METAL - SPECTACLES

Metals

END-USER REQUIREMENTS
How does the end-user benefit? In general terms, consumers now have a wide choice of eyewear, which cater to a variety of needs and tastes. The customer is in a position to find a frame that not only meets their prescription requirements but also offers properties, which suit their lifestyle, work environment and home lire. Consumer groups with particular needs - such as children and sports enthusiasts - gain from the improved comfort of the frames and their increased lightness and flexibility.

The requirements concerning the properties of materials used did not cease growing. The continual improvements in the various manufacturing processes are also the consequence of this evolution. The objective and the result: highest quality.

The fundamental requirements are as follows:

• 1. High corrosion resistance
  2. Solidity and hardness
  3. Great elasticity of the branches
  4. weak Weights 5. Deformability
  6. Solder ability and weld ability.

1. High corrosion resistance Of the metal
Glasses of high quality must resist corrosion. One reaches that point while using noble metals or while applying a surface coating corrosion resistant to a common basic material. The layer applied must without of porosities, cracks or slits. These properties should not be deteriorated either by the use, i.e., the strong constraint , of the glasses.

2. Solidity and hardness
the various elements particularly threatened because of inflection (such have  sides), must Be sufficiently solid and hard. The solidity necessary is obtained by the good choice of materials, the dimensioning and the degree of deformability.

3. Great elasticity of the sides
In addition, a quality frame is also characterized by the good elasticity of the sides and the facility of adaptation.

4. Light weight being given the tendency to light Frames,
The light weight is another important criterion to reach. In this respect it is important (the unit weight of material put aside) that the properties from the required material are assured even for a reduced section.

5. Deformability
Another condition for a perfect quality of the finished product, as for the precise techniques used for folding, working (for example, stamping) and shaping by removal of chips (for example, milling, polishing).

6. Solderability and weldability
the good solderability and weldability have a particular importance in the manufacture of high quality metal frames. It should especially be taken care that the materials do not soften too much at the time of reheating and that a sufficient solidity of the assemblage points is guaranteed. In order to give you an outline of the multitude of materials which can be used today for the manufacture of a metal frames, we drew the following pictures which also indicate their properties.

Spectacle industry in SOLID GOLD
Gold is a metal element of yellow colour, of sharp brightness. On the other hand, the white gold is always an alloy combined with gold and other metal like nickel, palla­dium, cadmium or zinc. By alloy of these elements as well as copper and silver, one obtains a gold titrated from 8 to 18 carats whose colors can vary  from yellow to red while passing by the white and the brilliant green. A frame in solid gold assures greater resistance to corrosion and is well accepted by the skin.

GOLD plated
Is a denomination corresponding to a group of bimetals. In the case of plated, its characteristic is to be always consisted the deposit of the noble metal, in the majority of the cases, an alloy of gold. The second metal, the support is common, for example: an alloy of bronze, tombac, copper nickel zinc alloy or nickel. The coating out of noble metal as well as the metal support are dependent in an inseparable way by welding under pressure (mechanical plating). By cold deformation the final form is obtain. However, an annealing of softening is sometimes necessary. The gold title varies on average between 1 to 5 % of the total weight. Gold plated is realized in the shape of sheets, wire and tubes.

ALUMINUM
Strong, lightweight and durable, aluminium is a popular frame material. Its rigidity used to make lens and hinge insertion difficult, but technological innovations have overcome this problem. Aluminium alloys are also common. Aluminium lends itself well to surface treatments.

 

Chemical symbol	Al
Specific Weight	2,7 g/cm2
Atomic number	13
Atomic weights	26,98
Alloy	Al-Mn-Mg-Si-Cu = seuls additifs possible
melting Point	660° C
Brazing faculty	mauvaise, possible seulement sous vide
Brazing methode

 

BERYLLIUM
Lightweight, hypo-allergenic and non-corrosive, beryllium is a metallic element used as a hardener in metal alloys. Most commonly combined with copper in frame designs.

