30lb Combat: Materials: Difference between revisions
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====2024 Al==== | ====2024 Al==== | ||
2024 Aluminum is mostly the material of choice for many robot frames in iRobotics. It has a good balance of strength and toughness, meaning that it is resistant to fracture and permenant deformation. | 2024 Aluminum is mostly the material of choice for many robot frames in iRobotics. It has a good balance of strength and toughness, meaning that it is resistant to fracture and permenant deformation. | ||
Non-weldable | |||
====7075 Al==== | ====7075 Al==== | ||
High strength and stiffness aluminum alloy. However, it has lower elongation at break comapred to other aluminums, which means it will tend to break and crack more than other aluminums, which will just deform instead. Depending on your application, this might be favorable or unfavorable. For instance, it could be a good choice for a bottom plate that needs to be stiff and should not deform (which could high center the robot). However, 7075 would be less advantageous compared to another alloy like 2024 for exterior aluminum armor panels, as it would tend to break apart easier than other aluminums. | High strength and stiffness aluminum alloy. However, it has lower elongation at break comapred to other aluminums, which means it will tend to break and crack more than other aluminums, which will just deform instead. Depending on your application, this might be favorable or unfavorable. For instance, it could be a good choice for a bottom plate that needs to be stiff and should not deform (which could high center the robot). However, 7075 would be less advantageous compared to another alloy like 2024 for exterior aluminum armor panels, as it would tend to break apart easier than other aluminums. | ||
More difficult to machine than 2024 and 6061 but weldable. | |||
====6061 Al==== | ====6061 Al==== | ||
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Often the material of choice for robot weapons and armor. | Often the material of choice for robot weapons and armor. | ||
Can be bent, machined, and welded. Cold forming is preferable as heating ar above 500 can anneal the area, removing its incredible properties. Properly welding AR requires careful setup and planning. It MUST be cleaned with ALL mill scale in the area removed and degreased with acetone. Weld order and heat management is very important or the material will soften and warp. It is recommended to read the following document https://aemach.com/hardox/pdf/011_SSAB_plate_welding_UK.pdf | |||
====Chromoly Steel==== | ====Chromoly Steel==== | ||
====Tool Steels==== | ====Tool Steels==== | ||
====Mild Steels==== | ====Mild Steels==== | ||
===Titaniums=== | |||
====Ti-6Al-4V “Grade 5”==== | |||
Twice as strong as mild steel but half the weight. This is the material of choice when aluminum is too soft for a component and steel is too heavy. Commonly used for armor, cleats, and mounting plates. While very strong and tough, it has a hrc rating of 34C which is lower than most weapons. In addition, the material is very expensive and difficult to machine. | |||
Machining precautions: | |||
Titanium rapidly work hardens when drilled. Use low speeds, moderate pressure, and plenty of coolant. Carbide tooling is preferred | |||
Welding titanium is exceedingly difficult due to its affinity for oxygen. If any portion of the material comes into contact with oxygen while above 400 degrees, it will become brittle and fracture on impact. Cleanliness is a MUST, all parts need to be cleaned with a wire brush then wiped with acetone. Grade 2 filler rods should be used for ductility and wiped with an acetone soaked rag. Weld in half inch sections with a trailing shield, high gas flow rate, and >12 second post flow. Gas coverage on the back of weld surface is absolutely critical. If not welding tube, parts should be welded in an inert chamber. Silver and straw colored welds are acceptable, any other will be brittle. | |||
====“Commercially Pure Titaniums”==== | |||
Encompassing grades 1-4, these materials are easily formable but have less than half the strength of grade 5. | |||
Unsuitable for combat | |||
==Plastics== | ==Plastics== | ||
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==Composite== | ==Composite== | ||
===Carbon Fiber=== | ===Carbon Fiber=== | ||
====Sheets==== | |||
Formed from layers of carbon fabric in an epoxy matrix. This material boasts the highest stiffness and strength to weight ratio out of all common materials. Robot parts are typically 2d profiles milled out of sheets. Common applications include base and top plates, mounts, and occasionally weapon rails. Carbon fiber does not tolerate impacts and great care must be taken so it is not directly hit. | |||
Notes: Do not waterjet! | |||
Try to minimize pocketing as material is highly anisotropic | |||
Try not to countersink | |||
Sources: cncmadness.com | |||
====Forged==== | |||
Forged carbon fiber parts are made by packing a mold with chopped tow, pouring in resin, and squeezing excess out. By strategically placing long strands of tow, parts with incredible strength can be made. Hardware can be imbedded in mold to add attachment points. Non impact-resistant and can fail prematurely if improperly made. | |||
Revision as of 23:25, 27 April 2024
Metals
Aluminums
2024 Al
2024 Aluminum is mostly the material of choice for many robot frames in iRobotics. It has a good balance of strength and toughness, meaning that it is resistant to fracture and permenant deformation.
