Understanding Blade Dulling: Why Your Stainless Steel Boxcutter Gets Dull Cutting Cardboard
Often, we come across situations where the understanding of blade dulling doesn't align with our expectations. For instance, you might have noticed that your stainless steel blade boxcutter becomes dull after cutting cardboard, which, to our knowledge, seems less challenging than slicing steel. This prompts the question, 'How is it possible that my stainless steel blade boxcutter gets dull from cutting cardboard, when steel is much harder than cardboard, isn’t it?'
This article delves into the intricate factors that contribute to the dulling of stainless steel blades, focusing on the specific case of cutting cardboard. By expanding on material composition, fiber structure, cutting technique, blade geometry, and the role of debris and contaminants, we hope to shed light on the surprising dynamics at play.
Material Composition of Stainless Steel
Stainless steel is designed to resist corrosion and staining, making it a desirable material for lightweight and durable cutting blades. However, its hardness is not the most defining factor when it comes to edge retention. The specific alloy and heat treatment are crucial elements that affect the hardness and edge retention of a blade. Generally, stainless steel is softer compared to other steels used for cutting tools, which makes it more susceptible to dulling when subjected to abrasive materials like cardboard.
The Role of Fiber Structure in Cardboard
Cardboard is composed of cellulose fibers, which are tightly packed and can be quite abrasive. When a blade encounters these fibers, it can lead to gradual wear and dulling over time. The nature of cellulose fibers as part of the cardboard structure means that they act as tiny abrasives, gradually removing the edge of the blade through repeated cutting.
Impact of Cutting Technique
The way the blade is used plays a significant role in its edge retention. Incorrect techniques can lead to increased friction and wear on the blade, causing it to dull more quickly. For example, applying too much force, starting with a dull blade, or using the blade for tasks other than its intended purpose (like using it as a scraper) can worsen this issue.
Blade Geometry and Edge Angle
The geometry of the blade, particularly the angle of the edge, has a substantial impact on cutting efficiency. An edge that is too obtuse or that becomes damaged will not cut cleanly, leading to more wear and dulling. Maintaining the appropriate angle of the blade edge is essential for optimal performance and longevity.
Debris and Contaminants
Cardboard can contain various contaminants such as dirt, glue, or other materials. These contaminants can act like abrasives, further contributing to the dulling of the blade. Even if the cardboard is seemingly clean, these hidden particles can still affect the blade's edge.
Additional Insights From a Butcher
A butcher learned that to keep knives sharp longer, one should not wash them in hot water. Instead, soaking the blades in bleach and rinsing them off with cold water is recommended. Hot water can cause tempering to be altered, affecting the blade's edge retention. This method of cleaning can help maintain the integrity of the blade without compromising its sharpness.
Blade Dulling Due to Pressure and Misalignment
The blade can become dull not just from material hardness, but also due to the displacement of the sharp edge toward the side when pressure is applied against the blade edge. Imagine the sharp blade as a letter 'I' tapering to a narrow edge. Cutting through materials that may not be hard but are dense enough can cause the blade to bend and effectively turn the 'I' into a 'J'. This misalignment results in a blade that is no longer sharp and leads to increased wear.
Sharpening Steel: A Misunderstood Tool
A sharpening steel, commonly used by chefs and butchers, is a tool designed to straighten the misaligned blade. It doesn't remove metal but straightens the edge to reestablish the original sharpness. This tool cannot be used to sharpen a truly dull knife blade. There are many misconceptions about how the sharpening steel works, but its operation is very simple and does not require being magnetized.
Conclusion
In conclusion, while steel is generally harder than cardboard, the interaction between the blade and the material, combined with the various factors mentioned, can lead to the blade becoming dull after cutting cardboard. Regular maintenance, such as proper cleaning and sharpening techniques, can help prolong the life of your blade. Understanding the dynamics involved can help in maintaining your tools effectively and efficiently.
References
For a video example of blade dulling, you can refer to the solution provided by Rodney Price in his response to 'Why do edges dull if the substrate being cut is softer than the edge material'.