CJ Buck
Moderator
- Joined
- Apr 15, 1999
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Here is the information from the engineers at Buck. Bill Keys and Pete Quintanilla (of pcks fame). If these images do not come through here is a web address to visit... following all this is a write up that Bill Keys did on steels and angles.
http://www.buckknives.com/bldfor.html
EFFECTS ON EDGE SHARPNESS
STEEL TYPES AND EDGE GEOMETRY
by Bill Keys
Engineering Supervisor
Buck Knives, Inc.
As with many complex issues, there are several different factors that can and do influence the sharpness of a knife blade, such as blade steel, heat treatment and edge geometry. Even the term sharpness itself refers to more than a single issue. There is the initial sharpness of the blade, how well does it cut the first time it is used?, and secondly how long does the blade keep its useable edge?
The graphs shown were created using information obtained from Buck Knives CATRA machine. Each line on the graph represents the mean of several tests conducted using the identified steel/condition. The CATRA machine is used under controlled conditions when testing is being performed. The operation of the machine is such that a sharpened steel sample is moved in a slicing motion against paper strips, while a constant load is applied to the stack of paper strips. The machine measures, in millimeters, the depth of cut with each movement. This type of testing eliminates the variable human factor of varying pressure, stroke, etc. The paper is even produced to specific standards so as to prevent inconsistencies due to the variation in the papers abrasiveness. The vertical axis of the graph shows the depth of cut for each stroke/cycle while the horizontal axis shows the number of strokes/cycles performed. As a standard, we limit the number cycles/strokes to 60, since at that point, all of the samples tested are considered dull by that time, if not before then.
Graph number one compares the following tests:
420HC stainless steel before edge 2000
420HC stainless steel with edge 2000 (E2K)
ATS-34 stainless steel with edge 2000 (E2K)
BG-42 stainless steel with edge 2000 (E2K)
440C stainless steel with edge geometry just outside of edge 2000
Some of the conclusions that can be readily drawn from the test are as follows:
The ATS-34 w/E2K BG-42 w/E2K and the 420HC w/E2K all began with essentially the same level of initial sharpness. The 420HC without E2K and the 440C started at a point slightly less than the other samples, likely due to the edge geometry.
The 420HC without E2K exhibited a dramatic decline in edge retention very quickly
Through nine cycles, all blades with E2K followed essentially the same slope on the curve.
From 10 cycles through 60 cycles, the 440C and the 420HC w/E2K followed similar curves. The ATS-34 maintained its edge slightly better than the 420HC w/E2K and the 440C. The BG-42 maintained its edge slightly better than the ATS-34.
For all samples, except the 420HC without E2K, the curve flattens substantially at approximately 40 cycles. The 420HC without E2K the curve flattens at 25 cycles.
The edge geometry on the 420HC steel significantly altered the performance of the steel.
Graph number two compares the following tests:
420HC with E2K
ATS-34 without E2K- included angle of 40 degrees
BG-42 without E2K- included angle of 40 degrees
Conclusions that can be drawn as a result of graph number two are as follows:
The 420HC w/E2K began with an initial sharpness greater than either the ATS-34 or the BG-42.
The curves of the 420HC, ATS-34 and the BG-42 do not intersect until approximately 27-30 cycles. The curve becomes essentially flat at approximately 40 cycles.
The geometry of edge has a substantial impact on the initial sharpness as well as the longevity of the edge. Optimum edge geometry on good cutlery steel will outperform a common edge geometry on premium steel.
The edge angle of 40 degrees (included) is within the range of edge geometry commonly found on many knives, both high end and low end.
When various grades of blade steel are discussed and compared, it is easy to misidentify steel types. For example, 420 stainless steel is similar to 420HC stainless steel, but it is not the same material. 420 stainless steel is a martensitic stainless steel that can be heat treated to a range of Rc 53-57 max. Its carbon content can be as high as .38 percent, but only need be above .15 percent to meet the industry specifications. 420HC is also a martensitic stainless but with a minimum carbon content significantly greater (.43 percent) than standard 420. Bucks 420HC generally ranges between .44 and .46 percent. This allows Buck to harden 420HC blades to a range of Rc 58-60 for their standard production products. Of note, there is no AISI designation of 420HC. This is a designation created by some of our steel suppliers to denote 420 stainless steel with a specific level of carbon that is well above the industry standard for 420. ATS-34 is generally hardened to a range of Rc 59-61 to achieve best results, while BG-42 often falls into the range of Rc 60-62.
Buck undertook their edge testing in an effort to provide to the market place products that are top quality in the targeted market segments. There is no question that a blade produced from ATS-34 with E2K will perform at a higher level than a blade produced from 420HC with E2K. There is also no question that a blade produced from 420HC with E2K will perform very well. That is why we use 420HC, with E2K, for many standard production models that the general consumer will purchase, and ATS-34 with E2K for markets, such as Tactical, that require a premium steel.