 

Chemical symbo	Be
Specific Weight
Atomic number	4
Atomic weights	9,0122
Alloy	Be 0,5-2 % Cu 98-99,5 %
Point de fusion	1285° C
melting Point	bonne après traitement préalable correspondant
Brazing methode	Métal d'apport de brasage: Ag

 

METAL ALLOYS
Metal alloys are now commonly used to produce optical frames and hi-tech sunglasses. Manufacturers are researching and developing new alloys, which are extremely light, durable and versatile, e.g. Monel, a commonly used metal alloy.
Which is extremely ductile. It exhibits excellent durability' and corrosion resistance.

STAINLESS STEEL
Stainless steel is a strong, non-corrosive metal. Frames are produced from steel wire or plates, depending upon the design. The primary advantage of stainless steel it is easily adjusted and not easily damaged. Also adapts well to finishes and does hot discolor.

See Henry Jullien

TITANlUM (100%)
Lightweight, flexible, durable, corrosion-resistant, hypo-allergenic. Titanium has been widely used in the aerospace, medical and chemical industries since it was first brought into production in 1947. Il is used to produce highly resistant, lightweight consumer goods (camera parts, hi-tech sports equipment etc.)

BETA TITANIUM
This alloy, which contains 75% titanium, combines pure titanium with vanadium anti aluminum, the only other known element that is lighter than titanium. Il is flexible and can be cut thinner that 100% titanium. Other flexible, fatigue-resistant titanium-based alloys have also been developed e.g. Marehon's Flexon, a titanium/nickel combination, also called a memory metal because it than return to its original shape. Flexon was originally discovered by metallurgists who were creating titanium-based alloys for use in missile heat shields.

20/20  09/2000

Rodenstock titanium frames.

Only pure titanium or beta titanium is used for Rodenstock titanium frames. These extremely light materials have a very high durability and are extremely corrosion resistant. Pure titanium frames have a titanium content of between 99.4 % and 99.7 %. The remaining 0.3 % to 0.6 % is made up of iron, carbon, nitrogen and oxygen. Where the design of the spectacle frame requires a particularly high degree of flexibility (for example, when it has very fine cross-sections), we use beta titanium instead of pure titanium. Beta titanium is
also an extremely durable titanium alloy that is absolutely free of nickel. Depending on the colour, the galvanic coating consists of a high quality, nickel free gold and palladium alloy or pure palladium.
To ensure perfect functionality, other materials (high grade steel or nickel silver) are used for screws, friction discs and the slide elements or the springs in spring hinges. This is to prevent so-called cold welding from occurring. Rodenstock titanium frames thus meet all the legal requirements for nickel-free frames.

Nickel allergy

Studies have shown that up to 10 % of end users are allergic to nickel. Where there is an associated sensitization, in most cases the allergy is due to wearing costume jewellery.
But spectacle frames containing nickel can also cause allergic reactions. Titanium, a so-called biocompatible material, is particularly kind to the skin. This is why, apart from their other advantages of extreme durability and very lightweight, titanium frames are particularly recommended for spectacle wearers already sensitized to nickel.

TITANflex®

The material

TITANflex® would be a perfectly normal frame if it weren't for that certain something: the material from which it is made with a super elastic titanium alloy, the material of the future. TITANflex® is over ten times more elastic than conventional spring steel. This super elasticity is achieved by utilising an effect which scientists call phase transition. Such transitions take place at particular temperatures. We have treated the material in such a way as to gain optimum elasticity at temperatures of between -15 ° and +40 ° Celsius. In this temperature range, the frame reverts to its original shape even offer extreme distortion. Not just once but always. That's why it always fits. The adjacent illustration shows a schematic comparison of the pliability of TITANflex®, on the one hand, and stain less steel, on the other.

  

Comparison of the pliabilily of TITANflex® and stainless steel.

The manufacturing process at TITANflex®

This special titanium alloy is produced by means of a melting process, generally in an extreme vacuum by means of electron rays, vacuum arc or vacuum induction, Conventional heat and cold transformation results in wire and also sheets or pips of the moulded blocks. The material undergoes strictly controlled thermo-mechanical treatment to gain super elastic pliability in the desired temperature range.  

