How to Remove Residual Adhesive from Cemented Carbide Slitting Circular Blades

In the slitting process of materials such as adhesive tape, film, and label paper, cemented carbide slitting circular knives are prone to residual adhesives (e.g., hot-melt adhesive, pressure-sensitive adhesive) on the cutting edge and knife body surface. If not removed in time, these residues can cause problems like “adhesive sticking to the knife,” “burrs on the cut edge,” and “jamming during knife rotation.” They not only affect slitting precision (e.g., dimensional deviation > 0.1mm) but also accelerate knife wear and increase equipment downtime. This article details residue removal methods suitable for tungsten carbide and other cemented carbide slitting circular knives from four dimensions: “hazard of residues → cleaning preparation → step-by-step operation → precautions.” It covers various solutions including manual cleaning, semi-automatic tools, and automatic equipment, helping practitioners select efficient cleaning methods based on actual scenarios to ensure stable knife performance.

1. First, Understand: 3 Major Hazards of Residual Adhesive to Slitting Circular Knives

During slitting, adhesives (especially the adhesive layers of hot-melt tape and double-sided tape) can adhere to the knife surface and gaps of the cutting edge due to high temperature, pressure, or electrostatic adsorption on the knife surface, causing the following issues:

1. Reduced slitting precision: Accumulated residues change the outer diameter of the knife (e.g., thickness increases by 0.05mm), leading to uneven pressure during slitting and problems like “edge stretching” and “dimensional fluctuation”;
2. Diminished cutting edge sharpness: The adhesive layer covers the cutting edge (thickness ≥ 0.1mm), requiring greater pressure during slitting, which causes local overload on the edge and increases wear rate by more than 30%;
3. Abnormal equipment operation: Residues stick to materials, resulting in uneven winding and tension fluctuations. In severe cases, it triggers equipment alarms and shutdowns (e.g., a packaging factory shuts down 8-10 times a month due to residue issues).

2. Preparation Before Cleaning: Tool and Material Selection (Classified by Scenarios)

Select suitable cleaning tools based on adhesive type (soft/cured adhesive), residual area (local/large-area), and production scale. Pay special attention to the chemical compatibility of cemented carbide (to avoid corrosion):

2.1 Basic Manual Tools (Suitable for Small-Area Residues and Temporary Cleaning)

Tool Name	Specifications/Material	Suitable Adhesive Type	Operation Points	Precautions
Plastic Scraper	Edge curvature matches the knife, hardness ≤ Shore 50A	Uncured soft adhesive (e.g., fresh pressure-sensitive adhesive)	Hold the scraper at a 15°-20° angle to the knife body, and gently scrape along the knife rotation direction (pressure ≤ 10N)	Metal scrapers are prohibited (prone to scratching the knife surface)
Fiber Cleaning Cloth	Contains diamond powder (10-20μm)	Semi-cured adhesive (e.g., cooled hot-melt adhesive)	Dip in alcohol or special adhesive remover, and wipe the knife surface clockwise (rotation speed 50-100r/min)	Replace the cloth regularly to avoid residue buildup
Soft Brush	Nylon bristles (diameter 0.1-0.2mm)	Gap residues (e.g., chamfered edges of the cutting edge)	Scrub radially along the knife, and blow off debris with an air gun (air pressure ≤ 0.3MPa)	The brush must be soft to avoid damaging edge precision

2.2 Semi-Automatic Tools (Suitable for Moderate Residues and Batch Cleaning)

• Pneumatic Cleaning Gun: Equipped with a circular sponge head (5-8mm diameter) soaked in adhesive remover. Driven by air pressure, the sponge head adheres to the knife surface (pressure 0.2-0.4MPa), cleaning while the knife rotates. Suitable for knives with diameter ≤ 300mm, with cleaning efficiency 50% higher than manual operation;
• Heated Adhesive Removal Device: Uses an electric heating plate (temperature controlled at 50-80℃) to preheat residues on the knife surface (3-5 minutes) to soften cured adhesive layers. Then scrape off evenly with a rubber scraper. Suitable for stubborn residues ≥ 0.3mm thick (e.g., aged hot-melt adhesive).

