knife was created
in Prato (Italy) in 1997.
The company is active in the development, prototyping and production of
civil and military knives.
Its production is based on specifications as well as on the development of
new knives and pocket knives according to customers requirements.
The company peculiarity consists of having extended the high quality
standards requested by the civil market to the military production.
This high quality level is obtained through the designs functionality ,the
choice of the best materials and the most modern manufacturing process.
Ratio began creating knives of sport use, but today it is dedicated to the
elaboration of military knives
first military customers were special units of the Italian Army which gave a
strong technical and professional impulse to the development of all the
Thanks to the development of specific instruments the company itself can
carry out efficiency and resistance tests.
The co-operation with the Faculty of Motorial Sciences of the University of
Perugia concerning thethe ergonomic aspect of the products grants the
effective capability of adapting them to the user.
It also co-operates with the Faculty of Engineering of the University of
Florence which carries out products tests as well as structural, material
and coating analyses.
The company is certified ISO 9001 and is part of the Armed Forces suppliers’
list, NATO Code (N/CAGE): AD856.
of knife and penknives is coming
through a considerable development on the Italian and international market.
The Extrema Ratio knife, which is technical and essential, satisfies the
professional consumer which pays much attention to the innovations, but is
concentrated on the functionality.
Born with the aim of producing sporting knives for civil use, of high
industrial niche, it specializes soon in the production of tactical knives
of the same qualitative niche.
The product is born to satisfy the demands of a civil market that is
extremely specialized and hard to please as regards refinement of materials,
modernity of finishing and efficacy of design, accuracy of workmanship and
completeness of accessory.
In thisphase Extrema Ratio acquires that conception of quality which is
typical of the civil market (where each piece is inspected by the purchaser)
and extends it unchanged to the military market.
New product’s types have been added to the original one of the sporting
knife; this development and gradual increase corresponds with the strategy
of Extrema Ratio for the next years.
The aim consists in designing a line of pocket knives and knife in which the experience and
the demands of the civil market join with the experience and the demands of
the military market in order to create a new product’s concept: the
standard Extrema Ratio.
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
The choice in materials is the best among what the market offers, which
contributes in giving high performance to our products.
Our knives and penknife are not art pieces, they’re simple and efficient professional
produces tactical knives, that is fixed blade or openable knives for severe
The use of special steels, of polymers like KRATON and of processes like
vacuum hardening, make our knives the best cutting instruments.
Care in details, like stainless steels screws, detachable handles, technical
scabbards equipped with belts and extensions make these instruments the top.
This quality results in the adoption of these instruments by important
operative army units.
elaboration of its knives, Extrema Ratio uses special steels
Extrema Ratio is a mechanical workshop, therefore we can virtually face the
production of mechanical and plastic instruments.
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.
working area enables us to face production orders both of bulk quantities
and of small amounts (50-100 pieces), upon request from military units.
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
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.
steel is an essential material for the manufacture knives
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
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
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.
On the contrary, an increase in toughness and elasticity brings a higher
capacity in crash absorbing, higher ductility and ease of workability, but
also a decrease in deformation point.
From this examples it’s clear that if the to be treated steel is aimed at
the production of knives and pocket knife, the latter treatment will be
preferred, seeing less strict tempering and stronger drawing so that breaks
due to crashes can be avoided. On the other hand, by using steel for blades
and knives blades production, you will use a strict tempering and a soft
drawing, meant to stretch the material by keeping hardness at the maximun
compatible level. A very satisfying way to check these aspects is the
Rockwell test, which measures hardness.
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
Carbon: increases duration of edge and
elasticity point; increases hardness and fatigue to abrasion resistance.
Chrome: increases hardness, elasticity
and tenacity; helps in fatigue resistance and corrosion.
Cobalt: increases resistance and hardness
and allows high temperature endurance; multiplies the effects of other
elements of the alloy.
Copper: increases resistance to corrosion
and fatigue resistance.
Manganese: improves capacity to hardness
increase; deoxidates and degasses metals during bulk thermic treatments,
increases hardness and dicreases brittleness.
Molybdenum: increases tenacity, capacity
of hardening and fatigue resistance; increases workability and
resistance to corrosion.
Nickel: increases resistance, hardness
and resistance to corrosion.
Phosphorus: dicreases brittleness when in
high concentrations; increases resistance, workability and hardness.
Sylicium: increases workability,
elasticity, deoxidates and degasses many metals.
Sulphur: increases workability when used
in small amounts.
Tungsten: increases resistance, hardness
Vanadium: increases resistance, hardness
and crash resistance; inhibits granulation.
Belts are produced in polymers with high mechanical and
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.
N 690 is a martensistic special steel with 17% chrome and it differentiates
from AISI 440C steel thanks to a higher level of molybden (double). Not only
molybden is a strong generator of carbides (improving cutting features) but
increases resistance to corrosion in those steels highly connected to chrome.
Moreover vanadium and cobalt alloys add ons increase the performances of
(vanadium is a also carbides generator with resulting increase in resistance
to wear and therefore capacity of keeping edge sharpness for longer; cobalt
prevents granulosity at high temperatures and improves drawing capacity and
high temperatures resistance) .
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
For our customers sharping service is free. Customers will have to pay only
for shipping fees.
Extrema Ratio knives ]