Non-weldable
7075 Al
High strength and stiffness aluminum alloy. However, it has lower elongation at break comapred to other aluminums, which means it will tend to break and crack more than other aluminums, which will just deform instead. Depending on your application, this might be favorable or unfavorable. For instance, it could be a good choice for a bottom plate that needs to be stiff and should not deform (which could high center the robot). However, 7075 would be less advantageous compared to another alloy like 2024 for exterior aluminum armor panels, as it would tend to break apart easier than other aluminums.
More difficult to machine than 2024 and 6061 but weldable.
6061 Al
Cheap, easy to machine, but lower strength than the other options.
Steels
AR Steels (600/500/400)
AR: Abrasion Resistant. The number in the name refers to its hardness. As with most steels, higher hardness leads to higher strength and resistance to damage, but increased brittleness.
Often the material of choice for robot weapons and armor.
Can be bent, machined, and welded. Cold forming is preferable as heating ar above 500 can anneal the area, removing its incredible properties. Properly welding AR requires careful setup and planning. It MUST be cleaned with ALL mill scale in the area removed and degreased with acetone. Weld order and heat management is very important or the material will soften and warp. It is recommended to read the following document https://aemach.com/hardox/pdf/011_SSAB_plate_welding_UK.pdf
Chromoly Steel
Tool Steels
Mild Steels
Titaniums
Ti-6Al-4V “Grade 5”
Twice as strong as mild steel but half the weight. This is the material of choice when aluminum is too soft for a component and steel is too heavy. Commonly used for armor, cleats, and mounting plates. While very strong and tough, it has a hrc rating of 34C which is lower than most weapons. In addition, the material is very expensive and difficult to machine. Machining precautions: Titanium rapidly work hardens when drilled. Use low speeds, moderate pressure, and plenty of coolant. Carbide tooling is preferred
Welding titanium is exceedingly difficult due to its affinity for oxygen. If any portion of the material comes into contact with oxygen while above 400 degrees, it will become brittle and fracture on impact. Cleanliness is a MUST, all parts need to be cleaned with a wire brush then wiped with acetone. Grade 2 filler rods should be used for ductility and wiped with an acetone soaked rag. Weld in half inch sections with a trailing shield, high gas flow rate, and >12 second post flow. Gas coverage on the back of weld surface is absolutely critical. If not welding tube, parts should be welded in an inert chamber. Silver and straw colored welds are acceptable, any other will be brittle.
“Commercially Pure Titaniums”
Encompassing grades 1-4, these materials are easily formable but have less than half the strength of grade 5.
Unsuitable for combat
Plastics
UHMW-PE
Polycarbonate
3D Printed
TPU
PLA+
Composite
Carbon Fiber
Sheets
Formed from layers of carbon fabric in an epoxy matrix. This material boasts the highest stiffness and strength to weight ratio out of all common materials. Robot parts are typically 2d profiles milled out of sheets. Common applications include base and top plates, mounts, and occasionally weapon rails. Carbon fiber does not tolerate impacts and great care must be taken so it is not directly hit.
Notes: Do not waterjet! Try to minimize pocketing as material is highly anisotropic Try not to countersink
Sources: cncmadness.com
Forged
Forged carbon fiber parts are made by packing a mold with chopped tow, pouring in resin, and squeezing excess out. By strategically placing long strands of tow, parts with incredible strength can be made. Hardware can be imbedded in mold to add attachment points. Non impact-resistant and can fail prematurely if improperly made.