2.3 Automatic Cleaning Equipment (Suitable for Continuous Production and High-Precision Requirements)

Refer to patented technology (e.g., slitting machine patent by Hefei Wenyuan Printing), integrating a “scraper + sponge cleaning” module:

• Scraper Assembly: An adjustable PTFE scraper (Shore hardness 70A) with a contact angle of 25°-30° to the knife surface. Driven by an air cylinder (pressure 0.5MPa), it scrapes off large residues in real-time during slitting;
• Sponge Cleaning Box: Built-in high-density sponge (porosity ≥ 80%) soaked in adhesive remover. When the knife rotates, it automatically rubs and cleans (rotation speed 100-200r/min). Adhesive remover (e.g., alcohol, ester solvents) can be replenished to the sponge through a liquid injection port, realizing “cleaning while slitting” and reducing downtime.

3. Step-by-Step Operation: 3 Key Phases from “Stubborn Residues” to “Clean Knives”

Whether manual or automatic cleaning, follow the logic of “first soften → then peel → finally refine” to avoid damaging the knife surface due to violent cleaning (especially since cemented carbide is hard but brittle).

3.1 Phase 1: Soften Residues (Reduce Cleaning Difficulty)

• Uncured Soft Adhesive: Directly spray industrial alcohol (purity ≥ 95%) or isopropanol on the residue surface (dosage 5-10ml/㎡) and let it stand for 1-2 minutes to swell and soften the adhesive layer;
• Cured Hard Adhesive: Use low-temperature heating (infrared lamp irradiation, temperature 60-70℃) or apply a special softener (containing ester solvents such as ethyl acetate). Wait 5-10 minutes until the adhesive layer shows slight wrinkles (depression when pressed with a fingernail).

3.2 Phase 2: Peel Residues (Core Cleaning Step)

Manual Cleaning (Suitable for Small Batches and Shutdown Maintenance)

1. Locate Residue Areas: Observe the knife surface with a magnifying glass and mark large-area residues (> 20mm²) and residues around the cutting edge (key cleaning areas);
2. Layered Scraping:
   • Outer Adhesive Layer: Insert the plastic scraper from the edge of the residue at an angle ≤ 20°, and push evenly along the tangential direction of the knife (speed 5-10cm/s), scraping off ≤ 0.2mm thickness at a time;
   • Residual Adhesive Traces: Wipe with a fiber cloth dipped in adhesive remover in a “figure-8″ motion (pressure ≤ 15N) until no obvious traces remain;
3. Gap Cleaning: For dead corners such as edge chamfers and mounting holes, clean with a soft brush and air gun (loosen debris first, then blow off with 0.2MPa air pressure).

Semi-Automatic Cleaning (Suitable for Medium-Scale Cleaning)

Taking the pneumatic cleaning gun as an example:

1. Install a sponge head matching the knife width (10-20mm wider than the knife), and inject adhesive remover (alcohol and water mixed at 3:1) to moisten the sponge;
2. Fix the knife on a rotating bracket (rotation speed 150r/min), start the pneumatic gun (air pressure 0.3MPa), and make the sponge head adhere to the knife surface (contact width ≥ 10mm);
3. Stop and inspect every 2 minutes during cleaning. If debris accumulates on the sponge head, replace or clean it in time (to avoid secondary contamination).

Automatic Cleaning (Suitable for Real-Time Production Line Cleaning)

Refer to the “scraper + sponge” linkage device in the patent:

1. Adjust the scraper angle to 25° (precisely controlled by a dial) to ensure the gap between the scraper edge and the knife surface ≤ 0.05mm;
2. Start the liquid injection pump to inject adhesive remover into the sponge cleaning box (flow rate 5-10ml/min) to keep the sponge moist;
3. When the slitting machine is running (speed 80-120m/min), the rotating knife drives the scraper to remove large residues, and the sponge synchronously wipes off residual traces, achieving a cleaning efficiency of over 95%.

3.3 Phase 3: Refine and Inspect (Ensure No Residues)

1. Visual Inspection: Observe the knife surface under a 3000K color temperature light source. There should be no obvious adhesive traces or uneven reflection areas (residues cause local matte surfaces);
2. Touch Test: Lightly touch the knife with cotton gloves. There should be no “sticky feeling” or “granular feeling” (residual debris > 50μm can be felt);
3. Slitting Test: Perform a test cut on waste materials for 10-20 meters. Check if the cut edge is flat and free of “adhesive dragging” (qualified standard: no wire drawing or adhesive spots on the edge).

