Extrema Ratio knife was created in Prato (Italy) in 1997.
Extrema Ratio began creating knives of sport use, but today it is dedicated to the elaboration of military knives
The first military customers were special units of the Italian Army which gave a strong technical and professional impulse to the development of all the subsequent production.
of knife and penknives is coming
through a considerable development on the Italian and international market.
The Extrema Ratio company elaborates knives of military use, police use, and services of emergencies
are demanded to numerical control machinery, but every single knife receives
a peculiar handcrafted care in the finishing process, mechanical adjustments
and, most of all, regarding the sharping which is thoroughly performed by
produces tactical knives, that is fixed blade or openable knives for severe
In the elaboration of its knives, Extrema Ratio uses special steels
As said, Extrema Ratio is a mechanical workshop, therefore we can virtually face the production of mechanical and plastic instruments.
We have chosen to take in charge the production of tactic knives but the white weapons license of production and the techical qualification for the production of common and war weapons held by the two partners open unlimited horizons in the blade production field. We can thus produce double edged blades, bayonets, automatic knives and pocket knives.
The present working area enables us to face production orders both of bulk quantities and of small amounts (50-100 pieces), upon request from military units.
High quality in steel is the basis for the maximum performance and endurance of a blade produced for cutting objects (knives, scissors, precision or medical bistouris etc.). Steel must be hard in order to keep a sharp cutting edge for long, being at the same flexible enough to bend without breaking. Moreover it must be stainless and performing a high resistance to corrosion. You obtain such qualities only by using rough materials of top quality and power.
The alloy "steel":
The materials normally used by the best blades manufacturers are high carbon content "AISI (Arerican Iron and Steel Institute) 440 e AISI 420", chrome hardenable steels . In other words they are stainless martensitic steels that contain at least 12 % chrome, which potential can be developed through an appropriate building and thermic treatment cycle. Martensitic steels are made of iron, carbon and chrome alloys, sometimes enriched with vanadium, molybden, nickel and tungsten in order to increase inoxidability, hardness and toughness. The best mix, distribution and fusion of this elements allows the production of top quality steel for this knives.
The steel is an essential material for the manufacture knives
The thermic tratment also called hardening is used to exploit martensitic stainless steel qualities at their best.
When steel is mixed to other elements, it develops peculiar qualities; depending from the characteristics that need to be intensificated, use wise. A thermic treatment is what usually transforms an alloy steel into an optimum kniving steel. Any alloy steel has its own critical temperature, reaching which the steel crystal structure changes, causing the carbon solubility in the ferritic matrix to increase. Such temperature must be always kept constant in order to obtain steel austenitize, but not for too long because an increase in granulation dimension (which especially for knives blades should be kept preferrably low) must be avoided.
The next step cools down the temperature (tempering) thanks to different means (water, oil, salt emulsions, ice, air etc.) in order to achieve the hardness level you want
After tempering, steel is hard and brittle at the same time. To achieve a suitable compromise between hardness (longer life of edges) and brittleness decrease (higher resistance in crash) a second thermic treatment is carried out. Scope of this treatment is to stretch the material subject to the internal cohesion state caused by tempering and to remove any left tension.
In case of breakage of the knife it´s possible to replace a single part, instead of all the knife
You should always keep in mind that increasing the hardening point implies an increase also in permanent strain point (when material deformation changes from elastic to plastic and the tension breaking point increases) but diminishes ductility and resistance to crashes.
All metals, excluding precious ones like gold and platinum, tend to alter when coming in contact with atmosphere, water and with chemical industrial knives. Resistance to corrosion of stainless steels is due to the formation of a passive superficial layer, called “passive film”.
In order to let this fine layer form, the chrome percentage in steel must be over 12%. This element generates an oxide upon the metal surface able to stop corrosion. Please keep always in consideration though that all steels (even stainless ones), having a strong ferrous matrix, are subject to oxidation and only a good maintenance preserves their integrity.
Extrema Ratio uses different types from elements so that the knives do not oxodize
Belts are produced in polymers with high mechanical and chemical resistance
N 690 Steel:
QuThis kind of steel,
selected for its exceptional features and used to produce all blades of
from Austria and is manufactured by a small steel plant; highly specialized
in high quality special steels.
This steel features high resistance to corrosion and wear, keeps a sharpened edge for longer, can be easily polished and features also high levels in hardness, over 60 HRC (more than traditional steel AISI 440 C) that can be reached through the thermic treatment of tempering.
These are the reasons why its employ is oriented towards blades and professional knives production. Thanks to the peculiar edge keeping quality and to oxidation resistance this steel is used in industrial kniving (food and fishing industries) and for butchering jobs. In the medical area, it’s mainly used for surgical instruments production.
WARRANTY NOTICE AND MAINTENANCE
Being EXTREMA RATIO positive about the high quality of its knives and pocket knives, guarantees a quick replacement of products (upon stock availability) in case of:
This warranty covers our knives for unlimited time. Scabbards have a 6 years warranty, from purchase by first customer. This warranty does not cover damages due to wearing and oxidation, which can be avoided thanks to careful lubrication and polishing, even on the best stainless steels. In order to profit from this warranty, please send faulty items back along with original copy of the purchase receipt. Should EXTREMA RATIO certify the fault, the faulty parts will be replaced for free, including expenses due for shipping items back.
The knives Extrema Ratio knife have good warranties because are products of great quality
Should a repair be necessary, EXTREMA RATIO offers a customer service repairing and replacing damaged parts assistance. The costs for repairs will be communicated upon receiving of the knife and pocket knife. For our customers sharping service is free. Customers will have to pay only for shipping fees.
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