------------------
CJ Buck
Buck Knives, Inc.
AKTI Member #PR00003
http://www.buckknives.com/bldfor.html
EFFECTS ON EDGE SHARPNESS
STEEL TYPES AND EDGE GEOMETRY
by Bill Keys
Engineering Supervisor
Buck Knives, Inc.
As with many complex issues, there are several different factors that can and do influence the sharpness of a knife blade, such as blade steel, heat treatment and edge geometry. Even the term sharpness itself refers to more than a single issue. There is the initial sharpness of the blade, how well does it cut the first time it is used?, and secondly how long does the blade keep its useable edge?
The graphs shown were created using information obtained from Buck Knives CATRA machine. Each line on the graph represents the mean of several tests conducted using the identified steel/condition. The CATRA machine is used under controlled conditions when testing is being performed. The operation of the machine is such that a sharpened steel sample is moved in a slicing motion against paper strips, while a constant load is applied to the stack of paper strips. The machine measures, in millimeters, the depth of cut with each movement. This type of testing eliminates the variable human factor of varying pressure, stroke, etc. The paper is even produced to specific standards so as to prevent inconsistencies due to the variation in the papers abrasiveness. The vertical axis of the graph shows the depth of cut for each stroke/cycle while the horizontal axis shows the number of strokes/cycles performed. As a standard, we limit the number cycles/strokes to 60, since at that point, all of the samples tested are considered dull by that time, if not before then.
Graph number one compares the following tests:
420HC stainless steel before edge 2000
420HC stainless steel with edge 2000 (E2K)
ATS-34 stainless steel with edge 2000 (E2K)
BG-42 stainless steel with edge 2000 (E2K)
440C stainless steel with edge geometry just outside of edge 2000
Some of the conclusions that can be readily drawn from the test are as follows:
The ATS-34 w/E2K BG-42 w/E2K and the 420HC w/E2K all began with essentially the same level of initial sharpness. The 420HC without E2K and the 440C started at a point slightly less than the other samples, likely due to the edge geometry.
The 420HC without E2K exhibited a dramatic decline in edge retention very quickly
Through nine cycles, all blades with E2K followed essentially the same slope on the curve.
From 10 cycles through 60 cycles, the 440C and the 420HC w/E2K followed similar curves. The ATS-34 maintained its edge slightly better than the 420HC w/E2K and the 440C. The BG-42 maintained its edge slightly better than the ATS-34.
For all samples, except the 420HC without E2K, the curve flattens substantially at approximately 40 cycles. The 420HC without E2K the curve flattens at 25 cycles.
The edge geometry on the 420HC steel significantly altered the performance of the steel.
Graph number two compares the following tests:
420HC with E2K
ATS-34 without E2K- included angle of 40 degrees
BG-42 without E2K- included angle of 40 degrees
Conclusions that can be drawn as a result of graph number two are as follows:
The 420HC w/E2K began with an initial sharpness greater than either the ATS-34 or the BG-42.
The curves of the 420HC, ATS-34 and the BG-42 do not intersect until approximately 27-30 cycles. The curve becomes essentially flat at approximately 40 cycles.
The geometry of edge has a substantial impact on the initial sharpness as well as the longevity of the edge. Optimum edge geometry on good cutlery steel will outperform a common edge geometry on premium steel.
The edge angle of 40 degrees (included) is within the range of edge geometry commonly found on many knives, both high end and low end.
When various grades of blade steel are discussed and compared, it is easy to misidentify steel types. For example, 420 stainless steel is similar to 420HC stainless steel, but it is not the same material. 420 stainless steel is a martensitic stainless steel that can be heat treated to a range of Rc 53-57 max. Its carbon content can be as high as .38 percent, but only need be above .15 percent to meet the industry specifications. 420HC is also a martensitic stainless but with a minimum carbon content significantly greater (.43 percent) than standard 420. Bucks 420HC generally ranges between .44 and .46 percent. This allows Buck to harden 420HC blades to a range of Rc 58-60 for their standard production products. Of note, there is no AISI designation of 420HC. This is a designation created by some of our steel suppliers to denote 420 stainless steel with a specific level of carbon that is well above the industry standard for 420. ATS-34 is generally hardened to a range of Rc 59-61 to achieve best results, while BG-42 often falls into the range of Rc 60-62.
Buck undertook their edge testing in an effort to provide to the market place products that are top quality in the targeted market segments. There is no question that a blade produced from ATS-34 with E2K will perform at a higher level than a blade produced from 420HC with E2K. There is also no question that a blade produced from 420HC with E2K will perform very well. That is why we use 420HC, with E2K, for many standard production models that the general consumer will purchase, and ATS-34 with E2K for markets, such as Tactical, that require a premium steel.
------------------
CJ Buck
Buck Knives, Inc.
AKTI Member #PR00003