Applications

Because of its favourable biocompatibility, these super elastic wires were initially used in medical technology. They were first utilised in the USA as so-called orthodontic bows in dental correction applications. With their almost constant tension over a wide elasticity range, they offer ideal properties for low-strain treatment. In addition, super elastics titanium alloys are particularly suitable for use with instruments and machinery for numerous diagnostic and therapeutic activities. Buckle proof, easy to control and extremely pliable, super elastic titanium alloys are uniquely suited to these applications. It has been created a revolutionary frame from this material.

Focusing on quality

TITANflex®  frames fulfils or exceed the requirements of Directive 93/42/EC for medical products and consequently carry the CE mark.  

Warranty: If defects arise which are due to faulty workmanship or faulty materials we provide a warranty in accordance with the legal requirements. Damage arising from improper treatment, carelessness, accidents as normal wear and tear and consequential damage are not covered by this warranty.

Points to Observe: TITANffex®  frames are extremely flexible, but not unbreakable! TITANflex® components should not be bent by more than 90 °.

GENIUM:

Goodbye metal allergies, hello Genium:
the world's first allergy-free, "bio-compatible" metal

 

Allison S.p.A., a company of the IT Holding Group recognised in the sector for its constant research on new, leading-edge technological materials, has created Genium: the world's first high-tech, bio-compatible metal. A revolution for the world of ultralight frames.

 

Thanks to its nickel-free composition and absolute skin compatibility and tolerance, Genium is the world's first material to have passed the frame cyto-toxicity test, receiving the "bio-compatible" material certification (Fraunhofer Institute safety certificate, 10993 DIN and ISO standard compliant). This discovery will allow all allergy sufferers to choose frames with "different eyes".

 

 

The Genium alloy, used by Allison for the Try Ultralight line in frames for prescription glasses as well as sunglasses, also has other important features: corrosion resistance, lightweight construction and a durable shape. This high-tech metal can be used to manufacture ultra-thin frames, with a minimum thickness down to 5/10 mm, while remaining incredibly flexible and perfectly balanced.

 

Diamant polish	titan	Stainless steel

 

	Stainless steel	Titan	New Titanleg.	GENIUM
Traction test. /N/mm²	750	850	1100	2200

	Stainless steel	Titan	New Titanleg.	GENIUM
90 degree folding test	3	4	5	9

 

KERONITE Ltd offers a revolutionary new environmentally friendly electrolytic ceramic coating for Magnesium. The treatment is a very effective substitute to the traditional toxic chromating process. KERONITE is a corrosion resistant, hard oxide (400 ... 600 HV) of the substrate material. Thickness ranges from 10 to 60 microns. The layer is completely
uniform and well bonded to the Magnesium substrate.
 

FEATURES BENEFITS

• Extreme hardness and wear resistance

• The hardness ranges from 400 to 600 HV (Rc 36 ... 55). In two body abrasive wear scenarios, Magnesium alloy part coated with KERONITE has 20 times the wear of an uncoated part.

• Low friction coefficient KERONITE eliminates the high friction and galling
  normally associated with Magnesium. Once polished, the coating has a friction coefficient of less than 0.15 (against steel).

• High corrosion resistance Outdoor tests show months of exposure producing no corrosion. Salt spray tests have shown over 1000 hours
  with rating 9.

• Dimensional predictability Coating thickness ranges from 10 to 60 microns and provides a completely uniform surface layer of controllable thickness. Coating rate is about 2 microns per minute.

• High dielectric strength Withstands voltages in excess of 1000 V DC. It is an ideal surface for mounting electrical components

• Excellent heat resistance KERONITE serves as a good thermal barrier and thermal protection coating.

 

Ticral

Ticral, which is relatively new to the market, is an alloy of titanium, copper and chrome. It is nickel-free and thus hypoallergenic. It's also extremely lightweight and offers many of the features of titanium without the high cost. It can be cut a bit thicker than titanium, which enables it to have the popular look of a thin plastic frame while still offering light weight. The material is also strong, durable and available in a variety of colours.

A coating for protecting titanium aluminide alloys, including the TiAl γ+Ti₃ Al (α₂) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000° C. is disclosed. This protective coating consists essentially of titanium, aluminum, and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

 

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