Robot Lightweight Parts Processing: Material Selection is the Lighter the Better, Balancing Strength, Weight, Cost

Lightweight is a core design constraint in the design of humanoid robots collaborative robots. Many R&D teams simplify the goal of lightweighting as using materials with lower density. After the prototype was processed, it was discovered that the weight index met the standard, but the structural stiffness was insufficient, the anti vibration ability deteriorated, the materials brought high processing procurement costs, resulting in a decrease in overall project revenue rather than an increase.

Based on the DFM review practice of a large number of robot parts processing, it can be seen that lightweighting is a set of multi constraint design sets, material grade is just one of the variables. The final performance of the part will be determined by the structural topology, wall thickness, hole edge fillet, blank state, subsequent assembly conditions. Equating lightweighting with the use of low-density materials is a trap that is very easy to fall during the design phase

Lightweight parts processing for robots: material selection requires comprehensive consideration of multiple conditions

The following table is for engineering reference only is intended as a delivery commitment. The actual selection will be based on the comprehensive evaluation of part load, assembly, batch size

1. Material strength cannot be solely determined by static parameters in the manual

The strength indicators indicated in the material manual are only theoretical references. The reliability of robot parts during actual operation is also affected by the direction of force, wall thickness, hole edge distance, fillet size, thread depth, assembly preload, residual stress after processing. For example, a common phenomenon in the industry is that Al7075 has excellent strength indicators, but if the thin-walled connecting plate has dense openings small rounded transitions, local stress concentration will still occur under vibration impact conditions. PEEK has outstanding wear resistance insulation performance, but when used in high load cantilever structures, it may experience deformation due to insufficient stiffness. So lightweight design requires simultaneous evaluation of material selection structural design. Strengthening ribs should be added to the areas that need to be strengthened, windows should be opened reasonably in the weight reducing areas, sufficient hole margins should be reserved for key hole positions in order to truly leverage the performance advantages of the material itself.

2. Look at the weight reduction benefits of the whole machine, don't just focus on the weight of a single piece

The core goal of lightweighting is to improve the overall performance, endurance, load capacity of the machine, rather than making individual parts as lightweight as possible. Components located far the joint axis, such as the arm wrist end effector, have the highest overall benefits weight reduction; Some parts located near the base of the body, even if the weight reduction of a single piece is significant, have limited improvement in the dynamic performance of the entire machine. The industry often encounters situations ordinary parts are directly replaced aluminum alloy to nylon, resulting in a decrease in individual weight, but insufficient rigidity leads to positioning deviation; Some parts are made of PEEK, which does have corresponding temperature insulation requirements in actual working conditions, but bears high material processing costs. A more practical approach is to perform functional layering on the parts: prioritize the strength stiffness of the load-bearing components; Evaluation of PEEK engineering plastics for insulation wear-resistant parts; Consider nylon for buffer guide components; The shell ordinary installation structural components are optimized for weight using Al6061 Al7075 aluminum alloys.

3. Taking a comprehensive view of costs, it's just about raw material procurement prices

The comprehensive cost of lightweight parts cannot be simply equated with the unit price of material procurement. It also includes cutting cycle time, tool wear, yield, inspection time, surface treatment, implicit costs caused by assembly failures in the later stage. Nylon raw materials are inexpensive, but their water absorption thermal deformation characteristics can cause size fluctuations, resulting in additional verification costs during the small batch stage; PEEK material has a high unit price, but in the critical position of insulation wear resistance, it can reduce the risk of later failures; Titanium alloy has strong comprehensive performance, but it is difficult to cut has high delivery pressure, making it unsuitable for large-scale use of ordinary bracket parts. During the R&D inquiry stage, it is recommended to provide the functions, stress conditions, quantities, surface treatment, testing requirements of the parts simultaneously to facilitate the comprehensive evaluation of materials processes by the processing party.

4. Five key points need to be implemented during the processing stage

1. First, clarify the core functions of the parts: distinguish between load-bearing positioning, insulation wear resistance, buffering, appearance parts. Different functions have completely different material evaluation priorities.

