Many people focus on carbon‑carbon composite nozzle and thermal‑protection parts in aerospace field. Meanwhile, a large number of auxiliary graphite‑composite components serve for aerospace thermal‑test furnaces, ground simulation‑test equipment and spacecraft auxiliary bearing‑structures. These components include graphite composite connecting fasteners, heat‑insulation supporting assemblies, test‑fixture frames and high‑temperature sample‑carrying brackets. They bear combined load of high‑temperature, mechanical assembly stress and thermal‑shock impact, and require stable matching performance between multiple assembled graphite parts.
Graphite‑based composite parts have low ductility and brittleness. Traditional rigid interference‑fit connection used for metal parts cannot be copied directly. Improper assembly stress will produce invisible micro‑cracks inside composite graphite components. These micro‑cracks will expand rapidly under high‑temperature circulation, and finally cause assembly failure. Therefore, connection‑structure design and assembly‑gap matching are critical for multi‑part graphite composite assemblies.
Bolt‑connection is the most common assembling method for graphite composite components. Graphite‑material bolts and nuts are preferred for high‑temperature working‑environment to avoid thermal‑expansion mismatch brought by metal fasteners. Thread‑machining of graphite composite needs special tool‑path strategy to prevent thread tooth chipping. Thread tolerance design must consider thermal‑expansion difference between mating graphite parts. Too‑tight thread fit will generate huge stress after temperature rises, leading to thread cracking; too‑loose fit will cause position offset under vibration condition.
Anti‑ablation surface treatment is another core technology for aerospace graphite composite parts. TaC, HfC and multi‑layer composite coating systems are adopted to improve anti‑ablation performance under ultra‑high‑temperature scouring. Coating quality is not only decided by coating‑deposition process, but also closely related to substrate surface pretreatment. Substrate surface porosity, tiny crack and residue machining damage will affect coating bonding strength. If substrate has hidden micro‑defects, coating layer will produce bubbling and peeling under ablation condition.
Jincheng Graphite provides custom‑processing service for aerospace‑test‑equipment graphite‑composite‑related fixtures and assembly components. Facing multi‑part assembled graphite products, the factory's technical team will analyze assembly‑stress risk in drawing‑review phase. Engineers give suggestions for fit‑gap, thread‑structure and fastener‑selection. In machining procedure, special‑milling‑parameter is adopted for thread and thin‑wall assembling features to reduce chipping and micro‑damage risk. After machining, dimensional inspection for mating surfaces and threads is carried out to guarantee interchangeability of batch‑produced parts.
Complete set of assembly‑test suggestion will be provided to customers. For example, recommended tightening‑torque value of graphite threaded fasteners, installation‑sequence and anti‑collision protection notes. Many graphite‑component damages happen during assembly stage rather than in‑service working stage. Reasonable assembly guidance can effectively reduce scrap rate for end‑users.
Ground thermal‑simulation test is an indispensable verification link for aerospace graphite composite assemblies. Through cyclic high‑temperature test, hidden risks such as assembly‑mismatch and coating‑interface‑defect can be exposed in advance. Rich test‑feedback data helps continuously optimize machining‑process and structural‑design scheme.
Global aerospace ground‑test‑facility construction keeps increasing in recent years. Demand for various custom‑graphite‑composite test‑fixtures is rising steadily. End‑users not only require high‑precision machining, but also hope suppliers can provide comprehensive technical support covering assembly‑matching and application‑risk assessment. Jincheng Graphite keeps accumulating aerospace‑test‑fixture manufacturing experience, providing custom‑graphite‑component solutions for overseas aerospace‑research institutions and equipment manufacturers.
