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EDM Manufacturing Process of Thin-Wall0.3 Module Micro Straight Gears
Manufacturing Process of Thin-Wall Straight Gears
Thin-wall straight gears are widely used in aerospace prototype and testing equipment. These gears feature ultra-thin thickness (1.2mm–3.0mm) and large outer diameter, resulting in extremely low rigidity. The biggest manufacturing challenge is not tooth profile cutting, but controlling warpage, flatness, parallelism and residual stress throughout the entire process. Especially for high-precision micro gears, standard thick gear manufacturing methods cannot be applied directly.
Material Selection & Blank Preparation
Mainly use high-grade aerospace alloy steel such as AISI 4140, 4340 and 17-4 PH stainless steel. To minimize deformation, we do not use finished thin plates directly. Instead, we start from solid thick blocks with machining allowance reserved on all sides.
Standard blank procedure:
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Cut thick raw block
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Rough mill 6 surfaces with margin left
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Stress relief treatment to eliminate forging and cutting residual stress
This step is critical to prevent severe warpage after heat treatment.
Gear Machining Method (Wire EDM Process)
For low-volume, high-precision thin gear prototypes, we adopt precision slow-speed wire cutting (WEDM-LS) instead of hobbing or shaping.
Why slow wire cutting:
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Zero clamping deformation during tooth forming
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Multi-cut finishing ensures high-precision tooth profile
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No mechanical cutting force to bend thin plates
Strict processing rules:
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Tooth profile and outer contour are cut before heat treatment
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Reserve support tabs during cutting to avoid free-state stress release
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Secondary stress relief after wire cutting
Vacuum Heat Treatment
Heat treatment is the main source of thin gear deformation. We use vacuum furnace for uniform heating and oxidation-free surface.
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Alloy steel: vacuum quenching + tempering
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17-4 PH: solution treatment + H900/H1025 aging
- 1045 steel
- Brass
Thin gears are placed individually with special support tooling to avoid stacking deformation. After heat treatment, minor warpage naturally occurs, so grinding allowance is reserved for correction.
Double-Surface Precision Grinding
After heat treatment, we perform multi-stage precision grinding on both sides to correct flatness, parallelism and final thickness dimension.
Grinding is done step-by-step with small cutting depth to avoid thermal deformation. This process removes heat-treatment warpage and guarantees final plate flatness.
Inspection Explanation (2D VMM / CMM / Gear Tester)
2D VMM (Video Measuring Machine)
We have completed 2D inspection. The 2D readings are within tolerance. However, 2D equipment only calculates chordal tooth thickness based on planar projection. It cannot scan full tooth height profile deviation (Fα) or full tooth width lead deviation (Fβ). Due to minor thin-plate warpage, 2D projection data is for internal reference only and cannot fully meet AGMA Q10 formal compliance requirements.
Standard 3D CMM
CMM can collect discrete 3D points but lacks continuous full-tooth scanning function required by AGMA Q10. It is used for auxiliary reference only.
Professional Gear Measuring Center (Official Q10 Equipment)
Only dedicated gear inspection machines can perform continuous full-tooth-height and full-tooth-width scanning, providing certified normal tooth thickness, profile error, lead error and pitch error data.
Full Standard Process Flow
Raw block preparation → rough machining → stress relief → slow wire cutting tooth profile & contour → secondary stress relief → vacuum heat treatment → double-sided precision grinding → cleaning → dimension inspection → official gear inspection