How is thermal expansion influence in watches material

How is thermal expansion influence in watches material

thermal expansion How is thermal expansion influence in watches material   The influence of temperature changes in one material is measured by thermal expansion. This expansion affects the volume and length, measured by the coefficient of thermal expansion. This ratio measures the heat for solid energy stored in the atoms, which affects a change linearly as expansion and contraction. The ratio is dL / dT measured longitudinally in microstrain or mm if multiplied exponentially. Temperature changes in the materials of watches affecting the balance wheel, the hairspring and plates depending on the material. At first, the wheel must be made of an alloy with a low coefficient of thermal expansion as the Nivarox of 11 microstrain / ° C approximately. Also the balance wheel is very sensitive to temperature changes so that its constitution may be in nickel or Glucyidur. Nickel expansion range is 8-13 microstrain / ° C than is the same coefficient of the spiral and  is chosen to avoid distortions. The linear expansion that would result in a brass plate whose distance between axes is 10 mm, depend on the value of the linear coefficient of thermal expansion. The brass is 16.5 microstrain / C °, which increased 10 mm and 20 ° would give a linear expansion between the axes of 0,00033mm. This amount is low to disrupting the movement in respect of plates and bridges. The wheel balance is made of Glucydur or Nickel. Nickel has a thermal expansion of 13 microstrain x 10-6 what varies in +-3,5 seconds per degree in 24 h with respect of it, but nickle balance are mede of...
How 7075 aluminium reacts to stress corrosion surface treatment

How 7075 aluminium reacts to stress corrosion surface treatment

7075 alumium was developed by Sumitomo, which was later used to build the Zero fighter aircraft for the Japanese navy. 7075 aluminium is widely used in the aerospace, automotive, shipbuilding and other fields of the consumer industry for its good relationship between the density, very low, and resistance, very high. The 7075 include 6.1% zinc, 2.5% magnesium, 1.6% copper, aluminum and other metals. Its density is 2.8 g / cm3 with a Vickers hardness of 175, similar like some steels. The elongation is 11% lower compared to steel. Their fatigue strength is high, but behaves differently depending on surface treatment. This is also associated with physiological fluids corrosion, such as sweat. A common solution to stress corrosion is the anodization process but this with the fatigue strength is decreased. It is easy for a piece that supports an effort may suffer breakages with an anodized surface. In a paper published in the Researchgate paper about the subject, it was developed a study of  surface treatments, sandblasted, anodized and untreated, to find out the response of 7075 to stress corrosion In Investigation of corrosion fatigue durability for a 7075 aluminum alloy subjected to blasting and anodizing by N. Michailidis, F. Stergioudi, A. Ragousis, G. Maliaris used C-Rings from 7075 untreated, sandblasted, anodized and sandblasted/anodized surface ,. The corrosive medium used was 3.5% sodium chloride and distilled water. It was observed that the C-Rings with sandblasting treatment allowed for a prolongation of the corrosion fatigue. Unlike anodizing fairy detrimental effect on corrosion fatigue life sandblasted/anodized has withstood immersed in a corrosive environment very bad, while the simple sandblasted surface increased resistance...
Why is it important good machining for sealing a watch diver?

Why is it important good machining for sealing a watch diver?

Most watch fans think that the most important to get a good sealing in diver are O-rings. They think that if there are two O-rings instead of one, the watch cases will be much more sealed. Although O-rings are important for sealed, with one is enough. What is important is that the contact surfaces of the middle case and the case back are well flattened. In Théorie de la construction horlogère pour ingénieurs the necessary parameters for a good surface finish are well described. To have the best seal between two surfaces is do not allow water to pass to the watch case inside when is assembled. The O-ring that is placed between two surfaces is compressed and helps not to pass the water. However, two of the easiest factors of altering it are flattened surfaces and its finishing. From this subject there are two parameters to consider, – Flattened defects should be less than 10% – The quality of roughness between the two surfaces must be N7 (Ra <1.6 μm and Rmax <3,2 μm ) for static sealing N6 (Ra <0.8 μm and Rmax <1,6 μm ) for dynamic sealing These defects are due to few machining time. A minimum of machining the surfaces to be assembled to flatten the surfaces, from a mold or turning or milling is needed. Hence, the well finished cases are more expensive due to the time of manufacture. In addition, to avoid unequal polished surfaces, often is used the vibratory finishing what allows to remove the surface material in a homogeneous way, without ending surfaces not flattened. Finally, to measure the surface roughness...
Is there a future for 3D printing watches?

