, should be timely to take off the core type, metamorphic materials be affected with damp be affected with damp, or mixing material error. The following four types of crack prevention measures: good plasticity of mixture of speed regulation, and the forming mould shall not exceed the prescribed standards for wear and tear, good flatness, template and pad iron selects the shim thickness to be consistent, spring shim of elastic should agree, as stipulated in the process sequence discharge mode.
6	Transverse crack	Molding material plasticity is poor, the unmoulding method is not appropriate. Forming mold base is uneven or the backing plate is not too parallel
7	Around the crack	Die wear is serious, when unloading die, too skew
8	Aperture cracks	Low strength of blank, too much vibration, too much core wear or too little taper, the order of unloading die is not in accordance with the process regulations
9	Diagonal crack	The selected spring pad iron has inconsistent spring force and produces diagonal grain when the die is deflected. The fine material grinding tool is pressed too fast, the pressure time is short and the die clearance is too large
10	The two sides are not parallel	Keep the precision of press table of press machine, operate according to the process
11	The surface uneven	Tooling equipment is maintained within the required accuracy range
12	Molding hardness mismatch	Pressing the first part must be checked, no less than 30% of each batch of blank check, weight sheet is often checked, and pressure is often observed
13	Bridge stare blankly uneven	Uniform cooling is required; The surface "warping" without a flat surface is called bridge deck. This is caused by uneven cooling resulting in inconsistent contraction of the parts or uneven plate mounting of the furnace. Come from thin section grinding wheel and fine grain thin product more. It is easy to produce the bridge end waste when the grinding wheel cools too fast
14	blister	Temperature hardening is controlled according to the hardening curve of product specification, and strict quality control is carried out on the mixing process. The forming temperature is too high or too low and needs to be adjusted. The curing temperature is too high and the curing furnace is out of control. The binder mismatch; The surface of the superhard grinding tool is convex and deformed or the whole surface expands, and some of them appear turtle cracks. Causes: 1. If the heating rate is too fast or the temperature fluctuates greatly, it is easy to make the parts with fine grain, high hardness and tight structure bubble and expand. Because this kind of product contains the binding dose more or the stoma is small, if the temperature control is not accurate to make the heating rate too fast, will cause the binding agent reaction is intense, the volatiles quantity increases sharply, the blank body internal gas pressure is big and causes the product to bubble and expand. 2. The mixture of the molding compound is not uniform, and the mixture contains a combination of binders or solvents with relatively low boiling point (such as ethanol and acetone). 3. Errors caused by mixing and molding process increase the binding dose, increase the single weight and increase the pressure.
15	Deformation and collapse	Charging and temperature control according to process regulations. The ratio of filling materials should be strictly controlled and adjusted. If the pressure is not enough, the cutting sheet will be deformed. Causes of deformation and collapse of ultra-hard grinding tools during hardening include: 1. When installing the furnace, the body of the billet is exposed to the hardening pad or the blank body is squeezed together, and the uneven pad makes the blank body tilt. 2 high thickness parts are not coated with paper and sand. Natural drying time is short or not low temperature drying directly into the furnace to harden. 4 the heating rate is too fast, and the binder melts rapidly, making the billet collapse after softening.
16	Red hearts	The hardening furnace exhaust system needs to be unimpeded, which is operated according to the hardening curve of product specification and controlled correctly. There is a red phenomenon in the center of ultra-hard grinding tool, resulting in uneven hardness of grinding wheel easily broken. Causes: Hardening equipment exhaust system is not good, exhaust gas difficult. 2. The hardening curve is unreasonable and the heating speed is too slow. 3 poor air permeability of gasket of liquid resin blank. The free phenol content of liquid resin is too high and the solid content is too low.
17	Inconsistency in hardening hardness and rotary rupture	Correct temperature control according to the hardening curve, the solidification of powder resin blank must be covered or buried with sand, in the process of loading, unloading and handling, to avoid the blank. The breaking of the ultra-hard grinding tool during the test rotation is due to low bonding strength or cracking in the grinding. The causes are: The hardening temperature is too high, and the binding agent has been partially carbonized to reduce the grinding tool strength. 2 mixing errors, such as more abrasive, less binder, or poor quality of the binder itself When unloading, transporting and loading the furnace, the parts are severely vibrated, resulting in mechanical damage and internal dark cracks. 4. Uneven structure of grinding wheel and excessive unbalanced grams. The grinding wheel is seriously eccentric or oversize.
18	Cut out the mesh during use	The quality of resin liquid and mesh should be qualified, and the technical formula should be reasonable. Some of these defects are related to improper manufacturing process
19	Hardness and strength do not match	1 the quality of the resin is unstable, the free phenol content of the resin increases or decreases. The so-called free phenol is the phenol that remains in the resin. The molecular formula is C6H5OH. 2. Non-uniform mixing of tree powder and ullotropine. The academic name of ullotropine is hexamethylenetetramine ((CH2) 6N4). If the content is too high, the excessive ulotropine does not combine with the resin and decomposes and volatilizes in the hardening process, increasing the pores of the grinding wheel and reducing its strength and hardness. 3. The size of the binding agent is too coarse, and the size of the binding agent should be fine, which is conducive to uniform distribution of the binding agent and sufficient contact of the hardener. If the particle size is too coarse, the forming material is not easy to be mixed evenly, which affects the hardness and strength of the grinding wheel. The size of the binding agent (resin powder) selected should be smaller than 320#, even for the resin flake cutting wheel and the cymbal wheel. The size requirement of the binder is several microns.
20	Off edge and off Angle	After forming until after hardening, should be careful operation, to ensure that the edge of the piece intact, avoid mechanical damage. The loose side and Angle are mostly caused by the mistake of loading and discharging in transportation. The unskilled workers should be trained to improve their skills. The wet strength of resin abrasive tool body is low, which should be transferred or taken out by turning over, and can not be moved directly by hand.