In the white corner we have Bi-Metal and in the yellow corner we have Bi-Metal Unique™. What are the differences and why is Starrett’s patented technology a multi cut above the rest…
Let us explain, first with a little bit of bimetal history…
Firstly, what does bimetal mean - it simply refers to an object that is composed of two separate metals joined together.
The earliest surviving bimetallic strip was made back in 1759 by Yorkshireman John Harrison. A clockmaker who made it to compensate for temperature changes in the balance spring for his marine chronometer. His earliest examples had two individual metal strips joined by rivets but he also invented the later technique of directly fusing molten brass onto a steel substrate.
There has been many differing techniques over the years to increase a saw blades longevity and cutting ability, differing steel, tooth shapes, pitches and TPI’s, but it wasn’t until the 1980’s that bimetal technology as we know today was first used.
So, in the white corner - Bi-Metal
The teeth are made of a strip of high-speed steel that is bonded by various methods such as electron beam welding or laser beam welding, to the high-strength carbon steel base creating two cutting edges. This double hard hitting combination makes for blades with a better cutting speed and durability than non-bimetal blades.
The advantages and disadvantages of each metal is utilised to its strengths: the high-speed steel used for teeth is harder, therefore cuts better, quicker and is more durable, the body area of the band is high-strength carbon steel which is softer, not good for cutting teeth, but less brittle and more resistant to cracking and breaking which is more desirable for the blades body.
And in the yellow corner – Starrett’s patented Bi-Metal Unique™
Still using High Speed steel teeth and a high strength carbon steel backing but with a totally different method. Bi-Metal unique™ uses a principal of solid state diffusion, which joins two strips of high speed steel wire to the backing steel in a solid phase, resulting in the carbon backing steel being sandwiched between the two high speed steel strips.
This two strip bonding increases the weld contact area by 170% more than the single strip bi-metal blades resulting in exceptionally strong teeth and an increased resistance to breakage and fracture making Starrett blades last 35% longer than other Bi-Metal blades.
After the blades initial use the softer carbon steel centre wears away leaving a groove in the centre of the two high speed steel strips turning the blade from a 2 edge blade to a 4 edge blade. This multi edge blade generates a thinner split chip which can be quickly and easily removed from the saw cut, making the blade cut smoother, more accurately and faster, in fact when tested 35% faster than other bi-metal blades.
All this combines to a blade that has less tooth breakage and fracture, smoother, faster cuts and a longer blade life guaranteeing it being more cost effective with a lower cost per cut.
To guarantee the best quality Starrett has a factory that produces the unique bimetal raw material for their saws, therefore controlling all the production process from start to finish to guarantee the best quality. The Starrett Quality Management System has been certified since 1995 by Bureau Veritas, with the NBR ISO 9001:2008, INMETRO and UKAS accreditations.
Starrett’s Bi-Metal Unique™ technology is available in its bandsaw blades, jigsaw blades, hand and power hacksaw blades.