Corrugated cardboard slitting is a core process in carton production, and excessive wear of slitting circular blades is a common pain point in the industry. Under normal circumstances, high-quality cemented carbide slitting blades can be used continuously for 60-80 hours. However, in actual production, many blades become dull after only 20-30 hours (resulting in frayed edges and dimensional deviations of slit cardboard) and have to be replaced. This not only increases tool procurement costs but also causes production line downtime due to frequent blade changes (about 1-2 hours per change, leading to a daily capacity loss of 10%-15%). The root cause of rapid blade wear is not simply "poor quality" but a combination of four factors: "mismatched selection, non-standard operation, insufficient equipment accuracy, and inadequate adaptation to cardboard characteristics". To solve the durability issue, we need to address these four dimensions rather than relying on "more expensive blades". This article will first analyze the core reasons for excessive wear, then provide practical solutions to help you extend the service life of slitting circular blades by over 50%.
1. First, Identify the Root Causes: 5 Main Reasons for Rapid Wear of Corrugated Cardboard Slitting Circular Blades
To solve the durability problem, it is necessary to first clarify "which factors accelerate blade wear" to avoid "blindly replacing blades" without addressing the root cause. Corrugated cardboard (composed of face paper, fluting paper, and corrugated base paper; characterized by "abundant fibers, wave-shaped fluting, and potential impurities") causes blade wear mainly due to the following 5 factors:
| Cause of Wear | Specific Manifestation | Impact on Blades (taking cemented carbide blades as an example) |
|---|---|---|
| Incorrect Tool Selection | Using high-speed steel blades (e.g., W18Cr4V) or low-toughness cemented carbide (e.g., YG3) for slitting | High-speed steel blades dull in 10-15 hours; YG3, with low Co content (3%), has edges easily chipped by corrugated fibers, becoming unusable within 30 hours |
| Improper Edge Treatment | Cutting edge is too sharp (unpassivated) or insufficiently polished (surface roughness Ra > 0.8μm) | Sharp edges easily get stuck in corrugated fibers, causing "chipping wear"; rough surfaces increase friction, accelerating wear by 30% |
| Unreasonable Slitting Parameters | Cutting speed > 250m/min, pressure > 0.3MPa, feed rate > 0.2mm/r | Excessive speed causes frictional heat between the edge and cardboard (over 700℃), softening the cobalt binder; excessive pressure squeezes the edge against corrugations, causing local overload and dulling |
| Insufficient Equipment Accuracy | Spindle runout > 0.01mm, or bearing wear causing blade tilt | Uneven force on the blade leads to "uneven wear" (one edge is worn flat, the other remains nearly intact), shortening service life by 40% |
| Poor Adaptation to Cardboard Characteristics | Slitting high-hardness flutes (AB-flute, B-flute) or cardboard containing impurities (staples, sand grains) | High-hardness cardboard increases cutting load on the edge; impurities directly scratch the edge, causing "scratch wear" with small gaps appearing within 10 hours |
2. Core Solutions: Systematically Improve Blade Durability Through Four Dimensions
Targeting the above reasons, we need to establish a full-process solution from "tool optimization, parameter control, equipment maintenance, and cardboard adaptation" to reduce wear at the source.
1. Tool Optimization: Choose the "Right Fit" to Lay the Foundation for Durability
The core requirements for corrugated cardboard slitting blades are "wear resistance (to handle fiber friction) + toughness (to withstand corrugation impact) + scratch resistance (to resist impurities)". Priority should be given to selecting suitable cemented carbide tools rather than blindly pursuing "high hardness".
(1) Material Selection: Balance "Wear Resistance and Toughness" to Match Corrugated Characteristics
The following cemented carbide formulas are recommended, covering over 90% of corrugated cardboard slitting scenarios:
- WC Grain Size: Medium-coarse grain WC (3-5μm) — Fine-grain WC is hard but brittle, easily scratched by corrugated impurities; coarse-grain WC has good toughness but poor wear resistance; medium-coarse grain can handle both fiber friction and corrugation impact, with a wear rate 20% slower than fine-grain.
