BAND SAWING

INTRODUCTION The increased cost of manufacturing today is forcing manufacturers and machine operators to seek more economical ways to cut steel. Fortunately, sawing technology has improved greatly. Modern, high technology metals have generated new saw machine designs, and improved saw blades are helping keep manufacturing costs under control. The information contained here is not meant to answer all of your band sawing questions. Each job is likely to present its own set of unique circumstances. However, by following the suggestions outlined here, you will be able to find economical and practical...

BLADE DESIGN Choosing the right blade for the material to be cut plays an important role in cost effective band sawing. Here are some guidelines to help you make the right decision. BLADE TERMINOLOGY A clear understanding of blade terminology can help avoid confusion when discussing cutting problems. 1. Blade Back: The body of the blade not including tooth portion. 2. Thickness: The dimension from side to side on the blade. 3. Width: The nominal dimension of a saw blade as measured from the tip of the tooth to the back of the band. 4. Set: The bending of teeth to right or left to allow clearance...

Blade Construction (cont.) Carbide Ground Tooth Teeth are formed in a high strength spring steel alloy backing material. Carbide is bonded to the tooth using a proprietary welding operation. Tips are then side, face and top ground to form the shape of the tooth. Set Style Carbide Tooth Teeth are placed in a high strength spring alloy backing material. Carbide is bonded to the tooth and ground to form the shape of the tooth. The teeth are then set, providing for side clearance. Tooth Construction As with a bi-metal blade design, there are advantages to differing tooth constructions. The carbide...

TOOTH SET The number of teeth and the angle at which they are offset is referred to as “tooth set.” Tooth set affects cutting efficiency and chip carrying ability. Modified Raker Raker: 3 tooth sequence with a uniform set angle (Left, Right, Straight). Modified Raker: 5 or 7 tooth sequence with a uniform set angle for greater cutting efficiency and smoother surface finish (Left, Right, Left, Right, Straight). The order of set teeth can vary by product. Vari-Raker: The tooth sequence is dependent on the tooth pitch and product family. Typically VariRaker set provides quiet, efficient cutting and...

TPI For maximum cutting efficiency and lowest cost per cut, it is important to select a blade with the right number of teeth per inch (TPI) for the material you are cutting. See Carbide Tooth Selection on page 18 or Bi-metal Tooth Selection on page 21. The size and shape of the material to be cut dictates tooth selection. Placing odd-shaped pieces of material in the vise a certain way will also influence tooth pitch. See “Vise Loading” page 12. Factors That Affect The Cost Of Cutting There are several factors that affect band sawing efficiency: tooth design, band speed, feed rates, vise loading,...

FEED Feed refers to the depth of penetration of the tooth into the material being cut. For cost effective cutting, you want to remove as much material as possible as quickly as possible by using as high a feed rate/pressure as the machine can handle. However, feed will be limited by the machinability of the material being cut and blade life expectancy. A deeper feed results in a lower shear plane angle. Cutting may be faster, but blade life will be reduced dramatically. Light feed will increase the shear plane angle, but increase cost per cut. How can you tell if you are using the right feed...

BAND SPEED Band speed refers to the rate at which the blade cuts across the face of the material being worked. A faster band speed achieves a higher, more desirable shear plane angle and hence more efficient cutting. This is usually stated as FPM (feet per minute) or MPM (meters per minute). LOWER BAND SPEED HIGHER BAND SPEED Band speed is restricted, however, by the machinability of the material and how much heat is pro­ uced by d the cutting action. Too high a band speed or very hard metals produce excessive heat, resulting in reduced blade life. How do you know if you are using the right band...

GETTING AROUND BLADE LIMITATIONS Once you understand how feed and gullet capacity limit cutting action, you will be able to choose the most effective feed rate for the material being cut. Here is an example. Assume you are cutting a piece of 4" round. There are actually three cutting areas to consider: 1. Entering the material, the blade en­ oun­ ers a small width and therefore c t meets minimum re­ is­ ance. Feed rate s t is the limiting factor here, so you can use a feed setting that maxi­ izes m cutting without losing blade life. 2. As the blade moves through the ma­ e­ ial, the width in­...

BLADE WIDTH AND RADIUS OF CUT A blade must bend and flex when cutting a radius. Blade width will be the factor that limits how tight a radius can be cut with that particular blade. The following chart lists the rec­ m­ ended blade o m width for the radius to be cut. MINIMUM RADIUS FOR WIDTH OF BLADE WIDTH

BEAM STRENGTH When resistance grows due to increased feed rate or the varying cross section of the material being cut, tension increases on the back edge of the blade and decreases on the tooth edge. This results in compression, forcing the blade into an arc, producing cuts which are no longer square. INCREASED TENSION CROSS SECTION DECREASED TENSION Beam strength is a blade’s ability to counter this resistance during the cutting process. A blade with greater beam strength can withstand a higher feed rate, re­ ult­ng in a smoother, more accurate cut. s i Beam strength depends on the width and...

INCREASE BEAM STRENGTH – REDUCE COST PER CUT Here’s an example of how increasing beam strength can improve cutting economy. A cus­ omer t needed to cut 31/4" squares of 4150 steel on a 11/4" blade width machine. The operator, trying to cut ef­ ­ iently, placed three pieces side by side. The fic three squares measured 91/4" wide - well within the 14" ma­ hine capacity. c With this arrangement, after only 40 cuts (120 pieces), the blade was still sharp, however, it would no longer cut square. The operator decided to call for help. LENOX® Technical Support suggested cutting one piece at a time,...