Turbomachine Blade Trailing Edge Thinning by Chemical Milling
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Solution Overview
Problem
The existing lost-wax casting technique for producing turbine engine bladed elements struggles to achieve very small dimensions and fine trailing edges, as it inherently results in minimum material thicknesses that are greater than required for optimal aerodynamic performance.
Innovation Solution
The method involves producing bladed elements through lost-wax casting followed by chemical milling to reduce the trailing edge thickness from the minimum achievable dimension to a thinner, desired value, utilizing a chemical milling bath with specific compositions and conditions to remove material precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lost-wax casting is used to produce bladed elements, then dimensional accuracy and surface appearance are improved, but the minimum trailing edge thickness is limited to a value greater than required for optimal aerodynamic performance
Solution Approach 1:
The lost-wax casting process is used first to create a preliminary bladed element with a trailing edge thickness that is greater than the final desired thickness. This preliminary structure serves as a base that can be subsequently refined through chemical milling to achieve the target thickness of 0.2-0.45 mm while maintaining overall dimensional accuracy.
Solution Approach 2:
Traditional mechanical machining methods are replaced with chemical milling to remove material from the trailing edge. The chemical milling process uses chemical reactions to precisely remove material without the mechanical contact and tool wear associated with conventional machining, enabling achievement of the very thin trailing edge thickness required for optimal aerodynamic performance.
2Productivity
If lost-wax casting is used to produce bladed elements, then production capability is maintained, but the ability to achieve very small dimensions and fine trailing edges is insufficient
Solution Approach 1:
The invention merges two different manufacturing processes - lost-wax casting and chemical milling - into a hybrid production method. The casting process provides high productivity and overall dimensional accuracy, while the chemical milling process adds the capability to achieve very fine trailing edge dimensions that casting alone cannot provide.
Solution Approach 2:
The chemical milling process allows precise control of material removal by adjusting parameters such as etchant concentration, temperature, and exposure time. This enables the trailing edge thickness to be precisely controlled within the 0.2-0.45 mm range, achieving the fine dimensions required for optimal aerodynamic performance while maintaining production efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the production of bladed elements with trailing edge thicknesses as low as 0.2-0.45 mm, enhancing aerodynamic performance by reducing material thickness precisely, while maintaining dimensional accuracy and surface finish.
Implementation Method 1
the chemical milling makes it possible to remove a sufficient quantity of material on the surface to pass from X2 to X1
Data Source
AI summary
The invention relates to a method for producing a metal bladed element for a turbomachine of an aircraft, said bladed element comprising at least one blade having a lower surface and an upper surface extending between a leading edge and a trailing edge of the blade, the trailing edge having to have a thickness X1, said method comprising the steps of: a) producing the bladed element by lost-wax casting, and b) finishing the bladed element, characterised in that step b) comprises the chemical milling at least of the trailing edge of the or each blade so as to obtain said thickness X1 which cannot be directly obtained by step a).