08-27-2021, 09:29 AM
[font=-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif]If steel and titanium are both equal in strength, then aluminum is half the strength. When you get into the 7000 series of aluminum they get to about two thirds the strength of titanium. The problem is that the ductility of aluminum is less than steel. This is what comes into play when designing parts, especially the axles and some bolts, like cylinder head bolts, the stretchiness becomes an issue with titanium. And the technical term for that is modulus of elasticity. That's why a when looking at a titanium spring, it has less coils in it. With the modulus number of titanium being half of steel it's going to flex twice as much for the same amount of load. [/font]
[font=-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif]So let's give an example. Let's say it's a steel bolt and you give it 1,000 pounds of force on the bolt, the bolt is going to stretch a certain amount. A titanium bolt with that same 1000 pounds of force is going to stretch twice as much. Because of stretching it will still carry the load as long as you are within the elastic limit. That's why people say they have a problem with the bolt stretching, but they both stretch until they come up to the clamp load that holds the assembly together. In motorcycle terms we see this in the triple clamps. There have only been a few riders we know that have the ability to tell the difference between steel bolts and titanium bolts. That same rider can tell the difference between 15 foot-pounds and 18 foot-pounds of torque. There are only a few riders that are that sensitive to tell the tiny differences in the triple clamps. Across the board right now we pretty much have everybody running titanium triple clamp bolts and titanium front axle pinch bolts.[/font]
machines were coming along and people could take titanium bar and machine it and make a fastener by just purely machining it out of bar stock. The problem with that is if you want to make an aircraft quality fastener, it needs to be hot forged, meaning it needs a forged head to get the proper grain structure, followed by the proper heat treating and then you need to have a rolled thread.
When you put a piece of bar stock into a CNC machine and mayou'd put on your cam lobes. Look for one with a 40 percent moly content. The molybdenum gets ground into the surface and prevents any galling between the titanium and aluminum, or ti on titanium nut. With axles, a thin layer of grease is recommended so the bearing isn't beating on the dry axle. Then, when you're doing your normal maintenance pull them out and drop them in 409 or Simple Green to soak them overnight or if you have an ultrasonic cleaner they'll come out super bright and clean again. In some places you need to use Loctite like on rear sprockets, you can use blue Loctite on it and it actually also keeps the bolts from galling.
Titanium screw(Most of titanium alloy screws are titanium Gr.5, Ti-6al4v) have high specific strength, tensile strength up to 100-140kgf/mm2, and density is only 60% of steel.
The medium temperature strength is good, the working temperature is several hundred degrees higher than aluminum alloy. Titanium alloy screws can maintain the required strength at moderate temperature, can work for a long time at 450 ~ 500 ℃.Not only is standard-size grade 2 titanium pipe and tube available from inventory or quick production runs, larger sizes also can be produced by independent fabricators. Many of them also can design and produce complete piping sWhen considering the design of a stud or Gr5 titanium bolt used for cyclically loaded fastener, it is important to consider both the fastener stiffness and the stiffness of the parts being clamped. A simple formula involving these quantities dictates how the service load is shared between the unloading of the joint, and the extra load borne by the fastener. This relationship has been covered in one of the early RET Monitor articles on fasteners and in a past article in Race Engine Technology magazine*.
Bicycle titanium bolt come closest to steel in terms of strength but Ti is 47% lighter.
[font=-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif]So let's give an example. Let's say it's a steel bolt and you give it 1,000 pounds of force on the bolt, the bolt is going to stretch a certain amount. A titanium bolt with that same 1000 pounds of force is going to stretch twice as much. Because of stretching it will still carry the load as long as you are within the elastic limit. That's why people say they have a problem with the bolt stretching, but they both stretch until they come up to the clamp load that holds the assembly together. In motorcycle terms we see this in the triple clamps. There have only been a few riders we know that have the ability to tell the difference between steel bolts and titanium bolts. That same rider can tell the difference between 15 foot-pounds and 18 foot-pounds of torque. There are only a few riders that are that sensitive to tell the tiny differences in the triple clamps. Across the board right now we pretty much have everybody running titanium triple clamp bolts and titanium front axle pinch bolts.[/font]
machines were coming along and people could take titanium bar and machine it and make a fastener by just purely machining it out of bar stock. The problem with that is if you want to make an aircraft quality fastener, it needs to be hot forged, meaning it needs a forged head to get the proper grain structure, followed by the proper heat treating and then you need to have a rolled thread.
When you put a piece of bar stock into a CNC machine and mayou'd put on your cam lobes. Look for one with a 40 percent moly content. The molybdenum gets ground into the surface and prevents any galling between the titanium and aluminum, or ti on titanium nut. With axles, a thin layer of grease is recommended so the bearing isn't beating on the dry axle. Then, when you're doing your normal maintenance pull them out and drop them in 409 or Simple Green to soak them overnight or if you have an ultrasonic cleaner they'll come out super bright and clean again. In some places you need to use Loctite like on rear sprockets, you can use blue Loctite on it and it actually also keeps the bolts from galling.
Titanium screw(Most of titanium alloy screws are titanium Gr.5, Ti-6al4v) have high specific strength, tensile strength up to 100-140kgf/mm2, and density is only 60% of steel.
The medium temperature strength is good, the working temperature is several hundred degrees higher than aluminum alloy. Titanium alloy screws can maintain the required strength at moderate temperature, can work for a long time at 450 ~ 500 ℃.Not only is standard-size grade 2 titanium pipe and tube available from inventory or quick production runs, larger sizes also can be produced by independent fabricators. Many of them also can design and produce complete piping sWhen considering the design of a stud or Gr5 titanium bolt used for cyclically loaded fastener, it is important to consider both the fastener stiffness and the stiffness of the parts being clamped. A simple formula involving these quantities dictates how the service load is shared between the unloading of the joint, and the extra load borne by the fastener. This relationship has been covered in one of the early RET Monitor articles on fasteners and in a past article in Race Engine Technology magazine*.
Bicycle titanium bolt come closest to steel in terms of strength but Ti is 47% lighter.