High speed steel single angle milling cutters belong to shovel tooth forming milling cutters, with the core feature being that the tooth back is a shovel back curved surface. Re grinding is only allowed to grind the front cutting surface, and it is strictly prohibited to grind the tooth back, otherwise it will change the original forming angle of the tool and cause the workpiece angle to exceed the tolerance. The wear of the blade tip is divided into mild wear, moderate wear, and severe damage such as chipping. It needs to be treated according to the level of damage, and equipped with grinding technology, inspection, and preventive control.
1、 Wear grade determination and corresponding treatment measures
1. Mild wear of the cutting edge (normal wear, no breakage, width of wear on the back of the blade surface ≤ 0.1~0.15mm)
Features: Uniform wear of the cutting edge arc, no gaps or cracks, only uniform wear marks appear on the rear cutting surface, the angle and roughness of the processed workpiece are still qualified, the cutting sound is smooth, and there are no obvious vibration marks.
Solution: It can continue to be used for a short period of time and be monitored simultaneously.
Reduce cutting line speed, increase cutting fluid supply appropriately, and minimize further development of wear;
Randomly inspect the angle and surface quality of a certain number of workpieces during processing;
After reaching the specified wear limit, immediately go offline for re grinding. It is not allowed to use beyond the limit to prevent tool tip breakage.
2. Moderate blade tip wear (rear blade wear width>0.15mm, no chipping, blade edge passivation)
Features: The tool tip becomes significantly dull, cutting resistance increases, surface roughness of the machined surface deteriorates, cutting temperature increases, chip deposits are easily generated, and the workpiece angle tends to drift, requiring offline re grinding.
Key principle: The high-speed steel shovel tooth single angle milling cutter only grinds the front cutting surface and does not grind the tooth back (rear cutting surface). The tooth back is a formed curved surface that is scraped and shaped at the factory. Once the tooth back is ground, the original cone angle and forming angle of the tool will change, and the tool will be directly scrapped.
1. Grinding wheel selection: Choose white corundum (WA) grinding wheel; Particle size 60 #~80 #, medium soft hardness (K/L);
2. Key points of sharpening operation
Clean the chips and oil stains between the teeth of the cutting tool before grinding; Check for cracks in the cutting tool;
Maintain the original rake angle of the front cutting surface, perform thin-layer grinding along the front cutting surface, control the feed rate of a single grinding, and strictly prohibit large feed dry grinding;
Full cooling (grinding fluid) is used throughout the process to control the temperature of the grinding area and prevent grinding burns (high temperatures can cause tempering of high-speed steel cutting edges, decrease in hardness, and premature tool failure);
Slight passivation treatment is applied to the cutting edge to eliminate small burrs and avoid micro chipping during further processing.
3. Inspection items after regrinding
Use a tool microscope/projector to check the forming angle and confirm that it is consistent with the original tool angle;
Check the straightness of the cutting edge, without burns or cracks;
Detect radial circular runout;
Trial cutting verification is required to confirm that the angle and surface roughness of the workpiece meet the process requirements before it can be put into use online.
3. Severe injuries (blade tip chipping, notches, grinding burns, thermal cracks)
Features: There are notches, chipping, serrated defects on the blade tip, or blue black burn discoloration and visible cracks on the cutting edge.
Solution:
1. Small scale local fracture: Without damaging the forming angle, the fracture area is completely removed from the cutting surface before grinding; Angle detection must be performed after regrinding. If the defect is close to the tooth root of the tool, the removal allowance is too large, and the effective tooth thickness of the tool is insufficient, it is directly judged as scrap.
2. Grinding burns and hot cracks: Cracks will continue to propagate under cutting impact, and it is not recommended to repair them. They should be scrapped directly and cannot be continued on the machine to prevent tooth loss and damage to the workpiece and machine tool during processing.
2、 Re grinding limitations and lifespan boundaries
1. Number of regrinding times: determined by the amount of shovel back. The reserved amount of shovel back on the tooth back of the shovel tooth milling cutter is the regrinding allowance, and as the front cutting surface is regrinding multiple times, the tooth thickness gradually decreases; When the tooth thickness is insufficient and the shovel back clearance is exhausted, the tool cannot be re ground and should be scrapped.
2. Prohibited behaviors: It is forbidden to manually grind the blade tip with a grinding wheel, to grind the tooth back forming surface, and to dry grind without cooling.
3. Coating tool note: If it is a high-speed steel single angle milling cutter with TiN/TiCN coating, the original coating will be removed after regrinding the front cutting surface; If it is necessary to restore the coating performance, the coating can be recoated after re grinding is completed.
3、 Process optimization after wear and tear (to avoid rapid wear and tear again)
After regrinding the tool, it is necessary to investigate the original cause of wear and adjust the cutting parameters:
If it is abrasive wear: reduce the cutting speed and check whether the workpiece material contains hard inclusions; Cast iron and fiberglass materials reduce cutting depth.
2. If accompanied by chip accumulation and sticking of the tool: replace the appropriate cutting fluid and reduce the feed rate per tooth; Processing aluminum, copper, and stainless steel can appropriately increase line speed and reduce chip accumulation.
3. Frequent chipping of the blade tip: reduces the impact of cutting and lowers the depth of a single cut; Check the rigidity of the machine tool and tool holder clamping, and eliminate vibration; Priority should be given to using M35/M42 cobalt containing high-speed steel cutting tools.
4、 Daily preventive control
Establish a tool wear inspection system, set wear limits, and conduct regular spot checks;
Store the cutting tools properly to prevent rust and avoid scratches on the cutting edges;
Ensure that the milling cutter rod does not jump during clamping, the clamping is reliable, and reduce the accelerated wear of the cutting tip caused by cutting vibration.

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