4. Cleaning Precautions: Avoid 5 Common Mistakes to Protect Knife Performance

4.1 Prohibit Strongly Corrosive Solvents

Cemented carbide (tungsten carbide + cobalt) is sensitive to strong acids (e.g., hydrochloric acid) and alkalis (e.g., sodium hydroxide). Long-term contact can cause loss of cobalt binder and pitting on the knife surface. Neutral solvents are recommended:

• Polar solvents: Alcohol, isopropanol (suitable for pressure-sensitive adhesive);
• Non-polar solvents: White spirit, n-hexane (suitable for hot-melt adhesive);
  Note: Newly developed water-based adhesive removers (pH 6-8) have better compatibility and can avoid solvent residue corrosion.

4.2 Control Cleaning Pressure to Avoid Edge Damage

Cemented carbide knives have high hardness (HRA 88-93) but high brittleness. Excessive cleaning force (e.g., metal scraper pressure > 20N) may cause micro-cracks on the edge. Correct practices:

• During manual cleaning, apply even force with the wrist and scrape in one direction (avoid back-and-forth friction);
• Automatic cleaning equipment should be equipped with a pressure sensor (threshold ≤ 0.6MPa), which automatically shuts down and alarms when exceeded.

4.3 Distinguish Knife Coatings and Select Suitable Cleaning Plans

For coated knives (e.g., DLC, TiN):

• Anti-adhesive coatings (e.g., PTFE): Avoid abrasive cleaning cloths (e.g., diamond-impregnated rags) to prevent coating wear. Use soft fiber cloths with neutral solvents;
• Wear-resistant coatings (e.g., TiN): Can withstand mild mechanical friction (e.g., nylon brushes), but control the brushing frequency (≤ 2 times a week) to avoid excessive coating loss.

4.4 Dry the Knife Timely After Cleaning to Prevent Rust

After cleaning, blow off solvent residues on the knife surface with dry compressed air (dew point ≤ -20℃) or wipe with anhydrous ethanol. Pay special attention to water-prone areas such as mounting holes and flange contact surfaces—residual moisture can cause rust on the edge of tungsten carbide knives (manifested as brown spots), affecting subsequent slitting precision.

4.5 Regular Maintenance and Establish Cleaning Records

It is recommended to formulate a “Knife Cleaning Record Form,” documenting for each cleaning:

• Time, type of slit material, and adhesive residue type;
• Cleaning tools used, solvent formula, and cleaning time;
• Post-cleaning slitting test results (e.g., cut defect rate).
  Through data accumulation, cleaning plans can be optimized targetedly (e.g., a film factory reduced the cleaning time for hot-melt adhesive residues from 30 minutes/time to 15 minutes/time through record analysis).

5. Comparison of Different Cleaning Plans: Quickly Match Your Production Scenario

Cleaning Plan	Applicable Scenarios	Cleaning Efficiency (Knives/Hour)	Residue Rate	Impact on Knife Precision	Cost (Yuan/Time)
Manual Cleaning	Small batches, temporary cleaning	5-8	5%-8%	Low (with correct operation)	10-20
Semi-Automatic Cleaning	Medium batches, regular maintenance	15-20	2%-3%	Medium (pressure controlled)	50-80
Automatic Cleaning	Continuous production, high-precision requirements	30-50	≤1%	Low (automatic pressure calibration)	200-300

Conclusion: Scientific Cleaning Keeps Cemented Carbide Slitting Circular Knives in Optimal Condition

Removing residual adhesive from cemented carbide slitting circular knives lies in “selecting tools based on residue characteristics, operating step-by-step to protect the knife, and optimizing plans according to production scenarios.” Manual cleaning is suitable for emergencies and small batches, semi-automatic tools improve efficiency, and automatic equipment is preferred for large-scale production—the key is to avoid corrosive solvents and excessive force to protect the knife surface and edge precision.

As a professional in the tungsten carbide industry, when recommending knives to customers, you can provide a “Residue Cleaning Guide” simultaneously, including a list of suitable cleaning tools (e.g., plastic scraper model, adhesive remover formula) and operation videos. This helps customers reduce knife loss caused by improper cleaning and improve the stability of the slitting process and production efficiency.

If you need a residue cleaning plan for specific slit materials (e.g., double-sided tape, foam tape) or want to learn about supporting selection of automatic cleaning equipment, feel free to contact us—we can provide customized cleaning solutions to support the efficient operation of the slitting process.