2. Material selection structural review are carried out simultaneously: Thin walls, deep cavities, windows, threads, hole margins all affect actual strength, cannot be solely based on brand parameters.

3. According to material matching processing technology: aluminum alloy control clamping deformation stress release; PEEK、 Nylon controls cutting heat clamping deformation; Key control of cutting tools cutting heat for titanium alloy.

4. Distinguish tolerance levels for testing: High precision fitting positions strictly control tolerances, ordinary weight reducing window areas do need to blindly tighten tolerances to avoid unnecessary cost increases.

5. Record the weight, size, trial assembly of the first piece, archive the repurchased version synchronously to ensure traceability the sampling stage to the small batch stage.

Huiwen Zhizao has passed the dual quality management system certification of ISO9001 IATF16949. It is a national high-tech enterprise a specialized innovative enterprise, capable of producing aluminum alloys PEEK、 Processing of various materials such as nylon titanium alloy parts, with a 20000 square meter factory, 370+precision production equipment, German Demage five axis Zeiss three coordinate detection equipment, serving science technology innovation enterprises research institutions such as Lenovo, Xinsong, Xiaomi Ecological Chain, Beijing Institute of Technology, Chinese Academy of Sciences, etc. We have accumulated a lot of practical experience in DFM evaluation of lightweight parts for multi material robots, single piece sampling to medium to large batch delivery.

High frequency misconceptions

1. Misconception: The lower the material density, the more successful the lightweight design will be

Lightweight is a system engineering that requires comprehensive consideration of structural stiffness, impact resistance, assembly stability. Simply using low-density materials does necessarily mean that the solution is feasible.  

2. Misconception: High performance materials can consume all parts

7075 PEEK、 Titanium alloys have their own applicable boundaries, blindly upgrading high-performance materials for all parts will result in budget waste.

3. Misconception: Choosing the right materials ensures that the performance of the parts meets the standards

The edge distance, fillet, wall thickness, residual stress during machining can all change the actual performance of the part, material selection needs to be carried out synchronously with structural review.

Frequently Asked Questions

Q: What are the priority indicators for selecting lightweight parts for robots?

A: Prioritize confirming the actual working conditions stress forms of the parts, then comprehensively evaluate their strength, stiffness, overall weight reduction benefits, processing difficulty, delivery time, overall cost, rather than simply referring to density.

Q: How to choose between Al6061 Al7075?

A: Al6061 processing anode comprehensive performance are balanced, suitable for shells ordinary brackets; Al7075 has higher strength is commonly used in joint connectors arm end load-bearing structural components. It is necessary to pay attention to the risks of blank stress anode color difference.

Q: Is PEEK suitable to replace aluminum alloy as a load-bearing structural component?

A: Suitable for evaluation replacement only under specific insulation wear-resistant working conditions; PEEK cannot directly replace aluminum alloy for load-bearing components with high load high stiffness requirements.

Q: What should be paid attention to when lightweighting nylon parts?

A: Nylon has obvious advantages in weight cost, but it can cause size drift due to water absorption thermal deformation. The scenarios of precise positioning long-term high stability need to be carefully evaluated.

Q: Does Huiwen Zhizao support lightweight parts processing with multi material robots?

A: Yes, it supports aluminum alloy PEEK、 DFM evaluation of components made of materials such as nylon titanium alloy, providing one-stop services single piece sampling to medium to large batch CNC machining, surface treatment, three-dimensional inspection.

Conclusion

When selecting lightweight materials for robots, it is important to avoid using "material density" as the sole criterion for evaluation. The ultimate goal of weight reduction is to improve the overall performance of the machine, rather than making individual parts lighter. It is necessary to weigh the stress conditions, structural design, processing technology, comprehensive cost together in order to avoid the feasibility of the prototype the concentrated exposure of various problems in the small batch stage. Huiwen Zhizao can conduct pre DFM review for lightweight components, provide material process selection suggestions based on the working conditions of the parts, covering the entire process sampling to medium to large batch processing delivery.