Views: 53 Author: Site Editor Publish Time: 2020-11-19 Origin: Site
The coarse grain size should be selected for the workpiece with large machining allowance and high grinding efficiency. When the machining allowance is small and the surface roughness value is low, the fine grain size should be selected.
For example, P16-P24 abrasives are used for rust removal of hull steel plate, burring of metal parts and grinding of welding seam.
For stainless steel surface polishing Ra0.8- 0.2, P60-P100 can be selected.
W20 grinding tool is used for surface polishing of stainless steel sheet rolling roller (RA = 0.025).
Generally speaking, the grinding efficiency of abrasive belt is higher than that of grinding wheel when processing the same kind of workpiece. That is to say, on the one hand, the embedded depth of abrasive belt particles on the surface of the workpiece is deeper than that of the grinding wheel; on the other hand, almost all the abrasive particles arranged orderly on the surface of the abrasive belt can play a grinding role.
Therefore, if the surface roughness of the workpiece is the same, the abrasive grain size of abrasive belt should be smaller than that of grinding wheel.
For example, screen grinder uses P36-P46 grinding wheel, if using abrasive belt, P46-P60 should be used.
Similarly, when P60-P80 grain size is used for external grinding wheel, the Ra value of roughness can reach 0.8- 0.4μm.
If sand belt is used, P80-P100 should be selected.
Of course, the choice of abrasive grain size should also be combined with the stability and operation skills of the grinder to achieve good results.
B. Workpiece roughness
When the requirements of workpiece roughness are the same, fine grain size should be used for the belt with high linear velocity, and slightly coarse grain size should be used for low linear velocity.
For example, for plywood surface polishing, the surface speed of the roll sander is only 15-20m / s, and the abrasive particle size is P36-P46; when the wide belt sander is used, the linear velocity of the abrasive belt reaches 32m / s, and the abrasive particle size is P60.
C. Processing metals and nonmetals
When processing metal materials and non-metallic materials, if the surface quality requirements of both are similar, the fine-grained material is used to process the metal workpiece; the coarse-grained particle size is selected for the processing of non-metallic material.
D. Dry and wet grinding
When processing the same kind of workpiece, the coarse abrasive grain size is used in dry grinding, while the fine grain size is used in wet grinding. If lubricating oil is used as the coolant, the abrasive grain size should be smaller.
E. Contact area with workpiece
If the contact area between the abrasive belt and the workpiece to be ground is large, the coarse grain size should be used; otherwise, the finer grain size should be selected. For example, the contact surface of screen grinding is generally larger than that of cylindrical grinding. Therefore, when processing the same material, the grain size of screen grinding belt should be slightly larger than that of cylindrical grinding belt.
F. Workpiece material
The particle size should be selected according to the material of the workpiece. When processing metals with higher toughness or softer properties, such as brass, red copper, soft bronze, aluminum and aluminum alloy, lead and lead alloy, the abrasives of abrasive belt are easy to be blocked by abrasive chips, so coarse grain size should be selected; when processing steel with higher hardness, finer grain size can be selected.
According to the characteristics of coated abrasives, the selection of common abrasive particle size is shown in Table 1.
Selection of abrasive particle size | ||||
Grinding objects | Grinding ways | Rough grinding | Medium grinding | Fine grinding |
Regular | Regular | 24#-60# | 80#-150# | 180#-400# |
Steel | abrasive belt | 24#-60# | 80#-120# | 150#-400# |
grinding plates | 16#-40# | 50#-80# | 100#-240# | |
cylinder | -- | -- | -- | |
Nonferrous metals | abrasive belt | 24#-60# | 80#-120# | 150#-400# |
grinding plates | 16#-40# | 50#-80# | 100#-240# | |
cylinder | -- | -- | -- | |
Wood | abrasive belt | 36#-80# | 100#-150# | 180#-320# |
grinding plates | 14#-36# | 40#-60# | 80#-120# | |
cylinder | 40#-80# | 100#-150# | 180#-240# | |
Glass | abrasive belt | 40#-80# | 100#-150# | 180#-240# |
grinding plates | 80#-100# | 120#-180# | 220#-800# | |
cylinder | -- | -- | -- | |
Painting | abrasive belt | 80#-150# | 180#-240# | 280#-800# |
grinding plates | -- | -- | -- | |
cylinder | -- | -- | -- | |
Leather | abrasive belt | 40#-60# | 80#-150# | 180#-500# |
grinding plates | 40#-60# | -- | -- | |
cylinder | 80#-120# | 150#-180# | 220#-500# | |
Rubber | abrasive belt | 16#-40# | 50#-120# | 150#-400# |
grinding plates | -- | -- | 150#-500# | |
cylinder | -- | -- | -- | |
Plastic | abrasive belt | 36#-80# | 100#-150# | 180#-400# |
grinding plates | 80#-120# | 150#-180# | 220#-800# | |
cylinder | 60#-120# | 120#-180# | 220#-500# | |
Ceramic | abrasive belt | 36#-80# | 100#-150# | 180#-400# |
grinding plates | 36#-60# | 80#-120# | 180#-800# | |
cylinder | -- | -- | -- | |
Stone | abrasive belt | 36#-80# | 100#-150# | 180#-400# |
grinding plates | 36#-60# | 80#-150# | 180#-800# | |
cylinder | -- | -- | -- | |