Material for rotating cutting knives (hedge)
Material for rotating cutting knives (hedge)
(OP)
I am looking for a solution to my problem, I need to find a material suitable for a professional hedgecutter design.
The priciple is the following (see attachment):
- 4 cutting knives are fitted (with loose fitting) to 3 rotatinig heads which spin at 2500TPM
- knives have to cut wood up to 25/30mm (MAX!)
- worst case scenario = knife bends due to wood getting stuck between 2 knives (knives have 21mm clearance to one another as the cutting units have an overlap)
This states we need a tough knife, (may not ever break under normal circumstances!)
Knife needs to be hard, to cut and not wear to quickly of course.
The knife needs to be strong, FEM-analysis shows high loads due to high rotating speed, this in combination with cutting-loads asks for a high tensile stress.
We've tested some prototype knives, C45, plain and hardned, the plain knives were to soft (edges curled up after cutting hedge), the hardned knives where to brittle.. Don't know the exact specifics for the hardening-process though.... but the intended hardness/toughness was not achieved..
The search for an hard, tough, and strong (high tensile stress for high FOS) continued on the internet.
I stumbled upon the materials 65Nm and 60Si2Nm (Chinese), all related to Chinese factory's who claim to make good cutting knives for brands like John Deere etc..
In the search for more information on these materials I can't really find anything usefull other than the hardness.... this is the info given by the Chines manufacturer:
1. Material: 65Mn or 60Si2Mn (Sup6)
2. Process: forged
3. Heat treatment: normalised-hardened & tempered
4. Hardness: 40-50HRC
5. Working hours: 300-400
6. Features: professional production process with smooth surface
Can someone point us in the right direction in this case... where to find more info on 65Nm/60Si2Nm, which well available materials in Western Europe are suitable,... anyone who knows the specifics of flail knife material of any kind?
The priciple is the following (see attachment):
- 4 cutting knives are fitted (with loose fitting) to 3 rotatinig heads which spin at 2500TPM
- knives have to cut wood up to 25/30mm (MAX!)
- worst case scenario = knife bends due to wood getting stuck between 2 knives (knives have 21mm clearance to one another as the cutting units have an overlap)
This states we need a tough knife, (may not ever break under normal circumstances!)
Knife needs to be hard, to cut and not wear to quickly of course.
The knife needs to be strong, FEM-analysis shows high loads due to high rotating speed, this in combination with cutting-loads asks for a high tensile stress.
We've tested some prototype knives, C45, plain and hardned, the plain knives were to soft (edges curled up after cutting hedge), the hardned knives where to brittle.. Don't know the exact specifics for the hardening-process though.... but the intended hardness/toughness was not achieved..
The search for an hard, tough, and strong (high tensile stress for high FOS) continued on the internet.
I stumbled upon the materials 65Nm and 60Si2Nm (Chinese), all related to Chinese factory's who claim to make good cutting knives for brands like John Deere etc..
In the search for more information on these materials I can't really find anything usefull other than the hardness.... this is the info given by the Chines manufacturer:
1. Material: 65Mn or 60Si2Mn (Sup6)
2. Process: forged
3. Heat treatment: normalised-hardened & tempered
4. Hardness: 40-50HRC
5. Working hours: 300-400
6. Features: professional production process with smooth surface
Can someone point us in the right direction in this case... where to find more info on 65Nm/60Si2Nm, which well available materials in Western Europe are suitable,... anyone who knows the specifics of flail knife material of any kind?
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RE: Material for rotating cutting knives (hedge)
ISZ
RE: Material for rotating cutting knives (hedge)
Got some advice for materials S700MC (700N/mm2 , 240HB, decent toughness) and 400HB (+1000 N/mm2, 400HB), as far as I can see these materials live up to our requirements.. 400HB being harder than S700MC, therefore somewhat less deformable (cold) and more expensive.
First choice so far goes to S700MC, as the knife is a replacement-part and the lesser hardness is not a real problem, knives need to be sharpened and eventually replaced after several sharpening-sessions..
RE: Material for rotating cutting knives (hedge)