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::: Doctor Blades ::: Blade Application ::: Typical Wear Pattern ::: Blade Holders

Products >> Paper >> Doctoring

In the Doctoring system one of the most important part is the doctor blade. These blades go inside the holder and perform their function. Its function is to remove water, keep the roll clean and condition the roll.

Kingsley Industries an ISO 9001 company has a full range of Doctor Blades and Doctor Holders for all positions in a paper machine.

The world-wide paper industry is rapidly becoming high-tech. The range of new roll synthetic covers is endless with new materials and application literally being tested weekly.

These new covers have high endurance and long life and are extremely expensive. Yet, time and time again, I see these expensive rolls and their covers damaged due to using the wrong Doctor Blades.

Doctor Blade applications are split into four (4) basic categories.

• ROLL CLEANING
• ROLL CONDITIONING
• SHEET TAKE-OFF
• WATER REMOVAL.

ROLL CLEANING

Entails removal of debris on a roll such as pulp, fiber, etc. Typically used on non-critical roll applications such as :

• FELT ROLLS
• WIRE ROLLS
• WIRE TURNING ROLLS
• PLAIN COUCH ROLLS

ROLL CONDITIONING

Entails removal of built-up debris on roll surface such as rust, pitch, stickies on the following typical rolls;

• DRYER CANS
• CHILLED IRON ROLL (CALENDER)

SHEET REMOVAL

Entails any position where the sheet is removed before passing to next section of paper machine; typical applications :

• CENTER PRESS ROLL
• LAST DRYER ROLL
• CALENDER KING ROLL
• REEL DRUM ROLL

All Doctor Blades fall into three (3) basic categories :

• METAL
• PLASTIC
• COMPOSITES

WATER REMOVAL

These are normally Twin Doctors utilized in Fourdrinier and Press rolls to prevent re-wetting of sheet due to excessive water on surface of Rolls. Typical applications :

• BLIND DRILLED ROLLS
• SUCTION PRESS ROLLS
• SUCTION COUCH ROLLS

METAL BLADES

Are used when a sharp knife edge is required to remove sheet or clean a roll surface. Typical metal Blades in this category include :

• CARBON STEEL
• BRONZE
• STAINLESS STEEL
• K-MONEL.

Carbon Steel Blades are normally much harder (46-48 RC) than any metal or synthetic roll on a paper machine. Most common mis-use is in the Dryer sections. Some of the commonly reported problems are :

• Metal to metal contact cause high friction. Sparking is common and hood fires with paper dust are quite frequent.

• Carbon Steel blades are harder than cast iron dryer cans. Grooving and damage of dryer surface is common.

• Metal to metal blades provide rozor-sharp edge which is a continuous safety hazard to operator.

Bronze, Stainless Steel and K-Monel Blads have some definite advantages in some applications on paper machines.

BRONZE

Commonly used on Dryers (Cast Iron Rolls)
Calenders (Chilled Iron Rolls)

STAINLESS STEEL

Commonly used on Granite Rolls

K-Monel Blades are excellent Blades and can be used in all Carbon Steel, Bronze and Stainless Steel applications listed above, but it is a very expensive Blade.

GENERAL RULES (METAL BLADES)

PLASTIC BLADES

Are used in limited applications for cleaning the surfaces of the Roll in the wet and on well-lubricated Rolls or on very soft Roll Covers. Blades in this category are :

• HDP
• TEFLON

COMPOSITE BLADES

The introduction of Fiberglass Blades several years ago together with the advances of bonding agents have produced Synthetic Blades with wear characteristic of Metal Blades. Temperatures in excess of Metal Blades and the ability to use various fibers of cotton (denim), fiberglass and Carbon Fiber and various combinations of each of the foregoing.

Our complete line of composite Blades covers the full spectrum of applications on the paper machine covering every Roll Cover presently in use.

It is now possible and in fact many paper machines running speeds in excess of 1200 MPP (4000 FPM) now run their paper machines without any metal Blades.

The attached chart shows typical paper machine rolls, typical Doctor Blade application together with our Blade selection for each job.