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Doctor Blade |
Precision is the trademark for Gvaradan doctor blades and quality performance is the standard for G-Varadan. We select from more than 20 premium quality materials to produce the exact doctor blade you need, engineered and manufactured to precise specifications for superior doctoring efficiency. G-varadan manufactures doctor blades for every paper and board machine application, doctoring condition and paper grade, as well as for many other industrial doctoring situations. |
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Quality Control |
Although G-Varadan purchases the highest quality raw materials, our technicians carefully check incoming stock for metallurgical and chemical specifications. We also perform Rockwell hardness tests to confirm the integrity of the materials before the blades are manufactured. Our quality assurance procedure identifies each blade with its raw material source.
Gvaradan doctor blade is parallel ground or machined for straightness and to eliminate camber. Dimensional tolerances and bevel uniformity are also assured. Each blade we produce is hand finished, deburred, and cleaned for optimal performance on your machine. |
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Packaging |
G-varadan blades are finished with clips, tabs, rivets and buttons for all types of holders. Our precision blades are then coiled, nested and packaged in specially designed cartons for the protection of the blades and the safety of your personnel. Blade edge protectors, corrosion resistant packaging, individual blade boxing and flat wood crates are also available to meet your requirements. |
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Delivery |
Mils can depend on us for normal shipments within 6-8 working days and same day or overnight shipments for emergency needs.. including weekends and holidays. To minimize emergencies, we will inventory your critical items for just-in-time delivery. |
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Troubleshooting - Blade Wear Identification |
Blade Appearance and Symptoms |
Probable Causes |
Remedy |
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Poor roll surface.
Damaged or dirty blade holder.
Deposits. |
Use more flexible blade.
Clean, repair or replace holder.
Use abrasive blade. |
Doctor not machined to match roll crown.
Old doctor sagging into/away from roll. |
Refit and shim holder to doctor back as necessary. (Return new doctor for re-planning if mismatch is excessive.)Replace old, sagging doctor. |
Doctor misaligned – not parallel to roll axis. |
Shim, or move bearings and brackets as necessary to align doctor parallel to axis of roll. |
Deposits on roll.
Excessive pressure on blade.
Blade material too hard. |
Use abrasive blade as required.
Reduce pressure.
Use softer blade. |
Deposits left on roll by sheet. |
Use abrasive blade as required.
Trim blade edges frequently.
Use end slotted blades to prevent build-up of excessive pressure on roll ends. |
Sheet lubricates roll. |
Slot blade ends to relieve pressure. |
Blade attacked by (1) Electrostatic discharge, (2) Electrolysis, (3) Heat. |
Insulate doctor from machine frame or use non-metallic blade. |
Blade material too soft.
Excessive pressure.
Blade angle too flat. |
Use harder blade.
Reduce pressure.
Move bearings or brackets to increase angle.
Check for correct angle with gauge. |
Blade overhangs roll
Not Centered.
Too long.
Not oscillating properly. |
Center blade.
Trim length.
Adjust oscillation stroke. |
Blade caught scab on roll at start-up. (Most common on old dryers.) |
Change blade and remove scab. |
Blade pressure changed after initial wear-in; (opens blade tip to trap particles and lift blade – may cause wrap. |
Reduce blade pressure or change blade. |
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