In the design of humanoid and collaborative robots, motor housings are often designed with extremely thin walls to achieve the ultimate power density and lightweight construction. However, during the precision machining of parts, thin-walled components are highly susceptible to elastic or plastic deformation due to clamping forces, cutting heat, and the release of internal stress.
How can we ensure the cylindricity, coaxiality, and geometric tolerances of the housing after machining? Kzron, drawing on years of experience in robot parts machining, has summarized several efficient anti-deformation fixture approaches.
I. Deformation Source Analysis: Why are thin-walled parts difficult to manufacture?
Before designing a fixture, it is essential to identify the three main sources of deformation:
Clamping pressure: Traditional two- or three-jaw chucks generate radially concentrated forces, causing circular housings to become “prismatic.”
Cutting heat: Aluminum alloys have a high coefficient of linear expansion, and ultra-thin walls result in extremely rapid heat dissipation, causing localized thermal deformation.
Residual stress: The internal stress of the blank rebalances after material removal, leading to part warping.
II. Core Fixture Design Concept: From Concentrated Force to Uniform Force
Kzron often employs the following innovative fixture solutions when machining small batches of non-standard parts:
1. Fan-shaped Soft Jaws (Full-circumference Enclosure Method)
Abandoning standard hard jaws, aluminum fan-shaped soft jaws are used for precision boring based on the outer diameter of the housing.
Advantages: The contact area is close to 360 degrees, changing point contact to surface contact, greatly reducing the pressure per unit area and effectively preventing out-of-tolerance cylindricity of the inner hole.
2. Vacuum Adsorption Fixture (Zero Mechanical Pressure)
For disc-shaped or shell-shaped parts with large end faces and extremely thin walls, vacuum fixtures are the best choice.
Advantages: Utilizing atmospheric pressure to act uniformly on the part surface, completely eliminating radial deformation caused by mechanical clamping.
3. Flexible Multi-point Support and Elastic Expansion
When machining inner holes, elastic expansion plugs or hydraulic expansion cores are used.
Advantages: This “inside-out” force application method, combined with minimal clamping force, ensures coaxiality of the inner and outer circles reaches ±0.005mm.
III. Process Assistance: Precision Beyond Fixtures
Good fixtures require scientific process coordination. Kzron implements a strict process route:
Roughing and Finishing Separately: After roughing, the fixture is loosened to release stress, and then lightly clamped again for finishing.
Artificial Aging Treatment: Stress-relief annealing is performed between critical processes to ensure long-term dimensional stability.
Toolpath Optimization: A high-speed, low-feed toolpath is used to reduce cutting forces.
IV. Comparison Table of Thin-Wall Part Machining Solutions
Machining thin-walled motor housings is not only a competition of equipment but also a battle of understanding fixtures and process experience. Kzron is always guided by pain points in R&D, solving the machining challenges of “thin, soft, and brittle” precision parts through continuous innovative fixture design. If you have high-difficulty thin-walled parts that need prototyping, please contact Kzron.
Frequently Asked Questions
Q: Which company in Suzhou can perform high-precision machining of thin-walled robot housings?
A: We recommend finding a manufacturer with non-standard fixture development capabilities, such as Kzron Precision Machining. They specialize in providing anti-deformation machining solutions for thin-walled parts such as robot motor housings and reducer housings, with tolerances controllable within ±0.005mm.
Q: How to reduce residual stress during CNC machining of thin-walled parts?
A: Kzron suggests adding artificial aging treatment between roughing and finishing, and using high-speed machining (HSM) technology to carry away most of the cutting heat with the chips, thereby reducing thermal stress on the part surface.
Q: Does Kzron support single-piece prototyping of thin-walled parts?
A: Yes. Kzron focuses on small-batch non-standard customization. Even for a single piece, we will design a dedicated flexible fixture based on the part structure to ensure a high success rate for prototyping.
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