Is there a future for 3D printing watches?

Is there a future for 3D printing watches?   Sintering processes are widely applied for all kinds of product design materials such as plastics, metal, ceramics, etc. From a CAD, the piece is printed resulting in a product with the same shape as designed. The laser fuses different layers of a metal powder tray in an inert atmosphere, the shape has been entered in the machine through the software. After printing, the product is ready to be finished with different operations such as polished, sanded, threaded, if the material we used is from sintered metal. Sintering advantages are many, for example, a rapid transition from design to 3D printing. The implementation code for sintering a product is not as complex as the machining. Furthermore cutters tools or holders are not necessary for bars and plates, because with the metal power tray is enough and therefore, the logistics are considerably less complex. Also in the powder to sinter tray can be made several pieces with different shapes without loss of material. Their disadvantages are that the precision achieved is not equal to a machining. For example, the threaded edges can not be sintered, because the walls are very small, whereby the threaded screw is inevitable. Another disadvantage is the finishing because it is difficult to finish with low roughness. Good machining should achieve the piece 1.66 microns roughness Ra = N 7, but with the sintered “only” N 10 equivalent to 0.012 mm roughness is reached. Furthermore, the fusion time is still relatively slow for it to be industrialized for serial watches, but not for prototypes and small series. The...
Can 316 L stainless steel withstand low temperatures?

Can 316 L stainless steel withstand low temperatures?

  Following the presentation of a case study in the MOOC of EDX Tenaris University, I have learned the problems the designers had had by the Titanic ship, with the choice of materials for the construction of the metal plates that supported the structure of the ship and rivets of poor quality. Apparently, the cold water of the North Atlantic, about 35 degrees Fahrenheit or 2.7 degrees Celsius even less, transformed the molecular structure of steel plates, instead of ductile became brittle. This meant that the first crash of the ship with the iceberg, the plates did not bend and the rivets were fractured, allowing the entry of water very quickly. The problem was because of that the steel chosen had a high content of sulfur and phosphorus, besides their relationship with manganese was very high. The crystal structure of steel from the Titanic became very brittle at low temperatures in the North Atlantic. The property which measures the relation between brittle and ductile is toughness.  Today, researchers have learned a lot from this and other failures such as the Liberty series freighters. Steels have been greatly improved and they can withstand the low temperatures like austenitic stainless steel 316 L. One of its many uses is to contain the liquid helium at temperatures of -269 degrees Celsius. Besides, the passage of austenite to martensite is more difficult in these types of steel, reducing and often tempering is needed, especially for watch cases. So it is a good choice to use steel 316 L for diver watch cases. Perhaps the only problem I see with this type of steel is the...
Why not niobium for watchcases?

Why not niobium for watchcases?

                        There is some brand is using Niobium for making watch cases but is unusual. Why? Because niobium was not commercialized until 20th century. It was called columbium even some of us we remembered it with this name. I thought niobium belonged to the category of rare earth elements, so it was very expensive and very difficult to find. But I was wrong. Niobium is relatively common with 33 number position among them. It is ductile and soft when is almost pure between 80-130 HV, similar like bronze. It is used in different alloys because it enhances the strength of them. Maybe some of the most interesting features is its inert allergenic activity. Now it is very used in medical devices. As well is very used in jewelry because when niobium is anodized it is produced a wide variety of colours very nice. At the end, niobium adquieres a bluish tinge when it is exposed to air long time. I would like to look at a niobium watchcase long time after being manufactured. Like patina bronze, niobium with bluish tinge should be very attractive for me and for customer. Morever, it is not so expensive like I thought. Some of the propierties Mechanical Bulk Modulus 150 – 184 GPa Compressive Strength * 75 – 105 MPa Elongation 25 – 40 % Elastic Limit 75 – 105 MPa Endurance Limit * 65 – 105 MPa Fracture Toughness * 90 – 120 MPa.m^1/2 Hardness – Vickers 80 – 160 HV Loss Coefficient * 1.8e-3 – 2.7e-3 Modulus of Rupture * 75...