- Co Content: 8%-10% Co — Co content below 6% results in insufficient toughness and easy chipping; above 12% reduces wear resistance, making the edge prone to dulling from fiber friction. 8%-10% Co achieves the optimal balance, especially suitable for common flutes like A-flute and B-flute.
- Additives: Add 1%-2% tantalum carbide (TaC) — TaC improves the blade’s impact resistance and thermal stability, preventing edge softening due to frictional heat (over 600℃) during slitting, which is more effective for high-hardness flutes like AB-flute.
- Recommended Models: Choose YG8 (basic model, suitable for ordinary corrugated) for standard use; YG10X (contains TaC, better impact resistance) for high-hardness or impurity-containing corrugated. Avoid low-Co models like YG3/YG6 or high-speed steel blades.
(2) Edge Treatment: Reject "Sharpness as Optimal" and Focus on "Passivation + Polishing"
Many assume "the sharper the edge, the smoother the slitting", but corrugated fibers easily get stuck in sharp edges, accelerating wear. Correct edge treatment methods:
- Edge Passivation: Use a dedicated passivation machine to control edge sharpness to 0.02-0.03mm (not absolutely sharp), forming a "micro-arc" edge. This can cut fibers smoothly while avoiding edge chipping due to stress concentration, reducing initial wear by 30%.
- Edge Polishing: Precision grinding with a diamond wheel to achieve an edge surface roughness of Ra ≤ 0.4μm — A rough edge increases friction with cardboard fibers; polishing reduces the friction coefficient, extending the edge wear cycle (from 30 hours to 50 hours).
2. Parameter Control: Avoid "Overload Slitting" to Reduce Unnecessary Wear
Improper slitting parameters are a major cause of "abnormal wear" of blades. Speed, pressure, and feed rate must be adjusted according to corrugated flute type (hardness), with specific references as follows:
| Corrugated Flute Type (Hardness) | Cutting Speed (m/min) | Slitting Pressure (MPa) | Feed Rate (mm/r) | Key Notes |
|---|---|---|---|---|
| A-flute (soft, thick fluting) | 180-220 | 0.15-0.2 | 0.12-0.15 | Excessive speed causes fluting fiber stretching, increasing edge friction |
| B-flute (hard, thin fluting) | 150-180 | 0.2-0.25 | 0.1-0.12 | Excessive pressure squeezes the edge against fluting, causing local overload and dulling |
| AB-flute (high hardness) | 120-150 | 0.25-0.3 | 0.08-0.1 | Must match YG10X blades; pressure must not exceed 0.3MPa (to avoid edge deformation) |
Parameter Setting Principles:
- For hard flutes (B-flute, AB-flute): Use low speed, small feed rate, and medium pressure to reduce cutting load on the edge.
- For soft flutes (A-flute, C-flute): Use medium-high speed, medium feed rate, and low pressure to avoid fiber sticking to the edge.
- Test Cutting Verification: Before using new parameters, test-slit 10-20 sheets of cardboard. Only start mass production after confirming flat edges (no fraying, no indentations).
3. Equipment Maintenance: Control "Accuracy Deviation" to Avoid "Uneven Wear Loss"
Even with proper tools and parameters, insufficient equipment accuracy can still cause "uneven wear" of blades. Key components require regular maintenance:
(1) Spindle and Bearings: Control Runout to Avoid "Eccentric Wear"
Spindle runout must be ≤ 0.008mm (measured with a micrometer at the spindle end). Excessive runout (>0.01mm) causes the blade to rotate "eccentrically" during slitting, leading to excessive local wear.
- Maintenance Method: Clean spindle bearings monthly and replace worn ones (imported precision bearings are recommended, with a service life 2-3 times that of ordinary bearings). Before installing the blade, wipe the spindle locating surface with alcohol to avoid iron chips causing blade tilt.
(2) Paper Press Rollers: Control Pressure to Avoid "Additional Load"
Uneven pressure from paper press rollers causes cardboard conveying deviation, requiring the edge to "exert extra force" for cutting, accelerating wear.
- Maintenance Method: Check press roller pressure weekly with a pressure gauge (pressure on both sides must be consistent, usually 0.1-0.15MPa). If pressure deviation exceeds 0.02MPa, adjust the press roller cylinder pressure to ensure stable cardboard conveying.
