Improving Knife Life

This information has been prepared by Reichel & Drews to assist manufactures of asphalt roofing shingles in obtaining maximum life from cutting cylinder knives. Even though Reichel & Drews is constantly improving the quality of its knives, the mechanical assemblies used in cutting shingles, as well as the raw materials used, all interact and play a role in affecting knife life. We believe that the information contained here will aid in increasing knife life and improving cutting cylinder performance by calling attention to various items, both large and small, that affect knife life.

The information given is intended to act as a guide for production and maintenance personnel. Your comments are welcome and will be helpful in preparing future updates.

When evaluating knife life, comparative operating speed and web thickness should also be taken into consideration.

Raw Materials

Knife wear is affected and can be accelerated by different types of raw material – i.e. sand backing causes knives to wear much faster than talc backing. Different sized granules and granule sources also have an effect on the life of a set of knives. Other factors affecting the rate of knife wear include the percent of filler content, the nature of the filler, and of course the prominence (and type) of fiberglass mat used in today’s products. The last factor mandates greater care and finer adjustment of the cutting cylinder in relation to the anvil roll.


Lubrication of various types affects how well knives will perform. The cutting cylinder should be kept properly lubricated using only the manufacturer’s recommended lubricant. Additionally, an ample water spray must be applied to the cutting cylinder face, and in some cases a light application of moisture of the anvil roll is helpful. This should be started even before the threading process is begun.

Anvil Roll Assembly

Check anvil roll assembly for:

  • Level and perpendicular alignment with the shingle cutter. Note: Shingle Cutter must be aligned with the balance of the machine line.
  • Roundness using a dial indicator. If the assembly is more than 0.006″ out-of-round, check the O.D. of the anvil core and the I.D. of the anvil rings for concentricity. If the core is out-of round, replace or metalize and regrind. If the rings are out-of-round, replace.
  • Worn journals. Check anvil roll journals against manufacturer’s recommended tolerance. R&D recommends +.000″/-.002″. If out of tolerance, replace core or metalize and regrind journals.
  • Worn anvil rings. If the rings are excessively worn or have variances in the OD, replace or regrind.
  • Bearing play. If core, journals, and rings are within tolerance, use a prybar and dial indicator to check anvil roll for play in any direction. Adjust to remove play (maximum of .003″) if possible, otherwise replace bearings.
  • Fit. Check for bearing fit into bearing housing and bearing housing to shingle cutter frame for bearing wear and housing wear. Correct or replace as required.

Cutting Cylinder

Tab Ejector Mechanism

The internal parts of the cutting cylinder should be checked regularly. These include the eccentric bearings, eccentric shaft, collector rings, plungers, plunger holes or bushings, and plunger springs if used. One way to check the wear of the internal components is to rotate the cylinder until a row of plungers are facing down in the fully extended position. The plunger tops should extend 1/8″ beyond the tip of a set of new knives. Apply a modest upward pressure to the plunger head. The head should stay beyond the top of the knife. If the plunger top can be pushed to a point even with the tip of the knife, there is excessive wear on one or more of the internal components. The cylinder should then be disassembled, each part checked, and worn parts replaced.

Knife Holding System

It is important that the cutting cylinder knife holding system be kept in “like-new” condition. If knife seats become worn or grooved, a new set of knives will give different cutting heights.
Installation into Shingle Cutter
When a cutting cylinder is raised into position it is important that the axis of the cylinder be parallel with the axis of the anvil roll. Use a feeler gauge to adjust the cylinder to within 0.012″ of the anvil roll at the cut-off knife. If the cylinder cannot be kept parallel to the anvil roll, the following should be checked:

  • Roundness using a dial indicator.
  • Concentricity of the cylinder face and knife tip to the cylinder journals. Reichel and Drews recommends .003″ TIR
  • Cylinder journals for wear exceeding manufacturer’s recommended tolerance. Reichel and Drews recommends +.000″/-.002.
  • Bearing play. If items a-c above are within tolerance, use a prybar and dial indicator to check cylinder for play in any direction. Adjust to remove play (maximum of .003″) if possible, otherwise replace bearings.
  • Fit. Check for bearing fir into bearing housing and bearing housing into cutter carriage for bearing wear and housing wear. Correct or replace as required.


Shingle Cutter Carriage (for Universal Shingle Cutter).

When the shingle cutter carriage is raised into place, it is important that the four corners of the carriage that meet the cutter frame are equally tight against the frame and the locating pins and mating block at the top corners of the carriage provide a snug fit.


Installation. When installing a set of knives in a cutting cylinder:

  • All the knives should be firmly seated. Carefully clean the knife seats of all foreign matter before installing knives.
  • When tightening the wedge screws, avoid tipping the knife with the wedge blocks.
  • Be sure to use full-sized filler blocks in the punch knives in order to avoid tipping the knife legs in. Note: The thickness of the filler blocks is critical. Wear will allow tipping of the knife legs.
  • Allow a 0.002″ – 0.005″ gap between the land of a slitter knife and the tip of a hook of any adjoining crosscut or punch knife.
  • Allow a 0.002″- 0.005″ gap between the tip of a crosscut hook and the “U” portion of a punch knife.
  • Knife Failure and/or Abnormal Wear. If all mechanical items have been checked and are in good operating order, a cracked, chipped, or broken knife might be attributed to an error in the cutting cylinder adjustment, the presence of a foreign object, or the knife itself.

If a particular Reichel & Drews knife or set of knives wears more rapidly than normal, return the entire set of knives to Reichel & Drews for inspection. Reichel & Drews will work with you to resolve any problem with your knives or cutting cylinder parts.

Please Contact Us to learn more about Improving Knife Life.