Cutting tube, pipe structural shapes and solid bar materials can be done economically with a band saw. However, choosing the right blade to use is very important in achieving the lowest cost per cut.

Work piece geometry can make sawing tube and pipe and structural shapes more difficult than sawing solid bars or plate because the saw blade is performing two types of cuts. As it enters the work piece, it is cutting a solid. After the blade penetrates the inner wall of the hollow work piece, it is cutting two thin solids with a space between them (called an interrupted cut). When cut in stacks and bundles pieces can shift, spin or move causing tooth strippage and/or blade pinching issues. Blade variables and band saw settings have to be selected to provide the best overall performance for sawing those materials.

Another sawing problem can occur with stacked stock if the coolant is not fl owing into the cut properly. A bundle of tubing or pipe has numerous cavities where the coolant can be diverted, keeping it from reaching the tooth tips. If coolant is not evenly supplied to both sides of the cut, the blade will deflect, resulting in an inaccurate cut.

Setting the flow rate for maximum fl ow also helps ensure that sufficient coolant is reaching the sawing area. It not only lubricates and cools the blade, it also helps wash away any chips caught in the spaces in the stack.

Band Speed
Band speed must be matched to the work metal. Excessive band speed overheats, softens, and dulls teeth quickly. However, too slow a band speed not only reduces the cutting rate, it also increases tooth load to make work spinning and tooth stripping more likely.

Feed Force
Feed force also is a factor in determining cutting rate. Inadequate feed force, at best, reduces the cutting rate and, at worst, causes work hardening. Excessive feed force, like low band speed, increases tooth load and makes spinning and stripping more likely.

Proper Blade Pitch
The number of teeth in contact with the work piece determines both blade performance and longevity.

If too few teeth are in contact with the work piece, the teeth can be stripped from the blade. At the other extreme, when too many teeth are in contact, the force on each tooth is so low that there is little penetration or none at all. If the teeth are unable to penetrate the work piece, work hardening may occur, making the tube that much harder.

The Tooth Tip
While blade pitch may be the most important factor in selecting the best blade, it is not the only factor. Another factor to consider is tooth tip composition. Bimetal blades with an M42 tooth tip are generally considered the best choice for mild steel tube and pipe. The edge provides superior tooth toughness with good abrasion resistance, so tooth chipping is minimized. For cutting tougher and more abrasive materials such as stainless steel, bimetal blades with X3000 (M51) teeth are recommended because of their superior abrasion resistance.

Wikus has several options in its extensive portfolio of product to help reduce both tooth strippage and blade pinching.

• Marathon

• Marathon SW

• Proflex

• Proflex SW

• Proflex Premium

• Proflex Premium SW (coated)