4. Cardboard Adaptation: Reduce "External Damage" to Minimize Additional Blade Wear
The characteristics of corrugated cardboard (hardness, impurities, humidity) directly affect blade wear, requiring proper preprocessing and adaptation:
(1) Remove Cardboard Impurities
Corrugated cardboard may contain impurities such as staples, sand grains, and glue lumps during production or storage. These impurities directly scratch the cutting edge, causing "scratch wear".
- Solution: Install a "magnetic separator + air blower" before the slitting machine — The magnetic separator adsorbs metal impurities like staples, and the air blower removes sand grains and glue lumps. Meanwhile, manually inspect cardboard edges to remove obvious impurities.
(2) Adjust for Cardboard Humidity
Excessive cardboard humidity (>18%) softens fibers, causing them to stick to the edge during slitting and increasing frictional wear. Insufficient humidity (<8%) hardens and embrittles cardboard, increasing edge force and causing easy chipping.
- Solution: Measure cardboard humidity with a hygrometer. If humidity >18%, reduce cutting speed appropriately (by 10%-15%) and apply a small amount of food-grade lubricating oil to the edge (to reduce sticking). If humidity <8%, switch to YG10 tools with 10% Co (better toughness) and reduce slitting pressure (by 5%-10%).
3. Clarifying Common Misconceptions: Avoid Practices That "Accelerate Wear"
In many cases, poor blade durability stems from "one-sided cognition" misconceptions. The following 3 common mistakes require key correction:
Misconception 1: "The Harder the Blade, the Better; Fine-Grain WC Tools Are More Wear-Resistant"
Fact: Fine-grain WC tools have poor toughness and are prone to chipping when slitting corrugated cardboard. A factory used fine-grain WC (2μm) + 6% Co tools to slit AB-flute cardboard. Due to high corrugated hardness and minor impurities, the edges chipped every 20 hours. After switching to medium-coarse grain WC (4μm) + 8% Co YG8 tools, the edges lasted 60 hours without chipping. Although hardness was slightly lower, overall service life increased by 2 times.
Misconception 2: "Faster Slitting Speed = Higher Efficiency; Wear Is Not a Concern"
Fact: Excessively high speed increases frictional heat, accelerating edge wear. A factory increased A-flute slitting speed from 200m/min to 280m/min to boost capacity. As a result, blade life shortened from 80 hours to 30 hours, and blade change frequency increased by 1.7 times. Downtime losses (¥5,000 per occurrence) far exceeded the capacity gains from higher speed. After restoring speed to 200m/min, hourly capacity decreased by 15%, but monthly blade changes dropped from 8 to 3, reducing overall costs by 25%.
Misconception 3: "Worn Blades Should Be Discarded Directly; Re-Sharpening Is Unnecessary"
Fact: Properly re-sharpened blades can be reused 2-3 times. When the flank wear of corrugated cardboard slitting blades is ≤0.2mm, they can be re-sharpened with a diamond grinding wheel (grain size 180-240 mesh). Re-sharpened blades can achieve 70% of the service life of new blades. A factory reduced monthly tool procurement costs from ¥12,000 to ¥5,000 through re-sharpening, saving ¥84,000 annually. (Note: During re-sharpening, maintain the original passivated arc of the edge to avoid grinding it into a sharp edge.)
4. Conclusion: The Core of Durability Improvement Is "Comprehensive Adaptation"
Solving the problem of rapid wear of corrugated cardboard slitting circular blades centers on "adaptation" — tool materials must match cardboard characteristics, parameters must match equipment accuracy, and maintenance must match usage frequency. It is not about pursuing "high hardness" or "high speed" alone. For professionals in the tungsten carbide industry, when recommending tools, it is essential to first understand the customer’s "corrugated flute type, cardboard humidity, and equipment accuracy", then provide customized solutions including "material formula + edge treatment + parameter suggestions", rather than just recommending general models.
If your enterprise still struggles with rapid wear of corrugated cardboard slitting blades, or needs customized cemented carbide slitting blades for specific flutes (e.g., AB-flute, E-flute), feel free to communicate. We can provide tool sample testing and slitting parameter adjustment guidance to help you implement the solution quickly.