Henry Cutlery Company
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Current position:HOME > Process

Different models of knives go through somewhat different processes. These are the steps we use to make a knife.
1. Laser cutting or fine blanking.
First, the blade must be cut out of raw steel. We use raw steel in two forms--plates and coils.
Plate stock used for the larger knives typically requires thicker blades or higher hardness and edge retention. Blades and metal knife components are cut out of steel plates through the use of a computer programmed laser.
Coil stock - used for the smaller knives that typically have thinner blades. Blades and knife components are cut out of steel coils through a process known as "fine blanking" that uses a specifically shaped die to press the blades out of the raw steel coils.
2. Rough grinding.
The first step created the blade. Now, both sides of the blade are ground to achieve a desired blade thickness through CNC machining (computer numerically controlled).
3. Stamping.
The next step in the process is stamping. Depending on the model, stamping might include special features, such as a nail notch or groove.
4. Heat-Treating
Heat-treating is the process by which the cut steel blades are prepared to make them suitable for their end use in a specific type of knife. Heat-treating imparts special qualities to metals, such as hardness, strength, ductility and others. When heating and subsequent cooling are applied to metals in their solid state, the physical and structural properties of these metals are changed (but not the chemical composition). Since different steels are used for different types of knives, they require slightly different heat-treating processes to acquire the desired properties. We take each blade through a carefully controlled three-step heat-treating process that brings the blade to a blend of properties appropriate for the end use of the knife. To ensure uniform heating, the blades are separately laid out on a continuous, slow moving conveyor belt.
A**First, the blades are heated to a high temperature (then cooled to room temperature).
B**Next, the blades are lowered into a cryogenic freezer where they are subjected to below zero temperatures (then brought back to room temperature).
C**after that, the blades are placed in an oven where the temperature is slowly raised to between 350F to 950F, depending on the end use and steel type.
This tempering process toughens the steel and brings 420 and 440 stainless steel blades to 58 on the Rockwell scale, the preferred hardness for edge holding. Tempered 1095 high-carbon steel and D2 steel blades can be hardened to RC59.5-61. To achieve the desired properties, some blades are tempered more than once. Only after this rigorous heat-treat process is a blade ready to be edged-the other vitally important process in creating a great blade. High hardness, good toughness can help to sharpen an edge. Fine grinding manual way with excellent sharpness preservation in thin blade area makes it good sharpness. Hair can easily scratch on the blade, arbitrary cutting newspaper.
5. Close Tolerance Grinding.
After heat-treating, each blade is fine ground (both sides) to a close tolerance through CNC machining. This step gives each blade a consistent thickness so it will fit with all the other knife parts for that model.
6. Blade Finish.
Depending on the desired appearance for the blade, it may be rough tumbled to achieve a satin finish or fine polished to achieve a bright, shiny finish. To some extent, this step smoothes out the marks created during the grinding process.
7. Hollow grinding.
The next step in blade making is the hollow grinding process. Here, blades are ground (computer machined) to achieve a desired shape and slope from the top of the blade down to the cutting edge at the bottom. Predominantly, we use a "semi-hollow" grind to create an edge that will be sharp out of the box, retain its sharpness, be easy to re-sharpen and enable the blade to maintain its strength. Robotics is used for grinding to achieve a consistency not possible with hand grinding. These cross-section diagrams show the four most common grinds used for knife blades.
Semi-Hollow - Creates a nice balance between a sharp edge and overall blade strength. It is the most common grind used today.
Full Hollow - Produces the thinnest and sharpest edge but is the most vulnerable to abuse.
Flat Grind (V-Grind) - Produces a very sharp cutting edge with reasonable blade strength. Easy to re-sharpen.
Flat Grind (Rolled Edge) - Produces the strongest blade, the cutting edge becomes thicker after repeated use and re-sharpening. It's a little harder to re-sharpen.
8. Final Grinding.
In this step, some blades receive grinding for special features, such as serrations, gut-hooks, and chamfers. As with previous grinding, this is a CNC step (computer numerically controlled).
9. Assembly.
Knives are assembled using various processes, materials, fasteners and adhesives, depending on the model.
10. Shaping.
Some knife models (in particular, knives with natural handle materials-wood, bone, etc.) go through a shaping process whereby the handle materials are ground, sanded or buffed to achieve a smooth fit and finish. Models with metal handles (and most plastic handles) may not go through this stage. Tactical knives would be an example of knives that do not require the shaping stage.
11. Polishing.
For those knives that went through the shaping stage, next they get fine polished (handle materials).
12. Edging the blade.
We follow a blade-edging protocol that produced blades with excellent edge-holding qualities. Along with our engineers, quality and production supervisors, and experienced blade edges, experimented with angles and materials before coming up with the exact edge geometry specification to create this new, thinner, sharper edge. This edge was achieved by changing the included angle (the total of the angles on both sides of the blade) from a range of 35 to 50 to a range of 26 to 32. This range allows knife greater flexibility to match the angle of the blade to the function of the knife.
The initial part of creating the edge is performed during step #7, hollow grinding, which is a computer controlled, automated machine process. During this grinding process, blades are tapered to a specific profile. This yields a consistent blade thickness at the edge that cannot be duplicated by hand.
Then the human hand takes over on an edging wheel. Another key to the success of process is that we converted to using laminated leather stropping wheels instead of stitched cloth. The sturdiness of the leather wheels enables us to eliminate "rollover" (where the edge can lose its ideal keenness) and create razor-sharp blades with consistency.
13. Sharpening.
In the same way the blades are finish-edged by hand, blades are sharpened by hand on a sharpening wheel. Each blade is tested for sharpness.
14. Logo.
Logo in the blades is laser, etching and silkscreen and etc.
Logo in the handles is laser, etching engraving, burnt, silkscreen and etc.
15. Cleaning.
Each knife is given a final cleaning and lubrication prior to being packaged.